Patent Publication Number: US-2023164279-A1

Title: Reading apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to reading apparatuses. 
     Description of the Background Art 
     Japanese Patent Application Laid-Open No. 61-267451 discloses technology of reading image information from a storage phosphor sheet. 
     It would be desirable to improve usability of a reading apparatus that reads a radiograph from an imaging plate. 
     SUMMARY 
     It is thus an object of the present disclosure to provide technology enabling improvement in usability of a reading apparatus that reads a radiograph from an imaging plate. 
     One aspect of a reading apparatus is a reading apparatus that reads a radiograph from an imaging plate, and includes: a first light source that irradiates the imaging plate with excitation light; a first detector that detects photostimulated light from the imaging plate emitted by the excitation light; a second light source that irradiates an object with light; and a second detector that detects reflected light of the light from the object. 
     A radiograph based on detection of the photostimulated light from the imaging plate emitted by the excitation light and a reflected light image based on detection of the reflected light of the light from the object can be acquired to improve usability of the reading apparatus. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram illustrating one example of appearance of a reading apparatus; 
         FIG.  2    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  3    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  4    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  5    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  6    is a block diagram showing one example of a configuration of the reading apparatus; 
         FIG.  7    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  8    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  9    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  10    is a schematic diagram illustrating one example of an IP image region, an excitation light irradiation range, and a detection range; 
         FIG.  11    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  12    is a schematic diagram illustrating one example of the IP image region, the excitation light irradiation range, and the detection range; 
         FIG.  13    is a schematic diagram illustrating one example of the IP image region, the excitation light irradiation range, and the detection range; 
         FIG.  14    is a schematic diagram showing one example of an acquired whole image; 
         FIG.  15    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  16    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  17    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  18    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  19    is a schematic diagram illustrating one example of a tilt of an imaging plate; 
         FIG.  20    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  21    is a schematic diagram for explaining one example of tilt angle identification processing; 
         FIG.  22    is a schematic diagram for explaining one example of the tilt angle identification processing; 
         FIG.  23    is a schematic diagram for explaining one example of size identification processing; 
         FIG.  24    is a diagram showing one example of types of sizes of the imaging plate; 
         FIG.  25    is a schematic diagram showing examples of the imaging plate; 
         FIG.  26    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  27    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  28    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  29    is a schematic diagram showing an example of display of the acquired whole image; 
         FIG.  30    is a schematic diagram showing an example of display of the acquired whole image; 
         FIG.  31    is a schematic diagram for explaining one example of tilt correction processing; 
         FIG.  32    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  33    is a schematic diagram for explaining one example of cutting-out processing; 
         FIG.  34    is a schematic diagram showing one example of a cutout image; 
         FIG.  35    is a schematic diagram for explaining one example of the cutting-out processing; 
         FIG.  36    is a schematic diagram showing one example of the cutout image; 
         FIG.  37    is a schematic diagram showing an example of display of the cutout image; 
         FIG.  38    is a schematic diagram for explaining one example of the cutting-out processing; 
         FIG.  39    is a schematic diagram showing one example of the cutout image; 
         FIG.  40    is a schematic diagram showing one example of the cutout image; 
         FIG.  41    is a schematic diagram illustrating one example of a configuration of a holder; 
         FIG.  42    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  43    is a schematic diagram for explaining one example of the cutting-out processing; 
         FIG.  44    is a schematic diagram for explaining one example of the cutting-out processing; 
         FIG.  45    is a schematic diagram showing one example of the cutout image; 
         FIG.  46    is a schematic diagram showing one example of the acquired whole image; 
         FIG.  47    is a schematic diagram for explaining one example of the cutting-out processing; 
         FIG.  48    is a schematic diagram showing one example of the cutout image; 
         FIG.  49    is a schematic diagram showing one example of the cutout image; 
         FIG.  50    is a schematic diagram showing an example of display of unexposure notification information; 
         FIG.  51    is a schematic diagram showing an example of display of the unexposure notification information; 
         FIG.  52    is a schematic diagram showing an example of display of the unexposure notification information; 
         FIG.  53    is a schematic diagram showing an example of display of the unexposure notification information; 
         FIG.  54    is a schematic diagram showing an example of display of the unexposure notification information; 
         FIG.  55    is a schematic diagram showing an example of display of the unexposure notification information; 
         FIG.  56    is a schematic diagram showing one example of a radiograph included in the acquired whole image; 
         FIG.  57    is a schematic diagram showing one example of an IP whole reflected light image included in the acquired whole image; 
         FIG.  58    is a schematic diagram showing an example of display of the cutout image; 
         FIG.  59    is a schematic diagram showing an example of display of the cutout image; 
         FIG.  60    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  61    is a schematic diagram showing one example of dividing an IP reflected light image into a plurality of subregions; 
         FIG.  62    is a schematic diagram showing an example of display of the reading apparatus; 
         FIG.  63    is a schematic diagram showing an example of display of the reading apparatus; 
         FIG.  64    is a schematic diagram showing one example of a back surface of the imaging plate; 
         FIG.  65    is a schematic diagram showing one example of the IP reflected light image included in the acquired whole image; 
         FIG.  66    is a schematic diagram showing one example of a front surface of the imaging plate; 
         FIG.  67    is a schematic diagram showing one example of the front surface of the imaging plate; 
         FIG.  68    is a schematic diagram showing one example of the imaging plate; 
         FIG.  69    is a schematic diagram showing one example of the imaging plate; 
         FIG.  70    is a schematic diagram showing one example of the imaging plate; 
         FIG.  71    is a schematic diagram showing one example of the imaging plate; 
         FIG.  72    is a schematic diagram showing one example of the imaging plate; 
         FIG.  73    is a schematic diagram showing one example of the imaging plate; 
         FIG.  74    is a schematic diagram showing one example of the imaging plate; 
         FIG.  75    is a schematic diagram showing one example of the imaging plate; 
         FIG.  76    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  77    is a schematic diagram showing an example of display of the reading apparatus; 
         FIG.  78    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  79    is a schematic diagram illustrating one example of setting the imaging plate; 
         FIG.  80    is a schematic diagram illustrating one example of setting the imaging plate; 
         FIG.  81    is a schematic diagram illustrating one example of setting the imaging plate; 
         FIG.  82    is a schematic diagram illustrating one example of setting the imaging plate; 
         FIG.  83    is a schematic diagram illustrating one example of setting the imaging plate; 
         FIG.  84    is a schematic diagram illustrating one example of setting the imaging plate; 
         FIG.  85    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  86    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  87    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  88    is a schematic diagram showing one example of an evaluation member; 
         FIG.  89    is a schematic diagram showing one example of the evaluation member; 
         FIG.  90    is a schematic diagram showing one example of the evaluation member; 
         FIG.  91    is a schematic diagram showing one example of the evaluation member; 
         FIG.  92    is a flowchart showing one example of operation of the reading apparatus; 
         FIG.  93    is a schematic diagram showing one example of an evaluation whole image; 
         FIG.  94    is a schematic diagram showing one example of the evaluation whole image; 
         FIG.  95    is a schematic diagram showing one example of the evaluation whole image; 
         FIG.  96    is a schematic diagram showing one example of the evaluation whole image; 
         FIG.  97    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  98    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  99    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  100    is a schematic diagram illustrating one example of a configuration of the reading apparatus; 
         FIG.  101    is a schematic diagram illustrating one example of a configuration of the reading apparatus; and 
         FIG.  102    is a schematic diagram showing one example of a configuration of the reading apparatus. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG.  1    is a schematic diagram illustrating one example of appearance of a reading apparatus  1 . The reading apparatus  1  is an apparatus that reads, from an imaging plate  10  on which a radiograph is recorded, the radiograph. It can be said that the reading apparatus  1  is an apparatus that detects the radiograph recorded on the imaging plate  10 . The wording of “reading apparatus” can be replaced with wording of “reader” or “imaging plate reader”. 
     The imaging plate  10  is a recording medium which is flat to include a radiograph formation layer  11  and on which the radiograph is recorded. The imaging plate  10  has a substantially rectangular flat shape with four rounded corners, for example. The radiograph formation layer  11  is a layer in which energy of emitted radiation is stored and which emits photostimulated light responsive to the stored energy. For example, the radiograph formation layer  11  is formed by applying a photostimulable phosphor to one main surface of a film formed of resin. As radiation with which the radiograph formation layer  11  is irradiated, an X-ray is used, for example. When the imaging plate  10  is irradiated with an X-ray from an X-ray generator having passed through an imaging object, energy responsive to intensity of the X-ray is stored in the radiograph formation layer  11 . The intensity of the X-ray is based on distribution of an X-ray absorption region of the imaging object, so that distribution of the energy stored in the radiograph formation layer  11  is a radiograph of the imaging object by the X-ray. As described above, the radiograph by the X-ray is recorded on the imaging plate  10  as a latent image, for example. The reading apparatus  1  reads the radiograph from the radiograph formation layer  11 , and generates an image signal (also referred to as image data) representing the read radiograph. 
     In this example, the imaging plate  10  is irradiated with radiation in a state of being inserted into a person&#39;s mouth, for example. The imaging plate  10  is thus sized to be insertable into the person&#39;s mouth. A radiograph of teeth is recorded on the radiograph formation layer  11  of the imaging plate  10 , for example. Application of the imaging plate  10  is not limited to this application. 
     A main surface of the imaging plate  10  on a side of the radiograph formation layer  11  is hereinafter also referred to as a front surface. A main surface of the imaging plate  10  opposite the front surface is also referred to as a back surface. 
     As illustrated in  FIG.  1   , the reading apparatus  1  includes a housing  2 , for example. Components to read the radiograph from the imaging plate  10  are contained in the housing  2 . The components will be described below. 
     The housing  2  has an inlet  2   a  and an outlet  2   b.  The inlet  2   a  is formed in an upper surface of the housing  2 , for example. A user of the reading apparatus  1  can insert the imaging plate  10  into the housing  2  through the inlet  2   a.  The radiograph is read from the imaging plate  10  in the housing  2 . The outlet  2   b  is formed in a lower portion of one side surface of the housing  2 , for example. The imaging plate  10  (also referred to as the read imaging plate  10 ) from which the radiograph has been read is discharged to the outlet  2   b.  The user of the reading apparatus  1  can retrieve the read imaging plate  10  through the outlet  2   b.    
     In this example, the reading apparatus  1  can erase the radiograph from the imaging plate  10  after reading the radiograph from the imaging plate  10 . The imaging plate  10  from which the radiograph has been erased is discharged to the outlet  2   b,  for example. 
     An operation unit  4  that receives an operation from the user is provided to the housing  2 , for example. The operation unit  4  includes a plurality of operation buttons  4   a,  for example. The operation buttons  4   a  are hardware buttons, for example. The operation buttons  4   a  include a power supply button and a start button to provide instructions to start reading, for example. The operation unit  4  may include a touch sensor that detects a touch operation of the user. 
     A display  3  is provided to the housing  2 , for example. The display  3  is configured by a liquid crystal display panel or an organic electro-luminescence (EL) display panel, for example. The display  3  can display various pieces of information, such as characters, symbols, graphics, and images. The display  3  may display the radiograph (i.e., a detected radiograph) read from the imaging plate  10 . 
     When the operation unit  4  includes the touch sensor, the touch sensor and the display  3  may constitute a touch panel display having a display function and a touch detection function. In this case, at least one of the plurality of operation buttons  4   a  may be replaced with a software button displayed on the touch panel display, or the operation unit  4  may not include the plurality of operation buttons  4   a.  The reading apparatus  1  may not include the display  3 . 
     Plate containment cases  6  and  7  that can contain the imaging plate  10  are provided to the housing  2 , for example. The plate containment cases  6  and  7  are provided to the upper surface of the housing  2 , for example. The plate containment case  6  is a compartmentalized case, and the plate containment case  7  is a case with a lid. The reading apparatus  1  may not include at least one of the plate containment cases  6  and  7 . 
     A cable  5   a  of an AC adapter  5  extends outward from the housing  2 . Power is supplied from the AC adapter  5  to each component of the reading apparatus  1 . The reading apparatus  1  may include not only the AC adapter  5  but also a battery that supplies power to each component of the reading apparatus  1 . Alternatively, the reading apparatus  1  may include the battery in place of the AC adapter  5 . 
     &lt;One Example of Mechanism in Housing&gt; 
       FIGS.  2  to  5    are schematic diagrams each illustrating one example of a configuration in the housing  2 .  FIG.  3    is a schematic diagram illustrating one example of a cross-sectional configuration along the line A-A of  FIG.  2   .  FIG.  5    is a schematic diagram illustrating one example of a cross-sectional configuration along the line B-B of  FIG.  4   .  FIG.  6    is a block diagram mainly showing one example of a configuration of a controller  80  of the reading apparatus  1 . As will be described below, a holder  20  that holds the imaging plate  10  can be moved along a predetermined direction DR 10  in the housing  2 .  FIG.  4    illustrates the imaging plate  10  and the holder  20  having been moved from a state illustrated in  FIG.  2   . 
     As illustrated in  FIGS.  2  to  6   , the reading apparatus  1  includes the holder  20 , a light source  30 , a detector  40 , a driver  50 , a pair of guides  60 , an erasing light source  70 , the controller  80 , and an interface  95 , for example. These components are contained in the housing  2 . 
     &lt;Controller&gt; 
     The controller  80  can manage operation of the reading apparatus  1  in an integrated manner, and can be said to be a control circuit. The controller  80  can control the display  3 , the holder  20 , the light source  30 , the detector  40 , the driver  50 , the erasing light source  70 , and the interface  95 , for example. The controller  80  can also perform processing in response to a user operation received by the operation unit  4 . 
     The controller  80  is configured by a computer device including at least one processor and a storage, for example. The at least one processor of the controller  80  may include a central processing unit (CPU) or may include a processor other than the CPU. The at least one processor of the controller  80  executes a program in the storage (also referred to as a storage circuit) to perform various functions described below. 
     The at least one processor of the controller  80  executes the program in the storage to form, as functional blocks, an image processing unit  81 , a display control unit  82 , a drive control unit  83 , a holding control unit  84 , a detection control unit  85 , a light emission control unit  86 , and an erasing control unit  87 , for example. 
     The image processing unit  81  can perform image processing on an image signal, which will be described below, output from the detector  40 , for example. The display control unit  82  can control display of the display  3 . The drive control unit  83  can control the driver  50 . The holding control unit  84  can control the holder  20 . The detection control unit  85  can control the detector  40 . The light emission control unit  86  can control the light source  30 . The erasing control unit  87  can control the erasing light source  70 . 
     Some or all of the functions of the controller  80  may be performed by a hardware circuit without the need for software (i.e., a program) to perform the functions. For example, some or all of the functions of the image processing unit  81  may be performed by a hardware circuit without the need for software to perform the functions. The image processing unit  81  may be an image processing circuit independent of the other components. Some or all of the functions of the display control unit  82  may be performed by a hardware circuit without the need for software to perform the functions. The display control unit  82  may be a display control circuit independent of the other components. Some or all of the functions of the drive control unit  83  may be performed by a hardware circuit without the need for software to perform the functions. The drive control unit  83  may be a drive control circuit independent of the other components. Some or all of the functions of the holding control unit  84  may be performed by a hardware circuit without the need for software to perform the functions. The holding control unit  84  may be a holding control circuit independent of the other components. Some or all of the functions of the detection control unit  85  may be performed by a hardware circuit without the need for software to perform the functions. The detection control unit  85  may be a detection control circuit independent of the other components. Some or all of the functions of the light emission control unit  86  may be performed by a hardware circuit without the need for software to perform the functions. The light emission control unit  86  may be a light emission control circuit independent of the other components. Some or all of the functions of the erasing control unit  87  may be performed by a hardware circuit without the need for software to perform the functions. The erasing control unit  88  may be an erasing control circuit independent of the other components. 
     &lt;Interface&gt; 
     The interface  95  can communicate with a device external to the housing  2  (hereinafter also referred to as an external device), and can be said to be an interface circuit, a communication circuit, or a communication unit. The external device may include a personal computer, a mobile phone, such as a smartphone, and other computer devices. The external device may include a data recording medium (e.g., flash memory) removable from the reading apparatus  1 . The interface  95  can receive a signal from the external device, and input the received signal to the controller  80 . The interface  95  can also transmit a signal from the controller  80  to the external device. For example, the interface  95  can transmit the image signal on which the image processing has been performed by the image processing unit  81  of the controller  80  to the external device. The interface  95  may communicate with the external device by wire or wirelessly. Communication between the interface  95  and the external device may conform to Ethernet, Universal Serial Bus (USB), WiFi, or other standards. 
     &lt;Holder&gt; 
     The holder  20  holds the imaging plate  10  inserted through the inlet  2   a  of the housing  2 . The holder  20  includes a support plate  21  that supports the imaging plate  10  and a fixture  22  that fixes a position of the imaging plate  10  supported by the support plate  21 , for example. 
     The support plate  21  has a main surface  21   a  (also referred to as a support surface  21   a ) that supports the back surface of the imaging plate  10  and a main surface  21   b  (also referred to as a back surface  21   b ) opposite the main surface  21   a.  The fixture  22  includes a plurality of fixing portions  22   a  to be close to a peripheral edge portion of the imaging plate  10 , for example. It can be said that the fixture  22  is a fixing member. The plurality of fixing portions  22   a  are to be close to the peripheral edge portion of the imaging plate  10  to surround the peripheral edge portion. The position (i.e., a relative position) and an orientation (i.e., a relative orientation) of the imaging plate  10  relative to the support plate  21  are thereby fixed. In this example, two fixing portions  22   a  are to be close to each of long sides of the imaging plate  10 , and one fixing portion  22   a  is to be close to each of short sides of the imaging plate  10 , for example. 
     Each of the fixing portions  22   a  can be moved between a close position where the fixing portion  22   a  is close to the imaging plate  10  supported by the support plate  21  and a spaced position where the fixing portion  22   a  is spaced apart from the imaging plate  10  supported by the support plate  21  through control performed by the holding control unit  84 . With each of the fixing portions  22   a  being in the spaced position, the imaging plate  10  is inserted into the housing  2  through the inlet  2   a,  and is supported by the support plate  21 . Each of the fixing portions  22   a  is then moved from the spaced position to the close position, so that the position and the orientation of the imaging plate  10  are fixed by the fixture  22 . Each of the fixing portions  22   a  is in contact with the peripheral edge portion of the imaging plate  10  when being in the close position, for example. 
     At least one of the fixing portions  22   a  may not be in contact with the peripheral edge portion of the imaging plate  10  when being in the close position. A configuration of the fixture  22  is not limited to the above-mentioned configuration. A configuration of the holder  20  is also not limited to the above-mentioned configuration. 
     &lt;Driver and Pair of Guides&gt; 
     The driver  50  can move the holder  20  along the predetermined direction DR 10  through control performed by the drive control unit  83 . The imaging plate  10  held by the holder  20  can thereby be moved along the predetermined direction DR 10 . It can be said that the driver  50  can move the imaging plate  10  along the predetermined direction DR 10  via the holder  20 . 
     The pair of guides  60  extends along the predetermined direction DR 10  with the holder  20  being sandwiched therebetween. Each of the guides  60  has, in the inside thereof, a groove extending along the predetermined direction DR 10 . Side edge portions of the support plate  21  opposing each other fit into respective grooves in the insides of the guides  60 . The pair of guides  60  can thus guide the holder  20  so that the holder  20  is moved along the predetermined direction DR 10 . A configuration of the guides  60  is not limited to this configuration. 
     The driver  50  is configured by a ball screw mechanism including a motor  51 , a threaded shaft  52 , and a nut  53 , for example. The motor  51  is controlled by the drive control unit  83 . The threaded shaft  52  is a rod-like member having threads in the periphery thereof. The threaded shaft  52  extends along the predetermined direction DR 10 , and is rotated by the motor  51 . The nut  53  is fixed to the holder  20 . The nut  53  is fixed to the back surface  21   b  of the support plate  21  of the holder  20 , for example. The threaded shaft  52  is screwed into the nut  53 . The threaded shaft  52  is rotated in a forward direction or in a reverse direction in response to rotation of the motor  51  in the forward direction or in the reverse direction. The holder  20  is moved to one side along the predetermined direction DR 10  in response to rotation of the threaded shaft  52  in the forward direction. In this case, the pair of guides  60  guides the holder  20  so that the holder  20  is moved to the one side. On the other hand, the holder  20  is moved to the other side along the predetermined direction DR 10  in response to rotation of the threaded shaft  52  in the reverse direction. In this case, the pair of guides  60  guides the holder  20  so that the holder  20  is moved to the other side. A configuration of the driver  50  is not limited to this configuration. 
     The driver  50  can move the holder  20  holding the imaging plate  10  to a reading start position where reading of the radiograph from the imaging plate  10  starts. When reading of the radiograph from the imaging plate  10  ends, the driver  50  can move the holder  20  holding the imaging plate  10  to an erasing position where the radiograph is erased from the imaging plate  10 .  FIGS.  2  and  3    illustrate reading of the radiograph from the imaging plate  10 .  FIGS.  4  and  5    illustrate erasing of the radiograph from the imaging plate  10 . 
     &lt;Light Source and Detector&gt; 
     In this example, the light source  30 , the light emission control unit  86  that controls the light source  30 , the detector  40 , and the detection control unit  85  that controls the detector  40  constitute a light measuring instrument  90  that reads the radiograph from the front surface of the imaging plate  10  as shown in  FIG.  6   . The light source  30 , the detector  40 , the detection control unit  85 , and the light emission control unit  86  constituting the light measuring instrument  90  may be contained in a single case to be unitized, or may not be contained in the single case. 
     The light source  30  can irradiate the imaging plate  10  held by the holder  20  with excitation light L 10  to excite the radiograph formation layer  11 . An object of irradiation with the excitation light L 10  is the imaging plate  10  as a light receiver in biological radiography, for example. The light source  30  emits the excitation light L 10  toward the support surface  21   a  of the holder  20 . The light source  30  can scan the imaging plate  10  with the excitation light L 10  in a single direction (also referred to as a main scanning direction DRm). The main scanning direction DRm is a direction perpendicular to the predetermined direction DR 10 . That is to say, the main scanning direction DRm is a direction perpendicular to a direction of movement of the holder  20 . The light source  30  can irradiate not only the imaging plate  10  but also a region around the imaging plate  10  with the excitation light L 10 . 
     In the present disclosure, light acting on an object is referred to as acting light L 1 . Light generated by the acting light L 1  acting on the object is referred to as acted light L 2 . The excitation light L 10  is one example of the acting light L 1 . Light not having an excitation force to generate the photostimulated light but generating reflected light from the object is another example of the acting light L 1 . It can be said that the acting light L 1  is light including at least one of the excitation light and the acting light that is not the excitation light. The acted light L 2  is light emitted from the object by being acted on by the acting light L 1 . 
     The excitation light L 10  is visible laser light, for example. The excitation light L 10  may be red laser light, or may be laser light of another color, for example. The detector  40  detects the acted light L 2  from the imaging plate  10  generated by irradiation with the excitation light L 10  as the acting light L 1 , and outputs an electric signal responsive to the intensity of the detected acted light L 2 , for example. The detector  40  also detects the acted light L 2  from outside the imaging plate  10  generated by irradiation with the excitation light L 10 , and outputs an electric signal responsive to the intensity of the detected acted light L 2 . 
     The light source  30  includes a laser generator that generates and outputs the excitation light L 10  and a scanner that scans the imaging plate  10  with the excitation light L 10  in the main scanning direction DRm, for example. The laser generator includes a semiconductor laser oscillator, for example, and is controlled by the light emission control unit  86 . The laser generator may include a laser diode, or may include another semiconductor laser. The scanner includes a micro electro mechanical systems (MEMS) mirror that reflects the excitation light L 10  from the laser generator toward the radiograph formation layer  11  of the imaging plate  10 , for example. The MEMS mirror changes a reflection angle of the excitation light L 10  so that a point of irradiation with the excitation light L 10  on the radiograph formation layer  11  is moved in the main scanning direction DRm through control performed by the light emission control unit  86 . The scanner may include another mirror, such as a galvanometer mirror, in place of the MEMS mirror. 
     The detector  40  detects the acted light L 2  from a position as a target of irradiation with the excitation light L 10 . The detector  40  includes an optical filter  42  that the acted light L 2  (see  FIG.  3   ) from the position as the target of irradiation with the excitation light L 10  enters and a sensor  41  that detects the acted light L 2  emitted from the optical filter  42 , for example. The sensor  41  is controlled by the detection control unit  85 . The optical filter  42  is disposed to oppose a detection surface of the sensor  41  where the acted light L 2  is detected and to be located between the main surface  21   a  of the support plate  21  and the detection surface. That is to say, the optical filter  42  is disposed between the position as the target of irradiation with the excitation light L 10  and the detection surface. The acted light L 2  from the position as the target of irradiation with the excitation light L 10  first enters the optical filter  42 , and the acted light L 2  having undergone filtration is emitted from the optical filter  42 , and enters the detection surface of the sensor  41 . 
     A region of the radiograph formation layer  11  in which energy of radiation is stored due to irradiation with radiation is excited by the excitation light L 10 . It can thus be said that a region of the radiograph formation layer  11  in which energy of radiation is stored and which is in a range of the target of irradiation with the excitation light L 10  is an excited region excited by the excitation light L 10 . It can be said that the excited region is a radiograph region, a latent image region, or an image recording region as the radiograph is recorded in the excited region as the latent image. 
       FIG.  7    is a schematic diagram illustrating an enlarged view around the light detector  40  of  FIG.  3   . When the excited region of the radiograph formation layer  11  is irradiated with the excitation light L 10 , the excited region emits light in response to distribution of energy stored in the excited region, and photostimulated light L 5  is emitted from the excited region. The photostimulated light L 5  is visible blue light, for example. When the excited region of the radiograph formation layer  11  is irradiated with the excitation light L 10 , reflected light (hereinafter also referred to as reflected light L 4 ) of the excitation light L 10  in the excited region is also generated. The reflected light L 4  may be referred to as excited region reflected light L 4 . The emitted light L 2  can be thought to be light of which luminescence start position is at the imaging plate  10  without reflection. The photostimulated light L 5  is an example of the emitted light L 2 . 
     Light from the excited region (hereinafter also referred to as excited region light L 20 ) includes the photostimulated light L 5  emitted from the excited region and the reflected light L 4  from the excited region. It can be said that the excited region light L 20  is radiograph region light, latent image region light, or image recording region light. The excited region light L 20  is light including at least the photostimulated light L 5 . When the excited region refers to the latent image region in the range of the target of irradiation with the excitation light L 10 , a region excited by irradiation with the excitation light L 10 , and, specifically, a region excited to emit the photostimulated light L 5 , the excited region light L 20  is light including at least the photostimulated light L 5  from the excited region. While the excited region light L 20  is light including the photostimulated light L 5  and the reflected light L 4  in the above-mentioned example, the excited region light L 20  can include only the photostimulated light L 5  as will be described below. 
     The acted light L 2  entering the optical filter  42  includes the excited region light L 20 . The excited region light L 20  enters the sensor  41  after undergoing filtering processing performed by the optical filter  42 . Transmittance of the photostimulated light L 5  (also referred to as photostimulated light transmittance) of the optical filter  42  is extremely high in this example. The optical filter  42  thus sufficiently transmits the photostimulated light L 5  from the excited region of the imaging plate  10 , and emits the transmitted photostimulated light L 5  to the sensor  41 . On the other hand, transmittance of the excitation light L 10  (also referred to as excitation light transmittance) of the optical filter  42  is lower than the photostimulated light transmittance. For example, the optical filter  42  having an excitation light transmittance of approximately 10% of the photostimulated light transmittance may be used. The optical filter  42  attenuates the reflected light L 4  of the excitation light L 10  from the excited region of the imaging plate  10  toward the sensor  41 . The optical filter  42  attenuates the excitation light L 10 , but transmits the excitation light L 10  to some extent. The sensor  41  thus not only detects the photostimulated light L 5  but also detects the reflected light L 4  of the excitation light L 10  from the excited region to some extent in this example. The excited region light L 20  emitted from the optical filter  42  thus includes the photostimulated light L 5  and the reflected light L 4 . 
     The sensor  41  can detect the excited region light L 20  having been transmitted by the optical filter  42 , and output an electric signal responsive to the intensity of the detected excited region light L 20 . The sensor  41  may be configured by a plurality of photodiodes, or may be configured by a photomultiplier, for example. In this example, the acted light L 2  detected by the sensor  41  (i.e., the acted light L 2  detected by the detector  40 ) includes the photostimulated light L 5  and the reflected light L 4 , for example. 
     When the reading apparatus  1  performs processing (also referred to as reading processing) of reading the radiograph from the imaging plate  10 , the holder  20  holding the imaging plate  10  is transferred to the reading start position by the driver  50 . The light measuring instrument  90  then starts the reading processing. In the reading processing, the light source  30  repeatedly performs processing (also referred to as main scanning direction scanning) of scanning the imaging plate  10  with the excitation light L 10  in the main scanning direction DRm through control performed by the light emission control unit  86 . On the other hand, in the reading processing, the driver  50  moves the holder  20  holding the imaging plate  10  in one direction DRs (also referred to as a subscannig direction DRs) along the predetermined direction DR 10 . The subscannig direction DRs is a direction perpendicular to the main scanning direction DRm. The main scanning direction scanning is repeatedly performed during movement of the holder  20  in the subscannig direction DRs to two-dimensionally irradiate the radiograph formation layer  11  of the imaging plate  10  with the excitation light L 10  for raster scanning of the radiograph formation layer  11 . All regions of the radiograph formation layer  11  are thus sequentially irradiated with the excitation light L 10  to scan all the regions of the radiograph formation layer  11  with the excitation light L 10  in the reading processing. During raster scanning of the radiograph formation layer  11  with the excitation light L 10 , the sensor  41  of the detector  40  detects the excited region light L 20  (i.e., light including the photostimulated light L 5 ) sequentially coming from the radiograph formation layer  11  in response to raster scanning to read the radiograph from the radiograph formation layer  11 . The sensor  41  outputs an image signal representing the read radiograph (i.e., the detected radiograph) to the detection control unit  85  as a result of detection of the excited region light L 20  during raster scanning with the excitation light L 10 . The image signal includes luminance values (i.e., pixel values) of a plurality of pixels representing the read radiograph. The sensor  41  outputs a gray-scale image signal, for example. The radiograph read by the detector  40  is hereinafter also referred to as a detected radiograph. 
     Scanning with the excitation light L 10  is only required to be performed two-dimensionally over the whole region of a detection target range of the imaging plate  10  by determining coordinates thereof, and the main scanning direction DRm and the subscannig direction DRs may not be perpendicular to each other. For example, the main scanning direction DRm and the subscannig direction DRs may cross each other at an angle other than a right angle. One or both of the main scanning direction DRm and the subscannig direction DRs may be set to a curvilinear direction. 
     In this example, in a state of the imaging plate  10  being properly held by the holder  20 , a transverse direction of the imaging plate  10  is parallel to the main scanning direction DRm, and a longitudinal direction of the imaging plate  10  is parallel to the subscannig direction DRs as illustrated in  FIGS.  2  and  4   . An orientation of the imaging plate in the state of the imaging plate  10  being properly held by the holder  20  is herein referred to as a reference orientation, and, in this example, the reference orientation is an orientation of the imaging plate  10  in which the transverse direction of the imaging plate  10  is parallel to the main scanning direction DRm, and the longitudinal direction of the imaging plate  10  is parallel to the subscannig direction DRs. The reference orientation is not limited to this orientation. 
     The imaging plate  10  is basically held by the holder  20  in the reference orientation. When the holder  20  does not properly hold the imaging plate  10  due to a malfunction of the fixture  22  and the like, the imaging plate  10  is held by the holder  20  in an orientation tilting relative to the reference orientation. 
     In this example, the sensor  41  outputs a greater luminance value when detected light has a higher intensity, for example. The photostimulated light L 5  having a higher intensity is emitted from a portion of the radiograph formation layer  11  of the imaging plate  10  which is irradiated with radiation having a higher intensity and in which more energy is stored. On the other hand, the intensity of the reflected light L 4  from the excited region is substantially constant regardless of the stored energy when the excitation light L 10  has a constant intensity. The sensor  41  thus outputs a greater luminance value for an image based on detection of the excited region light L 20  from the portion in which more energy is stored in the excited region of the radiograph formation layer  11 . 
     Consider a case where a radiograph of teeth is recorded on the radiograph formation layer  11 , for example. In this case, the excited region light L 20  from a portion in which the radiograph of the teeth is recorded, that is, a portion irradiated with radiation having transmitted the teeth in the excited region of the radiograph formation layer  11  has a relatively low intensity. The sensor  41  thus outputs a relatively small luminance value for a portion of the detected radiograph in which the teeth appear. On the other hand, the excited region light L 20  from a portion (also referred to as a direct irradiation portion) directly irradiated with radiation in the excited region of the radiograph formation layer  11  has a relatively high intensity. The sensor  41  thus outputs a relatively great luminance value for an image corresponding to the direct irradiation portion of the radiograph formation layer  11  of the detected radiograph. 
     As described above, in this example, the sensor  41  detects not only the photostimulated light L 5  emitted from the excited region of the imaging plate  10  but also the reflected light L 4  from the excited region of the imaging plate  10  to some extent. A luminance value for the detected radiograph output from the sensor  41  thus includes a luminance value (also referred to as a photostimulated light corresponding luminance value) responsive to the intensity of the detected photostimulated light L 5  and a luminance value (also referred to as a reflected light corresponding luminance value) responsive to the detected reflected light L 4 . 
     The photostimulated light corresponding luminance value is a value equal to or greater than ten times the reflected light corresponding luminance value under a standard dose condition and source image distance (SID) condition, for example. The detected radiograph based on the image signal output from the detector  40  is less affected by the reflected light L 4 , and the reflected light L 4  is less likely to interfere with reading of the radiograph recorded on the imaging plate  10  and processing after the reading. The photostimulated light L 5  has a higher luminance intensity ratio than the reflected light L 4  in the excited region light L 20  detected by the sensor  41 , so that the influence of the reflected light L 4  is small. Thus, by outputting an electric signal responsive to the intensity of the detected excited region light L 20 , the detector  40  outputs an electric signal responsive to the intensity of the photostimulated light L 5 . 
     In this example, the radiograph formation layer  11  of the imaging plate  10  can partially include an unexposed portion in which energy responsive to irradiation with radiation is not stored. For example, when the imaging plate  10  is irradiated with radiation through the imaging object, the radiograph formation layer  11  can include the unexposed portion because a portion originally to be irradiated with radiation is sometimes not irradiated with radiation due to displacement of a light source that emits radiation and the like. The unexposed portion is also referred to as a cone cut. In this example, the imaging plate  10  is inserted into a mouth, and is irradiated with radiation. All or part of the imaging plate  10  is thus hidden in the mouth, so that the all or part of the imaging plate  10  can fall outside a range of irradiation with radiation even when an operator might believe that the light source that emits radiation is positioned properly. The cone cut is caused in such a case. The radiograph formation layer  11  can partially include the unexposed portion as the radiograph is unintentionally erased from the portion irradiated with radiation. For example, the imaging plate  10  on which the radiograph is recorded is typically stored after being covered not to be irradiated with ambient light. When the imaging plate  10  is not properly covered, however, a portion of the radiograph formation layer  11  can be irradiated with ambient light during storage of the imaging plate  10  to unintentionally erase the radiograph recorded in the portion. Also in this case, the radiograph formation layer  11  partially includes the unexposed portion (a portion once exposed but returning to an unexposed state due to erasing herein). 
     Energy of radiation is not stored in the unexposed portion of the imaging plate  10 , so that the unexposed portion is not excited even when being irradiated with the excitation light L 10 . It can thus be said that the unexposed portion is a region that is not the excited region, that is, an unexcited region. Even when the unexposed portion (i.e., the unexcited region) of the imaging plate  10  is irradiated with the excitation light L 10 , the photostimulated light L 5  is not emitted from the unexposed portion. Thus, when the unexposed portion is irradiated with the excitation light L 10 , the detector  40  detects the reflected light of the excitation light L 10  from the unexposed portion without detecting the photostimulated light L 5  as illustrated in  FIG.  8   . The image signal output from the detector  40  can thus include luminance values of a plurality of pixels representing an image in the unexposed portion, that is, an image based on detection of the reflected light of the excitation light L 10  from the unexposed portion. The reflected light of the excitation light L 10  from a region, such as an unexposed region, of the imaging plate  10  in which energy of radiation is not stored is hereinafter referred to as reflected light L 40 . 
     The reflected light MO from the unexposed portion enters the sensor  41  through the optical filter  42 . A whole image based on the image signal output from the detector  40  as a result of detection of the excited region light L 20  and the reflected light L 40  sometimes includes not only the detected radiograph based on detection of the excited region light L 20  but also the image in the unexposed portion (also referred to as an unexposed region image). A luminance value for the detected radiograph output from the detector  40  is equal to or greater than ten times a luminance value for the unexposed region image output from the detector  40  under the standard dose condition and SID condition, for example. It can be said that the reflected light L 40  from the unexposed portion, that is, the unexcited region is unexcited region light. The reflected light L 40  may be referred to as unexcited region reflected light L 40 . The acted light L 2  detected by the detector  40  also includes the reflected light MO. 
     When no radiograph is recorded on the imaging plate  10 , the sensor  41  detects the reflected light MO from the position as the target of irradiation with the excitation light L 10  without detecting the excited region light L 20 . As with the reflected light L 40  from the unexcited region and the reflected light L 4  from the excited region, the reflected light of the excitation light L 10  from the imaging plate  10  is sometimes expressed as non-photostimulable reflected light in contrast with the photostimulated light L 5 . The reflected light of the excitation light L 10  is also simply referred to as reflected light regardless of whether the excitation light L 10  is reflected from the imaging plate  10  or reflected from outside the imaging plate  10 . 
     In the present disclosure, a symbol IP representing the imaging plate  10  may be attached to a name of light from the imaging plate  10  or a name of light with which the imaging plate  10  is irradiated. For example, the excited region light L 20  may be referred to as IP excited region light L 20 . The unexcited region light may be referred to as IP unexcited region light. The photostimulated light L 5  may be referred to as IP photostimulated light L 5 . The reflected light L 4  may be referred to as IP reflected light L 4  (also referred to as IP excited region reflected light L 4 ), and the reflected light L 40  may be referred to as IP reflected light MO (also referred to as IP unexcited region reflected light MO). The non-photostimulable reflected light may be referred to as IP non-photostimulable reflected light. The acting light L 1  may be referred to as IP acting light L 1 , and the acted light L 2  may be referred to as IP acted light L 2 . The IP acted light L 2  may also simply be referred to as IP light L 2 . The excitation light L 10  may be referred to as IP excitation light L 10 . When there is no particular need to distinguish between the reflected light L 4  and the reflected light L 40 , each of them or a combination of them is hereinafter referred to as IP reflected light. 
     The excitation light L 10  includes a component to generate the photostimulated light L 5 . The excitation light L 10  also includes a component to generate the IP reflected light. The light source  30  is a photostimulated light generation light source as a source of light including the component to generate the photostimulated light L 5 . The light source  30  is also a reflected light generation light source as a source of light including the component to generate the IP reflected light. For example, the light source  30  as the photostimulated light generation light source is a first light source, and the light source  30  as the reflected light generation light source is a second light source. The photostimulated light generation light source and the reflected light generation light source are not required to be integral with each other, and may separately be provided. The reflected light generation light source is only required to emit light, which is not limited to the excitation light L 10 , to generate reflected light from an object. 
     The sensor  41  is a photostimulated light detector that detects the photostimulated light L 5 , and is also a reflected light detector that detects the IP reflected light. For example, the sensor  41  as the photostimulated light detector that detects the photostimulated light is a first detector, and the sensor  41  as the reflected light detector that detects the reflected light is a second detector. The sensor  41  is a detector that detects the excited region light L 20 . Since the excited region light L 20  is light including at least the photostimulated light L 5 , at least the photostimulated light L 5  is detected by detecting the excited region light L 20 . The sensor  41  is the photostimulated light detector in that sense. The sensor  41  as the first detector may be considered as an excited region light detector. The excited region light is the IP acted light, so that the first detector may be considered as an IP excited region light detector that detects the IP excited region light L 20 . The second detector may be considered as an unexcited region light detector that detects the unexcited region light. When the unexcited region light is the IP acted light, the second detector may be considered as an IP unexcited region light detector that detects the IP unexcited region light. The photostimulated light detector and the reflected light detector are not required to be integral with each other, and may separately be provided. 
     In the present disclosure, an image formed by certain light, that is, an image based on detection of the certain light may be referred to by a name of an image to which a name of the certain light has been attached. For example, an image formed by the excited region light L 20 , that is, an image based on detection of the excited region light L 20  may be referred to as an excited region light image. The above-mentioned detected radiograph acquired by the detector  40  is the excited region light image. An image formed by the reflected light, that is, an image based on detection of the reflected light may be referred to as a reflected light image. The reflected light image formed by the reflected light L 40  from the unexposed portion is the above-mentioned unexposed region image acquired by the detector  40 . An image formed by the non-photostimulable reflected light may be referred to as a non-photostimulable reflected light image, and an image formed by the acted light L 2  may be referred to as an acted light image. There can thus be a photostimulated light image, a reflected light image, an excited region reflected light image, an unexcited region light image, an unexcited region reflected light image, and the like. 
     In the present disclosure, the symbol IP representing the imaging plate  10  may be attached to a name of an image relating to the imaging plate  10 . For example, the excited region light image may be referred to as an IP excited region light image, an image formed by the IP reflected light (i.e., an image based on detection of the IP reflected light or an image acquired by detection of the IP reflected light) may be referred to as an IP reflected light image, the non-photostimulable reflected light image may be referred to as an IP non-photostimulable reflected light image, and the acted light image may be referred to as an IP acted light image. Similarly, there can be an IP photostimulated light image, an IP excited region reflected light image, an IP unexcited region light image, an IP unexcited region reflected light image, and the like. The IP acted light image may also simply be referred to as an IP image. The IP acted light image having been processed may be referred to as the IP acted light image (i.e., the IP image). 
     In the present disclosure, an image signal acquired as a result of detection of certain light may be referred to by a name of an image signal to which a name of the certain light has been attached. For example, an image signal acquired as a result of detection of the excited region light L 20  may be referred to as an excited region light image signal. An image signal acquired as a result of detection of the reflected light may be referred to as a reflected light image signal. An image signal acquired as a result of detection of the non-photostimulable reflected light image may be referred to as a non-photostimulable reflected light image signal. An image signal acquired as a result of detection of the acted light L 2  may be referred to as an acted light image signal. Similarly, there can be a photostimulated light image signal, an excited region reflected light image signal, an unexcited region light image signal, an unexcited region reflected light image signal, and the like. 
     In the present disclosure, the symbol IP representing the imaging plate  10  may be attached to a name of an image signal relating to the imaging plate  10 . For example, the excited region light image signal may be referred to as an IP excited region light image signal, the image signal acquired as a result of detection of the reflected light may be referred to as an IP reflected light image signal, the non-photostimulable reflected light image signal may be referred to as an IP non-photostimulable reflected light image signal, and the acted light image signal may be referred to as an IP acted light image signal. The IP acted light image signal may also simply be referred to as an IP image signal. Similarly, there can be an IP photostimulated light image signal, an IP excited region reflected light image signal, an IP unexcited region light image signal, an IP unexcited region reflected light image signal, and the like. 
     When the optical filter  42  completely blocks the reflected light L 4  and transmits only the photostimulated light L 5  as illustrated in  FIG.  9   , the acted light L 2  detected by the sensor  41 , in other words, the excited region light L 20  detected by the sensor  41  is the photostimulated light L 5 . A luminance value responsive to the intensity of the acted light L 2  (i.e., the excited region light L 20 ) output from the sensor  41  is thus a luminance value responsive to the intensity of the photostimulated light L 5 . In an example of  FIG.  9   , an image based on the photostimulated light L 5  detected by the detector  40  may be referred to as the photostimulated light image, or may be referred to as the IP photostimulated light image. An image signal output from the detector  40  as a result of detection of the photostimulated light L 5  may be referred to as the photostimulated light image signal, or may be referred to as the IP photostimulated light image signal. 
     In this example, not only the imaging plate  10  but also a portion of the holder  20  outside the imaging plate  10  is irradiated with the excitation light L 10  in the reading processing. An object irradiated with the excitation light L 10  in the reading apparatus  1  is herein referred to as an irradiation object  1200 . In this example, the irradiation object  1200  includes the holder  20  and the imaging plate  10  held by the holder  20 . A main surface  1200   a  of the irradiation object  1200  on a side of the support surface  21   a  is referred to as a support side main surface  1200   a.  In this example, the support side main surface  1200   a  includes a surface of the radiograph formation layer  11  of the imaging plate  10 , a surface of the fixture  22  of the holder  20 , and a region of the support surface  21   a  of the support plate  21  of the holder  20  not covered with the imaging plate  10  and the fixture  22 . A region of the support side main surface  1200   a  where an image formed by the acted light L 2  therefrom is the IP image is referred to as an IP image region R 100 . It can be said that the IP image region R 100  is an IP presence region of the support side main surface  1200   a  where the imaging plate  10  is present. A main surface of the irradiation object  1200  opposite the support side main surface  1200   a  matches the back surface  21   b  of the support plate  21 . 
     Light from the IP image region R 100  may be referred to as IP image region light. An image formed by the IP image region light may be referred to as an IP image region light image. An image signal output as a result of detection of the IP image region light may be referred to as an IP image region light image signal. The IP image region light can include only the excited region reflected light L 4 , can include only the unexcited region reflected light L 40 , or can include both the excited region reflected light L 4  and the unexcited region reflected light L 40 . 
     In this example, an irradiation range (also referred to as an excitation light irradiation range) R 120  of irradiation with the excitation light L 10  on the support side main surface  1200   a  in the reading processing is a range greater than the IP image region R 100  while including the IP image region R 100 . It can be said that the excitation light irradiation range R 120  is a scanning range of scanning with the excitation light L 10  in the reading processing. A detection range R 110  of detection performed by the detector  40  on the support side main surface  1200   a  in the reading processing is also a range greater than the IP image region R 100  while including the IP image region R 100 . 
       FIG.  10    is a schematic diagram illustrating one example of the excitation light irradiation range R 120 , the detection range R 110 , and the IP image region R 100 . In  FIG.  10    and  FIGS.  12  and  13    described below, illustration of the imaging plate  10  is omitted. As illustrated in  FIG.  10   , the excitation light irradiation range R 120  and the detection range R 110  are each a range greater than the IP image region R 100  while including the IP image region R 100 . The excitation light irradiation range R 120  and the detection range R 110  have the same size, and are present at the same position, for example. The excitation light irradiation range R 120  is illustrated to be slightly greater than the detection range R 110  in  FIG.  10    for the convenience of description. 
     As described above, the excitation light irradiation range R 120  and the detection range R 110  may be ranges matching each other. A configuration in which only the acted light L 2  from the excitation light irradiation range R 120  is detected is an example of a configuration in which the excitation light irradiation range R 120  and the detection range R 110  are ranges matching each other. 
     In the reading processing, the holder  20  holding the imaging plate  10  is moved in the subscannig direction DRs while the light source  30  repeatedly performs the main scanning direction scanning for raster scanning of the excitation light irradiation range R 120  with the excitation light L 10 . The sensor  41  sequentially outputs luminance values responsive to positions of irradiation with the excitation light L 10  in the detection range R 110  in response to raster scanning with the excitation light L 10 . 
     A region outside the IP image region R 100  and inside the excitation light irradiation range R 120  and the detection range R 110  on the support side main surface  1200   a  is herein referred to as an IP outside region R 130 . In this example, the excitation light irradiation range R 120  and the detection range R 110  are each a range greater than the IP image region R 100  while including the IP image region R 100 , so that the sensor  41  detects reflected light L 400  of the excitation light L 10  from the IP outside region R 130 . The IP outside region R 130  includes at least portion of a surface of the fixture  22  and at least portion of a region of the support surface  21   a  of the support plate  21  not covered with the imaging plate  10  and the fixture  22 , for example. The IP outside region R 130  is included in a surface of the holder  20 , specifically, a main surface of the holder  20  on a side of the imaging plate  10 .  FIG.  11    is a schematic diagram illustrating one example of detection of the reflected light L 400  performed by the sensor  41 . The acted light L 2  detected by the detector  41  includes the reflected light L 400 . 
     Even when the IP outside region R 130  is irradiated with the excitation light L 10 , the photostimulated light L 5  is not emitted from the IP outside region R 130 . The detector  40  thus detects the reflected light L 400  of the excitation light L 10  from the IP outside region R 130  without detecting the photostimulated light L 5  when the IP outside region R 130  is irradiated with the excitation light L 10 . Thus, in the reading processing, an image signal output from the detector  40  as a result of detection of the photostimulated light L 5  and the reflected light includes luminance values of a plurality of pixels representing a reflected light image in the IP outside region R 130 , that is, a reflected light image based on detection of the reflected light L 400  of the excitation light L 10  from the IP outside region R 130 . In this example, the whole image (also referred to as an acquired whole image) based on the image signal output from the detector  40  includes not only the detected radiograph but also the reflected light image in the IP outside region R 130 . When the imaging plate  10  includes the unexposed portion, the acquired whole image includes the detected radiograph, the unexposed region image, and the reflected light image in the IP outside region R 130 . The reflected light image in the IP outside region R 130  is hereinafter also referred to as an IP outside region image. 
     A region in the detection range R 110  excluding the IP image region R 100  may be referred to as an IP image region outside region. An image in the IP image region outside region may be referred to as an IP image region outside region image. The detection range R 110  is set to include at least the IP image region R 100 . When the detection range R 110  is set to a range being greater than the IP image region R 100  while including the IP image region R 100 , the detection range R 110  includes the IP image region R 100  and the IP image region outside region. The IP image region R 100  is a region of the imaging plate  10  where the excitation light L 10  is received, and thus may be referred to as an IP light receiving region. A region in the detection range R 110  excluding the IP light receiving region is the IP image region outside region, and thus the IP image region outside region may be referred to as an IP light receiving outside region. 
     In this example, processing of making the excitation light L 10  less likely to be reflected has been performed in the IP outside region R 130 . For example, black anodizing has been performed in the IP outside region R 130 . The detector  40  is thus less likely to detect the reflected light L 400  of the excitation light L 10  in the IP outside region R 130  than the reflected light L 40  of the excitation light L 10  in the unexposed portion of the imaging plate  10 . In this example, the excitation light L 10  is hardly reflected in the IP outside region R 130  due to black anodizing. A luminance value for the unexposed region image output from the detector  40  is equal to or greater than three times a luminance value for the IP outside region image output from the detector  40 , for example. Black anodizing may be performed in a region of the surface of the holder  20  other than the IP outside region R 130 . For example, black anodizing may be performed in all regions on the surface of the holder  20 . Processing of making the excitation light L 10  less likely to be reflected may be performed at least in a range of irradiation with the excitation light L 10  of a portion of the support surface  21   a  and the fixture  22  of the holder  20  in the detection range R 110 , for example. When the portion of the support surface  21   a  and the fixture  22  of the holder  20  in the detection range R 110  includes a range not irradiated with the excitation light L 10 , processing of making light less likely to be reflected may be performed in the range. 
     A relationship among the excitation light irradiation range R 120 , the detection range R 110 , and the IP image region R 100  is not limited to that in the above-mentioned example.  FIGS.  12  and  13    are schematic diagrams each illustrating another example of the excitation light irradiation range R 120 , the detection range R 110 , and the IP image region R 100 . In the example of  FIG.  12   , the excitation light irradiation range R 120  is greater than the detection range R 110  and the IP image region R 100  while including the detection range R 110  and the IP image region R 100 . In the example of  FIG.  12   , the IP image region outside region inside the detection range R 110  falls within the excitation light irradiation range R 120 . A region inside the detection range R 110  and the excitation light irradiation range R 120  and outside the IP image region R 100  may be referred to as an in-irradiation range IP image region outside region. The in-irradiation range IP image region outside region matches the above-mentioned IP outside region R 130 . In the example of  FIG.  12   , the IP image region outside region includes the in-irradiation range IP image region outside region. The IP outside region R 130  is hereinafter also referred to as the in-irradiation range IP image region outside region R 130 . 
     In the example of  FIG.  13   , the detection range R 110  is greater than the excitation light irradiation range R 120  and the IP image region R 100  while including the excitation light irradiation range R 120  and the IP image region R 100 . 
     As in the examples of  FIGS.  10 ,  12 , and  13   , the excitation light irradiation range R 120  and the detection range R 110  may match each other, or one of the excitation light irradiation range R 120  and the detection range R 110  may be greater than the other one of the excitation light irradiation range R 120  and the detection range R 110 . 
     In the example of  FIG.  13   , the detection range R 110  includes a region (also referred to as an out-of-irradiation range region) on the support side main surface  1200   a  other than the excitation light irradiation range R 120 . In the example of  FIG.  13   , the IP image region outside region inside the detection range R 110  includes a region inside the excitation light irradiation range R 120  excluding the IP image region R 100  and a region inside the detection range R 110  excluding the excitation light irradiation range R 120 . A region in the detection range R 110  outside the excitation light irradiation range R 120  may be referred to as an out-of-irradiation range IP image region outside region. In the example of  FIG.  13   , the IP image region outside region inside the detection range R 110  includes the in-irradiation range IP image region outside region and the out-of-irradiation range IP image region outside region. 
     Processing of making the excitation light L 10  less likely to be reflected may be performed in the excitation light irradiation range R 120 , and may be performed in the out-of-irradiation range IP image region outside region of the support side main surface  1200   a.  A condition of light in the out-of-irradiation range IP image region outside region may be referred to as an out-of-irradiation range IP image region outside region light condition. 
     In the reading processing, out-of-irradiation range detection processing is performed in the out-of-irradiation range IP image region outside region. In the out-of-irradiation range detection processing, the detector  40  may detect luminance of the out-of-irradiation range IP image region outside region light condition. It is already known that luminance of the out-of-irradiation range IP image region outside region light condition is low, so that luminance values of the out-of-irradiation range IP image region outside region light condition may collectively be set to a predetermined value to detect luminance of the out-of-irradiation range IP image region outside region light condition for efficiency, for example. The predetermined value is a luminance value lower than a luminance value for the IP image. The image signal output from the detector  40  also includes the luminance value of the out-of-irradiation range IP image region outside region light condition. 
     As described above, an image in the out-of-irradiation range IP image region outside region can be acquired in the reading processing even when light is not emitted from the out-of-irradiation range IP image region outside region. Processing of making the excitation light L 10  less likely to be reflected may be performed in the IP image region outside region. In this case, processing of making the excitation light L 10  less likely to be reflected may be performed at least in the out-of-irradiation range IP image region outside region. 
     An image signal acquired as a result of detection of the acted light L 2  from the detection range R 110  may be referred to as a detection range image signal. An image based on the detection range image signal may be referred to as a detection range image. The detection range image is the above-mentioned acquired whole image. 
     The image in the IP image region outside region may be referred to as the IP image region outside region image. An image in the in-irradiation range IP image region outside region may be referred to as an in-irradiation range IP image region outside region image. An image in the out-of-irradiation range IP image region outside region may be referred to as an out-of-irradiation range IP image region outside region image. In the case of  FIG.  12   , the in-irradiation range IP image region outside region image is the IP image region outside region image. In the case of  FIG.  13   , the in-irradiation range IP image region outside region image and the out-of-irradiation range IP image region outside region image constitute the IP image region outside region image. 
     When the reflected light L 400  having low luminance is generated as a result of irradiation of the in-irradiation range IP image region outside region R 130  (i.e., the IP outside region R 130 ) with the excitation light L 10 , and the detector  40  detects the reflected light L 400 , the in-irradiation range IP image region outside region image (i.e., the IP outside region image) is a reflected light image. The out-of-irradiation range IP image region outside region image is a dark image from pixels of the detection surface of the sensor  41  through which dark current flows, or a dark image generated by being artificially provided with a low value. The IP image region outside region image is an image including the reflected light image in the in-irradiation range IP image region outside region or including the reflected light image in the in-irradiation range IP image region outside region and the dark image in the out-of-irradiation range IP image region outside region. 
     &lt;Erasing Light Source&gt; 
     In this example, the erasing light source  70  and the erasing control unit  87  that controls the erasing light source  70  constitute an erasing unit  91  that performs erasing processing of erasing the radiograph form the imaging plate  10  as shown in  FIG.  6   . The erasing light source  70  and the erasing control unit  87  constituting the erasing unit  91  may be contained in a single case to be unitized, or may not be contained in the single case. The erasing light source  70  can irradiate the imaging plate  10  with erasing light L 3  to erase the radiograph from the imaging plate  10 . The erasing light L 3  is visible light, for example. The erasing light L 3  may be white light, red visible light, or visible light of another color. The erasing light source  70  may be a light emission diode (an LED), a halogen lamp, or another light source. 
     As illustrated in  FIGS.  4  and  5   , the erasing light source  70  can irradiate all the regions of the radiograph formation layer  11  of the imaging plate  10  with the erasing light L 3  at one time, for example. In the erasing processing, the radiograph formation layer  11  is irradiated with the erasing light L 3  to erase the radiograph from the radiograph formation layer  11 . 
     When the reading processing ends, the driver  50  moves the holder  20  holding the imaging plate  10  to the erasing position. When the holder  20  is moved to the erasing position, the erasing unit  91  performs the erasing processing. In the erasing processing, the erasing light source  70  irradiates all the regions of the radiograph formation layer  11  of the imaging plate  10  with the erasing light L 3  through control performed by the erasing control unit  87 . The radiograph is thereby erased from the imaging plate  10 . 
     When the radiograph is erased from the imaging plate  10 , the driver  50  moves the holder  20  to a discharge position. When the holder  20  is moved to the discharge position, each of the fixing portions  22   a  of the holder  20  is moved from the close position to the spaced position. The imaging plate  10  from which the radiograph has been erased is then discharged to the outlet  2   b.  An erased imaging plate  10  hereinafter refers to the imaging plate  10  from which the radiograph has been erased. 
     &lt;Image Processing Unit&gt; 
     The image processing unit  81  of the controller  80  associates luminance values included in the image signal from the sensor  41  with respective pixel positions of the acquired whole image. 
     The driver  50  herein moves the holder  20  in the subscannig direction DRs in response to repetition of the main scanning direction scanning in the reading processing. Specifically, the driver  50  moves the holder  20  in the subscannig direction DRs while the main scanning direction scanning is performed a predetermined number of times so that all regions of the excitation light irradiation range R 120  are irradiated with the excitation light L 10 . The sensor  41  sequentially outputs luminance values responsive to the positions of irradiation with the excitation light L 10  in the detection range R 110  in response to raster scanning with the excitation light L 10 . The reading apparatus  1  operates as described above in the reading processing, so that a position of a pixel of the acquired whole image corresponding to a luminance value output from the sensor  41  at a certain time can be known from the excitation light irradiation range R 120 , the detection range R 110 , time taken to perform the main scanning direction scanning at one time, a cycle of repetition of the main scanning direction scanning, and the number of times the main scanning direction scanning is performed in the reading processing. The image processing unit  81  associates the luminance values included in the image signal from the sensor  41  with the respective pixel positions based on the excitation light irradiation range R 120 , the detection range R 110 , the time taken to perform the main scanning direction scanning at one time, the cycle of repetition of the main scanning direction scanning, and the number of times the main scanning direction scanning is performed in the reading processing. The detection control unit  85  may associate the luminance values included in the image signal from the sensor  41  with the respective pixel positions. 
     The image processing unit  81  performs image processing on the image signal from the sensor  41 . The image processing unit  81  performs the image processing on the image signal (a detected image signal) from the sensor  41  as the first detector and the second detector. The image processing unit  81  outputs, to the display control unit  82 , image information in which luminance values of the image signal after the image processing are associated with respective pixel positions of the acquired whole image, for example. The display control unit  82  causes the display  3  to display the acquired whole image including the detected radiograph based on the image information, for example. 
     The image processing performed by the image processing unit  81  may include luminance reversal processing. The luminance reversal processing refers to processing of converting the luminance values of the image signal before the luminance reversal processing so that a greater luminance value is converted into a smaller luminance value. A maximum value of a range that the luminance value can take is herein referred to as a maximum luminance value. For example, a value obtained by subtracting a certain luminance value included in the image signal before the luminance reversal processing from the maximum luminance value is used as the certain luminance value after conversion. The luminance reversal processing is performed on the image signal, so that the radiograph based on detection of the excited region light L 20  from a portion of the imaging plate  10  in which less energy is stored has a greater luminance value, and the radiograph based on detection of the excited region light L 20  from a portion of the imaging plate  10  in which more energy is stored has a smaller luminance value in the image signal after the image processing in contrast to the image signal before the image processing. The luminance value for the unexposed region image and the luminance value for the IP outside region image are greater than the luminance value for the detected radiograph in the image signal after the image processing. 
     The image processing performed by the image processing unit  81  may not include the luminance reversal processing, or may include processing other than the luminance reversal processing. The image processing may include offset correction and logarithmic transformation as the processing other than the luminance reversal processing, for example. 
       FIGS.  14  and  15    are schematic diagrams each showing one example of the acquired whole image (also referred to as a before-reversal whole image)  100   a  based on the image signal before the luminance reversal processing.  FIGS.  16  and  17    are schematic diagrams each showing one example of the acquired whole image (also referred to as an after-reversal whole image)  100   b  based on the image signal after the luminance reversal processing. The before-reversal whole images  100   a  and the after-reversal whole images  100   b  are shown in grayscale in  FIGS.  14  to  17   .  FIGS.  14  to  17    show a brighter (i.e., white) image as the image has a greater luminance value and a darker (i.e., black) image as the image has a smaller luminance value. The same applies to drawings described below each showing an image acquired by the reading apparatus  1 . 
     An image acquired by scanning the imaging plate  10  used as the light receiver in biological radiography with the acting light L 1  to read a radiograph of a biological tissue as with the acquired whole image  100   a  in  FIG.  14    is referred to as a biological radiographically captured image. Scanning with the excitation light L 10  as the acting light L 1  may be performed. An image formed by the IP acted light L 2  (i.e., an image based on detection of the IP acted light L 2 ) in the biological radiographically captured image as with a radiograph  101   a  in  FIG.  14    is referred to as an IP biological radiographically captured image. The biological radiographically captured image and the IP biological radiographically captured image are each an image acquired by biological radiography, and is an acquired image acquired by biological radiography. 
       FIG.  14    shows the before-reversal whole image  100   a  including the radiograph (i.e., the detected radiograph or the IP excited region light image)  101   a  based on detection of the excited region light L 20  and an IP image region outside region image  102   a.  In the example of  FIG.  14   , the radiograph  101   a  is the IP image.  FIG.  15    shows the before-reversal whole image  100   a  including the radiograph (i.e., the IP excited region light image)  101   a,  the IP image region outside region image  102   a,  and an unexposed region image (i.e., the IP reflected light image or the IP non-photostimulable reflected light image)  103   a.  In the example of  FIG.  15   , the radiograph  101   a  and the unexposed region image  103   a  constitute the IP image.  FIG.  16    shows the after-reversal whole image  100   b  including a radiograph (i.e., the IP excited region light image)  101   b  and an IP image region outside region image  102   b.  In the example of  FIG.  16   , the radiograph  101   b  is the IP image.  FIG.  17    shows the after-reversal whole image  100   b  including the radiograph (i.e., the IP excited region light image)  101   b,  the IP image region outside region image  102   b,  and an unexposed region image (i.e., the IP reflected light image or the IP non-photostimulable reflected light image)  103   b.  In the example of  FIG.  17   , the radiograph  101   a  and the unexposed region image  103   b  constitute the IP image. In this example, the detection range R 110  of the sensor  41  is rectangular, so that the acquired whole image is rectangular as shown in  FIGS.  14  to  17   . 
     When the display control unit  82  causes the display  3  to display the after-reversal whole image  100   b  based on the image signal after the image processing, the display control unit  82  causes the display  3  to display the after-reversal whole image  100   b  in grayscale as shown in  FIGS.  16  and  17   , for example. It can be said that  FIGS.  16  and  17    are drawings each showing an example of display of the after-reversal whole image  100   b.  When the display control unit  82  causes the display  3  to display the before-reversal whole image  100   a  based on the image signal before the luminance reversal processing, the display control unit  82  causes the display  3  to display the before-reversal whole image  100   a  in grayscale as shown in  FIGS.  14  and  15   , for example. It can be said that  FIGS.  14  and  15    are drawings each showing an example of display of the before-reversal whole image  100   a.    
     &lt;Example of Operation of Reading Apparatus&gt; 
       FIG.  18    is a flowchart showing one example of operation of the reading apparatus  1 . When the imaging plate  10  inserted through the inlet  2   a  of the housing  2  is held by the holder  20 , and the start button included in the operation unit  4  is operated, step s 1  in  FIG.  18    is performed. It can be said that the operation on the start button is an operation to provide instructions to start a series of processes shown in  FIG.  18   . 
     In step s 1 , the driver  50  moves the holder  20  to the reading start position through control performed by the drive control unit  83 . Next, in step s 2 , the reading processing of reading the radiograph from the imaging plate  10  is performed. Next, in step s 3 , the driver  50  moves the holder  20  to the erasing position through control performed by the drive control unit  83 . Next, in step s 4 , the erasing light source  70  irradiates the imaging plate  10  with the erasing light L 3  to perform the erasing processing of erasing the radiograph from the imaging plate  10  through control performed by the erasing control unit  87 . Next, in step s 5 , the driver  50  moves the holder  20  to the discharge position through control performed by the drive control unit  83 . Next, in step s 6 , the imaging plate  10  is discharged to the outlet  2   b  of the housing  2 . In step s 7 , the display  3  displays the acquired whole image through control performed by the display control unit  82 . In step s 7 , the display  3  displays the after-reversal whole image in grayscale as shown in  FIGS.  16  and  17   , for example. Step s 7  may be performed at any time after step s 2 . For example, step s 7  may be performed between step s 3  and step s 4 . 
     &lt;Identification of Tilt Angle of Imaging Plate&gt; 
     The image processing unit  81  may perform tilt angle identification processing of identifying a tilt angle (also referred to as an IP tilt angle) of the imaging plate  10  relative to the reference orientation, for example. The wording of “tilt” can be replaced with wording of “deviate”. For example, “tilting” can be replaced with “deviated”, and “tilt” can be replaced with “deviation” or “deviated”. In the tilt angle identification processing, the image processing unit  81  identifies the IP tilt angle based on the image signal output from the detector  40 , specifically, the IP acted light image signal, for example. The image processing unit  81  functions as an identification unit (also referred to as a tilt angle identification unit) that identifies the IP tilt angle. In this example, a rotation angle relative to the reference orientation can be detected by performing principal component analysis in which a region where the imaging plate  10  is present is considered as a two-dimensional feature vector set. While a specific example of the tilt angle identification processing will be described below, the tilt angle identification processing is not limited to that in the example described below. 
     As described above, the reference orientation in this example is an orientation of the imaging plate  10  in which the transverse direction and the longitudinal direction of the imaging plate  10  are respectively parallel to the main scanning direction DRm and the subscannig direction DRs. In other words, the reference orientation is an orientation of the imaging plate  10  in which the transverse direction of the imaging plate  10  is parallel to the main scanning direction DRm and the longitudinal direction of the imaging plate  10  is parallel to the subscannig direction DRs, for example. When the holder  20  does not properly hold the imaging plate  10 , the imaging plate  10  can tilt relative to the reference orientation with the longitudinal direction (also referred to as an IP longitudinal direction) of the imaging plate  10  tilting relative to the sub scannig direction DRs as illustrated in  FIG.  19    when the imaging plate  10  held by the holder  20  is viewed from a side of the front surface thereof. In other words, the imaging plate  10  can tilt relative to the reference orientation with the transverse direction (also referred to as an IP transverse direction) of the imaging plate  10  tilting relative to the main scanning direction DRm. The imaging plate  10  in the reference orientation is indicated by a dashed line in  FIG.  19   . 
     In this example, the IP tilt angle, that is, the tilt angle of the imaging plate  10  relative to the reference orientation matches the tilt angle of the IP longitudinal direction relative to the subscannig direction DRs. In other words, the IP tilt angle matches the tilt angle of the IP transverse direction relative to the main scanning direction DRm. 
     On the other hand, a longitudinal direction of the detection range R 110  (see  FIG.  10    and the like) of the sensor  41  corresponds to a longitudinal direction of the acquired whole image based on the image signal from the sensor  41 . In this example, the longitudinal direction of the detection range R 110  is parallel to the subscannig direction DRs, so that it can be said that the longitudinal direction of the acquired whole image corresponds to the subscannig direction DRs. Thus, when the orientation of the imaging plate  10  is the reference orientation, the longitudinal direction of the acquired whole image and a longitudinal direction of a portion (also referred to as an IP corresponding portion) of the acquired whole image corresponding to the imaging plate  10  match each other. On the other hand, when the imaging plate  10  tilts relative to the reference orientation, the longitudinal direction of the IP corresponding portion of the acquired whole image tilts relative to the longitudinal direction of the acquired whole image. In other words, when the imaging plate  10  tilts relative to the reference orientation, a transverse direction of the IP corresponding portion of the acquired whole image tilts relative to a transverse direction of the acquired whole image. 
       FIG.  20    shows one example of the before-reversal whole image  100   a  acquired when the imaging plate  10  tilts relative to the reference orientation. The before-reversal whole image  100   a  shown in  FIG.  20    includes a tilting IP corresponding portion  105   a.    
     In this example, the tilt angle of the longitudinal direction of the IP corresponding portion (i.e., the IP image) relative to the longitudinal direction of the acquired whole image matches the IP tilt angle. The image processing unit  81  thus determines the tilt angle of the longitudinal direction of the IP corresponding portion relative to the longitudinal direction of the acquired whole image based on the image signal from the sensor  41 . The image processing unit  81  sets the determined tilt angle to the IP tilt angle. Operation of the image processing unit  81  in this case will be described in detail below. 
     In the tilt angle identification processing, the image processing unit  81  binarizes the before-reversal whole image based on the image signal (also referred to as a before-reversal image signal) before the luminance reversal processing to generate a binarized image. The image processing unit  81  first compares each of luminance values for the before-reversal whole image included in the before-reversal image signal with a preset threshold. The image processing unit  81  replaces a luminance value for the before-reversal whole image equal to or greater than the threshold with “1”, and replaces a luminance value for the before-reversal whole image smaller than the threshold with “0”. The before-reversal whole image is thereby binarized to acquire the binarized image. 
     The threshold used for binarization is set to a value greater than a luminance value for the IP image region outside region image included in the before-reversal image signal and smaller than a luminance value for the unexposed region image included in the before-reversal image signal, for example. Consider a case where IL 1  is the luminance value for the IP image region outside region image included in the before-reversal image signal, and IL 2  is the luminance value for the unexposed region image included in the before-reversal image signal, for example. An inequality IL 1 &lt;IL 2  holds. In this case, the threshold is set to IL 3  that satisfies a relationship indicated by an inequality IL 1 &lt;IL 3 &lt;IL 2 , for example. The threshold is set based on the before-reversal image signal acquired by the reading apparatus  1  before actual operation, and is stored in advance in the image processing unit  81  of the reading apparatus  1 , for example. The luminance value for the detected radiograph included in the before-reversal image signal is greater than the luminance value for the unexposed region image included in the before-reversal image signal (see  FIG.  15   ), so that the threshold is smaller than the luminance value for the detected radiograph included in the before-reversal image signal. 
     The threshold is set as described above, so that each of luminance values for a portion of the binarized image corresponding to the IP image region outside region is “0”. Each of luminance values for a portion of the binarized image corresponding to the imaging plate  10  is “1” regardless of whether the unexposed portion is included in the imaging plate  10 . 
       FIG.  21    is a schematic diagram showing one example of a binarized image  500 .  FIG.  21    shows the binarized image  500  acquired by binarizing the before-reversal whole image  100   a  shown in  FIG.  20   . In  FIG.  21   , a region (also referred to as a high luminance region)  501  of the binarized image  500  where the luminance value is “1” is shown in white, and a region (also referred to as a low luminance region)  502  of the binarized image  500  where the luminance value is “0” is shown in black. As can be understood from  FIG.  21   , the high luminance region  501  corresponds to the imaging plate  10 , and the low luminance region  502  corresponds to the IP image region outside region in the binarized image  500 . An outline of the high luminance region  501  has a shape responsive to an outline of the imaging plate  10 . An image (also referred to as a high luminance region image) in the high luminance region  501  is the IP image, and an image (also referred to as a low luminance region image) in the low luminance region  502  is the IP image region outside region image. 
     The shape of the imaging plate  10  is referred to as an imaging plate shape, and data on the imaging plate shape (i.e., data representing the imaging plate shape) is referred to as imaging plate shape data. The imaging plate shape data can include at least one of the size, the shape, and a tilt of the imaging plate  10  and the like. Processing of extracting the imaging plate shape may be referred to as imaging plate shape extraction processing. The imaging plate shape data can be acquired in the imaging plate shape extraction processing. An image, such as the before-reversal whole image  100   a  in  FIG.  20   , acquired by radiography of the imaging plate  10  is referred to as an imaging plate captured image. 
     An image, such as the binarized image  500  in  FIG.  21   , representing the imaging plate shape acquired by performing processing on an image acquired as a result of detection of the acted light generated by irradiation of the imaging plate  10  with light is referred to as an imaging plate shape image. An image, such as the image in the high luminance region  501  in  FIG.  21   , formed by extracting the imaging plate shape by performing processing on the IP acted light is referred to as an IP imaging plate shape image. The imaging plate shape image and the IP imaging plate shape image are each an image representing the imaging plate shape extracted by performing processing on the IP acted light image signal, and thus may each be referred to as an imaging plate shape extraction image. 
     The high luminance region  501  included in the binarized image  500  herein corresponds to the IP corresponding portion  105   a  included in the before-reversal whole image  100   a.  In the tilt angle identification processing, the image processing unit  81  performs the principal component analysis in which positions of a plurality of pixels constituting the high luminance region  501  included in the generated binarized image  500  are data to be analyzed to acquire a first principal component axis of the data to be analyzed. 
     In the principal component analysis, the image processing unit  81  determines a center of gravity  501   a  (see  FIG.  21   ) of the high luminance region  501  included in the binarized image  500 . The image processing unit  81  sets an XY coordinate system with the center of gravity  501   a  as the origin to the binarized image  500  as shown in  FIG.  21   . Assume that an X axis is parallel to a transverse direction of the before-reversal whole image  100   a,  and a Y axis is parallel to a longitudinal direction of the before-reversal whole image  100   a  in this case. As will be described below, the image processing unit  81  rotates the XY coordinate system about the center of gravity  501   a.  Assume that an angle of clockwise rotation of the XY coordinate system is a positive angle, and an angle of counterclockwise rotation of the XY coordinate system is a negative angle in this example. An orientation of the XY coordinate system in which the X axis is parallel to the transverse direction of the before-reversal whole image  100   a  and the Y axis is parallel to the longitudinal direction of the before-reversal whole image  100   a  is referred to as an initial orientation. 
     When setting the XY coordinate system in the initial orientation to the binarized image  500 , the image processing unit  81  determines a length L of a perpendicular from a position  510  of each of the plurality of pixels constituting the high luminance region  501  to the Y axis. Next, the image processing unit  81  determines a variance of a plurality of lengths L determined for respective pixels constituting the high luminance region  501 . The variance is referred to as a variance in the initial orientation. 
     The image processing unit  81  performs clockwise processing of rotating the XY coordinate system about the center of gravity  501   a  clockwise  520 R from the initial orientation by 0.1 degrees at a time, and determining the variance of the plurality of lengths L each time the XY coordinate system is rotated by 0.1 degrees. In the clockwise processing, the image processing unit  81  eventually rotates the XY coordinate system clockwise  520 R by 90 degrees, for example. The image processing unit  81  also performs counterclockwise processing of rotating the XY coordinate system about the center of gravity  501   a  counterclockwise  520 L from the initial orientation by 0.1 degrees at a time, and determining the variance of the plurality of lengths L each time the XY coordinate system is rotated by 0.1 degrees. In the counterclockwise processing, the image processing unit  81  eventually rotates the XY coordinate system counterclockwise  520 L by 90 degrees, for example. 
     When performing the clockwise processing and the counterclockwise processing, the image processing unit  81  identifies a minimum value of the variances determined by the clockwise processing and the counterclockwise processing and the variance in the initial orientation. The image processing unit  81  sets the Y axis of the XY coordinate system when the identified minimum value is acquired to the first principal component axis. It can be said that the first principal component axis is an axis to minimize the variance of the lengths of the perpendiculars from respective positions of the plurality of pixels constituting the high luminance region  501 . An axis being perpendicular to the first principal component axis and passing through the center of gravity  501   a  is hereinafter also referred to as a second principal component axis. The XY coordinate system when the minimum value of the variances determined by the clockwise processing and the counterclockwise processing and the variance in the initial orientation is determined is also referred to as an XY coordinate system in a minimum variance orientation. 
       FIG.  22    is a schematic diagram showing a first principal component axis  551  acquired from the binarized image  500  shown in  FIG.  21   . The Y axis of the XY coordinate system in the initial orientation is indicated by a dashed line in  FIG.  22   . As shown in  FIG.  22   , the first principal component axis  551  matches a longitudinal direction of the high luminance region  501 . When determining the first principal component axis  551 , the image processing unit  81  determines the rotation angle α of the XY coordinate system having the Y axis matching the first principal component axis  551 , that is, the XY coordinate system in the minimum variance orientation from the initial orientation. The image processing unit  81  sets the determined rotation angle α to the tilt angle α of the longitudinal direction of the IP corresponding portion relative to the longitudinal direction of the acquired whole image. The Y axis of the XY coordinate system in the initial orientation corresponds to the longitudinal direction of the acquired whole image, and the first principal component axis  551  (i.e., the Y axis of the XY coordinate system in the minimum variance orientation) corresponds to the longitudinal direction of the IP corresponding portion included in the acquired whole image. It can thus be said that the rotation angle α is the tilt angle of the longitudinal direction of the IP corresponding portion relative to the longitudinal direction of the acquired whole image. The rotation angle α has a positive value when the XY coordinate system in the minimum variance orientation is acquired by the clockwise processing, and has a negative value when the XY coordinate system in the minimum variance orientation is acquired by the counterclockwise processing. The rotation angle α is zero when the XY coordinate system in the minimum variance orientation matches the XY coordinate system in the initial orientation. 
     The image processing unit  81  determines the tilt angle α of the longitudinal direction of the IP corresponding portion relative to the longitudinal direction of the acquired whole image from the binarized image  500  of the acquired whole image as described above, and sets the determined tilt angle α to the IP tilt angle α. When the imaging plate  10  is viewed from a side of the front surface thereof in plan view, the imaging plate  10  tilts clockwise relative to the reference orientation when the IP tilt angle α is a positive angle, and tilts counterclockwise relative to the reference orientation when the IP tilt angle α is a negative angle. As for the tilt of the imaging plate  10 , a clockwise tilt hereinafter simply refers to a clockwise tilt when the imaging plate  10  is viewed from a side of the front surface thereof, and a counterclockwise tilt hereinafter simply refers to a counterclockwise tilt when the imaging plate  10  is viewed from a side of the front surface thereof. 
     The tilt angle identification processing as described above may be performed during the above-mentioned series of processes shown in  FIG.  18   , or may be performed at a different time from the processing shown in  FIG.  18   . The IP tilt angle determined by the image processing unit  81  may be displayed by the display  3 . In this case, the display  3  may display the IP tilt angle simultaneously with the acquired whole image in the above-mentioned step s 7 , or may display the IP tilt angle when the acquired whole image is not displayed. 
     Instead of calculating variances as described above each time, a covariance σXY may be determined in addition to variances σX 2  and σY 2  in the initial orientation, and may be used to calculate a variance after rotation. 
     As described above, in this example, the image processing unit  81  identifies the IP tilt angle based on the image signal as a result of detection of the emitted light L 2  and the reflected light from the imaging plate  10 , and thus can properly identify the IP tilt angle. 
     Consider a case where the sensor  41  cannot detect the reflected light, and the imaging plate  10  includes the unexposed portion, for example. In this case, luminance values for the unexposed region image and the IP image region outside region image included in the before-reversal whole image based on the image signal from the sensor  41  are each zero. Thus, in the binarized image  500  acquired by binarizing the before-reversal whole image, luminance values for portions corresponding to the unexposed region image and the IP image region outside region image are each “0”, and the portions corresponding to the unexposed region image and the IP image region outside region image are each the low luminance region  502 . When the imaging plate  10  includes the unexposed portion, the high luminance region  501  of the binarized image  500  does not include the portion corresponding to the unexposed portion, and the high luminance region  501  does not correspond to the IP corresponding portion included in the before-reversal whole image. That is to say, when the imaging plate  10  includes the unexposed portion, the outline of the high luminance region  501  does not have the shape responsive to the outline of the imaging plate  10 . Thus, when performing the principal component analysis on the high luminance region  501 , the image processing unit  81  sometimes cannot determine the first principal component axis corresponding to the longitudinal direction of the imaging plate  10 , and cannot properly determine the tilt angle of the longitudinal direction of the IP corresponding portion relative to the longitudinal direction of the acquired whole image. 
     In contrast, in this example, the sensor  41  can detect the reflected light to some extent, and the image processing unit  81  binarizes the before-reversal whole image based on the image signal as a result of detection of the photostimulated light L 5  and the reflected light from the imaging plate  10  to generate the binarized image  500 . Thus, in the binarized image  500 , the high luminance region  501  corresponds to the IP corresponding portion (i.e., the IP image) included in the before-reversal whole image as shown in  FIGS.  21  and  22    even when the imaging plate  10  includes the unexposed portion. That is to say, the outline of the high luminance region  501  has the shape responsive to the outline of the imaging plate  10 . For example, the binarized image in which the unexposed region is included in the IP image region as shown in  FIGS.  21  and  22    can be acquired by binarization processing even from the before-reversal whole image  100   a  including the unexposed region image  103   a  as shown in  FIG.  15   . Thus, when performing the principal component analysis on the high luminance region  501 , the image processing unit  81  can determine the first principal component axis corresponding to the longitudinal direction of the imaging plate  10 , and can properly determine the tilt angle of the longitudinal direction of the IP corresponding portion relative to the longitudinal direction of the acquired whole image. The image processing unit  81  can thus properly identify the IP tilt angle. An image, such as the image in the high luminance region  501 , acquired by performing the binarization processing on the IP image may be referred to as an IP binarized image. 
     &lt;Identification of Size of Imaging Plate&gt; 
     The image processing unit  81  may perform size identification processing of identifying the size (also referred to as an IP size) of the imaging plate  10 , for example. In the size identification processing, the image processing unit  81  identifies the IP size based on the image signal output from the detector  40 , for example. The image processing unit  81  functions as an identification unit (also referred to as a size identification unit) that identifies the IP size. While a specific example of the size identification processing will be described below, the size identification processing is not limited to that in the example described below. 
     The image processing unit  81  binarizes the before-reversal whole image based on the before-reversal image signal to generate the binarized image  500  similarly to the foregoing, for example. The image processing unit  81  identifies the IP size based on the generated binarized image  500 . For example, the image processing unit  81  numerically identifies a size in the longitudinal direction (also referred to as a longitudinal size) of the imaging plate  10  and a size in the transverse direction (also referred to as a transverse size) of the imaging plate  10 . 
     When identifying the IP size, the image processing unit  81  performs the principal component analysis in which the positions of the plurality of pixels constituting the high luminance region  501  included in the binarized image  500  are the data to be analyzed to acquire the first principal component axis  551  of the data to be analyzed similarly to the foregoing. The image processing unit  81  acquires a second principal component axis  552  being perpendicular to the first principal component axis  551  and passing through the center of gravity  501   a.    
       FIG.  23    is a schematic diagram showing one example of the first principal component axis  551  and the second principal component axis  552 .  FIG.  23    shows the binarized image  500  acquired by binarizing the before-reversal whole image  100   a  shown in  FIG.  14    described above and the first principal component axis  551  and the second principal component axis  552  acquired based on the binarized image  500 . The first principal component axis  551  is parallel to the longitudinal direction of the high luminance region  501  corresponding to the imaging plate  10 . The second principal component axis  552  is parallel to the transverse direction of the high luminance region  501 . 
     As shown in  FIG.  23   , the image processing unit  81  acquires the number of pixels (also referred to as the number of pixels in the longitudinal direction) N 1  along the first principal component axis  551  of the high luminance region  501 . The image processing unit  81  also acquires the number of pixels (also referred to as the number of pixels in the transverse direction) N 2  along the second principal component axis  552  of the high luminance region  501 . The image processing unit  81  acquires the longitudinal size of the imaging plate  10  based on the number of pixels N 1  in the longitudinal direction, and acquires the transverse size of the imaging plate  10  based on the number of pixels N 2  in the transverse direction. 
     A square region M mm on a side in the detection range R 110  of the sensor  41  herein corresponds to a single pixel of the acquired whole image and the binarized image  500  in this example. M mm is approximately 0.03 mm, for example. The image processing unit  81  sets a length obtained by multiplying the number of pixels N 1  in the longitudinal direction by M mm to the longitudinal size of the imaging plate  10 . The image processing unit  81  also sets a length obtained by multiplying the number of pixels N 2  in the transverse direction by M mm to the transverse size of the imaging plate  10 . The longitudinal size and the transverse size of the imaging plate  10  determined by the image processing unit  81  are hereinafter also referred to as an identified longitudinal size and an identified transverse size. 
     The image processing unit  81  may numerically identify the area of the main surface (also referred to as a main surface area) of the imaging plate  10  in the size identification processing. In this case, the image processing unit  81  may set a value obtained by multiplying the square of M mm by the total number of pixels constituting the high luminance region  501  to the main surface area of the imaging plate  10 . It can be said that the main surface area is the area of the front surface of the imaging plate  10 , and is the area of the back surface of the imaging plate  10 . The main surface area of the imaging plate  10  determined by the image processing unit  81  is hereinafter also referred to as an identified main surface area or an identified area. 
     The image processing unit  81  may identify a type of the size of the imaging plate  10  in the size identification processing. A plurality of types of sizes are prepared as the size of the imaging plate  10  in this example. In the reading apparatus  1 , the holder  20  can hold each of imaging plates  10  of the plurality of types of sizes. The reading apparatus  1  can read a radiograph from each of the imaging plates  10  of the plurality of types of sizes. 
       FIG.  24    shows one example of the types of sizes (also referred to as types of IP sizes) of the imaging plate  10 . Four types of sizes, including Size 0, Size 1, Size 2, and Size 3, are prepared as the types of IP sizes, for example. The transverse size and the longitudinal size of the imaging plate  10  of each of the types of sizes are herein respectively referred to as a nominal transverse size and a nominal longitudinal size. Sizes commonly used by many manufacturing entities and/or sizes determined by public standards may be used as the nominal transverse size and the nominal longitudinal size. 
     For example, the nominal transverse size and the nominal longitudinal size for Size 0 are respectively 22 mm and 31 mm according to the International Organization for Standardization (ISO) standard. The nominal transverse size and the nominal longitudinal size for Size 0 are respectively 21 mm and 35 mm in some cases. The nominal transverse size and the nominal longitudinal size for Size 1 are respectively 24 mm and 40 mm. The nominal transverse size and the nominal longitudinal size for Size 2 are respectively 31 mm and 41 mm. The nominal transverse size and the nominal longitudinal size for Size 3 are respectively 27 mm and 54 mm. A value obtained by multiplying the nominal transverse size and the nominal longitudinal size is referred to as a nominal main surface area or a nominal area. 
     The image processing unit  81  identifies the type of the size of the imaging plate  10  based on the identified transverse size, the identified longitudinal size, and the identified main surface area of the imaging plate  10 , for example. For example, when the identified transverse size is close to the nominal transverse size for Size 0, the identified longitudinal size is close to the nominal longitudinal size for Size 0, and the identified area is close to the nominal area for Size 0, the image processing unit  81  determines that the type of the IP size is Size 0. 
     The image processing unit  81  determines whether the identified transverse size is close to the nominal transverse size for Size 0 using a first threshold slightly smaller than the nominal transverse size for Size 0 and a second threshold slightly greater than the nominal transverse size for Size 0, for example. The image processing unit  81  determines that the identified transverse size is close to the nominal transverse size for Size 0 when the identified transverse size is greater than the first threshold and is smaller than the second threshold, for example. 
     The image processing unit  81  determines whether the identified longitudinal size is close to the nominal longitudinal size for Size 0 using a third threshold slightly smaller than the nominal longitudinal size for Size 0 and a fourth threshold slightly greater than the nominal longitudinal size for Size 0, for example. The image processing unit  81  determines that the identified longitudinal size is close to the nominal longitudinal size for Size 0 when the identified longitudinal size is greater than the third threshold and is smaller than the fourth threshold, for example. 
     The image processing unit  81  determines whether the identified area is close to the nominal area for Size 0 using a fifth threshold slightly smaller than the nominal area for Size 0 and a sixth threshold slightly greater than the nominal area for Size 0, for example. The image processing unit  81  determines that the identified area is close to the nominal area for Size 0 when the identified area is greater than the fifth threshold and is smaller than the sixth threshold, for example. 
     For example, when the identified transverse size is close to the nominal transverse size for Size 1, the identified longitudinal size is close to the nominal longitudinal size for Size 1, and the identified main surface area is close to the nominal main surface area for Size 1, the image processing unit  81  similarly determines that the type of the IP size is Size 1. 
     For example, when the identified transverse size is close to the nominal transverse size for Size 2, the identified longitudinal size is close to the nominal longitudinal size for Size 2, and the identified main surface area is close to the nominal main surface area for Size 2, the image processing unit  81  similarly determines that the type of the IP size is Size 2. 
     For example, when the identified transverse size is close to the nominal transverse size for Size 3, the identified longitudinal size is close to the nominal longitudinal size for Size 3, and the identified main surface area is close to the nominal main surface area for Size 3, the image processing unit  81  similarly determines that the type of the IP size is Size 3. 
     The size identification processing as described above may be performed during the above-mentioned series of processes shown in  FIG.  18   , or may be performed at a different time from the processing shown in  FIG.  18   . The display  3  may display at least one of the transverse size, the longitudinal size, the main surface area, and the type of the IP size identified by the image processing unit  81 , for example. In this case, the display  3  may display at least one of the transverse size, the longitudinal size, the main surface area, and the type of the IP size simultaneously with the acquired whole image in the above-mentioned step s 7 , or may display at least one of the transverse size, the longitudinal size, the main surface area, and the type of the IP size when the acquired whole image is not displayed, for example. The display  3  may display at least one of the transverse size, the longitudinal size, the main surface area, and the type of the IP size simultaneously with the IP tilt angle, or may display at least one of the transverse size, the longitudinal size, the main surface area, and the type of the IP size when the IP tilt angle is not displayed. The display  3  may simultaneously display at least two of the transverse size, the longitudinal size, the main surface area, and the type of the IP size. 
     As described above, in this example, the image processing unit  81  identifies the IP size based on the image signal as a result of detection of the emitted light L 2  and the reflected light from the imaging plate  10 , and thus can properly identify the IP size as in a case where the IP tilt angle is identified. As descried above, even when the imaging plate  10  includes the unexposed portion, the high luminance region  501  of the binarized image  500  corresponds to the IP corresponding portion of the before-reversal whole image, so that the image processing unit  81  can properly identify the transverse size, the longitudinal size, the main surface area, and the type of the IP size of the imaging plate  10 . 
     An example of setting of the excitation light irradiation range R 120  will be described in connection with description of the nominal transverse size and the nominal longitudinal size.  FIG.  25    schematically shows imaging plates  10  of Sizes 0 to 3. Positions of four sides of each of the imaging plates  10  in plan view of the imaging plate  10  are herein represented by upper, lower, left, and right positions. The holder  20  is commonly used for the imaging plates  10  of the plurality of sizes, for example. The holder  20  holds each of the imaging plates  10  so that left sides or right sides of the imaging plates  10  of the plurality of sizes are located in the same line, and upper sides or lower sides of the imaging plates  10  of the plurality of sizes are located in the same line as shown in  FIG.  25   , for example. 
     The longitudinal size of the imaging plate  10  for Size 3 is greater than the longitudinal size of the imaging plate  10  for Size 2, but the transverse size of the imaging plate  10  for Size 3 is smaller than the transverse size of the imaging plate  10  for Size 2. The excitation light irradiation range R 120  is set to have a longitudinal size equal to or greater than a maximum longitudinal size of longitudinal sizes for the plurality of IP sizes and have a transverse size equal to or greater than a maximum transverse size of transverse sizes for the plurality of IP sizes to suit each of the imaging plates  10  of the plurality of sizes as described above, for example. The excitation light irradiation range R 120  set as described above may be used for the imaging plate  10  of any of the plurality of IP sizes regardless of the IP size of the imaging plate  10 . 
     The excitation light irradiation range R 120  may be changed for each of the imaging plates  10 . In this case, the excitation light irradiation range R 120  may be set to at least have a longitudinal size equal to or greater than the maximum longitudinal size of the longitudinal sizes for the plurality of IP sizes and have a transverse size equal to or greater than the maximum transverse size of the transverse sizes for the plurality of IP sizes. 
       FIG.  26    is a flowchart showing one example of a series of operations of the image processing unit  81  when the image processing unit  81  identifies the IP tilt angle and the IP size. A series of processes shown in  FIG.  26    may be performed during the above-mentioned series of processes shown in  FIG.  18   , or may be performed at a different time from the processing shown in  FIG.  18   . 
     As shown in  FIG.  26   , in step s 11 , the image processing unit  81  binarizes the before-reversal whole image based on the before-reversal image signal to generate the binarized image  500 . Next, in step s 12 , the image processing unit  81  identifies the main surface area of the imaging plate  10  based on the binarized image  500  as described above. Next, in step s 13 , the image processing unit  81  performs the principal component analysis in which the positions of the plurality of pixels constituting the high luminance region  501  included in the binarized image  500  are the data to be analyzed to acquire the first principal component axis and the second principal component axis of the data to be analyzed. 
     Next, in step s 14 , the image processing unit  81  identifies the IP tilt angle and the transverse size and the longitudinal size of the imaging plate  10  based on the binarized image  500 , the first principal component axis, and the second principal component axis as described above. Next, in step s 15 , the image processing unit  81  determines whether the type of the IP size is Size 3 based on the identified transverse size, the identified longitudinal size, and the identified area. In step s 15 , the image processing unit  81  determines that the type of the IP size is Size 3 when the identified transverse size is close to the nominal transverse size for Size 3, the identified longitudinal size is close to the nominal longitudinal size for Size 3, and the identified area is close to the nominal area for Size 3 as described above, for example. 
     When affirmative determination is made in step s 15 , processing shown in  FIG.  26    ends. On the other hand, when negative determination is made in step s 15 , step s 16  is performed. In step s 16 , the image processing unit  81  determines whether the type of the IP size is Size 2 based on the identified transverse size, the identified longitudinal size, and the identified area. In step s 16 , the image processing unit  81  determines that the type of the IP size is Size 2 when the identified transverse size is close to the nominal transverse size for Size 2, the identified longitudinal size is close to the nominal longitudinal size for Size 2, and the identified area is close to the nominal area for Size 2 as described above, for example. 
     When affirmative determination is made in step s 16 , processing shown in  FIG.  26    ends. On the other hand, when negative determination is made in step s 16 , step s 17  is performed. In step s 17 , the image processing unit  81  determines whether the type of the IP size is Size 1 based on the identified transverse size, the identified longitudinal size, and the identified area. In step s 17 , the image processing unit  81  determines that the type of the IP size is Size 1 when the identified transverse size is close to the nominal transverse size for Size 1, the identified longitudinal size is close to the nominal longitudinal size for Size 1, and the identified area is close to the nominal area for Size 1 as described above, for example. 
     When affirmative determination is made in step s 17 , processing shown in  FIG.  26    ends. On the other hand, when negative determination is made in step s 17 , step s 18  is performed. In step s 18 , the image processing unit  81  determines that the type of the IP size is Size 0. After step s 18  is performed, processing shown in  FIG.  26    ends. In step s 18 , the image processing unit  81  may determine whether the type of the IP size is Size 0 based on the identified transverse size, the identified longitudinal size, and the identified area as in steps s 15  to s 17 . 
     While the image processing unit  81  identifies the type of the IP size based on the identified transverse size, the identified longitudinal size, and the identified area in the above-mentioned example, the type of the IP size can be identified based on one of the identified transverse size, the identified longitudinal size, and the identified area. As shown in  FIG.  24   , the nominal transverse size and the nominal longitudinal size each differ among the plurality of types of sizes in this example. The nominal area also differs among the plurality of types of sizes. The image processing unit  81  may set one of Sizes 0 to 3 having the nominal transverse size closest to the identified transverse size to the type of the size of the imaging plate  10 . The image processing unit  81  may set one of Sizes 0 to 3 having the nominal longitudinal size closest to the identified longitudinal size to the type of the size of the imaging plate  10 . The image processing unit  81  may set one of Sizes 0 to 3 having the nominal area closest to the identified area to the type of the size of the imaging plate  10 . 
     The image processing unit  81  may identify the type of the IP size based on two of the identified transverse size, the identified longitudinal size, and the identified area. For example, when the identified transverse size is close to the nominal transverse size for Size 1, and the identified longitudinal size is close to the nominal longitudinal size for Size 1, the image processing unit  81  may determine that the type of the IP size is Size 1. 
     In the size identification processing, the longitudinal size of the imaging plate  10  may not be identified, the transverse size of the imaging plate  10  may not be identified, and the main surface area of the imaging plate  10  may not be identified. The type of the size of the imaging plate  10  may not be identified in the size identification processing. 
     The reading apparatus  1  may have a configuration in which the user can identify the IP size through selection in addition to or in place of a configuration in which the image processing unit  81  identifies the IP size. The reading apparatus  1  may be configured to be switchable between the configuration in which the image processing unit  81  identifies the IP size and the configuration in which the user identifies the IP size through selection. In this case, whether to receive selection by the user is determined between steps s 13  and s 14 , and, when affirmative determination is made, the selection by the user is received, and then the image processing unit  81  identifies the IP tilt angle without identifying the IP size, for example. 
     &lt;Irradiation of Erased Imaging Plate with Excitation Light&gt; 
     In the reading apparatus  1 , the light source  30  may irradiate the erased imaging plate  10  with the excitation light L 10 , and the detector  40  may detect the reflected light L 40  from the erased imaging plate  10  to acquire a reflected light image in which the imaging plate  10  appears. In this case, the detector  40  also detects the reflected light L 400  from the in-irradiation range IP image region outside region R 130  in this example. In this example, the detector  40  detects the reflected light of the excitation light L 10  from the erased imaging plate  10  and the in-irradiation range IP image region outside region R 130 , and outputs an image signal as a result of detection. An example of operation of the reading apparatus  1  that irradiates the erased imaging plate  10  with the excitation light L 10  will be described below. 
     An image signal as a result of detection of the photostimulated light L 5  or the photostimulated light L 5  and the reflected light (excited region light L 20 ) when the imaging plate  10  on which the radiograph is recorded is held as with the image signal having been described so far is hereinafter referred to as a light emission-time image signal. A whole image including the radiograph, that is, a whole image based on the light emission-time image signal as with the acquired whole image having been described so far is referred to as a light emission-time whole image. The light emission-time whole image is one example of the biological radiographically captured image. The before-reversal whole image and the after-reversal whole image described above are respectively referred to as a before-reversal light emission-time whole image and an after-reversal light emission-time whole image. 
     Portions of the light emission-time image signal, the light emission-time whole image, the before-reversal light emission-time whole image, and the after-reversal light emission-time whole image representing the image of the imaging plate  10 , that is, the IP image may respectively be referred to as a light emission-time IP image signal, a light emission-time IP image, a before-reversal light emission-time IP image, and an after-reversal light emission-time IP image. The light emission-time IP image is one example of the IP biological radiographically captured image. When the imaging plate  10  includes the cone cut, the light emission-time IP image includes the IP excited region light image and the IP reflected light image (i.e., the IP non-photostimulable reflected light image). The light emission-time image signal may be defined as an image signal as a result of detection (acquisition of the biological radiographically captured image) when the imaging plate  10  held to read the radiograph is irradiated with the excitation light L 10 , that is, in a reading mode of reading the radiograph as in a case where step s 2  is performed. In this case, when the cone cut extends across the whole region of the imaging plate  10 , the light emission-time IP image (IP biological radiographically captured image) includes only the IP reflected light image (i.e., the IP non-photostimulable reflected light image). 
     An image signal as a result of detection of reflected light of light when the erased imaging plate  10  is held is referred to as an erasing-time image signal. A whole image based on the erasing-time image signal is referred to as an erasing-time whole image. In this example, the erasing-time whole image includes not only the reflected light image of the imaging plate  10 , that is, the reflected light image based on detection of the reflected light L 40  of the excitation light L 10  from the imaging plate  10  but also the IP image region outside region image, and does not include the radiograph. It can be said that the erasing-time whole image is the reflected light image in the detection range R 110  of the sensor  41 . The reflected light image of the erased imaging plate  10 , that is, the IP reflected light image representing the whole image of the imaging plate  10  is sometimes particularly referred to as an IP whole reflected light image. The reading apparatus  1  will be described below based on the assumption that the whole image based on the image signal output from the detector  40  as a result of detection of light is the acquired whole image. In description made below, the acquired whole image includes the light emission-time whole image and the erasing-time whole image. 
       FIG.  27    is a flowchart showing one example of operation of the reading apparatus  1  in this example. When the start button included in the operation unit  4  is operated, the reading apparatus  1  performs the above-mentioned steps s 1  to s 4  as shown in  FIG.  27   . In the reading processing in step s 2 , the detector  40  outputs the light emission-time image signal as a result of detection of the emitted light L 2  and the reflected light. 
     After the erasing processing in step s 4 , the driver  50  moves the holder  20  holding the erased imaging plate  10  to the reading start position in step s 21 . Step s 22  is performed next. In step s 22 , the light source  30  irradiates the front surface of the erased imaging plate  10  and the IP image region outside region with the excitation light L 10 . The detector  40  detects the reflected light of the excitation light L 10  from the front surface of the erased imaging plate  10  and the IP image region outside region, and outputs the erasing-time image signal as a result of detection. The erasing-time image signal is a gray-scale image signal as with the light emission-time image signal, for example. 
     After step s 22 , the above-mentioned steps s 5  and s 6  are performed to discharge the erased imaging plate  10  to the outlet  2   b  of the housing  2 . Next, in step s 27 , the display control unit  82  causes the display  3  to simultaneously and separately display the light emission-time whole image based on the light emission-time image signal acquired in step s 2  and the erasing-time whole image based on the erasing-time image signal acquired in step s 22 . In step s 27 , the image processing unit  81  displays the light emission-time whole image and the erasing-time whole image in grayscale, for example. 
     Step s 27  may be performed at any time after step s 22 . For example, step s 27  may be performed between step s 22  and step s 5 . The light emission-time whole image and the erasing-time whole image may not simultaneously be displayed. The light emission-time whole image may not be displayed in step s 27 . At least one of the size identification processing and the tilt angle identification processing described above may be performed during a series of processes shown in  FIG.  27   , or may be performed at a different time from the processing shown in  FIG.  27   . 
     The erasing-time image signal output from the detector  40  includes luminance values of a plurality of pixels constituting the IP whole reflected light image (i.e., the IP image) and luminance values of a plurality of pixels constituting the IP image region outside region image. The luminance values included in the erasing-time image signal are greater when the reflected light detected by the detector  40  has a higher intensity. Thus, when the reflected light has a higher intensity in a certain region of the erased imaging plate  10 , for example, luminance of the reflected light image in the certain region included in the erasing-time image signal is greater. 
       FIG.  28    is a schematic diagram showing one example of the erasing-time whole image  200 . As shown in  FIG.  28   , the erasing-time whole image  200  includes the IP whole reflected light image  201  and the IP image region outside region image  202 . In the example of  FIG.  28   , the front surface of the imaging plate  10  appears in the IP whole reflected light image  201 . The IP whole reflected light image  201  is a portion of the erasing-time whole image  200  corresponding to the imaging plate  10 , so that the IP whole reflected light image is also referred to as the IP corresponding portion. The IP whole reflected light image  201  is also the IP image, and is also the IP non-photostimulable reflected light image. 
     The image processing unit  81  performs image processing on the erasing-time image signal. In this example, the luminance reversal processing is not performed in the image processing performed on the erasing-time image signal, for example, in contrast to the image processing performed on the light emission-time image signal. Thus, when the reflected light has a higher intensity in a certain region of the imaging plate  10 , a luminance value of the reflected light image in the certain region included in the erasing-time image signal after the image processing is greater as with that included in the erasing-time image signal before the image processing. On the other hand, when the reflected light has a lower intensity in a certain region of the imaging plate  10 , the reflected light image in the certain region has a smaller luminance value. The erasing-time whole image  200  based on the erasing-time image signal on which the image processing not including the luminance reversal processing has been performed is hereinafter also referred to as a before-reversal erasing-time whole image  200 . 
     The luminance reversal processing may be performed in the image processing performed on the erasing-time image signal. In this case, the erasing-time whole image based on the erasing-time image signal on which the image processing including the luminance reversal processing has been performed may be referred to as an after-reversal erasing-time whole image. The erasing-time whole image may include both the before-reversal erasing-time whole image and the after-reversal erasing-time whole image. The after-reversal erasing-time whole image may be used in place of the before-reversal erasing-time whole image  200 . 
     Portions of the erasing-time image signal, the erasing-time whole image, the before-reversal erasing-time whole image, and the after-reversal erasing-time whole image representing the image of the imaging plate  10  may respectively be referred to as an erasing-time IP image signal, an erasing-time IP image, a before-reversal erasing-time IP image, and an after-reversal erasing-time IP image. 
     In step s 27 , the display control unit  82  may cause the display  3  to display the after-reversal light emission-time whole image  100   b  and the before-reversal erasing-time whole image  200  in grayscale, for example. In this case, the display  3  may display the after-reversal light emission-time whole image  100   b  in grayscale as shown in  FIGS.  16  and  17    described above, and display the before-reversal erasing-time whole image  200  in grayscale as shown in  FIG.  28    described above. 
       FIGS.  29  and  30    are schematic diagrams each showing one example of display of the after-reversal light emission-time whole image  100   b  and the before-reversal erasing-time whole image  200  on a display surface  3   a  of the display  3 .  FIG.  29    shows the after-reversal light emission-time whole image  100   b  and the before-reversal erasing-time whole image  200  when the imaging plate  10  does not include the unexposed portion.  FIG.  30    shows the after-reversal light emission-time whole image  100   b  and the before-reversal erasing-time whole image  200  when the imaging plate  10  includes the unexposed portion. 
     As shown in  FIGS.  29  and  30   , the display  3  may display the after-reversal light emission-time whole image  100   b  and the before-reversal erasing-time whole image  200  in the same size and side by side, for example. In this example, an image having a greater luminance value is displayed by the display  3  to be brighter, so that a portion where the teeth appear (i.e., the IP excited region light image) and the unexposed region image (i.e., the IP reflected light image or the IP non-photostimulable reflected light image)  103   b  of the after-reversal light emission-time whole image  100   b  are displayed to be brighter, for example. A portion where the imaging plate  10  appears of the before-reversal erasing-time whole image  200  is displayed to be brighter. 
     A position of an outer edge of the radiograph  101   b  relative to an outer edge of the after-reversal light emission-time whole image  100   b  and a position of an outer edge of the IP whole reflected light image  201  relative to an outer edge of the before-reversal erasing-time whole image  200  preferably correspond to each other in display. As described above, a position of an outer edge of the IP biological radiographically captured image relative to an outer edge of the biological radiographically captured image and a position of an outer edge of the IP imaging plate shape image relative to an outer edge of the imaging plate shape image may correspond to each other. A match between a position of radiography of the biological radiographically captured image and a position of radiography of the imaging plate shape image facilitates corresponding arrangements in the image processing. Even if there is a difference between these positions of radiography, knowing and calculating the difference allow for the corresponding arrangements in the image processing. 
     In place of the before-reversal erasing-time whole image  200  displayed side by side with the after-reversal light emission-time whole image  100   b,  an image formed by extracting only the IP whole reflected light image  201 , that is, the IP imaging plate shape image may be displayed side by side with the after-reversal light emission-time whole image  100   b.    
     As shown in  FIGS.  29  and  30   , the before-reversal erasing-time whole image  200  when the imaging plate  10  includes the unexposed portion and the before-reversal erasing-time whole image  200  when the imaging plate  10  does not include the unexposed portion are the same. The user can check the before-reversal erasing-time whole image  200  (i.e., the erasing-time whole image) displayed by the display  3  for appearance of the imaging plate  10 . A method of displaying the after-reversal light emission-time whole image  100   b  and the before-reversal erasing-time whole image  200  is not limited to that in the examples of  FIGS.  29  and  30   . 
     In the above-mentioned example of  FIG.  27   , the detector  40  detects the excited region light L 20  from the imaging plate  10  excited by the excitation light L 10  from the light source  30 , and outputs the light emission-time image signal as a result of detection. Then, after the radiograph is erased from the imaging plate  10 , the erased imaging plate  10  is irradiated with the excitation light L 10  from the light source  30 , and the detector  40  detects the reflected light of the excitation light L 10  from the imaging plate  10 . The reading apparatus  1  can thus easily acquire both the radiograph recorded on the imaging plate  10  and the reflected light image of the imaging plate  10  using the same light source  30  and the same detector  40 . 
     When the light emission-time whole image and the erasing-time whole image are simultaneously and separately displayed as in the examples of  FIGS.  29  and  30   , the user can easily compare the light emission-time whole image and the erasing-time whole image. That is to say, the user can easily compare the radiograph read from the imaging plate  10  and the appearance of the imaging plate  10 . The user can thus easily identify the unexposed portion that can be included in the imaging plate  10 , for example. Description will be made in this respect below. 
     When the imaging plate  10  includes the unexposed portion, the radiograph is not present in a region of the light emission-time whole image corresponding to the unexposed portion. However, it is difficult for the user to determine, only from display of the light emission-time whole image, whether the radiograph is not present in the region due to failure of the reading apparatus  1  although the radiograph is actually present in the region or the radiograph is not present in the region as the imaging plate  10  includes the unexposed portion. In contrast, when the light emission-time whole image and the erasing-time whole image are simultaneously and separately displayed as in the example of  FIG.  30   , the user can check display of the light emission-time whole image for the radiograph read from the imaging plate  10 , check display of the erasing-time whole image for the appearance of the imaging plate  10 , and compare them to easily identify the unexposed portion that can be included in the imaging plate  10 . The user can also easily identify a range of the unexposed portion that can be included in the imaging plate  10 . 
     While the image processing unit  81  identifies the IP tilt angle based on the light emission-time whole image in the above-mentioned example, the IP tilt angle may be identified based on the erasing-time whole image (i.e., the reflected light image based on the erasing-time image signal). The image processing unit  81  may similarly identify the IP size based on the erasing-time whole image. 
     A configuration in which the light emission-time whole image and the erasing-time whole image are simultaneously and separately displayed as in the examples of  FIGS.  29  and  30    may be modified to a configuration in which the light emission-time whole image and an image acquired by binarizing the light emission-time whole image are simultaneously and separately displayed by replacing the erasing-time whole image with an image such as the binarized image  500  in  FIG.  21   . It can be said that the erasing-time whole image is the imaging plate shape extraction image as the erasing-time whole image is an image representing the imaging plate shape extracted by performing processing on the IP acted light image signal as with the image such as the binarized image  500 . 
     The image processing unit  81  can identify the IP tilt angle and the IP size based on the erasing-time whole image as in a case where the IP tilt angle and the IP size are identified based on the light emission-time whole image. Specifically, the image processing unit  81  binarizes the before-reversal erasing-time whole image  200  to generate a binarized image, for example. The binarized image is also referred to as a second binarized image. The binarized image acquired by binarizing the before-reversal erasing-time whole image  200  is one example of an imaging plate shape radiograph. A threshold used when the before-reversal erasing-time whole image  200  is binarized is set to be greater than a luminance value for the IP image region outside region image  202  included in the before-reversal erasing-time whole image  200  and smaller than a luminance value for the IP whole reflected light image  201  as the IP image included in the before-reversal erasing-time whole image  200 , for example. Thus, the second binarized image is similar to the binarized image of the before-reversal light emission-time whole image, and a region corresponding to the IP image region outside region and a region corresponding to the imaging plate  10  of the second binarized image are respectively the low luminance region and the high luminance region. An outline of the high luminance region of the second binarized image has a shape responsive to the outline of the imaging plate  10  regardless of an exposed or unexposed state of the imaging plate  10  before erasing. The image processing unit  81  can identify the IP tilt angle, the transverse size, the longitudinal size, and the main surface area of the imaging plate  10 , and the type of the IP size based on the second binarized image similarly to the foregoing. The IP tilt angle and the IP size are identified by the image processing unit  81  as the identification unit. As processing, processing similar to that in steps S 11  to S 18  may be performed after step S 27 . 
     As described above, even when the erasing-time image signal representing the reflected light image of the imaging plate  10  is used to identify the IP tilt angle, the IP tilt angle can properly be identified as in a case where the light emission-time image signal is used. Even when the erasing-time image signal is used to identify the IP size, the IP size can properly be identified as in a case where the light emission-time image signal is used. 
     &lt;Correction of Tilt of IP Corresponding Portion&gt; 
     When the imaging plate  10  tilts relative to the reference orientation, the IP corresponding portion (i.e., the IP image) tilts in the acquired whole image as shown in  FIG.  20    and the like. Specifically, when the imaging plate  10  tilts clockwise relative to the reference orientation, the longitudinal direction of the IP corresponding portion tilts clockwise relative to a direction (the longitudinal direction of the before-reversal whole image  100   a  in  FIG.  20   ) corresponding to the subscannig direction DRs in the acquired whole image. On the other hand, when the imaging plate  10  tilts counterclockwise relative to the reference orientation, the longitudinal direction of the IP corresponding portion tilts counterclockwise relative to the direction corresponding to the subscannig direction DRs in the acquired whole image. When the acquired whole image is displayed with the IP corresponding portion tilting, the user can have difficulty viewing the tilting IP corresponding portion. 
     The image processing unit  81  may thus perform tilt correction processing of correcting a tilt of the IP corresponding portion on the acquired whole image based on the IP tilt angle α identified based on the light emission-time whole image or the erasing-time whole image. When the acquired whole image as a target of correction is the light emission-time whole image based on detection of the emitted light L 2 , the tilt of the IP corresponding portion is corrected to correct a tilt of the radiograph included in the IP corresponding portion in the tilt correction processing. On the other hand, when the acquired whole image as the target of correction is the erasing-time whole image based on detection of the reflected light, a tilt of the IP whole reflected light image in which the imaging plate  10  appears is corrected in the tilt correction processing. The image processing unit  81  may perform the tilt correction processing on the acquired whole image based on the image signal before the luminance reversal processing, or may perform the tilt correction processing on the acquired whole image based on the image signal after the luminance reversal processing. The display  3  may display the acquired whole image after the tilt correction processing. The tilt correction processing may be performed during the series of processes shown in  FIG.  18   , or may be performed at a different time from the processing shown in  FIG.  18   . The tilt correction processing may be performed during the series of processes shown in  FIG.  27   , or may be performed at a different time from the processing shown in  FIG.  27   . It can be said that the tilt correction processing is processing of correcting the tilt of the IP corresponding portion (i.e., the IP image) in the acquired whole image in response to the tilt of the imaging plate  10  relative to the reference orientation. 
       FIG.  31    is a schematic diagram for explaining one example of the tilt correction processing. An acquired whole image  250  before the tilt correction processing is shown at the top of  FIG.  29   , and an acquired whole image  250  after the tilt correction processing is shown at the bottom of  FIG.  29   . The acquired whole image  250  as the target of correction includes an IP corresponding portion (i.e., the IP image)  251  and an IP image region outside region image  252 . In  FIG.  31   , a longitudinal direction DR 1  of the IP corresponding portion  251  is indicated by a dashed line, and a direction DR 2  corresponding to the subscannig direction DRs in the acquired whole image  250  is indicated by an alternate long and short dashed line. 
     In the tilt correction processing, the image processing unit  81  determines a center of gravity  251   a  of the IP corresponding portion  251  included in the acquired whole image  250  as the target of correction. The center of gravity  251   a  of the IP corresponding portion  251  herein matches a center of gravity of the high luminance region of the binarized image of the acquired whole image  250 . The image processing unit  81  generates the binarized image of the acquired whole image  250 , and determines the center of gravity of the high luminance region of the generated binarized image to determine the center of gravity  251   a  of the IP corresponding portion  251  of the acquired whole image  250 . Next, the image processing unit  81  rotates the acquired whole image  250  about the determined center of gravity  251   a  by the IP tilt angle α. In this case, when the IP tilt angle α is a positive angle, the image processing unit  81  rotates the acquired whole image  250  counterclockwise  255 L by the IP tilt angle α as shown in  FIG.  31   . On the other hand, when the IP tilt angle α is a negative angle, the image processing unit  81  rotates the acquired whole image  250  clockwise by the IP tilt angle α. The tilt of the IP corresponding portion  251  is thereby corrected, so that the longitudinal direction DR 1  of the IP corresponding portion  251  is parallel to the direction DR 2  corresponding to the subscannig direction DRs in the acquired whole image  250 . 
       FIG.  32    is a schematic diagram showing one example of the tilt correction processing having been performed on the before-reversal light emission-time whole image  100   a  shown in  FIG.  20    described above. As can be understood from comparison between  FIGS.  20  and  32   , the tilt of the radiograph  101   a  included in the IP corresponding portion (i.e., the IP image)  105   a  is properly corrected by the tilt correction processing performed on the before-reversal light emission-time whole image  100   a.  The orientation of the IP corresponding portion  105   a  in the before-reversal light emission-time whole image  100   a  on which the tilt correction processing has been performed is the same as the orientation of the IP corresponding portion  105   a  in the before-reversal light emission-time whole image  100   a  acquired when the orientation of the imaging plate  10  is the reference orientation. The display  3  may display the before-reversal light emission-time whole image  100   a  after the tilt correction processing in grayscale as in  FIG.  32   , for example. Display of the acquired whole image hereinafter includes display of the acquired whole image after the tilt correction processing. 
     As described above, the image processing unit  81  corrects the tilt of the IP corresponding portion of the acquired whole image based on the IP tilt angle to acquire the IP corresponding portion whose tilt has been properly corrected. In this case, the image processing unit  81  functions as a correction processing unit that corrects a tilt of an image (the IP acted light image) of the imaging plate  10 . For example, when the tilt correction processing is performed on the light emission-time whole image, the radiograph whose tilt has been properly corrected can be acquired. When the tilt correction processing is performed on the erasing-time whole image, the IP whole reflected light image whose tilt has been properly corrected can be acquired. 
     &lt;Cutting-Out Processing on Acquired Whole Image&gt; 
     The image processing unit  81  may perform cutting-out processing of determining a cutout image to be cut out from the light emission-time whole image including the radiograph based on the IP tilt angle and the IP size, and cutting out the determined cutout image from the light emission-time whole image. A desired cutout image responsive to the IP tilt angle and the IP size can be acquired from the light emission-time whole image by the cutting-out processing. The image processing unit  81  functions as a cutting-out unit that performs the cutting-out processing. The cutting-out processing may be performed during the series of processes shown in  FIG.  18   , or may be performed at a different time from the processing shown in  FIG.  18   . The cutting-out processing may be performed during the series of processes shown in  FIG.  27   , or may be performed at a different time from the processing shown in  FIG.  27   . 
     In the cutting-out processing, the IP corresponding portion (i.e., the IP image) of the light emission-time whole image may be determined as the cutout image, for example. In this case, the image processing unit  81  determines the IP corresponding portion of the light emission-time whole image as the cutout image based on the type of the IP size and the IP tilt angle identified based on the light emission-time whole image or the erasing-time whole image, for example. One example of operation of the image processing unit  81  when the image processing unit  81  determines the IP corresponding portion of the light emission-time whole image as the cutout image will be described below. The type of the IP size identified by the image processing unit  81  is hereinafter also referred to as an identified size Z. In this example, Z has a value of any of 0, 1, 2, and 3. 
     In the cutting-out processing, the image processing unit  81  sets a cutout frame to the light emission-time whole image based on the type of the IP size and the IP tilt angle, for example. The image processing unit  81  determines a portion within the cutout frame of the light emission-time whole image as the cutout image. 
     The shape of the cutout frame is similar to a nominal outline of the imaging plate  10  of the identified size Z. In this example, the imaging plate  10  has a rectangular outline with four rounded corners, and thus the cutout frame has a rectangular shape with four rounded corners. The size in the transverse direction of the cutout frame has a value responsive to the nominal transverse size (also referred to as a nominal transverse size for the identified size Z) of the imaging plate  10  of the identified size Z, and the size in the longitudinal direction of the cutout frame has a value responsive to the nominal longitudinal size (also referred to as a nominal longitudinal size for the identified size Z) of the imaging plate  10  of the identified size Z. 
     The image processing unit  81  herein knows in advance, for each type of the IP size, the number of pixels in the acquired whole image corresponding to each of the nominal transverse size and the nominal longitudinal size. When P1 pixels correspond to the nominal transverse size for the identified size Z, and P2 pixels correspond to the nominal longitudinal size for the identified size Z, the image processing unit  81  sets the size in the transverse direction of the cutout frame to a length of P1 pixels, and sets the size in the longitudinal direction of the cutout frame to a length of P2 pixels. When equations P1=800 and P2=1100 hold, for example, the size in the transverse direction of the cutout frame is set to a length of 800 pixels, and the size in the longitudinal direction of the cutout frame is set to a length of 1100 pixels. 
     When determining the outline and the size of the cutout frame, the image processing unit  81  disposes the cutout frame on the light emission-time whole image so that the center of the cutout frame matches the center of gravity of the IP corresponding portion of the light emission-time whole image, and the longitudinal direction and the transverse direction of the cutout frame are respectively parallel to the longitudinal direction and the transverse direction of the light emission-time whole image. As described above, the center of gravity of the IP corresponding portion of the light emission-time whole image matches the center of gravity of the high luminance region of the binarized image of the light emission-time whole image. 
     Next, the image processing unit  81  rotates the cutout frame disposed on the light emission-time whole image about the center of gravity of the IP corresponding portion by the IP tilt angle. In this case, the image processing unit  81  rotates the cutout frame clockwise when the IP tilt angle is a positive angle, and rotates the cutout frame counterclockwise when the IP tilt angle is a negative angle. The portion within the cutout frame of the light emission-time whole image thus matches the IP corresponding portion. The image processing unit  81  determines a portion within the cutout frame rotated by the IP tilt angle of the light emission-time whole image as the cutout image. The image processing unit  81  then cuts out the determined cutout image from the light emission-time whole image. The IP corresponding portion is thereby cut out from the light emission-time whole image to acquire an image of only a portion corresponding to the imaging plate  10 . The cutting-out processing may be performed on the before-reversal light emission-time whole image or on the after-reversal light emission-time whole image. For the purpose of determining a cutout range, the nominal size may not necessarily be applied to the cutout frame, and an imaging plate range acquired as a result of binarization may be applied to the cutout frame. 
       FIG.  33    is a schematic diagram showing one example of setting of a cutout frame  150  to the after-reversal light emission-time whole image  100   b  shown in  FIG.  16    described above. The biological radiographically captured image, such as the after-reversal light emission-time whole image  100   b,  as a target of cutting-out includes the IP image region and the IP image region outside region image.  FIG.  34    is a schematic diagram showing one example of cutting-out of the cutout image  151  within the cutout frame  150  of the after-reversal light emission-time whole image  100   b  from the after-reversal light emission-time whole image  100   b  in the example of  FIG.  33   . As shown in  FIG.  34   , the IP corresponding portion  105   b  is properly cut out from the after-reversal light emission-time whole image  100   b.  The cutout image  151  includes a radiograph  151   a  that is the same as the radiograph (i.e., the excited region light image)  101   b  included in the after-reversal light emission-time whole image  100   b.    
     Application of the imaging plate shape data to the biological radiographically captured image to cut out the IP corresponding portion  105   b  from the after-reversal light emission-time whole image  100   b  is referred to as imaging plate shape application processing. The imaging plate shape application processing includes positioning of the imaging plate shape for cutting-out from the biological radiographically captured image, setting of the cutout frame, and extraction of the IP biological radiographically captured image as the cutout image from the biological radiographically captured image as a result of cutting-out. 
       FIG.  35    is a schematic diagram showing one example of setting of the cutout frame  150  to the after-reversal light emission-time whole image  100   b  shown in  FIG.  17    described above.  FIG.  36    is a schematic diagram showing one example of cutting-out of the cutout image  151  within the cutout frame  150  of the after-reversal light emission-time whole image  100   b  from the after-reversal light emission-time whole image  100   b  in the example of  FIG.  35   . As shown in  FIG.  36   , the IP corresponding portion  105   b  is properly cut out from the after-reversal light emission-time whole image  100   b  even when the after-reversal light emission-time whole image  100   b  includes the unexposed region image  103   b.  The cutout image  151  includes the radiograph  151   a  that is the same as the radiograph  101   b  included in the after-reversal light emission-time whole image  100   b  and an unexposed region image  151   b  that is the same as the unexposed region image (i.e., the IP reflected light image or the IP non-photostimulable reflected light image)  103   b  included in the after-reversal light emission-time whole image  100   b.    
     When the cutting-out processing is performed, the display  3  may display the cutout image  151  cut out from the light emission-time whole image under control performed by the display control unit  82 . In this case, the display  3  may display the cutout image  151  in grayscale as shown in  FIGS.  34  and  36   . It can be said that  FIGS.  34  and  36    are schematic diagrams each showing an example of display of the cutout image  151 . When the cutout image  151  is displayed, the user can check only a necessary image of the light emission-time whole image. When the IP corresponding portion is cut out from the light emission-time whole image as the cutout image  151  and displayed as in this example, the user can check only the IP corresponding portion that is necessary of the light emission-time whole image. The user can thus easily identify the unexposed portion that can be included in the imaging plate  10  by checking display of the cutout image  151  as shown in  FIG.  36   , for example. The user can also easily identify a range of the unexposed portion that can be included in the imaging plate  10 . 
     The display  3  may simultaneously and separately display the cutout image  151  cut out from the light emission-time whole image and the erasing-time whole image  200  under control performed by the display control unit  82 .  FIG.  37    is a schematic diagram showing one example of display of the cutout image  151  and the erasing-time whole image  200  in grayscale on the display surface  3   a  of the display  3 . The cutout image  151  including the unexposed region image  151   b  is shown in  FIG.  37   . As shown in  FIG.  37   , the display  3  may display the cutout image  151  and the erasing-time whole image  200  so that the cutout image  151  and the IP whole reflected light image (i.e., the IP corresponding portion or the IP image)  201  of the erasing-time whole image  200  have the same size, for example. The display  3  may display the cutout image  151  and the erasing-time whole image  200  side by side, for example. The display  3  simultaneously and separately displays the cutout image  151  and the erasing-time whole image  200 , so that the user can easily compare the cutout image  151  and the erasing-time whole image  200 . Thus, by comparing the IP whole reflected light image  201  included in the erasing-time whole image  200  and the cutout image  151 , the user can easily determine whether the IP corresponding portion has properly been cut out from the light emission-time whole image, for example. 
     The cutout frame  150 , that is, the cutout range may be determined based on the erasing-time whole image  200 . In this case, a range of the IP non-photostimulable reflected light image (i.e., the IP whole reflected light image) of the erasing-time whole image  200  may be identified by image processing, such as boundary processing, to determine the cutout range, and the determined cutout range may be set to the light emission-time whole image to generate the cutout image  151 , for example. In this case, acquisition of the IP binarized image may be used in the image processing, such as the boundary processing. Holding of the imaging plate  10  by the holder  20  in the same orientation during light emission and during erasing allows for positional application. 
     A configuration in which the cutout image and the erasing-time whole image are simultaneously and separately displayed as in the example of  FIG.  37    may be modified to a configuration in which the cutout image and the image acquired by binarizing the erasing-time whole image are simultaneously and separately displayed by replacing the erasing-time whole image with the image such as the binarized image  500  in  FIG.  21   . 
     As in the above-mentioned tilt correction processing, the image processing unit  81  may correct a tilt of the cutout image  151  cut out from the light emission-time whole image based on the IP tilt angle identified based on the light emission-time whole image or the erasing-time whole image. Thus, when the cutout image  151  after correction is displayed, the user can easily view the cutout image  151 , for example. Assume hereinafter that the tilt correction processing includes correction of the tilt of the cutout image  151 . 
     The image processing unit  81  corrects the tilt of the cutout image  151  as in the above-mentioned tilt correction processing performed on the light emission-time whole image, for example. The image processing unit  81  still functions as the correction processing unit that corrects the tilt of the image (the IP acted light image) of the imaging plate  10 . Specifically, the image processing unit  81  first determines a center of gravity of the cutout image  151 . The center of gravity of the cutout image  151  matches the center of gravity of the high luminance region of the binarized image of the light emission-time whole image. The image processing unit  81  thus determines the center of gravity of the high luminance region of the binarized image of the light emission-time whole image to determine the center of gravity of the cutout image  151 . Next, the image processing unit  81  rotates the cutout image  151  about the determined center of gravity by the IP tilt angle. In this case, when the IP tilt angle is a positive angle, the image processing unit  81  rotates the cutout image  151  counterclockwise by the IP tilt angle. On the other hand, when the IP tilt angle is a negative angle, the image processing unit  81  rotates the cutout image  151  clockwise by the IP tilt angle. The tilt of the cutout image  151  is thereby corrected. The tilt of the radiograph based on the light emission-time image signal included in the cutout image  151  is thereby corrected. 
       FIGS.  38  to  40    are schematic diagrams showing one example of the cutting-out processing performed on the light emission-time whole image and the tilt correction processing performed on the cutout image  151  after the cutting-out processing. In the example of  FIGS.  38  to  40   , the cutting-out processing is performed on the before-reversal light emission-time whole image  100   a  shown in  FIG.  20    described above. As shown in  FIG.  38   , the image processing unit  81  sets the cutout frame  150  to the before-reversal light emission-time whole image  100   a  as described above. Next, the image processing unit  81  cuts out the cutout image  151  within the cutout frame  150  of the before-reversal light emission-time whole image  100   a  from the before-reversal light emission-time whole image  100   a  as shown in  FIG.  39   . The image processing unit  81  then corrects the tilt of the cut out cutout image  151  based on the IP tilt angle as shown in  FIG.  40   . The tilt of the cutout image  151  responsive to the tilt of the imaging plate  10  relative to the reference orientation is thereby properly corrected. The orientation of the cutout image  151  whose tilt has been corrected is the same as the orientation of the cutout image  151  obtained when the orientation of the imaging plate  10  is the reference orientation. 
     While the image processing unit  81  sets the IP corresponding portion of the light emission-time whole image to the cutout image  151  in the above-mentioned example, a portion of the IP corresponding portion may be set to the cutout image  151 . One example of operation of the image processing unit  81  in this case will be described below. 
       FIG.  41    is a schematic diagram illustrating another example of the holder  20  that holds the imaging plate  10 .  FIG.  41    illustrates a state of each of the fixing portions  22   a  of the fixture  22  of the holder  20  being in the close position. In the holder  20  (also referred to as a holder  20 A) illustrated in  FIG.  41   , the fixture  22  has an overlapping portion  220  that covers a peripheral edge portion  10   a  of the imaging plate  10  when each of the fixing portions  22   a  is in the close position. The fixing portions  22   a  have respective overlapping portions  220   a  that cover the peripheral edge portion  10   a  of the imaging plate  10  when being in the close position. The overlapping portions  220   a  of the fixing portions  22   a  constitute the overlapping portion  220  of the fixture  22 . 
     When the holder  20 A holds the imaging plate  10 , the peripheral edge portion  10   a  of the imaging plate  10  is covered with the overlapping portion  220  of the fixture  22 , so that the light emission-time whole image in which the overlapping portion  220  appears can be acquired in the reading apparatus  1 . From a perspective of the imaging plate  10 , the overlapping portion  220  may be considered as a grasped portion of the imaging plate  10 . 
       FIG.  42    is a schematic diagram showing one example of the before-reversal light emission-time whole image  100   a  acquired when the imaging plate  10  is held by the holder  20 A. The before-reversal light emission-time whole image  100   a  shown in  FIG.  42    includes an image  120  (also referred to as an overlapping portion image  120 ) of the overlapping portion  220  of the fixture  22 . The overlapping portion image  120  is an image based on detection of the reflected light of the excitation light L 10  from the overlapping portion  220 . The overlapping portion image  120  includes images  120   a  (also referred to as overlapping portion images  120   a ) of the overlapping portions  220   a  of the fixing portions (also referred to as grasping portions)  22   a.  In this example, black anodizing has been performed on surfaces of the fixing portions  22   a,  for example. The overlapping portion image  120  included in the before-reversal light emission-time whole image  100   a  thus has a small luminance value. The overlapping portion images  120   a  are included in the IP image region outside region image  102   a,  and are not included in the radiograph  101   a  forming the IP image (IP image region light image). 
     When the overlapping portion image  120  is included in the light emission-time whole image, the image processing unit  81  may determine a portion of the IP corresponding portion as the cutout image  151  so that the cutout image  151  does not include the overlapping portion image  120  (i.e., the overlapping portion images  120   a ) in the light emission-time whole image. In this case, the image processing unit  81  sets the cutout frame  150  to the light emission-time whole image based on the type of the IP size and the IP tilt angle similarly to the foregoing, for example. An outline of the cutout frame  150  set as described above has a shape responsive to the outline of the imaging plate  10  (i.e., a contour of the imaging plate  10 ), so that the overlapping portion image  120  is included within the cutout frame  150  at this time point.  FIG.  43    is a schematic diagram showing one example of setting of the cutout frame  150  to the before-reversal light emission-time whole image  100   a  shown in  FIG.  42    as described above. The overlapping portion images  120   a  constituting the overlapping portion image  120  are included within the cutout frame  150  set to the before-reversal light emission-time whole image  100   a.    
     While the before-reversal light emission-time whole image  100   a  shown in  FIG.  42    includes an IP image (i.e., a partially missing IP image compared with that in  FIG.  32   ) in a state of the fixing portions  22   a  overlapping the imaging plate  10 , the cutout frame  150  responsive to the outline of the imaging plate  10  can be set as described below, for example. For example, the first principal component axis and the second principal component axis are determined by a method similar to the method described with reference to  FIGS.  21  to  23   . The first principal component axis and the second principal component axis can be determined similarly to the foregoing while the overlapping portion images  120   a  appear in the IP image but the amount of appearance is not large enough to interfere with calculation. A maximum value of a width in the longitudinal direction of the high luminance region  501  and a maximum value of a width in the transverse direction of the high luminance region  501  are determined respectively in a direction along the first principal component axis and a direction along the second principal component axis. The maximum value of the width in the longitudinal direction of the high luminance region  501  is set to a longitudinal width of the cutout frame  150 , and the maximum value of the width in the transverse direction of the high luminance region  501  is set to a transverse width of the cutout frame  150 . Alternatively, when the transverse sizes and the longitudinal sizes of the imaging plates  10  of the plurality of types of sizes are respectively stored as the nominal transverse sizes and the nominal longitudinal sizes as described above, the shapes of the imaging plates  10  of the respective sizes may be stored, any of the sizes that the determined maximum values suit may be checked, and the cutout frame may be set according to the shape of the imaging plate  10  of the size. 
     After setting the cutout frame  150  to the light emission-time whole image as described above, the image processing unit  81  reduces the size of the cutout frame  150  in a similar shape so that the overlapping portion image  120  is not included within the cutout frame  150 . In this case, the image processing unit  81  reduces the size of the cutout frame  150  in the similar shape so that the overlapping portion image  120  is not included within the cutout frame  150 , and the cutout frame  150  after size reduction is as large as possible. The image processing unit  81  can identify positions and ranges of the overlapping portion images  120   a  in the light emission-time whole image based on the binarized image of the light emission-time whole image, for example. The image processing unit  81  reduces the size of the cutout frame  150  in the similar shape so that the overlapping portion image  120  is not included within the cutout frame  150 , and the cutout frame  150  after size reduction is as large as possible based on the identified positions and ranges of the overlapping portion images  120   a.  The image processing unit  81  determines a portion within the cutout frame  150  after size reduction of the light emission-time whole image as the cutout image  151 . The cutout image  151  not including the overlapping portion image  120  but including a large portion of the IP corresponding portion  105   a  can thereby be acquired.  FIG.  44    is a schematic diagram showing one example of size reduction of the cutout frame  150  shown in  FIG.  43   . As shown in  FIG.  44   , the image processing unit  81  determines a portion within the cutout frame  150  after size reduction of the before-reversal light emission-time whole image  100   a  as the cutout image  151 . 
     When determining the cutout image  151 , the image processing unit  81  cuts out the cutout image  151  from the light emission-time whole image.  FIG.  45    is a schematic diagram showing one example of cutting-out of the cutout image  151  shown in  FIG.  44    from the before-reversal whole image  100   a.    
     As described above, when the image processing unit  81  determines a portion of the IP corresponding portion as the cutout image  151  so that the cutout image  151  does not include the overlapping portion image  120 , the cutout image  151  in which the overlapping portion  220  of the fixture  22  does not appear can be acquired. Thus, when the cutout image  151  is displayed, the user can check only a portion in which an image useful for a diagnosis is left as widely as possible without being distracted by the image of the overlapping portion  220 , for example. 
     An end portion of the surface on a side of the radiograph formation layer  11  of the imaging plate  10  in plan view is sometimes considered as a non-effective region, and most of a region in the center of the surface is sometimes considered as an effective region. For example, in  FIG.  44   , a region inside a boundary indicated by the cutout frame  150  is considered as the effective region, and a region outside the boundary is considered as the non-effective region. This is because pressure is sometimes applied to the end portion (non-effective region) of the imaging plate  10  in a manufacturing process, and, in this case, good storage of radiographs cannot be ensured in the non-effective region. Only an image in the effective region can be checked by displaying the cutout image  151  in which the overlapping portion  220  of the fixture  22  does not appear. 
     Even when the cutout image  151  in which the overlapping portion  220  does not appear is cut out from the light emission-time whole image, the image processing unit  81  may correct the tilt of the cut out cutout image  151  based on the IP tilt angle as described above. In this case, the display control unit  82  may cause the display  3  to display the cutout image  151  whose tilt has been corrected. 
       FIG.  46    is a schematic diagram showing another example of the before-reversal light emission-time whole image  100   a  acquired when the imaging plate  10  is held by the holder  20 A.  FIGS.  47  to  49    are schematic diagrams showing one example of the cutting-out processing performed on the before-reversal light emission-time whole image  100   a  shown in  FIG.  46    and the tilt correction processing performed on the cutout image  151  after the cutting-out processing. The image processing unit  81  sets the cutout frame  150  to the before-reversal light emission-time whole image  100   a  as described above, and then reduces the size of the cutout frame  150  in the similar shape so that the overlapping portion image  120  is not included within the cutout frame  150 , and the cutout frame  150  after size reduction is as large as possible as shown in  FIG.  47   . Next, the image processing unit  81  cuts out the cutout image  151  within the cutout frame  150  of the before-reversal light emission-time whole image  100   a  from the before-reversal light emission-time whole image  100   a  as shown in  FIG.  48   . The image processing unit  81  then corrects the tilt of the cut out cutout image  151  based on the IP tilt angle as shown in  FIG.  49   . The tilt of the cutout image  151  responsive to the tilt of the imaging plate  10  relative to the reference orientation is thereby properly corrected. 
     As described above, the image processing unit  81  determines at least portion of the IP corresponding portion of the light emission-time whole image as the cutout image based on the IP size and the IP tilt angle, so that at least portion of the IP corresponding portion can properly be cut out from the light emission-time whole image. The fixing portions  22   a  are portions being in contact with the end portion of the imaging plate  10  to fix the imaging plate  10 , and thus the overlapping portion image  120  is typically present only in the end portion of the whole image. The cutout image may thus be determined to be an image in a region of a central portion obtained by removing the end portion including the overlapping portion image  120 . 
     Even when the light emission-time whole image does not include the overlapping portion image  120 , the image processing unit  81  may reduce the size of the cutout frame  150  set to the light emission-time whole image in the similar shape, and determine the portion within the cutout frame  150  after size reduction of the light emission-time whole image as the cutout image  151 . Also in this case, a portion of the IP corresponding portion (i.e., the IP image) of the light emission-time whole image is determined as the cutout image  151 . The image processing unit  81  may increase the size of the cutout frame  150  set to the light emission-time whole image, for example, in a similar shape, and determine a portion within the cutout frame  150  after a size increase of the light emission-time whole image as the cutout image  151 . In this case, the IP corresponding portion and a portion around the IP corresponding portion (e.g., a portion of the IP image region outside region image or at least portion of the overlapping portion image  120 ) are determined as the cutout image  151  in the light emission-time whole image. 
     In the cutting-out processing, the image processing unit  81  may determine a cutout image (also referred to as a second cutout image) to be cut out from the erasing-time whole image including the IP whole reflected light image based on the IP tilt angle and the IP size, and cut out the determined second cutout image from the erasing-time whole image. In this case, the image processing unit  81  may determine at least portion of the IP corresponding portion (i.e., the IP whole reflected light image) of the erasing-time whole image as the second cutout image. When the erasing-time whole image includes the image of the overlapping portion  220 , the image processing unit  81  may determine the second cutout image so that the second cutout image does not include the image of the overlapping portion  220 . The display control unit  82  may cause the display  3  to display the second cutout image cut out from the erasing-time whole image. In this case, the display  3  may simultaneously and separately display the second cutout image and the cutout image (also referred to as a first cutout image)  151  cut out from the light emission-time whole image. The image processing unit  81  may also correct a tilt of the cut out second cutout image based on the IP tilt angle. The display control unit  82  may cause the display  3  to display the second cutout image whose tilt has been corrected. In this case, the display  3  may simultaneously and separately display the second cutout image whose tilt has been corrected and the first cutout image whose tilt has been corrected. 
     When the imaging plate  10  hardly tilts relative to the reference orientation, the image processing unit  81  may determine the first cutout image and the second cutout image based on the IP size without using the IP tilt angle. In this case, processing of rotating the cutout frame in response to the IP tilt angle is not necessary in the cutting-out processing. Display of the cutout image hereinafter includes display of the cutout image whose tilt has been corrected. 
     As described above, the image processing unit  81  sets the cutout range of the IP biological radiographically captured image being the image based on detection of the IP acted light from the biological radiographically captured image. The image in the portion corresponding to the imaging plate of the biological radiographically captured image can thereby properly be cut out. 
     &lt;Identification of Unexposed Region Image&gt; 
     The image processing unit  81  may perform unexposure identification processing of identifying the unexposed region image of the first cutout image  151  or the unexposed region image of the light emission-time whole image. The unexposure identification processing may be performed during the series of processes shown in  FIG.  18   , or may be performed at a different time from the processing shown in  FIG.  18   . The unexposure identification processing may be performed during the series of processes shown in  FIG.  27   , or may be performed at a different time from the processing shown in  FIG.  27   . The image processing unit  81  functions as an identification unit (also referred to as an unexposed region image identification unit) that identifies the unexposed region image. Identification of the unexposed region image facilitates identification of a biological image region in the acquired image acquired by biological radiography. 
     When at least portion of the IP corresponding portion is set to the first cutout image  151  as in the examples of  FIGS.  39 ,  45   , and the like, the image processing unit  81  generates a binarized image acquired by binarizing the first cutout image  151  in the unexposure identification processing, for example. The first cutout image  151  cut out from the after-reversal light emission-time whole image  100   b  as in  FIGS.  34  and  36    described above is herein referred to as an after-reversal first cutout image  151 . The first cutout image  151  cut out from the before-reversal light emission-time whole image  100   a  as in  FIGS.  45  and  48    described above is herein referred to as a before-reversal first cutout image  151 . 
     A threshold used to binarize the before-reversal first cutout image  151  is set to a value smaller than a minimum luminance value for the radiograph included in the before-reversal first cutout image  151  and greater than a luminance value for the unexposed region image included in the before-reversal first cutout image  151 , for example. Consider a case where IL 4  is the minimum luminance value for the radiograph included in the before-reversal first cutout image  151 , and IL 2  is the luminance value for the unexposed region image included in the before-reversal first cutout image  151 , for example. An inequality IL 2 &lt;IL 4  holds. In this case, the threshold is set to IL 50  that satisfies a relationship indicated by an inequality IL 2 &lt;IL 5 &lt;IL 4 , for example. A portion corresponding to the unexposed region image and a portion corresponding to the radiograph of a binarized image of the before-reversal first cutout image  151  being at least portion of the IP corresponding portion are thus respectively the low luminance region and the high luminance region. The image processing unit  81  can properly identify the unexposed region image of the before-reversal first cutout image  151  by identifying the low luminance region of the binarized image of the before-reversal first cutout image  151 . When the imaging plate  10  does not include the unexposed portion, the binarized image of the before-reversal first cutout image  151  does not include the low luminance region. 
     A threshold used to binarize the after-reversal first cutout image  151  is set to a value greater than a maximum luminance value for the radiograph included in the after-reversal first cutout image  151  and smaller than a luminance value for the unexposed region image included in the after-reversal first cutout image  151 , for example. A portion corresponding to the unexposed region image and a portion corresponding to the radiograph of a binarized image of the after-reversal first cutout image  151  being at least portion of the IP corresponding portion are thus respectively the high luminance region and the low luminance region. The image processing unit  81  can properly identify the unexposed region image of the after-reversal first cutout image  151  by identifying the high luminance region of the binarized image of the after-reversal first cutout image  151 . 
     As described above, the image processing unit  81  can properly identify the unexposed region image of the first cutout image  151  when at least portion of the IP corresponding portion is cut out from the light emission-time whole image as the first cutout image  151 . 
     In the unexposure identification processing, the image processing unit  81  may identify the unexposed region image of the first cutout image  151  including the IP image region outside region image. In this case, the image processing unit  81  may identify the unexposed region image of the first cutout image  151  including the first cutout image  151  included in the IP image region outside region image. When identifying the unexposed region image of the first cutout image  151  including the IP image region outside region image, the image processing unit  81  ternarizes the first cutout image  151  to generate a ternarized image. 
     The image processing unit  81  first compares each of luminance values of a plurality of pixels constituting the first cutout image  151  with a lower threshold and an upper threshold set in advance. The upper threshold is a value greater than the lower threshold. As for each of the luminance values of the plurality of pixels constituting the first cutout image  151 , the image processing unit  81  replaces a luminance value smaller than the lower threshold with a first value, replaces a value equal to or greater than the lower threshold and smaller than the upper threshold with a second value, and replaces a luminance value equal to or greater than the upper threshold with a third value. Herein, the third value is greater than the second value, and the second value is greater than the first value. The first cutout image  151  is thereby ternarized to acquire the ternarized image. A region of the ternarized image where the luminance value is the third value is hereinafter also referred to as the high luminance region, a region of the ternarized image where the luminance value is the second value is hereinafter also referred to as a medium luminance region, and a region of the ternarized image where the luminance value is the first value is hereinafter also referred to as the low luminance region. 
     The lower threshold (also referred to as a first threshold) used to ternarize the before-reversal first cutout image  151  is set to a value greater than the luminance value for the IP image region outside region image included in the before-reversal first cutout image  151  and smaller than the luminance value for the unexposed region image included in the before-reversal first cutout image  151 , for example. The upper threshold (also referred to as a second threshold) used to ternarize the before-reversal first cutout image  151  is set to a value greater than the luminance value for the unexposed region image included in the before-reversal first cutout image  151  and smaller than the minimum luminance value for the radiograph included in the before-reversal first cutout image  151 , for example. Consider a case where the minimum luminance value for the radiograph included in the before-reversal first cutout image  151  is 10000, the luminance value for the unexposed region image included in the before-reversal first cutout image  151  is 3000, and the luminance value for the IP image region outside region image included in the before-reversal first cutout image  151  is 1000, for example. In this case, the lower threshold is set to 2000, and the upper threshold is set to 5000, for example. A portion corresponding to the IP image region outside region image, a portion corresponding to the unexposed region image, and a portion corresponding to the radiograph of a ternarized image of the before-reversal first cutout image  151  are thus respectively the low luminance region, the medium luminance region, and the high luminance region. The image processing unit  81  can properly identify the unexposed region image of the before-reversal first cutout image  151  by identifying the medium luminance region of the ternarized image of the before-reversal first cutout image  151 . When the imaging plate  10  does not include the unexposed portion, the ternarized image of the before-reversal first cutout image  151  does not include the medium luminance region. 
     The lower threshold (also referred to as a first threshold) used to ternarize the after-reversal first cutout image  151  is set to a value greater than the maximum luminance value for the radiograph included in the after-reversal first cutout image  151  and smaller than the luminance value for the unexposed region image included in the after-reversal first cutout image  151 , for example. The upper threshold (also referred to as a second threshold) used to ternarize the after-reversal first cutout image  151  is set to a value greater than the luminance value for the unexposed region image included in the after-reversal first cutout image  151  and smaller than the luminance value for the IP image region outside region image included in the after-reversal first cutout image  151 , for example. A portion corresponding to the IP image region outside region image, a portion corresponding to the unexposed region image, and a portion corresponding to the radiograph of a ternarized image of the after-reversal first cutout image  151  are thus respectively the high luminance region, the medium luminance region, and the low luminance region. The image processing unit  81  can properly identify the unexposed region image of the after-reversal first cutout image  151  by identifying the medium luminance region of the ternarized image of the after-reversal first cutout image  151 . 
     As described above, the image processing unit  81  can properly identify the unexposed region image of the first cutout image  151  including the IP image region outside region image. 
     In the unexposure identification processing, the image processing unit  81  may identify the unexposed region image of the light emission-time whole image. In this case, the image processing unit  81  ternarizes the light emission-time whole image to generate a ternarized image as in a case where the unexposed region image of the first cutout image  151  including the IP image region outside region image is identified. A lower threshold and an upper threshold used to ternarize the before-reversal light emission-time whole image  100   a  are set similarly to the lower threshold and the upper threshold used to ternarize the before-reversal first cutout image  151 . The image processing unit  81  can properly identify the unexposed region image of the before-reversal light emission-time whole image  100   a  by identifying the medium luminance region of the ternarized image of the before-reversal light emission-time whole image  100   a.  A lower threshold and an upper threshold used to ternarize the after-reversal light emission-time whole image  100   b  are set similarly to the lower threshold and the upper threshold used to ternarize the after-reversal first cutout image  151 . The image processing unit  81  can properly identify the unexposed region image of the after-reversal light emission-time whole image  100   b  by identifying the medium luminance region of the ternarized image of the after-reversal light emission-time whole image  100   b.    
     When the image processing unit  81  identifies the unexposed region image of the first cutout image  151  or the light emission-time whole image, the display control unit  82  may cause the display  3  to display unexposure notification information  161  to provide notification that the unexposed region image is present in the first cutout image  151  or the light emission-time whole image. The user can thus easily recognize that the unexposed region image is present in the first cutout image  151  or the light emission-time whole image. The user can thus easily recognize that the imaging plate  10  includes the unexposed portion. 
       FIGS.  50  and  51    are schematic diagrams each showing an example of display of the unexposure notification information  161 . In the example of  FIG.  50   , the first cutout image  151  including the radiograph  151   a  and the unexposed region image  151   b  and the unexposure notification information  161  are displayed on the display surface  3   a  of the display  3 . In the example of  FIG.  51   , the after-reversal light emission-time whole image  100   b  and the unexposure notification information  161  are displayed on the display surface  3   a.  In the example of  FIG.  50   , a border line  1510  that borders a range of the unexposed region image  151   b  is displayed as the unexposure notification information  161  to provide notification that the unexposed region image  151   b  is present in the first cutout image  151 . Similarly, in the example of  FIG.  51   , a border line  1030  that borders a range of the unexposed region image  103   b  is displayed as the unexposure notification information  161  to provide notification that the unexposed region image  103   b  is present in the after-reversal light emission-time whole image  100   b.  The border lines  1510  and  1030  may each be displayed in at least one color. 
     The unexposure notification information  161  is not limited to that in the examples of  FIGS.  50  and  51   . For example, hatching lines, such as diagonal lines, attached to the unexposed region image may be displayed as the unexposure notification information  161 . The unexposed region image may be displayed in at least one color to display the unexposure notification information  161 . 
     As shown in  FIG.  52   , a frame-like graphic  1511  surrounding the first cutout image  151  may be displayed as the unexposure notification information  161 . While the frame-like graphic  1511  is hatched in the example of  FIG.  52    for the convenience of description, the frame-like graphic  1511  may not be hatched or may be hatched. The frame-like graphic  1511  may be displayed in at least one color. Similarly, when the unexposed region image is identified in the light emission-time whole image, a frame-like graphic surrounding the light emission-time whole image may be displayed as the unexposure notification information  161 . The unexposure notification information  161  may be displayed in at least one of characters and a symbol. 
     When the first cutout image  151  or the light emission-time whole image does not include the unexposed region image, that is, the image processing unit  81  does not identify the unexposed region image of the first cutout image  151  or the light emission-time whole image, the display control unit  82  may cause the display  3  to display notification information  162  to provide notification that the unexposed region image is not present in the first cutout image  151  or the light emission-time whole image. The user can thus easily recognize that the imaging plate  10  does not include the unexposed portion. 
       FIG.  53    is a schematic diagram showing an example of display of the notification information  162 .  FIG.  53    shows an example of display of the notification information  162  to provide notification that the unexposed region image is not present in the first cutout image  151 . In the example of  FIG.  53   , a frame-like graphic  1512  surrounding the first cutout image  151  not including the unexposed region image is displayed as the notification information  162 . While the frame-like graphic  1512  is hatched in the example of  FIG.  53    for the convenience of description, the frame-like graphic  1512  may not be hatched or may be hatched. The frame-like graphic  1512  may be displayed in at least one color. When the frame-like graphic  1511  in  FIG.  52    is displayed as the unexposure notification information  161 , the frame-like graphic  1511  as the unexposure notification information  161  and the frame-like graphic  1512  as the notification information  162  are displayed in different ways. In this case, the frame-like graphic  1511  and the frame-like graphic  1512  may be displayed in different colors. The frame-like graphic  1511  and the frame-like graphic  1512  may be hatched in different ways. Similarly, when the unexposed region image is not present in the light emission-time whole image, a frame-like graphic surrounding the light emission-time whole image may be displayed as the notification information  162 . The notification information  162  may be displayed in at least one of characters and a symbol. When the unexposed region image is present, notification of the presence of the unexposed region image is displayed in a different way from that in a case where the frame-like graphic  1512  is displayed, and thus it can be said that not providing notification of the presence of the unexposed region image means providing notification of the absence of the unexposed region image. 
     When the display control unit  82  causes the display  3  to simultaneously and separately display the first cutout image  151  and the erasing-time whole image  200 , and the first cutout image  151  includes the unexposed region image as shown in  FIG.  37    described above, the display control unit  82  may cause the display  3  to display the unexposure notification information  161  together as shown in  FIG.  54   . In this case, the second cutout image may be displayed in place of the erasing-time whole image  200 . When the display control unit  82  causes the display  3  to simultaneously and separately display the light emission-time whole image and the erasing-time whole image  200 , and the light emission-time whole image includes the unexposed region image as shown in  FIG.  30    described above, the display control unit  82  may cause the display  3  to display the unexposure notification information  161  together as shown in  FIG.  55   . In this case, the second cutout image may be displayed in place of the erasing-time whole image  200 . 
     When the display control unit  82  causes the display  3  to simultaneously and separately display the first cutout image  151  not including the unexposed region image and the erasing-time whole image  200 , the display control unit  82  may cause the display  3  to display the notification information  162  together. In this case, the second cutout image may be displayed in place of the erasing-time whole image  200 . Similarly, when the display control unit  82  causes the display  3  to simultaneously and separately display the light emission-time whole image not including the unexposed region image and the erasing-time whole image  200 , the display control unit  82  may cause the display  3  to display the notification information  162  together. In this case, the second cutout image may be displayed in place of the erasing-time whole image  200 . 
     As described above, the detector  40  according to this example can detect not only the emitted light L 2  from the imaging plate  10  but also the reflected light of the excitation light L 10  from the imaging plate  10  to some extent. The reading apparatus  1  can thus acquire the radiograph based on detection of the emitted light L 2  and the reflected light image (e.g., the unexposed region image) based on detection of the reflected light. Usability of the reading apparatus  1  is thereby improved. 
     For example, the reading apparatus  1  can properly identify the IP size, and properly identify the IP tilt angle as described above based on the radiograph based on detection of the emitted light L 2  from the imaging plate  10  and the light emission-time whole image including the reflected light image based on detection of the reflected light from the imaging plate  10 . 
     For example, the reading apparatus  1  simultaneously and separately displays the radiograph based on detection of the emitted light L 2  from the imaging plate  10  and the reflected light image based on detection of the reflected light from the imaging plate  10  as shown in  FIGS.  29 ,  30 ,  37 ,  54 ,  55   , and the like described above, so that the user can easily compare the radiograph read from the imaging plate  10  and the appearance of the imaging plate  10 . The user can thus easily identify the unexposed portion that can be included in the imaging plate  10 , for example. 
     &lt;Identification of Abnormality of Surface of Imaging Plate&gt; 
     When the IP whole reflected light image as the reflected light image based on detection of the reflected light from the imaging plate  10  is displayed as shown in  FIGS.  28  to  30 ,  54 ,  55   , and the like described above, the user can easily identify the presence or absence of any abnormality of the surface of the imaging plate  10 , for example. The abnormality of the surface of the imaging plate  10  includes a scratch, a depression, a chip, contamination, and adhesion of foreign matter, for example. 
       FIGS.  56  and  57    are schematic diagrams respectively showing one example of the radiograph  101   b  included in the after-reversal light emission-time whole image  100   b  acquired by the reading apparatus  1  and one example of the IP whole reflected light image  201  included in the before-reversal erasing-time whole image  200  acquired by the reading apparatus  1  when the front surface of the imaging plate  10  has an abnormality. 
     The before-reversal erasing-time whole image  200  is used as the erasing-time whole image in the shown examples.  FIG.  56    also shows an enlarged view  1010 L of an abnormal region image  1010  in which the abnormality of the surface of the imaging plate  10  appears in the radiograph  101   b.    FIG.  57    also shows an enlarged view  2010 L of an abnormal region image  2010  in which the abnormality of the surface of the imaging plate  10  appears in the IP whole reflected light image  201 .  FIGS.  56  and  57    respectively show the radiograph  101   b  and the IP whole reflected light image  201  when the front surface of the imaging plate  10  has a scratch. 
     As shown in  FIGS.  56  and  57   , a luminance value for the abnormal region image  1010  in which the abnormality of the surface of the imaging plate  10  appears is sometimes different from a luminance value for a portion around the abnormal region image  1010  in each of the radiograph  101   b  and the IP whole reflected light image  201 . On the other hand, when any lesion, such as a carious lesion, occurs in teeth as the imaging object, a luminance value for a region in which a portion of the teeth where the lesion occurs is sometimes different from a luminance value for a portion around the region in the radiograph  101   b.  Furthermore, in contrast to the example of  FIG.  56   , the luminance value for the abnormal region image  1010  can be close to the luminance value for a region in which the teeth appear in the radiograph  101   b.  In view of these points, it is not easy for the user to identify the abnormality of the surface of the imaging plate  10  based on the radiograph  101   b  displayed by the display  3 . 
     In contrast, the teeth do not appear in the IP whole reflected light image  201  of the imaging plate  10  in which the radiograph is not stored as the latent image. The user can thus easily identify the abnormality of the surface of the imaging plate  10  based on the IP whole reflected light image  201  displayed by the display  3 . That is to say, the user can easily identify the abnormality of the surface of the imaging plate  10  by recognizing the abnormal region image  1010  included in the IP whole reflected light image  201  displayed by the display  3 . The user may identify the abnormality of the surface of the imaging plate  10  based on the erasing-time whole image  200  including the IP whole reflected light image  201  displayed by the display  3 . The user may also identify the abnormality of the surface of the imaging plate  10  based on the second cutout image including at least portion of the IP whole reflected light image  201  displayed by the display  3 . 
     When the display  3  being controlled by the display control unit  82  simultaneously and separately displays the radiograph and the IP whole reflected light image, the user can easily identify a region corresponding to the abnormality of the surface of the imaging plate  10  in the radiograph. Thus, when a dentist is the user, for example, the dentist can easily exclude the region corresponding to the abnormality of the surface of the imaging plate  10  in the radiograph from information to make diagnostic determination. 
     The light source  30  functions as a first light source which irradiates the imaging plate  10  with the excitation light L 10 . The detector  40  functions as a first detector that detects the emitted light L 2  caused by the excitation light L 10  from the imaging plate  10 , and outputs a first image signal as a result of detection of the emitted light L 2 . 
     The construction of the present embodiment irradiates the imaging plate  10  with light as the acting light L 1  in order to generate reflected light L 4  from the imaging plate  10 . The acting light L  1  can be thought as to be irradiation light L  1 . The light source  30  such as a light source which can also irradiate the excitation light L 10  acting as the irradiation light L 1  to generate reflected light L 4  can be used. In this case, the light source  30  as the first light source functions also as the second light source. The first light source and the second light source can comprise separate bodies as described later. 
     The detector  40  such as a detector which can also detect the reflection light L 4  of the irradiation light L 1  can be used. In this case, the detector  40  as the first detector functions also as the second detector which outputs the second image signal as a result of detection of the reflected light L 4 . The first detector and the second detector can comprise separate bodies as described later. In above case, the optical filter  42  such as a filter of which transmittance of the emitted light L 2  and the reflected light L 4  is high and transmittance of other light is low can be preferably used. 
     After the light source  30  as the first light source irradiates the imaging plate  10  with the excitation light L 10  and the detector  40  as the first detector detects the emitted light L 2 , the light source  30  as the second light source can irradiate the excitation light L 10  as the irradiation light L 1  and the detector  40  as the second detector can detect the reflected light L 4 . And also between the detection of the emitted light L 2  and the detection of the reflected light L 4 , an irradiation of the erasing light L 3  can be inserted. Or, the imaging plate  10  which does not store the radiograph as the latent image before X-ray exposure can be irradiated by the excitation light L 10  as the irradiation light L 1  to detect the reflected light L 4  to secure the second image signal in advance. 
       FIG.  58    is a schematic diagram showing an example of display of the first cutout image  151  and the second cutout image  152  of the imaging plate  10  having the front surface having the abnormality. In the example of  FIG.  58   , the IP corresponding portion  105   b  of the after-reversal light emission-time whole image  100   b  is set to the first cutout image  151 , and the erased IP reflected light image (i.e., the IP corresponding portion)  201  of the before-reversal erasing-time whole image  200  is set to the second cutout image  152 . The second cutout image  152  includes the abnormal region image  2010  in which the abnormality of the surface of the imaging plate  10  appears. 
     The first cutout image  151  is an example of an image that contains a radiograph generated from the first image signal. The radiograph can occupy the whole image area. The second cutout image  152  is an example of an image that contains an IP reflected light image generated from the second image signal. The IP reflected light image can occupy the whole image area. 
     The abnormality of the surface of the imaging plate  10  is identified by generation of IP reflected light image  201  by the image processing unit  81 . Hereby the image processing unit  81  can identify the position and the shape of the abnormal region image  2010  in the IP reflected light image  201 . Herein the generation of IP reflected light image  201  causes the identification by exaggeration. 
     As shown in  FIG.  56   , one of the first cutout image  151  and the second cutout image  152  can be placed next to the other. This placement makes it easy to compare both. The row of the placement next to each other can be left right, or up down, or other row. 
     The image processing unit  81  which executes processing of generation of the IP reflected light image  201  can be regarded as an identification unit. Or the image processing unit  81  and the display control unit  82  executing processing of generation of the IP reflected light image and of the placement next to each other can be regarded as an identification unit. In this case, the generation of the IP reflected light image  201  and of the placement next to each other can be thought to be identification of the position and the shape of the abnormal region image  2010  in the radiograph. 
     The display of one of the first cutout image  151  and the second cutout image  152  next to the other is one example of abnormal region display which is a display of the position and the shape of the abnormal region against a radiograph generated by processing of the first image signal. 
     When display as shown in  FIG.  58    is performed, the user identifies the abnormal region image  2010  in the erased IP reflected light image  201  included in the displayed second cutout image  152 , for example. The user identifies the region corresponding to the abnormality of the imaging plate  10  in the radiograph  101   b  included in the first cutout image  151  based on the abnormal region image  2010  identified in the erased IP reflected light image  201 . 
     The display control unit  82  may cause the display  3  to simultaneously and separately display IP whole reflected light images of a plurality of imaging plates  10 .  FIG.  59    is a schematic diagram showing one example of such display. In the example of  FIG.  59   , a plurality of second cutout images  152  in which front surfaces of the respective imaging plates  10  appear are displayed on the display surface  3   a.  In the example of FIG.  59 , the IP whole reflected light images  201  of before-reversal erasing-time whole images  200  are set to the second cutout images  152 . As shown in  FIG.  59   , the IP whole reflected light images  201  in which the front surfaces of the respective imaging plates  10  appear are simultaneously and separately displayed, so that the user can easily identify, from among the imaging plates  10 , an imaging plate  10  having the abnormality in a relatively wide range. The user may discard the imaging plate  10  having the abnormality in the wide range, for example. A plurality of erasing-time whole images in which the front surfaces of the respective imaging plates  10  appear may simultaneously and separately be displayed by the display  3 . 
     When the operation unit  4  receives a predetermined operation from the user, the display control unit  82  may cause the display  3  to display a plurality of IP whole reflected light images  201  acquired in the past as shown in  FIG.  59   . When the operation unit  4  receives a predetermined operation from the user, the reading apparatus  1  may set an operation mode of the reading apparatus  1  to a quality check mode to check the quality of the imaging plates  10 , and the IP whole reflected light images  201  in which the respective imaging plates  10  appear may be acquired and displayed as shown in  FIG.  59    in the quality check mode. The imaging plates  10  are sequentially inserted into the reading apparatus  1  in the quality check mode by the user. When a single imaging plate  10  is inserted through the inlet  2   a,  the reading apparatus  1  in the quality check mode performs steps s 3 , s 4 , s 21 , and s 22  in  FIG.  27    described above to acquire the erasing-time whole image in which a front surface of the inserted imaging plate  10  appears, for example. The reading apparatus  1  performs steps s 5  and s 6  in  FIG.  27    to discharge the processed imaging plate  10 . When the processed imaging plate  10  is discharged from the reading apparatus  1 , a next imaging plate  10  is inserted into the reading apparatus  1 . The reading apparatus  1  in the quality check mode similarly operates to acquire an erasing-time whole image in which a front surface of the next imaging plate  10  appears, and discharges the processed imaging plate  10 . Insertion of the imaging plate  10  into the reading apparatus  1  and discharge of the imaging plate  10  from the reading apparatus  1  are hereinafter similarly repeated, so that the reading apparatus  1  in the quality check mode acquires the erasing-time whole images in which the respective imaging plates  10  appear. The display control unit  82  then causes the display  3  to perform display as shown in  FIG.  59    based on the acquired erasing-time whole images. The user identifies and discards the imaging plate  10  having the abnormality in the wide range based on display in  FIG.  59   , for example. 
     While the user identifies the abnormality of the surface of the imaging plate  10  based on the IP reflected light image displayed by the display  3  in the above-mentioned example, the image processing unit  81  may perform abnormality identification processing of identifying the abnormality of the surface of the imaging plate  10 . In this case, the image processing unit  81  functions as an identification unit (also referred to as an abnormality identification unit) that identifies the abnormality of the surface of the imaging plate  10 . 
       FIG.  60    is a flowchart showing one example of the abnormality identification processing. The image processing unit  81  identifies a position and a shape of the abnormal region image of the erasing-time whole image based on the erasing-time image signal to identify the abnormality of the surface of the imaging plate  10 , for example. The abnormality of the surface of the imaging plate  10  is hereinafter also referred to as an IP surface abnormality. 
     As shown in  FIG.  60   , in step s 101 , the image processing unit  81  identifies the IP reflected light image (i.e., the IP corresponding portion) of the erasing-time whole image based on the erasing-time image signal acquired in the above-mentioned step s 22 . The image processing unit  81  identifies the IP reflected light image of the before-reversal erasing-time whole image, for example. As described above, the image processing unit  81  can determine the IP reflected light image of the erasing-time whole image as the second cutout image, and thus can similarly identify the IP reflected light image of the before-reversal erasing-time whole image. 
     Next, in step s 102 , the image processing unit  81  divides the IP reflected light image identified in step s 101  into a plurality of subregions.  FIG.  61    is a schematic diagram showing one example of dividing the IP reflected light image  201  into a plurality of subregions  201   a.  When the imaging plate  10  is in clinical use, only a region of a portion of the radiograph formation layer  11  of the imaging plate  10  is used in some cases. The region is referred to as a usage target region. In step s 102 , the image processing unit  81  divides an identified region  2000  of the IP reflected light image  201  corresponding to the usage target region of the imaging plate  10  into the plurality of subregions  201   a,  for example. In this case, the image processing unit  81  is to identify the abnormal region image  2010  in the identified region  2000  of the IP reflected light image  201 . Each of the subregions  201   a  is composed of a plurality of pixels, for example. Each of the subregions  201   a  is square, for example. 
     As shown in  FIG.  61   , the image processing unit  81  divides the identified region  2000  into the subregions  201   a  in a matrix, for example. Assume herein that a transverse direction and a longitudinal direction of the IP reflected light image  201  are respectively a row direction and a column direction. The image processing unit  81  divides the identified region  2000  in a matrix so that P subregions  201   a  are arranged in the row direction and Q subregions  201   a  are arranged in the column direction.  FIG.  61    shows an example of a case where an equation P=Q=17 holds. The image processing unit  81  may divide the whole IP reflected light image  201  into the subregions  201   a.    
     Next, in step s 103 , the image processing unit  81  determines, for each of the subregions  201   a,  an evaluation value representing the possibility that the IP surface abnormality appears in the subregion  201   a.  It can be said that the evaluation value is a value representing the possibility that the subregion  201   a  is an image in a region of the imaging plate  10  having any abnormality. 
     In step s 103 , the image processing unit  81  determines an average value and a standard deviation of luminance values of a plurality of pixels constituting the subregion  201   a,  for example. The image processing unit  81  determines a value obtained by dividing the average value by the standard deviation as the evaluation value. The image processing unit  81  determines the evaluation value for each of the subregions  201   a  as described above. In this example, as the evaluation value increases, the possibility that the IP surface abnormality appears in the subregion  201   a  corresponding to the evaluation value increases. A method of determining the evaluation value is not limited to this method. 
     Next, in step s 104 , the image processing unit  81  determines a reference value to be compared with the evaluation value for each of the subregions  201   a.  The image processing unit  81  determines an average value of evaluation values determined for the respective subregions  201   a  in step s 103  as the reference value, for example. A method of determining the reference value is not limited to this method. 
     Next, in step s 105 , the image processing unit  81  performs, for each of the subregions  201   a,  determination processing of determining whether the IP surface abnormality appears in the subregion  201   a  using the reference value. In the determination processing, the image processing unit  81  compares the reference value and the evaluation value for each of the subregions  201   a,  for example. When the evaluation value for the subregion  201   a  exceeds the reference value (e.g., the evaluation value is smaller than the reference value), the image processing unit  81  determines that the IP surface abnormality appears in the subregion  201   a.  On the other hand, when the evaluation value for the subregion  201   a  does not exceed the reference value (e.g., the evaluation value is equal to or greater than the reference value), the image processing unit  81  determines that the IP surface abnormality does not appear in the subregion  201   a.  The subregion  201   a  determined as the subregion  201   a  in which the IP surface abnormality appears is hereinafter referred to as an abnormal subregion  201   a.  When the surface of the imaging plate  10  has any abnormality, at least one abnormal subregion  201   a  is identified in step s 105 . 
     Next, in step s 106 , the image processing unit  81  identifies a position and a shape of the abnormal region image  2010  (see  FIGS.  55  to  57   ) in which the IP surface abnormality appears in the IP reflected light image  201  of the before-reversal erasing-time whole image  200  based on a result of the determination processing performed for each of the subregions  201   a  in step s 105 . The image processing unit  81  sets an image in a partial region composed of at least one abnormal subregion  201   a  identified in step s 105  in the IP reflected light image  201  to the abnormal region image  2010 . The image processing unit  801  sets a position and a shape of the partial region composed of the at least one abnormal subregion  201   a  identified in step s 105  to the position and the shape of the abnormal region image  2010 . The image processing unit  801  can identify the position and the shape of the abnormal region image  2010  based on a position and a shape of each abnormal subregion  201   a.  When the position and the shape of the abnormal region image  2010  are identified, the abnormality identification processing ends. Identification of the position and the shape of the abnormal region image  2010  can be regarded as identification by extraction. The position and the shape of the abnormal region image  2010  identified by the image processing unit  81  are hereinafter also referred to as an abnormal region image position and an abnormal region image shape. 
     When it is determined that the IP surface abnormality appears in none of the subregions  201   a  in step s 105 , the abnormality identification processing ends without performing step s 106 . That is to say, when it is determined that the IP surface abnormality does not appear in the identified region  2000  of the IP reflected light image  201 , the abnormality identification processing ends without performing step s 106 . 
     As described above, the image processing unit  81  can properly identify any abnormality of the surface of the imaging plate  10  based on the image signal as a result of detection of the reflected light of the excitation light L 10  from the imaging plate  10 . 
     When the display control unit  82  causes the display  3  to display the detected radiograph, the abnormal region image shape may be superimposed on the detected radiograph at a position of the detected radiograph corresponding to the abnormal region image position.  FIG.  62    is a schematic diagram showing an example of display of the display  3  in this case. The superimpose display is one example of abnormal region display which is a display of the position and the shape of the abnormal region against a radiograph generated by processing of the first image signal. 
     In the example of  FIG.  62   , the after-reversal light emission-time whole image  100   b  including the radiograph  101   b  and the second cutout image  152  cut out from the before-reversal erasing-time whole image  200  are simultaneously and separately displayed on the display surface  3   a.  In the example of  FIG.  62   , the IP reflected light image  201  of the before-reversal erasing-time whole image  200  is set to the second cutout image  152 , and the second cutout image  152  includes the abnormal region image  2010 . In the example of  FIG.  62   , the abnormal region image shape (also referred to as an abnormal region image shape image)  2011  is superimposed on the radiograph  101   b  at the position of the radiograph  101   b  corresponding to the abnormal region image position. A relative position of the abnormal region image  2010  in the IP reflected light image  201  and a relative position of the abnormal region image shape  2011  in the radiograph  101   b  are the same. 
     When the abnormal region image shape  2011  is superimposed on the radiograph  101   b  at the position of the radiograph  101   b  corresponding to the abnormal region image position as in the example of  FIG.  62   , the user can easily identify a region corresponding to the abnormality of the surface of the imaging plate  10  in the radiograph  101   b.  Thus, when the dentist is the user, for example, the dentist can easily exclude the region corresponding to the abnormality of the surface of the imaging plate  10  in the radiograph  101   b  from the information to make diagnostic determination. 
     In a case where the abnormal region image shape  2011  is displayed on the radiograph  101   b  when the IP reflected light image  201  is displayed as in the example of  FIG.  62   , the user can easily compare the region corresponding to the abnormality of the surface of the imaging plate  10  in the radiograph  101   b  and the abnormal region image  2010  in the IP reflected light image  201 . The user can thus determine whether the position and the shape of the abnormal region image  2010  are properly identified by the reading apparatus  1 , for example. The IP reflected light image  201  may not be displayed when the abnormal region image shape  2011  is superimposed on the radiograph  101   b.    
     The reading apparatus  1  may switch between display and hiding of the abnormal region image shape  2011  in response to instructions from the user. In this case, the display  3  may display a switch button  300  to switch between display and hiding of the abnormal region image shape  2011 .  FIG.  63    is a schematic diagram showing an example of display of the display  3  in this case. 
     In the example of  FIG.  63   , a touch sensor included in the operation unit  4  and the display  3  constitute a touch panel display. The switch button  300  is a software button, and the operation unit  4  can receive a touch operation of the user on the switch button  300 . Each time the touch operation is performed on the switch button  300 , switching between display and hiding of the abnormal region image shape  2011  is made. When the operation unit  4  receives the user operation on the switch button  300  in a state of the abnormal region image shape  2011  being displayed as in  FIG.  63   , the abnormal region image shape  2011  is hidden. On the other hand, when the operation unit  4  receives the user operation on the switch button  300  in a state of the abnormal region image shape  2011  being hidden, the abnormal region image shape  2011  is displayed as in  FIG.  63   . 
     As described above, when switching between display and hiding of the abnormal region image shape  2011  is made in response to the instructions from the user, usability of the reading apparatus  1  is improved. 
     In the abnormality identification processing, only the presence or absence of any abnormality of the surface of the imaging plate  10  may be identified, and the position and the shape of the abnormal region image  2010  may not be identified. 
     As described above, the reading apparatus  1  can acquire the radiograph based on detection of the emitted light L 2  and the reflected light image based on detection of the reflected light, so that usability of the reading apparatus  1  is improved. 
     Luminance information (i.e., a luminance value) for the abnormal subregion  201   a  may be used to correct the detected radiograph. After identifying the position and the shape of the abnormal region image  2010  in step s 106 , the image processing unit  81  acquires, from the image signal from the detector  40 , luminance information (i.e., a luminance value) for the abnormal region image  2010  and luminance information for an image outside the abnormal region image  2010  of the second cutout image  152 . The image processing unit  81  uses the absolute value of a difference between the luminance information for the image outside the abnormal region image  2010  and the luminance information for the abnormal region image  2010  as a correction value when the detected radiograph is corrected. For example, when a luminance value for a region (an abnormality corresponding region) corresponding to the abnormality of the surface of the imaging plate  10  falls below a luminance value for the other region in the detected radiograph, the image processing unit  81  adds the correction value to the luminance value for the abnormality corresponding region. On the other hand, when the luminance value for the abnormality corresponding region exceeds the luminance value for the other region in the detected radiograph, the image processing unit  81  subtracts the correction value from the luminance value for the abnormality corresponding region. Such adjustment of the luminance information is referred to as abnormality corresponding region luminance adjustment processing. A proper radiograph can be acquired by the abnormality corresponding region luminance adjustment processing. A portion of the detected radiograph on which the abnormal region image shape  2011  is superimposed is the abnormality corresponding region. 
     &lt;Identification of Reverse Setting of IP&gt; 
     When the IP reflected light image is displayed, the user can identify reverse setting of the imaging plate  10  due to unusual insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward based on display of the IP reflected light image, for example. As described above, the surface of the imaging plate  10  on a side of the radiograph formation layer  11  is the front surface, and the surface of the imaging plate  10  opposite the front surface not on a side of the radiograph formation layer  11  is the back surface. While the user basically inserts the imaging plate  10  into the reading apparatus  1  with the front surface thereof facing forward in this example, the user sometimes inserts the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward by mistake. When the imaging plate  10  is set properly by being inserted with the front surface thereof facing forward, the support plate  21  of the holder  20  supports the back surface of the imaging plate  10  as described above. The front surface of the imaging plate  10 , in other words, the radiograph formation layer  11  of the imaging plate  10  is thus properly irradiated with the excitation light L 10  as described above. On the other hand, when the imaging plate  10  is set in reverse by being inserted with the back surface thereof facing forward by mistake, the support plate  21  supports the front surface of the imaging plate  10 , that is, the radiograph formation layer  11  of the imaging plate  10 . The back surface of the imaging plate  10  is thus irradiated with the excitation light L 10 . The detector  40  detects the reflected light of the excitation light L 10  from the back surface of the imaging plate  10  and the IP outside region R 130 , and outputs an image signal as a result of detection. 
     An image signal as a result of detection of light from the imaging plate  10  when the imaging plate  10  is set in reverse by being inserted into the reading apparatus  1  with the back surface thereof facing forward is hereinafter also referred to as a back insertion-time image signal. In the present embodiment, the back insertion-time image signal is acquired as a result of detection of the reflected light from the imaging plate  10 . A whole image based on the back insertion-time image signal is referred to as a back insertion-time whole image. The back insertion-time whole image does not include the radiograph, and includes the IP reflected light image in which the back surface of the imaging plate  10  appears and the IP outside region image, for example. Support of the front surface of the imaging plate  10  by the support plate  21  is also referred to as front surface support, and support of the back surface of the imaging plate  10  by the support plate  21  is also referred to as back surface support. The front surface support is backward setting of the imaging plate  10 , and the back surface support is forward setting of the imaging plate  10 . An act of backward setting of the imaging plate  10  is referred to as back insertion, and an act of forward setting of the imaging plate  10  is referred to as front insertion. 
     Assume that the imaging plate  10  is always set properly by being inserted into the reading apparatus  1  with the front surface thereof facing forward in description made above. That is to say, assume that the imaging plate  10  is always subjected to the back surface support in description made above. Thus, in description made above on processing shown in  FIG.  18   , the light emission-time whole image including the radiograph is acquired in step s 2 , and the light emission-time whole image including the radiograph is displayed in step s 7 . When the imaging plate  10  is inserted into the reading apparatus  1  with the back surface thereof facing forward, however, the acquired whole image acquired in step s 2 , in other words, the whole image based on the image signal output from the detector  40  in step s 2  is the back insertion-time whole image in which the back surface of the imaging plate  10  appears. That is to say, not the light emission-time whole image including the radiograph but the back insertion-time whole image not including the radiograph is acquired in step s 2 . Thus, when the imaging plate  10  is inserted into the reading apparatus  1  with the back surface thereof facing forward, the back insertion-time whole image is displayed in step s 7 . In the reading processing in step s 2 , the radiograph is read from the imaging plate  10  when the imaging plate  10  is set properly, and the back insertion-time whole image in which the back surface of the imaging plate  10  appears is acquired when the imaging plate  10  is set in reverse. 
     Similarly, when the imaging plate  10  is inserted into the reading apparatus  1  with the back surface thereof facing forward, the back insertion-time whole image is acquired in step s 2 , and the erasing-time whole image acquired in step s 22  is the back insertion-time whole image in the above-mentioned processing in  FIG.  27   . Thus, when the imaging plate  10  is inserted into the reading apparatus  1  with the back surface thereof facing forward, two back insertion-time whole images are displayed in step s 27 . The back insertion-time whole image in which the back surface of the imaging plate  10  appears and the erasing-time whole image acquired when the erased imaging plate  10  is held by the holder  20  each include only the reflected light image, and do not include the radiograph. 
       FIG.  64    is a schematic diagram showing one example of a back surface  10   y  of the imaging plate  10 . In this example, information (also referred to as back surface specific information)  600  specific to the back surface  10   y  of the imaging plate  10  is shown on the back surface  10   y  to be visible. At least one piece of back surface specific information  600  may be shown on the back surface  10   y  of the imaging plate  10 . 
     It can be said that the back surface specific information  600  is information not shown on the front surface of the imaging plate  10 . It can also be said that the back surface specific information  600  is back surface identification information or a back surface identifier to identify the back surface of the imaging plate  10 . It can also be said that the back surface specific information  600  is information indicating that the surface on which the back surface specific information  600  is shown is the back surface  10   y  of the imaging plate  10 . 
     In the example of  FIG.  64   , a plurality of pieces of back surface specific information  600  are shown on the back surface of the imaging plate  10 . The plurality of pieces of back surface specific information  600  include characters  600   a  representing the type of the size of the imaging plate  10 , characters  600   b  representing a manufacturer of the imaging plate  10 , a barcode  600   c,  and a barcode  600   d.  The barcode  600   c  and the barcode  600   d  may be the same, or may be different. At least one of the barcode  600   c  and the barcode  600   d  may represents a serial number of the imaging plate  10 , for example. 
       FIG.  65    is a schematic diagram showing one example of an IP reflected light image  301  included in the back insertion-time whole image acquired when the imaging plate  10  shown in  FIG.  64    is set in reverse. The back surface  10   y  of the imaging plate  10  shown in  FIG.  64    appears in the IP reflected light image  301 . 
     The IP reflected light image  301  shown in  FIG.  65    includes images  302  of the plurality of pieces of back surface specific information  600 . It can be said that the images  302  of the pieces of back surface specific information  600  are reflected light images of the pieces of back surface specific information  600 . The images  302  include an image  302   a  of the characters  600   a  representing the type of the size of the imaging plate  10 , an image  302   b  of the characters  600   b  representing the manufacturer of the imaging plate  10 , an image  302   c  of the barcode  600   c,  and an image  302   d  of the barcode  600   d,  for example. 
     A fringe region as an edge portion region of the imaging plate  10  is sometimes excluded from a target of image processing to acquire the radiograph. The back surface specific information  600  such as a barcode having an extremely small width may be shown in the fringe region, for example. 
     When the display  3  displays the back insertion-time whole image, the user can identify insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward, that is, reverse setting of the imaging plate  10  based on the IP reflected light image  301  included in the displayed back insertion-time whole image. Specifically, the user can identify insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward, that is, reverse setting of the imaging plate  10  by recognizing the images  302  (also referred to as back surface specific images  302 ) of the pieces of back surface specific information  600  included in the displayed IP reflected light image  301 . As described above, the user can recognize that the imaging plate  10  has not properly been inserted into the reading apparatus  1 . 
     Viewed another way, it can be said that the user can identify proper insertion of the imaging plate  10  into the reading apparatus  1  with the front surface thereof facing forward, that is, proper setting of the imaging plate  10  by recognizing the absence of any back surface specific images  302  included in the IP reflected light image displayed by the display  3 . 
     The back surface specific information  600  shown on the back surface of the imaging plate  10  is not limited to that described above. For example, a two-dimensional barcode may be shown on the back surface of the imaging plate  10  as the back surface specific information  600 . Characters, a symbol, or a graphic as the back surface specific information  600  may be shown in at least one of four corners on the back surface of the imaging plate  10 . Minimal back surface specific information  600  required to identify the back surface of the imaging plate  10  may be shown on the back surface of the imaging plate  10 . 
     The image processing unit  81  may cut out at least portion of the IP reflected light image  301  from the back insertion-time whole image as the cutout image as in a case where the second cutout image including at least portion of the IP reflected light image is cut out from the erasing-time whole image. In this case, the display control unit  82  may cause the display  3  to display the at least portion of the IP reflected light image  301  cut out from the back insertion-time whole image. The user can thus identify insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward by mistake based on the displayed at least portion of the IP reflected light image 
     While the back surface specific information shown on the back surface of the imaging plate  10  is used for the user to identify insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward in the above-mentioned example, information (also referred to as front surface specific information) specific to the front surface of the imaging plate  10  shown on the front surface may be used. At least one piece of front surface specific information may be shown on the front surface of the imaging plate  10  to be visible. It can be said that the front surface specific information is information not shown on the back surface of the imaging plate  10 . It can also be said that the front surface specific information is front surface identification information or a front surface identifier to identify the front surface of the imaging plate  10 . It can also be said that the front surface specific information is information indicating that the surface on which the front surface specific information is shown is the front surface of the imaging plate  10 . 
     An image signal as a result of detection of light from the imaging plate  10  when the imaging plate  10  is set by being inserted into the reading apparatus  1  with the front surface thereof facing forward may be referred to as a front insertion-time image signal. A whole image based on the front insertion-time image signal may be referred to as a front insertion-time whole image. 
     An image signal as a result of detection of light from the imaging plate  10  when the imaging plate  10  is set by being inserted into the reading apparatus  1  may be referred to as an insertion-time image signal, and a whole image based on the insertion-time image signal may be referred to as an insertion-time whole image. The front insertion-time image signal and the back insertion-time image signal are examples of the insertion-time image signal, and the front insertion-time whole image and the back insertion-time whole image are examples of the insertion-time whole image. 
     Light with which the imaging plate  10  is irradiated to acquire the insertion-time image signal may not necessarily be the excitation light L 10 . For example, when a surface of the imaging plate  10  is irradiated with light having no excitation ability, it may be determined that the surface is the back surface if the image of the back surface specific information  600  is acquired through detection of the reflected light. In this case, the reading processing through irradiation with the excitation light L 10  may be started when it is not determined that the surface is the back surface. 
       FIG.  66    is a schematic diagram showing one example of the imaging plate  10  having a front surface  10   x  on which front surface specific information  1000  is shown. In the example of  FIG.  66   , a single piece of front surface specific information  1000  is shown on the front surface  10   x  of the imaging plate  10 . The front surface specific information  1000  is characters, for example. The front surface specific information  1000  may be characters representing the manufacturer of the imaging plate  10 , for example, an initial letter of a name of the manufacturer of the imaging plate  10 . The radiograph formation layer  11  is provided to the front surface  10   x  of the imaging plate  10  excluding the front surface specific information  1000 . In this example, the light emission-time whole image based on detection of the emitted light L 2  and the reflected light from the imaging plate  10  includes a reflected light image of the front surface specific information  1000 . The user can identify insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward by mistake, that is, reverse setting of the imaging plate  10  by checking the absence of the image (i.e., the reflected light image) of the front surface specific information  1000  included in the acquired whole image or the cutout image displayed by the display  3 , for example. The user can also identify proper insertion of the imaging plate  10  into the reading apparatus  1  with the front surface thereof facing forward, that is, proper setting of the imaging plate  10  by checking the presence of the image of the front surface specific information  1000  included in the acquired whole image or the cutout image displayed by the display  3 . 
     The front surface specific information  1000  is not limited to that in the example of  FIG.  66   . As shown in  FIG.  67   , a plurality of pieces of front surface specific information  1000  may be shown on the front surface  10   x  of the imaging plate  10 . While the same two pieces of front surface specific information  1000  are shown on the front surface  10   x  of the imaging plate  10  in the example of  FIG.  67   , two different pieces of front surface specific information  1000  may be shown. Minimal front surface specific information  1000  required to identify the front surface  10   x  of the imaging plate  10  may be shown on the front surface of the imaging plate  10 . The back surface specific information may be shown on the back surface of the imaging plate  10  while the front surface specific information  1000  is shown on the front surface of the imaging plate  10 . 
     The fringe region as the edge portion region of the imaging plate  10  is sometimes excluded from the target of the image processing to acquire the radiograph. The front surface specific information  1000  such as a barcode having an extremely small width may be shown in the fringe region, for example. 
     The imaging plate  10  may have a protrusion  12  for the user to identify insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward, that is, reverse setting of the imaging plate  10 .  FIG.  68    shows one example of the imaging plate  10  having the protrusion  12 .  FIG.  68    shows a side of the front surface  10   x  of the imaging plate  10  in a state of the imaging plate  10  being set with the front surface thereof facing forward. In the example of  FIG.  68   , the imaging plate  10  has the protrusion  12  at a peripheral edge thereof. The imaging plate  10  has the protrusion  12  at one of four sides constituting the peripheral edge of the imaging plate  10  excluding a middle portion thereof. In the example of  FIG.  68   , the imaging plate  10  has the protrusion  12  at a short side thereof excluding a middle portion thereof. The radiograph formation layer  11  is not provided to a surface of the protrusion  12 , and black anodizing is not performed on the surface of the protrusion  12 . Not only the imaging plate  10  but also a region at the peripheral edge of the imaging plate  10  is scanned with the excitation light L 10 . A protrusion region as a region in which the protrusion  12  is present when the imaging plate  10  is inserted into the reading apparatus  1  with the front surface thereof facing forward is scanned with the excitation light L 10 . When the imaging plate  10  is inserted into the reading apparatus  1  with the back surface thereof facing forward, the protrusion  12  is not present in the protrusion region. The excitation light L 10  is reflected from the surface of the protrusion  12  to the same extent as the surface of the imaging plate  10 , for example. The acquired whole image based on the image signal output from the detector  40  includes a reflected light image of the protrusion  12  regardless of whether the imaging plate  10  is set in reverse. The imaging plate  10  may have the protrusion  12  at a long side thereof. 
     As described above, the imaging plate  10  has the protrusion  12  at one side thereof excluding the middle portion thereof, so that the protrusion  12  is always at different positions in a case where the imaging plate  10  is subjected to the back surface support and a case where the imaging plate  10  is subjected to the front surface support when the imaging plate  10  is viewed from a side of the light source  30 . 
       FIG.  69    is a schematic diagram showing one example of the imaging plate  10  viewed from a side of the front surface  10   x  as in  FIG.  68   .  FIG.  69    shows the imaging plate  10  shown in  FIG.  68    having been rotated by 180 degrees parallel to the main surface thereof.  FIGS.  70  and  71    are schematic diagrams each showing one example of the imaging plate  10  viewed from a side of the back surface  10   y  in a state of the imaging plate  10  being set with the back surface thereof facing forward.  FIG.  71    shows the imaging plate  10  shown in  FIG.  70    having been rotated by 180 degrees parallel to the main surface thereof. 
     As shown in  FIGS.  68  to  71   , a position of the protrusion  12  when the imaging plate  10  is viewed from a side of the front surface  10   x  and a position of the protrusion  12  when the imaging plate  10  is viewed from a side of the back surface  10   y  are always different. As shown in  FIGS.  68  and  69   , when the imaging plate  10  is viewed from a side of the front surface  10   x,  the protrusion  12  is present at a position closer to a side (an upper side in  FIG.  68   ) adjacent clockwise to the side to which the protrusion  12  is provided than to a side (a lower side in  FIG.  68   ) adjacent counterclockwise to the side to which the protrusion  12  is provided. In contrast, as shown in  FIGS.  70  and  71   , when the imaging plate  10  is viewed from a side of the back surface  10   y,  the protrusion  12  is present at a position closer to the side (a lower side in  FIG.  70   ) adjacent counterclockwise to the side to which the protrusion  12  is provided than to the side (an upper side in  FIG.  70   ) adjacent clockwise to the side to which the protrusion  12  is provided. 
     As described above, when the imaging plate  10  has the protrusion  12  at one side thereof excluding the middle portion thereof, the position of the protrusion  12  when the imaging plate  10  is viewed from a side of the front surface  10   x  and the position of the protrusion  12  when the imaging plate  10  is viewed from a side of the back surface  10   y  are always different. The protrusion  12  is thus always at different positions in a case where the imaging plate  10  is subjected to the back surface support and a case where the imaging plate  10  is subjected to the front surface support when the imaging plate  10  is viewed from a side of the light source  30 . In other words, the protrusion  12  is always at different positions in a case where the imaging plate  10  is set in reverse and a case where the imaging plate  10  is set properly when the imaging plate  10  is viewed from a side of the light source  30 . A position of an image (i.e., a reflected light image) of the protrusion  12  in the light emission-time whole image or the erasing-time whole image acquired when the imaging plate  10  is subjected to the back surface support and a position of an image (i.e., a reflected light image) of the protrusion  12  in the back insertion-time whole image acquired when the imaging plate  10  is subjected to the front surface support are thus always different. The user can easily identify the front surface support of the imaging plate  10 , that is, insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward by checking the position of the image of the protrusion  12  in the acquired whole image displayed by the display  3 . In other words, the user can easily identify reverse setting of the imaging plate  10  by checking the position of the protrusion  12  appearing in the acquired whole image displayed by the display  3 . Viewed another way, the user can easily identify proper setting of the imaging plate  10  by checking the position of the protrusion  12  appearing in the acquired whole image displayed by the display  3 . 
     The protrusion  12  may be removable from the imaging plate  10  as shown in  FIG.  72   . 
     The imaging plate  10  may have a plurality of protrusions  12  at the peripheral edge thereof.  FIGS.  73  and  74    are schematic diagrams showing one example of the imaging plate  10  having two protrusions  12  at the peripheral edge thereof.  FIG.  73    shows the imaging plate  10  viewed from a side of the front surface  10   x,  and  FIG.  74    shows the imaging plate  10  viewed from a side of the back surface  10   y.  In the example of  FIGS.  73  and  74   , the imaging plate  10  has the two protrusions  12  at two opposing sides thereof. The two protrusions  12  are present at positions point symmetric with respect to the center of the front surface  10   x  (or the back surface  10   y ) when the imaging plate  10  is viewed from a side of the front surface  10   x  (or the back surface  10   y ). Even when the imaging plate  10  has the two protrusions  12  at the peripheral edge thereof as shown in  FIGS.  73  and  74   , positions of images of the protrusions  12  in the light emission-time whole image or the erasing-time whole image acquired when the imaging plate  10  is subjected to the back surface support and positions of images of the protrusions  12  in the back insertion-time whole image acquired when the imaging plate  10  is subjected to the front surface support are always different. The user can thus easily identify insertion of the imaging plate  10  into the reading apparatus  1  with the back surface thereof facing forward, that is, reverse setting of the imaging plate  10  by checking the positions of the images of the protrusions  12  in the acquired whole image displayed by the display  3 . The user can also easily identify insertion of the imaging plate  10  into the reading apparatus  1  with the front surface thereof facing forward, that is, proper setting of the imaging plate  10  by checking the positions of the images of the protrusions  12  in the acquired whole image displayed by the display  3 . 
     The two protrusions  12  may each be removable from the imaging plate  10  as shown in  FIG.  75   . Only one of the two protrusions  12  may be removable from the imaging plate  10 . When the imaging plate  10  has at least one protrusion  12 , the front surface specific information may be shown on the front surface  10   x  of the imaging plate  10 , and the back surface specific information may be shown on the back surface  10   y  of the imaging plate  10 . 
     The image processing unit  81  may perform determination processing of determining whether the imaging plate  10  is set in reverse based on a result of detection of the detector  40 . In this case, the image processing unit  81  functions as a determination unit that determines whether the imaging plate  10  is set in reverse. It can be said that the determination processing is processing of determining whether the imaging plate  10  is inserted into the reading apparatus  1  with the back surface thereof facing forward. 
       FIG.  76    is a flowchart showing one example of operation of the reading apparatus  1  when the image processing unit  81  performs the determination processing. When the start button included in the operation unit  4  is operated after the imaging plate  10  inserted through the inlet  2   a  of the housing  2  is held by the holder  20 , that is, the imaging plate  10  is set in the reading apparatus  1 , the above-mentioned steps s 1  and s 2  are performed. At the start of step s 1 , it is not known whether the imaging plate  10  is set properly or is set in reverse in the reading apparatus  1 . 
     When the reading processing in step s 2  ends, the image processing unit  81  performs the determination processing in step s 201 . In the determination processing, the image processing unit  81  determines whether the imaging plate  10  is set in reverse based on the image signal output from the detector  40  in the reading processing in step s 2 . 
     Consider herein a case where the back surface specific information  600  is shown on the back surface of the imaging plate  10  as in the above-mentioned example of  FIG.  64   . In this case, the image processing unit  81  determines whether the acquired whole image based on the image signal acquired in step s 2  includes the image  302  (i.e., the back surface specific image  302 ) of the back surface specific information  600 . The image processing unit  81  determines whether the acquired whole image includes the image  302   c  of the barcode  600   c,  for example. When determining that the acquired whole image acquired in step s 2  includes the back surface specific image  302 , the image processing unit  81  determines that the imaging plate  10  is set in reverse. On the other hand, when determining that the acquired whole image acquired in step s 2  does not include the back surface specific image  302 , the image processing unit  81  determines that the imaging plate  10  is not set in reverse. That is to say, the image processing unit  81  determines that the imaging plate  10  is set properly. 
     Consider, as another example, a case where the front surface specific information  1000  is shown on the front surface of the imaging plate  10  as shown in  FIGS.  66  and  67    described above. In this case, the image processing unit  81  determines whether the acquired whole image acquired in step s 2  includes the image of the front surface specific information  1000 . When determining that the acquired whole image includes the image of the front surface specific information  1000 , the image processing unit  81  determines that the imaging plate  10  is not set in reverse. On the other hand, when determining that the acquired whole image does not include the image of the front surface specific information  1000 , the image processing unit  81  determines that the imaging plate  10  is set in reverse. 
     Consider, as yet another example, a case where the imaging plate  10  has at least one protrusion  12  to determine whether the imaging plate  10  is set in reverse at the peripheral edge thereof as in the above-mentioned examples of  FIGS.  68  to  74   . In this case, the image processing unit  81  checks the position of the image of the protrusion  12  in the acquired whole image acquired in step s 2 . The image processing unit  81  determines whether the imaging plate  10  is set in reverse based on the position of the image of the protrusion  12  in the acquired whole image. As described above, the position of the image of the protrusion  12  in the acquired whole image acquired when the imaging plate  10  is subjected to the back surface support and the position of the image of the protrusion  12  in the acquired whole image acquired when the imaging plate  10  is subjected to the front surface support are always different. The image processing unit  81  can thus determine whether the imaging plate  10  is set in reverse based on the position of the image of the protrusion  12  in the acquired whole image. The image processing unit  81  can identify the position of the image of the protrusion  12  in the acquired whole image based on the binarized image acquired by binarizing the acquired whole image, for example. 
     When it is determined that the imaging plate  10  is not set in reverse in step s 201 , the above-mentioned steps s 3  and s 4  are performed. After step s 4 , steps s 5 , s 6 , and s 7  may be performed as in the above-mentioned example of  FIG.  18   , or steps s 21 , s 22 , s 5 , s 6 , and s 27  may be performed as in the above-mentioned example of  FIG.  27   . 
     On the other hand, when it is determined that the imaging plate  10  is set in reverse in step s 201 , step s 202  is performed. In step s 202 , the reading apparatus  1  notifies the user of an alert. In this case, the display control unit  82  may cause the display  3  to display alert information  650  to notify the user of the alert. In this case, the display  3  functions as a notification unit that notifies the user of the alert. 
       FIG.  77    is a schematic diagram showing an example of display of the alert information  650 . In the example of  FIG.  77   , the alert information  650  includes notification information  650   a  that notifies the user of reverse setting of the imaging plate  10  and instruction information  650   b  that instructs the user to insert the imaging plate  10  again with the front surface thereof facing forward. It can be said that the instruction information  650   b  is instruction information to instruct the user to set the imaging plate  10  properly. 
     The alert information  650  is not limited to that in the above-mentioned example. The reading apparatus  1  may notify the user of the alert by means other than display of information. For example, when the reading apparatus  1  includes a sound output means, such as a speaker, of outputting a sound to the outside of the housing  2 , the reading apparatus  1  may notify the user of the alert by outputting a predetermined alert sound from the sound output means. In this case, the sound output means functions as the notification unit that notifies the user of the alert. When the reading apparatus  1  includes a light emitter, such as an LED, that outputs light to the outside of the housing  2 , the reading apparatus  1  may notify the user of the alert by causing the light emitter to emit light. In this case, the light emitter functions as the notification unit that notifies the user of the alert. 
     When notified of the alert by the reading apparatus  1 , the user operates a discharge button included in the operation unit  4 , for example. When the operation unit  4  receives an operation on the discharge button, the above-mentioned steps s 5  and s 6  are performed to discharge the imaging plate  10  from which the radiograph has not been erased to the outlet  2   b  in the reading apparatus  1 . The user then inserts the imaging plate  10  discharged from the reading apparatus  1  into the reading apparatus  1  again. Then, when the start button included in the operation unit  4  is operated, a series of processes in  FIG.  76    is performed again. 
     The reading apparatus  1  may cause the display  3  to display the acquired whole image (i.e., the back insertion-time whole image) acquired in step s 2  while notifying the user of the alert in step s 202 . In this case, the display  3  may simultaneously and separately display the alert information  650  and the back insertion-time whole image, for example. 
     As described above, the image processing unit  81  can determine whether the imaging plate is set in reverse based on the result of detection of the detector  40 . This allows the radiograph to be more surely read from the imaging plate  10  based on a result of determination. Notification of the user of the alert in response to a result of determination as in the above-mentioned example can prompt the user to properly set the imaging plate  10  to the reading apparatus  1 , for example. This allows the radiograph to be more surely read from the imaging plate  10 . 
     In the example of  FIG.  76   , the user is notified of the alert without performing the erasing processing when it is determined that the imaging plate is set in reverse. More specifically, in the example of  FIG.  76   , while the erasing processing is performed when it is not determined that the imaging plate is set in reverse, the erasing processing is not performed, and, further, the user is notified of the alert when it is determined that the imaging plate is set in reverse. In the example of  FIG.  76   , the user is notified of the alert without irradiating the imaging plate  10  with the erasing light L 3  when it is determined that the imaging plate is set in reverse. The user can thus be notified of the alert immediately upon determination that the imaging plate is set in reverse. Notification of the alert in step s 202  may be performed between steps s 3  and s 4 , or may be performed after step s 4 . 
     The erasing processing is accompanied by irradiation of the imaging plate  10  with the erasing light L 3 . Irradiation with the erasing light L 3  in a state of the imaging plate  10  being set in reverse can adversely affect the radiograph recorded on the imaging plate  10  as the latent image. For example, when there is a gap between the support plate  21  and the imaging plate  10 , the erasing light L 3  sometimes enters the gap to partially erase or fade the radiograph recorded on the imaging plate  10 . The imaging plate  10  can also generate heat to adversely affect the detected signal due to irradiation with the erasing light L 3 . It also takes additional time for the erasing processing. The erasing processing is not performed when the imaging plate is set in reverse to prevent these adverse effects and losses. 
     When at least one piece of back surface specific information  600  is shown on the back surface of the imaging plate  10  as in the example of  FIG.  64   , it is easy to determine whether the imaging plate  10  is set in reverse. 
     When at least one piece of front surface specific information  1000  is shown on the front surface of the imaging plate  10  as in the examples of  FIGS.  66  and  67   , it is easy to determine whether the imaging plate  10  is set in reverse. 
     When the imaging plate  10  has at least one protrusion  12  to determine whether the imaging plate  10  is set in reverse at the peripheral edge thereof as in the examples of  FIGS.  68  to  75   , it is easy to determine whether the imaging plate  10  is set in reverse. 
     While the reading apparatus  1  discharges the imaging plate  10  in response to the instructions from the user when it is determined that the imaging plate  10  is set in reverse in the above-mentioned examples, the imaging plate  10  may automatically be discharged without the instructions from the user. For example, step s 3  may be performed after step s 202 . In this case, after the erasing processing is performed, the above-mentioned steps s 5  and s 6  are performed to automatically discharge the imaging plate  10 . 
     As shown in  FIG.  78   , steps s 205  and s 206  may sequentially be performed after step s 202 . In step s 205 , the holder  20  is moved to the discharge position as in the above-mentioned step s 5 . In step s 206 , the imaging plate  10  is discharged to the outlet  2   b  as in the above-mentioned step s 6 . The imaging plate  10  is thereby automatically discharged when it is determined that the imaging plate  10  is set in reverse. That is to say, the imaging plate  10  is discharged in response to determination that the imaging plate  10  is set in reverse. 
     As described above, discharge of the imaging plate  10  when it is determined that the imaging plate  10  is set in reverse eliminates the need for the user operation to provide instructions to discharge the imaging plate  10  on the reading apparatus  1 . Usability of the reading apparatus  1  is thereby improved. Discharge of the imaging plate  10  can prompt the user to set the imaging plate  10  again. 
     In the example of  FIG.  78   , the imaging plate  10  is discharged without performing the erasing processing when it is determined that the imaging plate is set in reverse. The imaging plate  10  can thereby be discharged immediately upon determination that the imaging plate is set in reverse. 
     After affirmative determination in step s 201 , steps s 205  and s 206  may be performed without performing step s 202 . That is to say, the imaging plate  10  may be discharged without notifying the user of the alert when it is determined that the imaging plate  10  is set in reverse. Step s 202  may be performed after steps s 205  and s 206 , or may be performed between steps s 205  and s 206 . 
     When the plurality of pieces of back surface specific information  600  are shown on the back surface of the imaging plate  10  as in the example of  FIG.  64   , reverse setting of the imaging plate  10  can be identified immediately even if the orientation of the imaging plate when the imaging plate  10  is set is not constant. Description will be made in this respect below. 
     In the reading processing, the driver  50  moves the holder  20  holding the imaging plate  10  in the subscannig direction DRs while the light source  30  performs scanning processing of repeatedly performing main scanning direction scanning of scanning the imaging plate  10  with the excitation light L 10  in the main scanning direction DRm as described above. The imaging plate  10  is thus raster scanned with the excitation light L 10 . It can be said that the start of the reading processing is the start of the scanning processing of the light source  30 . 
       FIGS.  79  and  80    are schematic diagrams each illustrating one example of reverse setting of the imaging plate  10  having the back surface  10   y  on which the plurality of pieces of back surface specific information  600  are shown. In the examples of  FIGS.  79  and  80   , only the barcodes  600   c  and  600   d  are shown on the back surface  10   y  of the imaging plate  10 . The barcodes  600   c  and  600   d  are provided to respective end portions in a longitudinal direction of the back surface  10   y  of the imaging plate  10 . A scanning direction DRr in which the imaging plate  10  is scanned with the excitation light L 10  in the scanning processing (i.e., raster scanning) is shown in each of  FIGS.  79  and  80   . In the example of  FIG.  80   , the imaging plate  10  is set in a state of being rotated by 180 degrees parallel to the main surface thereof compared with that in the example of  FIG.  79   . 
     One of opposite sides in the longitudinal direction of the imaging plate  10  on which raster scanning starts is referred to as a scanning forward side, and the other one of the opposite sides in the longitudinal direction of the imaging plate  10  on which raster scanning ends is referred to as a scanning backward side. The scanning forward side of the imaging plate  10  is a left side in each of  FIGS.  79  and  80   , and the scanning backward side of the imaging plate  10  is a right side in each of  FIGS.  79  and  80   . In the examples of  FIGS.  79  and  80   , the back surface specific information  600  is shown in each of the end portion on the scanning forward side and the end portion on the scanning backward side on the back surface  10   y  of the imaging plate  10 . In this example, the imaging plate  10  is sometimes set so that one of opposite end portions in the longitudinal direction thereof is located on the scanning forward side, and is sometimes set so that the other one of the opposite end portions in the longitudinal direction thereof is located on the scanning forward side as illustrated in  FIGS.  79  and  80   . 
     As described above, in the reading processing according to this example, the main scanning direction scanning is repeatedly performed during movement of the imaging plate  10  in the subscannig direction DRs. Scanning (also referred to as unit scanning) of the imaging plate  10  with the excitation light L 10  in a direction crossing the longitudinal direction of the imaging plate  10  is thus repeatedly performed from the scanning forward side to the scanning backward side as shown by the scanning direction DRr in each of  FIGS.  79  and  80   . In each of  FIGS.  79  and  80   , each of a plurality of arrows showing the scanning direction DRr represents the unit scanning. 
     When the imaging plate  10  is set so that the barcode  600   c  is located on the scanning forward side as illustrated in  FIG.  79   , the image of the barcode  600   c  is acquired in the first half of the reading processing in step s 2 . When the imaging plate  10  is set so that the barcode  600   d  is located on the scanning forward side as illustrated in  FIG.  80   , the image of the barcode  600   d  is acquired in the first half of the reading processing. The image processing unit  81  can thus determine whether the acquired whole image includes the image of the back surface specific information  600  by checking not the acquired whole image acquired in the reading processing as a whole but only the image acquired in the first half of the reading processing in the acquired whole image in the above-mentioned step s 201 . When the image acquired in the first half of the reading processing in the acquired whole image includes the image of the back surface specific information  600 , the image processing unit  81  determines that the imaging plate  10  is set in reverse. On the other hand, when the image acquired in the first half of the reading processing in the acquired whole image does not include the image of the back surface specific information  600 , the image processing unit  81  determines that the imaging plate  10  is not set in reverse. 
     In contrast, consider a case where the barcode  600   c  is not shown on the back surface  10   y  of the imaging plate  10 , for example. In this case, the image of the barcode  600   c  is acquired in the first half of the reading processing when the imaging plate  10  is set in the orientation in  FIG.  79   . The image of the barcode  600   c,  however, is acquired in the second half of the reading processing when the imaging plate  10  is set in the orientation in  FIG.  80   . The image processing unit  81  is thus required to check the acquired whole image as a whole, and determine whether the acquired whole image includes the image of the back surface specific information  600  to identify reverse setting of the imaging plate  10  when the imaging plate  10  is set in the orientation in  FIG.  79    and when the imaging plate  10  is set in the orientation in  FIG.  80   . 
     As described above, the image processing unit  81  can determine whether the acquired whole image includes the image of the back surface specific information  600  by checking only a portion of the acquired whole image even when the plurality of pieces of back surface specific information  600  are shown on the back surface of the imaging plate  10 , and the orientation of the imaging plate when the imaging plate  10  is set is not constant. The image processing unit  81  can thus determine whether the acquired whole image includes the image of the back surface specific information  600  immediately. The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. As a result, the reading apparatus  1  can notify the user of the alert immediately, and can discharge the imaging plate  10  immediately, for example. 
     In a case where the back surface specific information  600  is shown in each of the end portion on the scanning forward side and the end portion on the scanning backward side on the back surface of the imaging plate  10  as in the examples of  FIGS.  79  and  80   , the image processing unit  81  can determine whether the acquired whole image includes the image of the back surface specific information  600  by checking only an image acquired early in the reading processing in the acquired whole image when the imaging plate  10  is set in the orientation in  FIG.  79    and when the imaging plate  10  is set in the orientation in  FIG.  80   . The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. The number of pieces of back surface specific information  600  shown on the back surface of the imaging plate  10  may be one. A position on the back surface of the imaging plate  10  where the back surface specific information  600  is shown is not limited to that in the above-mentioned example. 
     When the plurality of pieces of front surface specific information  1000  are shown on the front surface of the imaging plate  10  as in the example of  FIG.  67   , reverse setting of the imaging plate  10  can similarly be identified immediately even if the orientation of the imaging plate  10  when the imaging plate  10  is set is not constant. 
       FIGS.  81  and  82    are schematic diagrams each illustrating one example of normal setting of the imaging plate  10  having the front surface  10   x  on which the plurality of pieces of front surface specific information  1000  are shown. In the examples of  FIGS.  81  and  82   , letters  1000   a  and  1000   b  as the pieces of front surface specific information  1000  are shown on the front surface  10   x  of the imaging plate  10 . The letters  1000   a  and  1000   b  are shown in the end portion on the scanning forward side and the end portion on the scanning backward side on the front surface  10   x  of the imaging plate  10 . In the example of  FIG.  82   , the imaging plate  10  is set in a state of being rotated by 180 degrees parallel to the main surface thereof compared with that in the example of  FIG.  81   . 
     When the imaging plate  10  is set so that the letter  1000   a  is located on the scanning forward side as illustrated in  FIG.  81   , an image of the letter  1000   a  is acquired in the first half of the reading processing. When the imaging plate  10  is set so that the letter  1000   b  is located on the scanning forward side as illustrated in  FIG.  82   , an image of the letter  1000   b  is acquired in the first half of the reading processing. The image processing unit  81  can thus determine whether the acquired whole image includes the image of the front surface specific information  1000  by checking only the image acquired in the first half of the reading processing in the acquired whole image acquired in the reading processing in step s 201 . When the image acquired in the first half of the reading processing in the acquired whole image does not include the image of the front surface specific information  1000 , the image processing unit  81  can determine that the imaging plate  10  is set in reverse. 
     As described above, the image processing unit  81  can determine whether the acquired whole image includes the image of the front surface specific information  1000  by checking only a portion of the acquired whole image even when the plurality of pieces of front surface specific information  1000  are shown on the front surface of the imaging plate  10 , and the orientation of the imaging plate  10  when the imaging plate  10  is set is not constant. The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. 
     In a case where the front surface specific information  1000  is shown in each of the end portion on the scanning forward side and the end portion on the scanning backward side on the front surface of the imaging plate  10  as in the examples of  FIGS.  81  and  82   , the image processing unit  81  can determine whether the acquired whole image includes the image of the front surface specific information  1000  by checking only the image acquired early in the reading processing in the acquired whole image when the imaging plate  10  is set in the orientation in  FIG.  81    and when the imaging plate  10  is set in the orientation in  FIG.  82   . The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. 
     In the examples of  FIGS.  81  and  82   , the front surface specific information  1000  is shown, in the end portion on the scanning forward side on the front surface  10   x  of the set imaging plate  10 , on a side closer to a position where unit scanning of raster scanning starts than a middle portion is. The image processing unit  81  can thus determine whether the acquired whole image includes the image of the front surface specific information  1000  by checking only a smaller portion of the acquired whole image. The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. 
     A position on the front surface of the imaging plate  10  where the front surface specific information  1000  is shown is not limited to that in the above-mentioned example. The back surface specific information  600  may be shown, in the end portion on the scanning forward side on the back surface of the imaging plate  10 , on a side closer to a position where unit scanning of raster scanning starts than a middle portion is. The image processing unit  81  can thus determine whether the acquired whole image includes the image of the back surface specific information  600  by checking only a smaller portion of the acquired whole image. The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. 
     When the imaging plate  10  has the plurality of protrusions  12  at the peripheral edge thereof as in the examples of  FIGS.  73  to  75   , the image processing unit  81  can similarly identify reverse setting of the imaging plate  10  immediately even if the orientation of the imaging plate  10  when the imaging plate  10  is set is not constant. 
       FIGS.  83  and  84    are schematic diagrams each illustrating one example of reverse setting of the imaging plate  10  having the plurality of protrusions  12 . The imaging plate  10  has protrusions  12   a  and  12   b  at the peripheral edge thereof in the examples of  FIGS.  83  and  84   . The imaging plate  10  has the protrusions  12   a  and  12   b  at a short side on the scanning forward side and a short side on the scanning backward side of the peripheral edge thereof. In the example of  FIG.  84   , the imaging plate  10  is set in a state of being rotated by 180 degrees parallel to the main surface thereof compared with that in the example of  FIG.  83   . 
     When the imaging plate  10  is set so that the protrusion  12   a  is located on the scanning forward side as illustrated in  FIG.  83   , an image of the protrusion  12   a  is acquired in the first half of the reading processing. When the imaging plate  10  is set so that the protrusion  12   b  is located on the scanning forward side as illustrated in  FIG.  84   , an image of the protrusion  12   b  is acquired in the first half of the reading processing. The image processing unit  81  can thus determine whether the acquired whole image includes the image of the protrusion  12  by checking only the image acquired in the first half of the reading processing in the acquired whole image acquired in the reading processing in step s 201 . When the image acquired in the first half of the reading processing in the acquired whole image includes the image of the protrusion  12 , the image processing unit  81  identifies the position of the protrusion  12  relative to the imaging plate  10  based on the position of the image of the protrusion  12  in the image acquired in the first half of the reading processing. When the identified position of the protrusion  12  matches the position (see  FIGS.  73  and  74   , for example) of the protrusion  12  when the imaging plate  10  is subjected to the front surface support, the image processing unit  81  determines that the imaging plate  10  is set in reverse. On the other hand, when the identified position of the protrusion  12  does not match the position of the protrusion  12  when the imaging plate  10  is subjected to the front surface support, the image processing unit  81  determines that the imaging plate  10  is not set in reverse. 
     As described above, even when the imaging plate  10  has the plurality of protrusions  12  at the peripheral edge thereof, and the orientation of the imaging plate  10  when the imaging plate  10  is set is not constant, the image processing unit  81  can determine whether the acquired whole image includes the image of the protrusion  12  by checking only a portion of the acquired whole image. The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. 
     In a case where the imaging plate  10  has the protrusions  12  at a side on the scanning forward side and a side on the scanning backward side of the peripheral edge thereof as in the examples of  FIGS.  83  and  84   , the image processing unit  81  can determine whether the acquired whole image includes the image of the protrusion  12  by checking only an image acquired early in the reading processing in the acquired whole image when the imaging plate  10  is set in the orientation in  FIG.  83    and when the imaging plate  10  is set in the orientation in  FIG.  84   . The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. 
     In the examples of  FIGS.  83  and  84   , the imaging plate  10  has the protrusion  12  at a side of the scanning forward side of the peripheral edge thereof on a side closer to a position where unit scanning of raster scanning starts than a middle portion is. The image processing unit  81  can thus determine whether the acquired whole image includes the image of the protrusion  12  by checking only a smaller portion of the acquired whole image. The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately. A position at the peripheral edge of the imaging plate  10  where the imaging plate  10  has the protrusion  12  is not limited to that in the above-mentioned example. 
     While the determination processing is performed after the reading processing in step s 2  ends in the above-mentioned example, the reading processing and the determination processing may be performed in parallel.  FIG.  85    is a flowchart showing one example of operation of the reading apparatus  1  in this case. When the start button included in the operation unit  4  is operated to perform step s 1 , the reading processing starts in step s 211 . 
     When the reading processing starts, in other words, the scanning processing starts, the image processing unit  81  determines whether reverse setting of the imaging plate  10  can be identified based on luminance values sequentially output from the detector  40  in response to raster scanning in step s 212 . Specifically, the image processing unit  81  determines whether reverse setting of the imaging plate  10  can be identified based on a plurality of luminance values (i.e., a plurality of pixel signals or a plurality of pixel values) sequentially output from the detector  40  from the start of the reading processing to a current time. Step s 212  may be performed each time a single luminance value is output from the detector  40 , or each time a plurality of luminance values are output from the detector  40 , for example. Step s 212  may be performed each time a row of raster scanning with the excitation light L 10  is performed, or each time a plurality of rows of raster scanning with the excitation light L 10  are performed, for example. 
     Consider herein a case where the back surface specific information  600  is shown on the back surface of the imaging plate  10 . In this case, the image processing unit  81  determines whether an image (also referred to as a determination target image) represented by the plurality of luminance values output from the detector  40  from the start of the reading processing to the current time includes the image  302  (i.e., the back surface specific image  302 ) of the back surface specific information  600  in step s 212 . Luminance values of a plurality of pixels constituting the determination target image include the luminance values output from the detector  40  from the start of the reading processing to the current time. The determination target image is at least portion of the acquired whole image acquired by completion of the reading processing. When determining that the determination target image includes the back surface specific image  302 , the image processing unit  81  determines that reverse setting of the imaging plate  10  can be identified. That is to say, the image processing unit  81  determines that the imaging plate  10  is set in reverse. On the other hand, when determining that the determination target image does not include the back surface specific image  302 , the image processing unit  81  determines that reverse setting of the imaging plate  10  cannot be identified. 
     Consider, as another example, a case where two pieces of front surface specific information  1000  are shown on the front surface of the imaging plate  10  as illustrated in  FIGS.  81  and  82    described above, for example. In this case, the image processing unit  81  determines whether the determination target image includes the images of the pieces of front surface specific information  1000  in step s 212 . When determining that the determination target image includes the images of the pieces of front surface specific information  1000 , the image processing unit  81  determines that reverse setting of the imaging plate  10  cannot be identified. On the other hand, when determining that the determination target image does not include the pieces of front surface specific information  1000 , the image processing unit  81  determines whether the determination target image corresponds to the half of the acquired whole image, for example. When determining that the determination target image corresponds to the half of the acquired whole image, the image processing unit  81  determines that reverse setting of the imaging plate  10  can be identified. On the other hand, when determining that the determination target image does not correspond to the half of the acquired whole image, in other words, when determining that the determination target image is less than half of the acquired whole image, the image processing unit  81  determines that reverse setting of the imaging plate  10  cannot be identified. 
     The determination target image not including the image of the front surface specific information  1000  and corresponding to the half of the acquired whole image herein means that the image acquired in the first half of the reading processing in the acquired whole image does not include the image of the front surface specific information  1000 . It can thus be said that, when the image acquired in the first half of the reading processing in the acquired whole image does not include the image of the front surface specific information  1000 , the image processing unit  81  determines that reverse setting of the imaging plate  10  can be identified. 
     Consider, as another example, a case where the imaging plate  10  has the protrusion  12  at the peripheral edge thereof. In this case, the image processing unit  81  determines whether the determination target image includes the image of the protrusion  12  in step s 212 . When determining that the determination target image includes the image of the protrusion  12 , the image processing unit  81  identifies the position of the protrusion  12  relative to the imaging plate  10  based on the position of the image of the protrusion  12  in the determination target image. When the identified position of the protrusion  12  matches the position (see  FIGS.  83  and  84   , for example) of the protrusion  12  when the imaging plate  10  is subjected to the front surface support, the image processing unit  81  determines that reverse setting of the imaging plate  10  can be identified. On the other hand, when the identified position of the protrusion  12  does not match the position of the protrusion  12  when the imaging plate  10  is subjected to the front surface support, the image processing unit  81  determines that reverse setting of the imaging plate  10  cannot be identified. In other words, when the identified position of the protrusion  12  matches the position (see  FIG.  73   , for example) of the protrusion  12  when the imaging plate  10  is subjected to the back surface support, the image processing unit  81  determines that reverse setting of the imaging plate  10  cannot be identified. 
     When the image processing unit  81  determines that reverse setting of the imaging plate  10  can be identified, in other words, when the image processing unit  81  determines that the imaging plate  10  is set in reverse in step s 212 , step s 214  is performed. The reading processing is stopped in step s 214 . That is to say, the light emission control unit  86  causes the light source  30  to stop the scanning processing, and the drive control unit  83  causes the driver  50  to stop moving the holder  20 . Useless continuation of the scanning processing can thereby be avoided. After step s 214 , the above-mentioned steps s 202 , s 205 , and s 206  are sequentially performed to notify the user of the alert, and discharge the imaging plate  10 . 
     On the other hand, when the image processing unit  81  determines that reverse setting of the imaging plate  10  cannot be identified in step s 212 , step s 213  is performed. In step s 213 , the image processing unit  81  determines whether the reading processing has ended (i.e., the reading processing has been completed). The image processing unit  81  can determine whether the reading processing has ended by being notified from the light emission control unit  86  that the scanning processing has ended, for example. 
     When the image processing unit  81  determines that the reading processing has not ended in step s 213 , step s 212  is performed again. The reading apparatus  1  then similarly operates. On the other hand, when determining that the reading processing has ended, the image processing unit  81  determines that the imaging plate  10  is set properly in step s 215 . That is to say, when the reading processing ends without identification of reverse setting of the imaging plate  10  by the image processing unit  81 , the image processing unit  81  determines that the imaging plate  10  is set properly. The above-mentioned steps s 3  and s 4  are then performed to erase the radiograph from the imaging plate  10 . After step s 4 , steps s 5 , s 6 , and s 7  may be performed as in the above-mentioned example of  FIG.  18   , or steps s 21 , s 22 , s 5 , s 6 , and s 27  may be performed as in the above-mentioned example of  FIG.  27   . 
     In a case where the front surface specific information  1000  is shown on the front surface of the imaging plate  10 , the imaging plate  10  is set properly when it is determined that the determination target image includes the image of the front surface specific information  1000  in step s 212 . Thus, step s 212  may not be performed until the reading processing ends after it is determined that the determination target image includes the image of the front surface specific information  1000  in step s 212 . 
     In a case where the imaging plate  10  has the protrusion  12  at the peripheral edge thereof, the imaging plate  10  is set properly when negative determination is made in step s 212 . Thus, in a case where the imaging plate  10  has the protrusion  12  at the peripheral edge thereof, step s 212  may not be performed until the reading processing ends after negative determination is once made in step s 212 . 
     Steps s 205  and s 206  may not be performed after step s 202 . When affirmative determination is made in step s 212 , steps s 205  and s 206  may be performed without performing step s 202 . Step s 202  may be performed between steps s 205  and s 206 , or may be performed after steps s 205  and s 206 . 
     In the example of  FIG.  85   , when it is determined that the imaging plate  10  is set in reverse during the reading processing, the reading processing is stopped, and the user is notified of the alert. In other words, when it is determined that the imaging plate  10  is set in reverse during the scanning processing of scanning the imaging plate  10  with the excitation light L 10 , the scanning processing is stopped, and the user is notified of the alert. The user can thereby be notified of the alert immediately. The user can thus know reverse setting of the imaging plate  10  immediately. As a result, the user can set the imaging plate  10  again immediately. 
     In the example of  FIG.  85   , when it is determined that the imaging plate  10  is set in reverse during the reading processing, the reading processing is stopped, and the imaging plate  10  is discharged. The imaging plate  10  can thereby be discharged immediately to prompt the user to set the imaging plate  10  again. 
     When the plurality of pieces of back surface specific information  600  are shown on the back surface of the imaging plate  10  as in the example of  FIG.  64   , the determination target image including the image of the back surface specific information  600  can be acquired immediately from the result of detection of the detector  40  even if the orientation of the imaging plate  10  when the imaging plate  10  is set is not constant. For example, when the imaging plate  10  is set so that the barcode  600   c  is located on the scanning forward side as illustrated in  FIG.  79    described above, the determination target image including the image of the barcode  600   c  is acquired early in the reading processing. When the imaging plate  10  is set so that the barcode  600   d  is located on the scanning forward side as illustrated in  FIG.  80    described above, the determination target image including the image of the barcode  600   d  can be acquired early in the reading processing. The image processing unit  81  can thus acquire the image of the back surface specific information  600  from the result of detection of the detector  40  immediately. The image processing unit  81  can thus identify reverse setting of the imaging plate  10  immediately from the start of the reading processing. As a result, the reading processing can be stopped immediately when the imaging plate  10  is set in reverse. 
     When the plurality of pieces of front surface specific information  1000  are shown on the front surface of the imaging plate  10  as in the example of  FIG.  67   , reverse setting of the imaging plate  10  can similarly be identified immediately even if the orientation of the imaging plate  10  when the imaging plate  10  is set is not constant. In the above-mentioned step s 212 , the image processing unit  81  determines that the imaging plate  10  is set in reverse when the image acquired in the first half of the reading processing in the acquired whole image does not include the image of the front surface specific information  1000 . In a case where the plurality of pieces of front surface specific information  1000  are arranged as in  FIGS.  81  and  82   , the image processing unit  81  may determine that the imaging plate  10  is set in reverse when an image acquired in the first third of the reading processing in the acquired whole image does not include the image of the front surface specific information  1000 . Reverse setting of the imaging plate  10  can thereby be identified immediately from the start of the reading processing. 
     When the imaging plate  10  has the plurality of protrusions  12  at the peripheral edge thereof as in the examples of  FIGS.  73  to  75   , reverse setting of the imaging plate  10  can similarly be identified immediately even if the orientation of the imaging plate  10  when the imaging plate  10  is set is not constant. 
     In the example of  FIG.  85   , when affirmative determination is made in step s 212 , the reading processing may not be stopped, and step s 202  may be performed after the reading processing ends. 
     While whether the imaging plate  10  is set in reverse is determined based on the result of detection of the detector  40  in the reading processing in the above-mentioned example, whether the imaging plate  10  is set in reverse may be determined based on the result of detection of the detector  40  after the erasing processing is performed.  FIG.  86    is a flowchart showing one example of operation of the reading apparatus  1  in this case. When the start button included in the operation unit  4  is operated, steps s 1 , s 2 , s 3 , s 4 , and s 21  are sequentially performed as in  FIG.  27    described above. Once again, step s 4  is processing of irradiating the imaging plate  10  with the erasing light L 3  to erase the radiograph. 
     Next, in step s 221 , the reading apparatus  1  performs scanning detection processing of performing the scanning processing and detection of light by the detector  40 . The scanning detection processing is processing of scanning the imaging plate  10  having undergone the erasing processing. In the scanning detection processing, the reading apparatus  1  moves the holder  20  holding the imaging plate  10  in the subscannig direction DRs during the scanning processing. The imaging plate  10  is thus raster scanned with the excitation light L 10 . In the scanning detection processing, the detector  40  detects the reflected light of the excitation light L 10  from the imaging plate  10  and the IP outside region during raster scanning, and outputs the erasing-time image signal as a result of detection. Step s 221  is processing similar to that in step s 22  in  FIG.  27   . 
     When the scanning detection processing ends, the image processing unit  81  performs, in step s 222 , the determination processing of determining whether the imaging plate  10  is set in reverse based on the erasing-time image signal output from the detector  40  in step s 221 . In other words, the image processing unit  81  performs the determination processing based on the erasing-time whole image acquired in the scanning detection processing. The determination processing in step s 222  is similar to the determination processing in the above-mentioned step s 201 . 
     The acquired whole image acquired in the reading processing in step s 2  herein sometimes includes a radiograph not necessary for the determination processing. Thus, when the acquired whole image acquired in step s 2  is used in the determination processing, the image processing unit  81  can have difficulty determining whether the acquired whole image includes the image of the back surface specific information, the image of the front surface specific information, or the image of the protrusion  12 . Thus, when the acquired whole image acquired in the reading processing is used in the determination processing, the image processing unit  81  can thus have difficulty determining whether the imaging plate  10  is set in reverse. In contrast, the erasing-time whole image acquired in step s 221  does not include the radiograph not necessary for the determination processing. The image processing unit  81  can easily determine whether the imaging plate  10  is set in reverse when the erasing-time whole image is used in the determination processing. A large effect is obtained particularly when the front surface specific information is used because a radiograph that can be slipped in is erased. 
     When it is determined that the imaging plate  10  is set in reverse in step s 222 , steps s 202 , s 205 , and s 206  performed in  FIG.  78    described above are sequentially performed. On the other hand, when it is determined that the imaging plate  10  is not set in reverse in step s 222 , steps s 5 , s 6 , and s 27  performed in  FIG.  27    described above are sequentially performed. 
     Steps s 205  and s 206  may not be performed after step s 202 . When affirmative determination is made in step s 222 , steps s 205  and  206  may be performed without performing step s 202 . Step s 202  may be performed between steps s 205  and s 206 , or may be performed after steps s 205  and s 206 . 
     While the determination processing is performed after the scanning detection processing ends in the example of  FIG.  86   , the scanning detection processing and the determination processing may be performed in parallel.  FIG.  87    is a flowchart showing one example of operation of the reading apparatus  1  in this case. After the start button included in the operation unit  4  is operated, steps s 1 , s 2 , and s 3  are performed, and then steps s 4  and s 21  are performed. 
     After step s 21 , the scanning detection processing starts in step s 231 . When the scanning detection processing starts, the image processing unit  81  determines whether reverse setting of the imaging plate  10  can be identified based on luminance values sequentially output from the detector  40  in response to raster scanning in step s 232 . Processing in step s 232  is similar to that in the above-mentioned step s 212 . 
     When the image processing unit  81  determines that reverse setting of the imaging plate  10  can be identified, in other words, when the image processing unit  81  determines that the imaging plate  10  is set in reverse in step s 232 , step s 234  is performed. The scanning detection processing is stopped in step s 234 . The scanning processing and movement of the holder  20  are thereby stopped. Steps s 202 , s 205 , and s 206  are then sequentially performed. 
     On the other hand, when the image processing unit  81  determines that reverse setting of the imaging plate  10  cannot be identified in step s 232 , step s 233  is performed. In step s 233 , the image processing unit  81  determines whether the scanning detection processing has ended. The image processing unit  81  can determine whether the scanning detection processing has ended by being notified from the light emission control unit  86  that the scanning processing has ended, for example. 
     When the image processing unit  81  determines that the scanning detection processing has not ended in step s 233 , step s 232  is performed again. The reading apparatus  1  then similarly operates. On the other hand, when determining that the scanning detection processing has ended, the image processing unit  81  determines that the imaging plate  10  is set properly in step s 235 . Steps s 5 , s 6 , and s 27  are then sequentially performed. 
     Steps s 205  and s 206  may not be performed after step s 202 . When affirmative determination is made in step s 232 , steps s 205  and s 206  may be performed without performing step s 202 . Step s 202  may be performed between steps s 205  and s 206 , or may be performed after steps s 205  and s 206 . 
     In a case where the front surface specific information  1000  is shown on the front surface of the imaging plate  10 , and the erasing-time whole image is not required to be acquired, the scanning detection processing may be stopped, and step s 235  may be performed when it is determined that the determination target image includes the image of the front surface specific information  1000  in step s 232 . In a case where the imaging plate  10  has the protrusion  12  at the peripheral edge thereof, and the erasing-time whole image is not required to be acquired, the scanning detection processing may be stopped, and step s 235  may be performed when negative determination is once made in step s 232 . 
     In the example of  FIG.  87   , when it is determined that the imaging plate  10  is set in reverse during the scanning processing, the scanning processing is stopped, and the user is notified of the alert as in the example of  FIG.  85   . The user can thereby be notified of the alert immediately. In the example of  FIG.  87   , when it is determined that the imaging plate is set in reverse during the scanning processing, the scanning processing is stopped, and the imaging plate  10  is discharged. The imaging plate  10  can thereby be discharged immediately. 
     In the example of  FIG.  87   , when affirmative determination is made in step s 232 , the scanning detection processing may not be stopped, and step s 202  may be performed after the scanning detection processing ends. 
     &lt;Evaluation of Image Quality of Radiograph&gt; 
     While the object irradiated with the excitation light L 10  is the imaging plate  10  in the above-mentioned example, the object irradiated with the excitation light L 10  may be an object other than the imaging plate  10 . The object irradiated with the excitation light L 10  may be an evaluation member having, on the surface thereof, an evaluation pattern for evaluation of an image quality of the radiograph read from the imaging plate  10  by the reading apparatus  1 , for example. 
     The evaluation member has a similar size and a similar shape to those of the imaging plate  10 , and is inserted into the reading apparatus  1  through the inlet  2   a  of the reading apparatus  1 , for example. The evaluation member inserted into the reading apparatus  1  is held by the holder  20  as with the imaging plate  10 . The radiograph formation layer  11  may be formed, or may not be formed in the evaluation member. When the radiograph formation layer  11  is formed in the evaluation member, energy of radiation is not stored in the radiograph formation layer  11 . 
     When the holder  20  holds the evaluation member, the above-mentioned irradiation object  1200  includes the holder  20  and the evaluation member held by the holder  20 . A region of the support side main surface  1200   a  of the irradiation object  1200  in which an image formed by the acted light L 2  therefrom is an image of the evaluation member is hereinafter also referred to as an evaluation member image region, or is hereinafter simply referred to as a member image region. It can be said that the evaluation member image region is an evaluation member presence region of the support side main surface  1200   a  in which the evaluation member is present. A region excluding the member image region in the detection range R 110  is also referred to as an evaluation member image region outside region, or is simply referred to as a member image region outside region. The member image region corresponds to the IP image region R 100 , and the evaluation member image region outside region (i.e., the member image region outside region) corresponds to the IP image region outside region R 130 . 
       FIGS.  88  to  91    are schematic diagrams each showing one example of an evaluation member  900 .  FIG.  88    shows the evaluation member  900  (also referred to as a resolution evaluation member  900 A) for evaluating resolution of the detected radiograph.  FIG.  89    shows the evaluation member  900  (also referred to as a geometric accuracy evaluation member  900 B) for evaluating geometric accuracy of the detected radiograph.  FIG.  90    shows the evaluation member  900  (also referred to as a contrast evaluation member  900 C) for evaluating contrast of the detected radiograph.  FIG.  91    shows the evaluation member  900  (also referred to as an artifact evaluation member  900 D) for evaluating an artifact of the detected radiograph. 
     As shown in  FIG.  88   , a resolution evaluation pattern  902   a  for evaluating the resolution of the detected radiograph is shown on a front surface  901   a  of the resolution evaluation member  900 A. A line pair chart is used as the resolution evaluation pattern  902   a,  for example. In the resolution evaluation pattern  902   a,  a plurality of sets of lines are arranged so that widths of and spacing between lines differ among the plurality of sets of lines. 
     As shown in  FIG.  89   , a geometric accuracy evaluation pattern  902   b  for evaluating the geometric accuracy of the detected radiograph is shown on a front surface  901   b  of the geometric accuracy evaluation member  900 B. A pattern of a plurality of small points in a grid is used as the geometric accuracy evaluation pattern  902   b,  for example. The plurality of small points may be arranged to form a square with right angle corners as a whole. A plurality of rows forming the grid may be arranged in parallel, and a plurality of columns forming the grid may be arranged in parallel. 
     As shown in  FIG.  90   , a contrast evaluation pattern  902   c  for evaluating the contrast of the detected radiograph is shown on a front surface  901   c  of the contrast evaluation member  900 C. A pattern of a plurality of squares differing in brightness (i.e., density) expressed in grayscale is used as the contrast evaluation pattern  902   c,  for example. 
     As shown in  FIG.  91   , an artifact evaluation pattern  902   d  for evaluating the artifact of the detected radiograph is shown on a front surface  901   d  of the artifact evaluation member  900 D. A monochrome uniform pattern is used as the artifact evaluation pattern  902   d,  for example. For example, a plain white pattern is used as the artifact evaluation pattern  902   d.    
     In the reading apparatus  1 , the evaluation member  900  is held by the holder  20  so that the evaluation pattern thereof is directed toward the light source  30 . In other words, the evaluation member  900  is held by the holder  20  so that the front surface thereof is directed toward the light source  30 . The evaluation pattern of the evaluation member  900  is thereby irradiated with the excitation light L 10 . The detector  40  detects the reflected light of the excitation light L 10  from the front surface of the evaluation member  900  (i.e., the member image region) and the member image region outside region, and outputs an image signal as a result of detection. 
     An image signal as a result of detection of reflected light of light when the evaluation member  900  is held by the holder  20  is hereinafter referred to as an evaluation image signal. A whole image based on the evaluation image signal is referred to as an evaluation whole image. The evaluation pattern appears in the evaluation whole image, and the evaluation whole image includes a reflected light image (hereinafter referred to as an evaluation pattern image) of the evaluation pattern. The evaluation whole image does not include the radiograph. The evaluation whole image includes only the reflected light image. 
       FIG.  92    is a flowchart showing one example of operation of the reading apparatus  1  when the reading apparatus  1  acquires the evaluation whole image in which the evaluation pattern appears. When the evaluation member  900  inserted through the inlet  2   a  of the housing  2  is held by the holder  20 , and the operation unit  4  receives a predetermined operation from the user, step s 51  is performed as shown in  FIG.  92   . In step s 51 , the driver  50  moves the holder  20  to the reading start position through control performed by the drive control unit  83 . Step s 52  is performed after step s 51 . 
     In step s 52 , the light source  30  irradiates the front surface of the evaluation member  900  and the outside region with the excitation light L 10 . The detector  40  detects the reflected light of the excitation light L 10  from the front surface of the evaluation member  900  and the outside region, and outputs the evaluation image signal as a result of detection. The evaluation image signal is a gray-scale image signal. 
     After step s 52 , the driver  50  moves the holder  20  to the discharge position through control performed by the drive control unit  83  in step s 53 . Next, in step s 54 , the evaluation member  900  is discharged to the outlet  2   b  of the housing  2 . In step s 55 , the display control unit  82  causes the display  3  to display the evaluation whole image in grayscale based on the evaluation image signal, for example. When the resolution evaluation member  900 A is inserted into the reading apparatus  1 , the evaluation whole image including an image of the resolution evaluation pattern  902   a  is displayed in step s 55 . When the geometric accuracy evaluation member  900 B is inserted into the reading apparatus  1 , the evaluation whole image including an image of the geometric accuracy evaluation pattern  902   b  is displayed in step s 55 . When the contrast evaluation member  900 C is inserted into the reading apparatus  1 , the evaluation whole image including an image of the contrast evaluation pattern  902   c  is displayed in step s 55 . When the artifact evaluation member  900 D is inserted into the reading apparatus  1 , the evaluation whole image including an image of the artifact evaluation pattern  902   d  is displayed in step s 55 . Step s 55  may be performed at any time after step s 52 . 
       FIG.  93    is a schematic diagram showing one example of the evaluation whole image including the image of the resolution evaluation pattern  902   a.    FIG.  94    is a schematic diagram showing one example of the evaluation whole image including the image of the geometric accuracy evaluation pattern  902   b.    FIG.  95    is a schematic diagram showing one example of the evaluation whole image including the image of the contrast evaluation pattern  902   c.    FIG.  96    is a schematic diagram showing one example of the evaluation whole image including the image of the artifact evaluation pattern  902   d.  The display  3  displays the evaluation whole image in grayscale in step s 55  as shown in  FIGS.  93  to  96   , for example. 
     The user can evaluate the image quality of the detected radiograph based on the evaluation pattern image included in the evaluation whole image displayed by the display  3 . That is to say, the user can evaluate the image quality of the detected radiograph based on the evaluation pattern image displayed by the display  3 . For example, the user evaluates the resolution of the detected radiograph based on the image of the resolution evaluation pattern  902   a  displayed by the display  3 . The resolution may be evaluated by evaluating whether lines can be detected even when the lines have smaller widths or whether lines can be detected independently of one another even when the spacing between lines is reduced, for example. The user evaluates the geometric accuracy of the detected radiograph based on the image of the geometric accuracy evaluation pattern  902   b  displayed by the display  3 . The geometric accuracy may be evaluated based on whether arrangement of the small points is detected to be faithfully reproducible, for example. The user evaluates the contrast of the detected radiograph based on the image of the contrast evaluation pattern  902   c  displayed by the display  3 . The user evaluates the artifact of the detected radiograph based on the image of the artifact evaluation pattern  902   d  displayed by the display  3 . 
     As described above, in this example, the light source  30  and the detector  40  to acquire the detected radiograph are used to acquire the evaluation image signal as a result of detection of the reflected light of the excitation light L 10  from the front surface of the evaluation member  900 . The image quality of the detected radiograph can thereby properly be evaluated based on the evaluation pattern image included in the reflected light image based on the evaluation image signal. The image quality of the detected radiograph can thereby properly be evaluated without using an expensive evaluation phantom to record the image of the evaluation pattern on the radiograph formation layer  11  of the imaging plate  10 . 
     The evaluation member  900  may be formed of paper, resin, or metal, for example. The evaluation pattern may be formed by being printed on the front surface of the evaluation member  900 . At least one of the resolution evaluation pattern  902   a  and the geometric accuracy evaluation pattern  902   b  may be irregularities in the front surface of the evaluation member  900 . When the evaluation pattern is printed on the front surface of the evaluation member  900 , the evaluation pattern having high accuracy can be acquired by printing technology. The image quality of the detected radiograph can thereby properly be evaluated. The evaluation member  900  may be formed of printed paper on which the evaluation pattern is printed. In this case, the image quality of the detected radiograph can be evaluated using an inexpensive evaluation member  900 . The evaluation member  900  may be formed of cardboard. 
     According to the present embodiment, the light source  30  irradiates the imaging plate  10  with the excitation light L 10 . The detector  40  functions as a first detector that detects the emitted light L 2  by the excitation light L 10  from the imaging plate  10 , and outputs a first image signal as a result of detection of the emitted light L 2 . The light source  30  irradiates the evaluation member  900  having, on the surface thereof, the evaluation pattern to evaluate the image quality of the detected radiograph based on the first image signal with the excitation light L 10 . The detector  40  functions as a second detector that detects the reflected light of the excitation light L 10  from the surface of the evaluation member  900 , and outputs a second image signal as a result of detection of the reflected light. 
     While the detector  40  combines the first detector and the second detector in the present embodiment, the first detector and the second detector may be provided separately to detect the emitted light using the first detector and detect the reflected light using the second detector as will be described below. 
     &lt;Another Example of Configuration of Reading Apparatus&gt; 
     While the holder  20  is moved in the above-mentioned example, the holder  20  may not be moved. In this case, the light source  30 , the detector  40 , and the erasing light source  70  are moved with the holder  20  being stopped to achieve processing similar to the above-mentioned processing in the reading apparatus  1 . The light source  30 , the detector  40 , the erasing light source  70 , and the holder  20  may be moved. 
     The reading apparatus  1  may include a plurality of light sources.  FIG.  97    is a schematic diagram illustrating an example of a configuration of the reading apparatus  1  (also referred to as a reading apparatus  1 A) including two light sources. 
     As illustrated in  FIG.  97   , the reading apparatus  1 A includes the above-mentioned light source  30  and a light source  130  different from the light source  30 . The light source  130  can irradiate the imaging plate  10  or the evaluation member  900  held by the holder  20  with irradiation light L 11 . The light source  130  has a similar configuration to the light source  30 , for example, and can perform scanning with the irradiation light L 11  in the main scanning direction DRm. The irradiation light L 11  is visible laser light, for example. The irradiation light L 11  may have the same wavelength as the excitation light L 10 , or may have a different wavelength from the excitation light L 10 . The light source  130  is controlled by the light emission control unit  86  as with the light source  30 . It can be said that the irradiation light L 11  is the acting light L 1 . 
     The light source  130  may be used in step s 22  in  FIG.  27    described above, for example. In this case, not the light source  30  but the light source  130  irradiates the front surface (i.e., the IP image region) of the erased imaging plate  10  and the IP image region outside region with the irradiation light L 11  in step s 22 . In step s 22 , the light source  130  repeatedly performs processing of scanning the imaging plate  10  and the IP image region outside region with the irradiation light L 11  in the main scanning direction DRm through control performed by the light emission control unit  86  as with the light source  30 . On the other hand, in step s 22 , the driver  50  moves the holder  20  holding the imaging plate  10  in the subscannig direction DRs as in the above-mentioned reading processing. Processing of performing scanning with the irradiation light L 11  in the main scanning direction DRm is repeatedly performed while the holder  20  is moved in the subscannig direction DRs to raster scan the imaging plate  10  and the IP image region outside region with the irradiation light L 11  as with the excitation light L 10 . In step s 22 , while the imaging plate  10  is raster scanned with the irradiation light L 11 , the detector  40  detects the reflected light of the irradiation light L 11  from the imaging plate  10 , and outputs the erasing-time image signal as a result of detection. The erasing-time whole image based on the erasing-time image signal includes the IP whole reflected light image and the IP image region outside region image, and does not include the radiograph as with the above-mentioned erasing-time whole image based on detection of the reflected light of the excitation light L 10 . The erasing-time whole image based on detection of the reflected light of the irradiation light L 11  is displayed in step s 27  in  FIG.  27   . The reading apparatus  1  A can use the erasing-time whole image based on detection of the reflected light of the irradiation light L 11  as with the erasing-time whole image based on detection of the reflected light of the excitation light L 10 . The reading apparatus  1 A may identify the IP tilt angle, or may identify the IP size based on the erasing-time whole image based on detection of the reflected light of the irradiation light L 11 , for example. The reflected light of the irradiation light L 11  is included in the acted light L 2 . 
     In a case where the reading apparatus  1 A performs processing in  FIG.  27    when the imaging plate  10  is inserted into the reading apparatus  1 A with the back surface thereof facing forward, the back insertion-time whole image based on detection of the reflected light of the irradiation light L 11  is acquired in step s 22  as with the above-mentioned back insertion-time whole image based on detection of the reflected light of the excitation light L 10 . The user can identify insertion of the imaging plate  10  into the reading apparatus  1  A with the back surface thereof facing forward based on the back insertion-time whole image displayed by the display  3  of the reading apparatus  1 A. 
     The light source  130  may be used in step s 52  in  FIG.  92    described above, for example. In this case, in the reading apparatus  1 A, not the light source  30  but the light source  130  irradiates the front surface of the evaluation member  900  and the member image region outside region with the irradiation light L 11  in step s 52 . Operation of the reading apparatus  1 A in step s 52  is similar to operation of the reading apparatus  1 A in the above-mentioned step s 22 . In step s 52 , while the evaluation member  900  and the member image region outside region are raster scanned with the irradiation light L 11 , the detector  40  detects the reflected light of the irradiation light L 11  from the evaluation member  900  and the outside region, and outputs the evaluation image signal as a result of detection. The evaluation whole image based on the evaluation image signal includes the evaluation pattern image, and does not include the radiograph as with the above-mentioned evaluation whole image based on detection of the reflected light of the excitation light L 10 . In step s 55  in  FIG.  92   , the evaluation whole image based on detection of the reflected light of the irradiation light L 11  is displayed by the display  3  based on the evaluation image signal acquired in step s 52 . The user can evaluate the image quality of the detected radiograph based on the evaluation pattern image included in the evaluation whole image displayed by the display  3  of the reading apparatus  1 A. 
     The reading apparatus  1  may include a plurality of detectors.  FIG.  98    is a schematic diagram illustrating an example of a configuration of the reading apparatus  1  (also referred to as a reading apparatus  1 B) including two detectors and one light source. 
     As illustrated in  FIG.  98   , the reading apparatus  1 B includes the above-mentioned detector  40  and a detector  140  different from the detector  40 . The reading apparatus  1 B includes the light source  30 , and does not include the light source  130 . The detector  140  has a similar configuration to the detector  40 , for example. The detector  140  can detect the emitted light L 2  from the imaging plate  10  as with the detector  40 . The detector  140  can also detect the reflected light of the excitation light L 10  from the imaging plate  10  or the evaluation member  900  and the reflected light of the excitation light L 10  from the IP image region outside region or the member image region outside region as with the detector  40 . 
     The detector  140  may be used in step s 22  in  FIG.  27    described above, for example. In this case, in the reading apparatus  1 B, while the light source  30  raster scans the front surface of the erased imaging plate  10  and the IP image region outside region, the detector  140  detects the reflected light of the excitation light L 10  from the imaging plate  10  and the IP image region outside region, and outputs the erasing-time image signal as a result of detection in step s 22 . The erasing-time whole image based on the erasing-time image signal includes the IP whole reflected light image and the IP image region outside region image, and does not include the radiograph as with the erasing-time whole image described so far. The reading apparatus  1 B can perform various types of processing, such as identification of the IP tilt angle, based on the erasing-time whole image acquired in step s 22 . 
     In a case where the reading apparatus  1 B performs processing in  FIG.  27    when the imaging plate  10  is inserted into the reading apparatus  1 B with the back surface thereof facing forward, the back insertion-time whole image in which the back surface of the imaging plate  10  appears is acquired in step s 22  as with the back insertion-time whole image described so far. 
     The detector  140  may be used in step s 52  in  FIG.  92    described above, for example. In this case, in the reading apparatus  1 B, while the light source  30  raster scans the front surface of the evaluation member  900  and the member image region outside region, the detector  140  detects the reflected light of the excitation light L 10  from the evaluation member  900  and the member image region outside region, and outputs the evaluation image signal as a result of detection in step s 52 . The evaluation whole image based on the evaluation image signal includes the evaluation pattern image, and does not include the radiograph as with the evaluation whole image described so far. 
     The reading apparatus  1  may include a plurality of detectors and a plurality of light sources.  FIG.  99    is a schematic diagram illustrating an example of a configuration of the reading apparatus  1  (also referred to as a reading apparatus  1 C) including the detectors  40  and  140  and the light sources  30  and  130 . 
     The reading apparatus  1 C may use the detector  140  and the light source  130  in step s 22  in  FIG.  27    described above, for example. In this case, in the reading apparatus  1 C, while the light source  130  raster scans the front surface of the erased imaging plate  10  and the IP image region outside region, the detector  140  detects the reflected light of the excitation light L 10  from the imaging plate  10  and the IP image region outside region, and outputs the erasing-time image signal as a result of detection in step s 22 . The erasing-time whole image based on the erasing-time image signal includes the IP whole reflected light image and the IP image region outside region image, and does not include the radiograph as with the erasing-time whole image described so far. In a case where the reading apparatus  1 C performs processing in  FIG.  27    when the imaging plate  10  is inserted into the reading apparatus  1 C with the back surface thereof facing forward, the acquired whole image in which the back surface of the imaging plate  10  appears is acquired in step s 22 . 
     The reading apparatus  1 C may use the detector  140  and the light source  130  in step s 52  in  FIG.  92    described above, for example. In this case, in the reading apparatus  1 C, while the light source  130  raster scans the front surface of the evaluation member  900  and the member image region outside region, the detector  140  detects the reflected light of the excitation light L 10  from the evaluation member  900  and the member image region outside region, and outputs the evaluation image signal as a result of detection in step s 52 . The evaluation whole image based on the evaluation image signal includes the evaluation pattern image, and does not include the radiograph as with the evaluation whole image described so far. 
     In each of the reading apparatuses  1 A and  1 C, the light source  130  may output light other than visible light as the irradiation light L 11 . For example, the irradiation light L 11  may be infrared rays, or may be ultraviolet rays. In this case, a detector that can detect infrared rays or ultraviolet rays is used as each of the detector  40  and the detector  140 . The irradiation light L 11  output from the light source  130  may be light that cannot excite the radiograph formation layer  11  of the imaging plate  10 . That is to say, the emitted light L 2  may not be output from the radiograph formation layer  11  even when the radiograph formation layer  11  on which the radiograph is recorded is irradiated with the irradiation light L 11 . 
     In each of the reading apparatuses  1 A and  1 C, when the irradiation light L 11  does not excite the radiograph formation layer  11 , the determination processing of determining whether the imaging plate  10  is set in reverse may be performed before the reading processing. In this case, the image processing unit  81  can determine whether the imaging plate  10  is set in reverse based on the image signal output from the detector  40  as a result of detection of the reflected light of the irradiation light L 11  from the imaging plate  10 . 
     In each of the reading apparatuses  1 B and  1 C, the detector  140  that detects the reflected light of the irradiation light L 11  may include a CCD sensor or a CMOS sensor used in a camera, for example. CCD is an abbreviation for “charge coupled device”, and CMOS is an abbreviation for “complementary metal oxide semiconductor”. 
     In the reading apparatus  1 C, the light source  130  may irradiate the whole range of the imaging plate  10  or the evaluation member  900  with the irradiation light L 11  in a single irradiation as with the erasing light source  70  without performing scanning with the irradiation light L 11 . In this case, the detector  140  may include the CCD sensor or the CMOS sensor used in the camera, for example. 
     In each of the reading apparatuses  1 B and  1 C, the detector  40  may not be able to detect the reflected light of the excitation light L 10 . In this case, the optical filter  42  of the detector  40  may not transmit the excitation light L 10 . In the reading apparatus  1 C, the detector  40  may not be able to detect the reflected light of the irradiation light L 11 . In this case, the optical filter  42  of the detector  40  may not transmit the irradiation light L 11 . 
     In the light emission-time whole image acquired when the detector  40  does not detect the reflected light of the excitation light L 10 , the luminance value for the unexposed region image and the luminance value for the IP image region outside region image have similar values when the imaging plate  10  includes the unexposed portion. When the imaging plate  10  includes the unexposed portion, the image processing unit  81  has difficulty identifying the IP tilt angle and the IP size based on the light emission-time whole image by a method using the binarized image as described above. Even when the imaging plate  10  includes the unexposed portion, however, the image processing unit  81  can properly identify the IP tilt angle and the IP size as described above based on the erasing-time whole image based on the erasing-time image signal output from the detector  140 . 
     In each of the reading apparatuses  1 B and  1 C, the detector  140  may not be able to detect the photostimulated light L 5 . In this case, each of the reading apparatuses  1 B and  1 C can acquire the IP whole reflected light image without erasing the radiograph from the imaging plate  10 . For example, the reading apparatus  1 B may simultaneously operate the detectors  40  and  140  in the reading processing in the above-mentioned step s 2 . In this case, detection of the excited region light L 20  by the detector  40  and detection of the reflected light of the excitation light L 10  from the imaging plate  10  by the detector  140  are performed in parallel. The whole image based on the image signal output from the detector  140  is similar to the erasing-time whole image, and includes the IP whole reflected light image and the IP image region outside region image, and does not include the radiograph. The reading apparatus  1 C may simultaneously operate the detectors  40  and  140  while simultaneously operating the light sources  30  and  130  in the reading processing in the above-mentioned step s 2 . In this case, detection of the excited region light L 20  by the detector  40  and detection of the reflected light of the irradiation light L 11  from the imaging plate  10  by the detector  140  are performed in parallel. Also in this case, the whole image based on the image signal output from the detector  140  is similar to the erasing-time whole image, and includes the IP whole reflected light image and the IP image region outside region image, and does not include the radiograph. As described above, acquisition of not only the radiograph based on detection of the excited region light L 20  but also the reflected light image based on detection of the reflected light of the excitation light L 10  or the irradiation light L 11  eliminates the need for processing in steps s 21  and s 22  in  FIG.  27   . That is to say, the radiograph based on detection of the excited region light L 20  and the reflected light image based on detection of the reflected light of the excitation light L 10  or the irradiation light L 11  can be acquired during the above-mentioned series of processes in  FIG.  18   . Operation of the reading apparatus  1  can thereby be simplified. 
     In the example of  FIGS.  2  to  6    or the example of  FIG.  98    described above, the light source to read the radiograph from the imaging plate  10  and the light source to acquire the reflected light image of the imaging plate  10  are the same. In other words, the light source to read the radiograph from the imaging plate  10  functions as the light source to acquire the reflected light image of the imaging plate  10 . A configuration of the reading apparatus  1  can thereby be simplified. 
     It can be said that, in the example of  FIGS.  2  to  6    or the example of  FIG.  98    described above, light to acquire the reflected light image of the imaging plate  10  functions as excitation light to read the radiograph from the imaging plate  10 . This eliminates the need for a light source to irradiate the imaging plate  10  with the excitation light separately from a light source to irradiate the imaging plate  10  with light to acquire the reflected light image of the imaging plate  10 . The configuration of the reading apparatus  1  can thereby be simplified. 
     In the example of  FIGS.  2  to  6    or the example of  FIG.  97    described above, the detector to detect the emitted light L 2  and the detector to detect the reflected light of light are the same. In other words, the detector to detect the emitted light L 2  functions as the detector to detect the reflected light of light. The configuration of the reading apparatus  1  can thereby be simplified. 
     It can be said that, in the example of  FIGS.  2  to  6    or the example of  FIG.  97    described above, the detector to detect the reflected light of light also detects the emitted light L 2 . This eliminates the need for the detector to detect the emitted light L 2  separately from the detector to detect the reflected light of light. The configuration of the reading apparatus  1  can thereby be simplified. 
     While a plurality of components other than the AC adapter  5  are integrated in the housing  2  in the reading apparatus  1  in the above-mentioned example, they may not be integrated. For example, the reading apparatus  1  may include a display  13  located outside the housing  2  separately from or in place of the display  3  provided to the housing  2 .  FIG.  100    is a schematic diagram illustrating one example of a configuration of the reading apparatus  1  (also referred to as a reading apparatus  1 D) including the display  13  outside the display surface of the housing  2 . It can be said that the display  13  is a display device  13 . 
     The display  13  is a liquid crystal display or an organic EL display, and can display various pieces of information, such as characters, symbols, graphics, and images, for example. The display  13  is controlled by the display control unit  82  of the controller  80  within the housing  2 . The display control unit  82  can control the display  13  via the interface  95  within the housing  2 , for example. Communication between the interface  95  and the display  13  may conform to USB, DisplayPort, or HDMI (High-Definition Multimedia Interface)®. The interface  95  may be connected to the display  13  by wire or wirelessly. The display  13  may display the acquired whole image, or may display the cutout image. While the display  3  is provided to the housing  2  of the reading apparatus  1 D in the example of  FIG.  100   , the display  3  may not be provided. The reading apparatus  1 D may include a plurality of light sources, or may include a plurality of detectors as shown in  FIGS.  97  to  99   . 
       FIGS.  101  and  102    are schematic diagrams each showing another example of the configuration of the reading apparatus  1 . In the reading apparatus  1  (also referred to as a reading apparatus  1 E) shown in each of  FIGS.  101  and  102   , a computer device  950  having one or more functions of the reading apparatus  1 E is provided outside the housing  2 . As shown in  FIG.  102   , the computer device  950  includes the display  3 , the image processing unit  81 , and the display control unit  82  described above, for example. The computer device  950  may be a personal computer (also referred to as a general-purpose computer), for example. In this case, the computer device  950  may be a notebook computer device, or may be a desktop computer device. In the reading apparatus  1 E, the housing  2 , the plurality of components integrated by the housing  2 , and the AC adapter  5  are hereinafter also collectively referred to as a reading apparatus main body  9 . 
     The computer device  950  can communicate with the reading apparatus main body  9 . The computer device  950  includes a controller  951  including the image processing unit  81  and the display control unit  82  and an interface  952  that communicates with the reading apparatus main body  9 , for example. The computer device  950  also includes an operation unit  953  that receives an operation from the user. 
     The controller  951  can manage operation of the computer device  950  in an integrated manner, and can be said to be a control circuit. The controller  951  can control the display  3  and the interface  952 , for example. The controller  951  can perform processing responsive to a user operation received by the operation unit  953 . 
     The controller  951  includes at least one processor and a storage, and can be said to be a computer device, for example. The at least one processor of the controller  951  may include a CPU, or may include a processor other than the CPU. The at least one processor of the controller  951  executes a program in the storage (also referred to as a storage circuit) to perform various functions. The at least one processor of the controller  951  executes the program in the storage to form the image processing unit  81  and the display control unit  82  described above as the functional blocks. 
     The operation unit  953  includes a keyboard and a mouse, for example. The operation unit  953  may include a touch sensor that detects a touch operation of the user. When the operation unit  953  includes the touch sensor, the touch sensor and the display  3  may constitute the touch panel display having the display function and the touch detection function. 
     The interface  952  can communicate with the interface  95  of the reading apparatus main body  9 . Communication between the interface  952  and the interface  95  of the reading apparatus main body  9  may conform to Ethernet, USB, WiFi, or other standards. The interface  952  may communicate with the interface  95  by wire or wirelessly. It can be said that the interface  952  is an interface circuit, a communication unit, or a communication circuit. The controller  951  of the computer device  950  and the controller  80  of the reading apparatus main body  9  can exchange information via the interface  952  and the interface  95 . 
     In the reading apparatus  1 E, the controller  951  of the computer device  950  and the controller  80  of the reading apparatus main body  9  cooperate with each other to perform the above-mentioned various types of processing performed by the controller  80 . In the reading apparatus  1 E, the detection control unit  85  outputs the image signal output from the detector  40  to the interface  95 . The interface  95  outputs the input image signal to the interface  952 . The interface  952  inputs the input image signal into the controller  951 . The image processing unit  81  performs the above-mentioned image processing on the image signal input into the controller  951 . The image processing unit  81  performs the tilt angle identification processing, the size identification processing, and the cutting-out processing described above based on the image signal after the image processing. The display control unit  82  causes the display  3  to display the acquired whole image based on the image signal after the image processing, for example. 
     The operation unit  953  of the computer device  950  may receive at least one or more of a plurality of user operations received by the operation unit  4  of the reading apparatus main body  9 . For example, the operation unit  953  may receive a user operation to provide instructions to start the series of processes in  FIG.  18   , may receive a user operation to provide instructions to start the series of processes in  FIG.  26   , may receive a user operation to provide instructions to start the series of processes in  FIG.  27   , or may receive a user operation to provide instructions to start the series of processes in  FIG.  74   . In this case, the controller  951  notifies the reading apparatus main body  9  of the user operation received by the operation unit  953  via the interface  952 . In the reading apparatus main body  9 , the controller  80  receives the notification from the controller  951  via the interface  95 , and the operation unit  953  performs processing responsive to the received user operation. 
     The operation unit  953  may receive a user operation not received by the operation unit  4 , or the operation unit  4  may receive a user operation not received by the operation unit  953 . When the user operation received by the operation unit  953  and the user operation received by the operation unit  4  compete against each other, processing responsive to the user operation received by the reading apparatus main body  9  may preferentially be performed in the reading apparatus  1 E, for example. 
     The reading apparatus  1 E may include a display provided to the housing  2  as illustrated in  FIG.  1    and the like described above. The reading apparatus  1 E may include a plurality of light sources, or may include a plurality of detectors as shown in  FIGS.  97  to  99   . The reading apparatus  1 E may not include one of the operation units  4  and  953 . In the reading apparatus  1 E, the controller  80  of the reading apparatus main body  9  may instead perform one or more of a plurality of processes performed by the image processing unit  81  of the computer device  950 . For example, the controller  80  may perform the image processing on the image signal from the detector  40 , and the image signal after the image processing may be input into the image processing unit  81 . 
     While the reading apparatus  1  has been described in detail as described above, the foregoing description is in all aspects illustrative and does not limit the present disclosure. Various modifications described above can be combined with each other for application unless any contradiction occurs. It is understood that numerous unillustrated modifications can be devised without departing from the scope of the present disclosure. 
     The present description and drawings disclose the following aspects: 
     A reading apparatus according to a first aspect is a reading apparatus that reads a radiograph from an imaging plate, and includes: a first light source that irradiates the imaging plate with excitation light; a first detector that detects photostimulated light from the imaging plate emitted by the excitation light; a second light source that irradiates an object with light; and a second detector that detects reflected light of the light from the object. 
     According to the first aspect, the radiograph based on detection of the photostimulated light from the imaging plate emitted by the excitation light and a reflected light image based on detection of the reflected light of the light from the object can be acquired to improve usability of the reading apparatus. 
     A second aspect is the reading apparatus according to the first aspect, wherein the first light source functions as the second light source, and irradiates the object with the excitation light as the light. 
     According to the second aspect, the first light source functions as the second light source to simplify the configuration of the reading apparatus. 
     A third aspect is the reading apparatus according to the first or the second aspect, wherein the object is the imaging plate, and the first detector detects the photostimulated light from the imaging plate from IP acted light, the second detector detects the reflected light from the imaging plate from the IP acted light, and the first detector and the second detector output an IP acted light image signal being an image signal as a result of detection of the IP acted light, the IP acted light being light emitted by the imaging plate being acted on by at least one of the excitation light and the light. 
     According to the third aspect, the second detector detects the reflected light from the imaging plate from the IP acted light to acquire a reflected light image of the imaging plate. 
     A fourth aspect is the reading apparatus according to the third aspect, wherein the first detector functions as the second detector, and the first detector outputs the IP acted light image signal. 
     According to the fourth aspect, the first detector functions as the second detector to simplify the configuration of the reading apparatus. 
     A fifth aspect is the reading apparatus according to the third or the fourth aspect further including at least one processor that identifies a size of the imaging plate based on the IP acted light image signal. 
     According to the fifth aspect, the size of the imaging plate can properly be identified based on the IP acted light image signal as a result of detection of the IP acted light from the imaging plate. 
     A sixth aspect is the reading apparatus according to the fifth aspect, wherein the at least one processor identifies, based on the identified size, a type of the size. 
     According to the sixth aspect, the type of the size of the imaging plate can properly be identified. 
     A seventh aspect is the reading apparatus according to the fifth or the sixth aspect, wherein the first detector detects the reflected light from the imaging plate from which the radiograph has been erased, and outputs an erasing-time IP image signal being an image signal as a result of detection of the reflected light, and the at least one processor identifies the size of the imaging plate based on the erasing-time IP image signal. 
     According to the seventh aspect, the at least one processor identifies the size of the imaging plate based on the erasing-time IP image signal, so that the size of the imaging plate can properly be identified based on the reflected light not affected by the radiograph from the imaging plate. 
     An eighth aspect is the reading apparatus according to any one of the third to the seventh aspects further including at least one processor that identifies a tilt angle of the imaging plate relative to a reference orientation based on the IP acted light image signal. 
     According to the eighth aspect, the tilt angle of the imaging plate relative to the reference orientation can properly be identified based on the IP acted light image signal as a result of detection of the IP acted light from the imaging plate. 
     A ninth aspect is the reading apparatus according to the eighth aspect, wherein the at least one processor corrects a tilt of an image of the imaging plate based on the tilt angle. 
     According to the ninth aspect, the tilt of the image of the imaging plate is corrected based on the tilt angle identified based on the IP acted light image signal as a result of detection of the IP acted light from the imaging plate, so that the image of the imaging plate whose tilt has been properly corrected can be acquired. 
     A tenth aspect is the reading apparatus according to any one of the fifth to the ninth aspects further including at least one processor that performs image processing on a detected image signal from the first detector and the second detector, and the at least one processor sets a cutout range of an IP biological radiographically captured image from a biological radiographically captured image, the biological radiographically captured image being an image acquired by scanning the imaging plate as a light receiver in biological radiography with the excitation light, the IP biological radiographically captured image being an image based on detection of the IP acted light. 
     According to the tenth aspect, the cutout range of an image based on detection of the IP acted light from the imaging plate from the biological radiographically captured image is set, so that an image in a portion corresponding to the imaging plate of the biological radiographically captured image can properly be cut out. 
     An eleventh aspect is the reading apparatus according to any one of the third to the tenth aspects further including: a display; and at least one processor that controls the display, wherein the at least one processor causes the display to simultaneously and separately display an acquired image acquired in biological radiography and an imaging plate shape extraction image representing a shape of the imaging plate extracted by performing processing on the IP acted light image signal. 
     According to the eleventh aspect, the image acquired in biological radiography and the image representing the shape of the imaging plate can easily be compared. 
     A twelfth aspect is the reading apparatus according to the eleventh aspect, wherein the at least one processor identifies an unexposed region image of a portion not exposed to radiation in the acquired image acquired in biological radiography. 
     According to the twelfth aspect, identification of the unexposed region image of the unexposed portion facilitates identification of a biological image region in the acquired image acquired by biological radiography. 
     The present description and drawings also disclose the following aspects: 
     A reading apparatus according to a first aspect is a reading apparatus that reads a radiograph from an imaging plate, and includes: a first light source that irradiates the imaging plate with excitation light; a first detector that detects emitted light from the imaging plate emitted by the excitation light, and outputs a first image signal as a result of detection of the emitted light; a second light source that irradiates the imaging plate with light; a second detector that detects reflected light of the light from the imaging plate, and outputs a second image signal as a result of detection of the reflected light; and at least one processor that performs identification processing of identifying any abnormality of a surface of the imaging plate based on the second image signal. 
     According to the first aspect, the abnormality of the surface of the imaging plate can properly be identified based on the second image signal as a result of detection of the reflected light of the light from the imaging plate. 
     A second aspect is the reading apparatus according to the first aspect, wherein the first light source functions as the second light source, and irradiates the imaging plate with the excitation light as the light. 
     According to the second aspect, the first light source functions as the second light source to simplify the configuration of the reading apparatus. 
     A third aspect is the reading apparatus according to the first or the second aspect, wherein the first detector functions as the second detector. 
     According to the third aspect, the first detector functions as the second detector to simplify the configuration of the reading apparatus. 
     A fourth aspect is the reading apparatus according to the second aspect, wherein the first detector functions as the second detector, the reading apparatus further includes an erasing light source that irradiates the imaging plate with erasing light to erase the radiograph from the imaging plate after the first detector outputs the first image signal, the first light source irradiates the imaging plate from which the radiograph has been erased with the excitation light as the light, and the first detector detects the reflected light from the imaging plate from which the radiograph has been erased. 
     According to the fourth aspect, the erasing light source that irradiates the imaging plate with the erasing light to erase the radiograph from the imaging plate after the first detector outputs the first image signal as a result of detection of the emitted light is provided, so that both the radiograph recorded on the imaging plate and a reflected light image of the imaging plate can easily be acquired. 
     A fifth aspect is the reading apparatus according to any one of the first to the fourth aspects, wherein the at least one processor identifies a position and a shape of an abnormal region image in which the abnormality appears in a reflected light image based on the second image signal, and a display displays an abnormal region display which is a display of a position and a shape of an abnormal region against a radiograph generated by processing of the first image signal. 
     According to the fifth aspect, the user can easily visualize a region corresponding to the abnormality of the surface of the imaging plate in the radiograph. 
     A sixth aspect is the reading apparatus according to any one of the first to the fifth aspects, wherein the at least one processor identifies a position and a shape of an abnormal region image in which the abnormality appears in a reflected light image based on the second image signal in the identification processing, and, when the radiograph based on the first image signal is displayed, superimposes the shape on the radiograph at a position of the radiograph corresponding to the position. 
     According to the sixth aspect, the user can easily identify a region corresponding to the abnormality of the surface of the imaging plate in the radiograph. 
     A seventh aspect is the reading apparatus according to the fifth or the sixth aspect, wherein switching between display and hiding of the shape is made in response to instructions from the user. 
     According to the seventh aspect, switching between display and hiding of the shape of the abnormal region image is made in response to the instructions from the user to improve usability of the reading apparatus. 
     An eighth aspect is the reading apparatus according to any one of the fifth to the seventh aspects, wherein abnormality corresponding region luminance adjustment processing of adjusting luminance information for an abnormality corresponding region corresponding to the abnormality in the read radiograph based on luminance information for the abnormal region image is performed. 
     According to the eighth aspect, a proper radiograph can be acquired by the abnormality corresponding region luminance adjustment processing. 
     A computer readable non-transitory recording medium according to a ninth aspect stores a program to cause a computer device to perform the identification processing performed in the reading apparatus according to the first or the fifth aspect. 
     The present description and drawings also disclose the following aspects: 
     A reading apparatus according to a first aspect is a reading apparatus that reads a radiograph from an imaging plate, and includes: a light source that irradiates the imaging plate with light; a detector that detects reflected light of the light from the imaging plate; and at least one processor that determines whether the imaging plate is set in reverse based on a result of detection performed by the detector. 
     According to the first aspect, whether the imaging plate is set in reverse can be determined based on a result of detection performed by the detector. This allows the radiograph to be more surely read from the imaging plate based on a result of determination. 
     A second aspect is the reading apparatus according to the first aspect, wherein the light functions as excitation light to excite the imaging plate to read the radiograph from the imaging plate. 
     According to the second aspect, the light emitted from the light source functions as the excitation light to excite the imaging plate to read the radiograph from the imaging plate. This eliminates the need for another light source to irradiate the imaging plate with the excitation light. The configuration of the reading apparatus can thereby be simplified. 
     A third aspect is the reading apparatus according to the first or the second aspect, wherein the detector detects emitted light from the imaging plate emitted by the excitation light. 
     According to the third aspect, the detector detects the emitted light from the imaging plate. This eliminates the need for another detector to detect the emitted light from the imaging plate. The configuration of the reading apparatus can thereby be simplified. 
     A fourth aspect is the reading apparatus according to any one of the first to the third aspects, wherein at least one piece of back surface specific information is shown on a back surface of the imaging plate. 
     According to the fourth aspect, the at least one piece of back surface specific information is shown on the back surface of the imaging plate, so that whether the imaging plate is set in reverse can easily be determined. 
     A fifth aspect is the reading apparatus according to the fourth aspect, wherein the light source scans the imaging plate with the light, and a plurality of pieces of back surface specific information are shown on the back surface of the imaging plate. 
     According to the fifth aspect, when the light source scans the imaging plate with the light, the plurality of pieces of back surface specific information are shown on the back surface of the imaging plate. Reverse setting of the imaging plate can thus be identified immediately even if an orientation of the imaging plate when the imaging plate is set is not constant. 
     A sixth aspect is the reading apparatus according to any one of the first to the fifth aspects, wherein at least one piece of front surface specific information is shown on a front surface of the imaging plate. 
     According to the sixth aspect, the at least one piece of front surface specific information is shown on the front surface of the imaging plate, so that whether the imaging plate is set in reverse can easily be determined. 
     A seventh aspect is the reading apparatus according to the sixth aspect, wherein the light source scans the imaging plate with the light, and a plurality of pieces of front surface specific information are shown on the front surface of the imaging plate. 
     According to the seventh aspect, when the light source scans the imaging plate with the light, the plurality of pieces of front surface specific information are shown on the front surface of the imaging plate. Reverse setting of the imaging plate can thus be identified immediately even if the orientation of the imaging plate when the imaging plate is set is not constant. 
     An eighth aspect is the reading apparatus according to any one of the first to the seventh aspects, wherein the imaging plate has, at a peripheral edge thereof, at least one protrusion to determine whether the imaging plate is set in reverse. 
     According to the eighth aspect, the imaging plate has, at the peripheral edge thereof, the at least one protrusion to determine whether the imaging plate is set in reverse, so that whether the imaging plate is set in reverse can easily be determined. 
     A ninth aspect is the reading apparatus according to the eighth aspect, wherein the imaging plate has, at the peripheral edge thereof, a plurality of protrusions to determine whether the imaging plate is set in reverse, and the light source scans the imaging plate with the light, and scans a region at the peripheral edge with the light. 
     According to the ninth aspect, when the light source scans the imaging plate with the light, the imaging plate has, at the peripheral edge thereof, the plurality of protrusions to determine whether the imaging plate is set in reverse. Reverse setting of the imaging plate can thus be identified immediately even if the orientation of the imaging plate when the imaging plate is set is not constant. 
     A tenth aspect is the reading apparatus according to any one of the first to the ninth aspects, wherein a user is notified of an alert when it is determined that the imaging plate is set in reverse. 
     According to the tenth aspect, the user is notified of the alert when it is determined that the imaging plate is set in reverse. This can prompt the user to properly set the imaging plate. 
     An eleventh aspect is the reading apparatus according to any one of the first to the tenth aspects, wherein the imaging plate from which the radiograph has been read is irradiated with erasing light to erase the radiograph when it is determined that the imaging plate is not set in reverse, and the imaging plate is not irradiated with the erasing light when it is determined that the imaging plate is set in reverse. 
     According to the eleventh aspect, the imaging plate is not irradiated with the erasing light when it is determined that the imaging plate is set in reverse. The radiograph recorded on the imaging plate is thus less likely to be affected by the erasing light. 
     A twelfth aspect is the reading apparatus according to any one of the first to the eleventh aspects, wherein the light source performs scanning processing of scanning the imaging plate with the light, and stops the scanning processing when it is determined that the imaging plate is set in reverse during the scanning processing. 
     According to the twelfth aspect, the scanning processing is stopped when it is determined that the imaging plate is set in reverse during the scanning processing. Useless continuation of the scanning processing can thereby be avoided. 
     A thirteenth aspect is the reading apparatus according to any one of the first to the tenth aspects, wherein the imaging plate is discharged when it is determined that the imaging plate is set in reverse. 
     According to the thirteenth aspect, the imaging plate is discharged when it is determined that the imaging plate is set in reverse. This eliminates the need for a user operation to provide instructions to discharge the imaging plate on the reading apparatus. Furthermore, discharge of the imaging plate can prompt the user to set the imaging plate again. 
     A fourteenth aspect is the reading apparatus according to the thirteenth aspect, wherein the imaging plate from which the radiograph has been read is irradiated with erasing light to erase the radiograph when it is determined that the imaging plate is not set in reverse, and the imaging plate is discharged without being irradiated with the erasing light when it is determined that the imaging plate is set in reverse. 
     According to the fourteenth aspect, the imaging plate is discharged without being irradiated with the erasing light when it is determined that the imaging plate is set in reverse. The imaging plate can thereby be discharged immediately when it is determined that the imaging plate is set in reverse. 
     A fifteenth aspect is the reading apparatus according to the thirteenth or the fourteenth aspect, wherein the light source performs scanning processing of scanning the imaging plate with the light, and stops the scanning processing and discharges the imaging plate when it is determined that the imaging plate is set in reverse during the scanning processing. 
     According to the fifteenth aspect, the scanning processing is stopped, and the imaging plate is discharged when it is determined that the imaging plate is set in reverse during the scanning processing. The imaging plate can thereby be discharged immediately when it is determined that the imaging plate is set in reverse. 
     A computer readable non-transitory recording medium according to a sixteenth aspect stores a program to control a reading apparatus that reads a radiograph from an imaging plate, and includes: a light source that irradiates the imaging plate with light; and a detector that detects reflected light of the light from the imaging plate, and the program causes the reading apparatus to determine whether the imaging plate is set in reverse based on a result of detection performed by the detector. 
     A seventeenth aspect is the computer readable non-transitory recording medium according to the sixteenth aspect, wherein the program causes the reading apparatus to notify a user of an alert when it is determined that the imaging plate is set in reverse. 
     An eighteenth aspect is the computer readable non-transitory recording medium according to the sixteenth or the seventeenth aspect, wherein the program causes the reading apparatus to discharge the imaging plate when it is determined that the imaging plate is set in reverse. 
     The present description and drawings also disclose the following aspects: 
     A reading apparatus according to a first aspect is a reading apparatus that reads a radiograph from an imaging plate, and includes: a light source that irradiates the imaging plate with excitation light; and a first detector that detects emitted light from the imaging plate emitted by the excitation light, and outputs a first image signal as a result of detection of the emitted light, wherein the light source irradiates an evaluation member having, on a surface thereof, an evaluation pattern to evaluate an image quality of a detected radiograph based on the first image signal with the excitation light, and the reading apparatus further includes a second detector that detects reflected light of the excitation light from the surface of the evaluation member, and outputs a second image signal as a result of detection of the reflected light. 
     According to the first aspect, the image quality of the detected radiograph, that is, the radiograph read from the imaging plate can properly be evaluated based on an image of the evaluation pattern included in a reflected light image based on the second image signal. 
     A reading apparatus according to a second aspect is the reading apparatus according to the first aspect, wherein the first detector functions as the second detector, and the first detector detects the emitted light and the reflected light. 
     According to the second aspect, the first detector functions as the second detector to simplify the configuration of the reading apparatus. 
     A third aspect is the reading apparatus according to the first or the second aspect, wherein the evaluation pattern is printed on the surface of the evaluation member. 
     According to the third aspect, the evaluation pattern is formed by printing, so that the evaluation pattern having high accuracy can be acquired. The image quality of the detected radiograph can thereby properly be evaluated. 
     A fourth aspect is the reading apparatus according to the third aspect, wherein the evaluation member is printed paper. 
     According to the fourth aspect, the evaluation member is the printed paper, so that the image quality of the detected radiograph can be evaluated using an inexpensive evaluation member. 
     A fifth aspect is the reading apparatus according to any one of the first to the fourth aspects, wherein a reflected light image based on the second image signal is displayed. 
     According to the fifth aspect, a user can evaluate the image quality of the detected radiograph by checking an image of the evaluation pattern included in the reflected light image based on the second image signal. 
     While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.