Abstract:
Disclosed is a radiation image processing device including a storage unit; and a control unit that performs a control operation to associate a radiation image used in making a diagnosis among a plurality of radiation images of an object with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image, the plurality of radiation images being captured with radiation from different angles, and to store the radiation image used in making the diagnosis together with the information into the storage unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority under 35 USC 119 from Japanese Patent Application No. 2010-194394 filed on Aug. 31, 2010, the disclosure of which is incorporated by reference herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a radiation image processing device, a radiation image processing method and a storage medium, and more particularly, to a radiation image processing device and a radiation image processing method for storing stereoscopically captured radiation images, and a storage medium 
         [0004]    2. Related Art 
         [0005]    Concerning stereoscopic viewing of radiation images, Japanese Patent Application Laid-Open (JP-A) No. 2003-245274 discloses obtaining a first image by capturing an object from the front, obtaining a second image by capturing an image from a direction at a predetermined angle with respect to the front, storing those images associated with information about the image capturing directions, stereoscopically displaying the first image and the second image, using the first image (the image captured from the front) as an image captured in a conventional manner, and the like. 
         [0006]    When stereoscopic viewing is performed, a diagnosis is made with the use of plural radiation images. However, it is not clear which image is actually used in making the diagnosis, and a problem related to that might arise later. Since images are captured from different image capturing angles, the resultant images of course differ from one another. Therefore, the image captured from the front may not necessarily show a desired imaging result, and an image captured from a direction at a predetermined angle might be used as a diagnosis confirmation image. However, the system according to JP-A No. 2003-245274 is incapable of recognizing such a situation. 
         [0007]    A main object of the present invention is to provide a radiation image processing device and a radiation image processing method that make clear which image is used in making a diagnosis when stereoscopic viewing is performed with plural radiation images. 
       SUMMARY 
       [0008]    According to a first aspect of the present invention, there is provided a radiation image processing device comprising: 
         [0009]    a storage unit; and 
         [0010]    a control unit that performs a control operation to associate a radiation image used in making a diagnosis among a plurality of radiation images of an object with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image, the plurality of radiation images being captured with radiation from different angles, and to store the radiation image used in making the diagnosis together with the information into the storage unit. 
         [0011]    According to a second aspect of the present invention, there is provided a radiation image capturing apparatus comprising: 
         [0012]    an image capturing unit that obtains a plurality of radiation images by capturing images of an object with radiation from different angles; 
         [0013]    a first control unit that controls the image capturing unit to use a lower resolution to capture a radiation image not to be used in making a diagnosis among the plurality of radiation images, the lower resolution being lower than a resolution of a radiation image to be used in making the diagnosis among the plurality of radiation images; 
         [0014]    a storage unit; and 
         [0015]    a second control unit that performs a control operation to associate the radiation image used in making the diagnosis with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image among the plurality of radiation images of the object captured with radiation from the different angles, and to store the radiation image used in making the diagnosis together with the information into the storage unit. 
         [0016]    According to a third aspect of the present invention, there is provided a radiation image capturing apparatus comprising: 
         [0017]    an image capturing unit that obtains a plurality of radiation images by capturing images of an object with radiation from different angles; 
         [0018]    a first control unit that controls the image capturing unit to capture the radiation image to be used in making the diagnosis before the radiation image not to be used in making the diagnosis among the plurality of radiation images; 
         [0019]    a storage unit; and 
         [0020]    a second control unit that performs a control operation to associate the radiation image used in making the diagnosis with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image among the plurality of radiation images of the object captured with radiation from the different angles, and to store the radiation image used in making the diagnosis together with the information into the storage unit. 
         [0021]    According to a fourth aspect of the present invention, there is provided a radiation image processing method comprising: storing a radiation image used in making a diagnosis into a storage unit under a control of a control unit, with the radiation image used in making the diagnosis being associated with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image among the plurality of radiation images of the object captured with radiation from the different angles. 
         [0022]    According to a fifth aspect of the present invention, there is provided a radiation image capturing method comprising: 
         [0023]    performing an image capturing operation with radiation, using a lower resolution to capture a radiation image not to be used in making a diagnosis among a plurality of images obtained by capturing images of an object from different angles, the lower resolution being lower than a resolution of a radiation image to be used in making the diagnosis among the plurality of radiation images; and 
         [0024]    storing the radiation image used in making the diagnosis into a storage unit under a control of a control unit, with the radiation image used in making the diagnosis being associated with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image among the plurality of radiation images of the object captured with radiation from the different angles. 
         [0025]    According to a sixth aspect of the present invention, there is provided a radiation image capturing method comprising: 
         [0026]    capturing a radiation image to be used in making a diagnosis before capturing a radiation image not to be used in making the diagnosis among a plurality of radiation images obtained by capturing images of an object from different angles with radiation, and storing the radiation image used in making the diagnosis into a storage unit under a control of a control unit, with the radiation image used in making the diagnosis being associated with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image among the plurality of radiation images of the object captured with radiation from the different angles. 
         [0027]    According to a seventh aspect of the present invention, there is provided a non-transitory computer-readable medium storing a program that causes a computer to perform a process including storing a radiation image used in making a diagnosis into a storage unit under a control of a control unit, with the radiation image used in making the diagnosis being associated with information indicating that the radiation image used in making the diagnosis is a diagnosis confirmation image among the plurality of radiation images of the object captured with radiation from the different angles. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0029]      FIG. 1  is a schematic view for explaining a radiation image capturing apparatus according to a preferred exemplary embodiment of the invention; 
           [0030]      FIG. 2  is a schematic block diagram for explaining the radiation image capturing apparatus according to the preferred exemplary embodiment of the invention; 
           [0031]      FIG. 3  is a perspective view for explaining the structure of a stereo display device of the radiation image capturing apparatus according to the preferred exemplary embodiment of the invention; 
           [0032]      FIG. 4  is a diagram for explaining a case in which an image on the stereo display device of the radiation image capturing apparatus is stereoscopically viewed according to the preferred exemplary embodiment of the invention; 
           [0033]      FIG. 5  is a schematic view for explaining stereo image capturing using the radiation image capturing apparatus according to the preferred exemplary embodiment of the invention; and 
           [0034]      FIG. 6  is a schematic view for explaining stereo image capturing using the radiation image capturing apparatus according to the preferred exemplary embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    The following is a description of a preferred exemplary embodiment of the invention, with reference to the accompanying drawings. 
         [0036]    Referring to  FIG. 1 , a radiation image capturing apparatus  10  of the preferred exemplary embodiment of the invention includes a radiation generator  34 , a console  42 , a portable radiation image detecting device (hereinafter referred to as the “electronic cassette”)  32 , and a stereo display device  220 . 
         [0037]    The electronic cassette  32  is positioned at a distance from a radiation source  130  of the radiation generator  34  that generates a radiation ray such as an X-ray when a radiation image is captured. In this exemplary embodiment, the electronic cassette  32  is horizontally positioned below an object  50  lying on his/her back on a bed  46 , with a distance being kept between the electronic cassette  32  and the object  50 . The object  50  is located between the radiation source  130  of the radiation generator  34  and the electronic cassette  32 . When a radiation image capturing instruction is issued from the console  42 , the radiation source  130  emits an X-ray  131  of a radiation level in accordance with predetermined imaging conditions and the like. The X-ray  131  emitted from the radiation source  130  carries image information after transmitted through the object  50 , and then reaches the electronic cassette  32 . 
         [0038]    The radiation generator  34  includes a main body  150  and a C-shaped arm  140 . The radiation source  130  that emits the X-ray  131  is attached to one end  141  of the C-shaped arm  140 . 
         [0039]    The C-shaped arm  140  is provided to penetrate through a box  146 . A gear  143  is formed on an outer circumferential surface of a cylindrical face of the C-shaped arm  140 . Rollers  144  attached to the box  146  are in contact with an inner circumferential surface of the cylindrical surface of the C-shaped arm  140 . A gear  145  attached to the box  146  meshes with the gear  143  of the C-shaped arm  140 . As the gear  145  is rotated by a motor (not shown), the C-shaped arm  140  rotationally moves in a clockwise direction A and a counterclockwise direction A′ shown in the drawing. With this arrangement, the radiation source  130  attached to the C-shaped arm  140  rotationally moves in the clockwise direction A and the counterclockwise direction A′. 
         [0040]    As the radiation source  130  is rotated in the above manner, the radiation source  130  may be located in plural positions with parallaxes. 
         [0041]    With this arrangement, one of plural images captured in different positions with parallaxes is visually recognized by the right eye, and the other one of the images is visually recognized by the left eye. In this manner, an image may be stereoscopically viewed. 
         [0042]    A nut  147   b  of a ball screw  147  is attached to the box  146 . A screw shaft  147   a  of the ball screw  147  is attached to a support pillar  148 . As the screw shaft  147   a  is rotated by a motor (not shown), the nut  147   b,  the box  146 , and the C-shaped arm  140  move up and down. By moving the C-shaped arm  140  up and down, the height of the center of rotation of the C-shaped arm  140  may be varied. The lower end of the support pillar  148  is attached onto a pillar supporting member  152  that horizontally protrudes from near a lower end portion of the housing of the main body  150 . 
         [0043]    Wheels  154  are attached to the bottom of the main body  150 , so that the radiation generator  34  may move around. 
         [0044]    The main body  150  contains a communication interface unit  132 , a source control unit  134 , and a source drive control unit  136  that are described later. 
         [0045]      FIG. 2  is a block diagram showing the structure of the radiation image capturing apparatus  10  according to this exemplary embodiment. 
         [0046]    The radiation generator  34  has a connecting terminal  34 A for performing communication with the console  42 . The console  42  has a connecting terminal  42 A for performing communication with the radiation generator  34 . The radiation generator  34  is connected to the console  42  via a communication cable  35 . 
         [0047]    A radiation detector  60  installed in the electronic cassette  32  is formed by stacking a photoelectric conversion layer on a TFT active-matrix substrate  66 . The photoelectric conversion layer absorbs a radiation ray and convert the radiation ray into charges. The photoelectric conversion layer is made of amorphous selenium (a-Se) containing selenium as a main component (the content rate being 50% or higher, for example). When a radiation ray is applied to the photoelectric conversion layer, charges (pair of electron-hole) are internally generated in an amount equivalent to the level of the applied radiation. In this manner, the applied radiation ray is converted into charges. The radiation detector  60  may convert a radiation ray indirectly into charges by using a fluorescent material and a photoelectric conversion element (a photodiode), instead of the radiation-charge converting material such as amorphous selenium that converts a radiation ray directly into charges. As for the fluorescent material, gadolinium oxysulfide (GOS) and cesium iodide (CsI) are well known. In this case, a radiation-light conversion is performed with the fluorescent material, and a light-charge conversion is performed with the photodiode of the photoelectric conversion element. 
         [0048]    A large number of pixel units  74  (the photoelectric conversion layer corresponding to the respective pixel units  74  being schematically shown as photoelectric conversion units  72  in  FIG. 2 ) each including a storage capacitor  68  that stores charges generated from the photoelectric conversion layer and a TFT  70  for reading the charges stored in the storage capacitor  68  are arranged in a matrix fashion on the TFT active-matrix substrate  66 . The charges generated in the photoelectric conversion layer as a result of radiation application to the electronic cassette  32  are stored in the storage capacitors  68  of the respective pixel units  74 . With this arrangement, the image information carried by the radiation ray applied onto the electronic cassette  32  is converted into charge information, and is carried by the radiation detector  60 . 
         [0049]    Also, plural gate interconnects  76  and plural data interconnects  78  are provided on the TFT active-matrix substrate  66 . The gate interconnects  76  extend in one direction (the row direction), and switch on and off the TFTs  70  of the respective pixel units  74 . The data interconnects  76  extend in a direction perpendicular to the gate interconnects  78 , and read the stored charges from the storage capacitors  68  via switched-on TFTs  70 . The respective gate interconnects  76  are connected to a gate wire driver  80 , and the respective data interconnects  78  are connected to a signal processing unit  82 . When charges are stored in the storage capacitors  68  of the respective pixel units  74 , the TFTs  70  of the respective pixel units  74  are sequentially switched on by the row by signals supplied from the gate wire driver  80  via the gate interconnects  76 . The charges stored in the storage capacitors  68  of the pixel units  74  having the TFTs  70  switched on are transmitted as analog electrical signals through the data interconnects  78 , and are then input to the signal processing unit  82 . In this manner, the charges stored in the storage capacitor  68  of the respective pixel units  74  are sequentially read out by the row. 
         [0050]    The signal processing unit  82  operates under the control of a cassette control unit  92  described later, and detects the amount of charges stored in the storage capacitors  68  of the respective pixel units  74  by the row. The signal processing unit  82  then outputs digital image information. 
         [0051]    An image memory  90  is connected to the signal processing unit  82 . Image information and error information that are output from the signal processing unit  82  are sequentially stored into the image memory  90 . The image memory  90  has such a storage capacity as to store image information about a predetermined number of radiation images. Every time charges of one line are read out, the image information about the read one line is sequentially stored into the image memory  90 . 
         [0052]    The image memory  90  is connected to the cassette control unit  92  that controls operations of the entire electronic cassette  32 . The cassette control unit  92  is realized by a microcomputer, and includes a CPU  92 A, a memory  92 B containing a ROM and a RAM, and a nonvolatile storage unit  92 C formed by a HDD or a flash memory. 
         [0053]    A wireless communication unit  94  is connected to the cassette control unit  92 . The wireless communication unit  94  complies with wireless LAN (local area network) standards such as IEEE (Institute of Electrical and Electronics Engineers) 802.11a/b/g, and controls transmission of various kinds of information with external devices through wireless communication. The cassette control unit  92  may perform wireless communication with the console  42  via the wireless communication unit  94 , and may exchange various kinds of information with the console  42 . The cassette control unit  92  stores later described irradiation conditions received from the console  42 , and, based on the irradiation conditions, starts the reading of charges. 
         [0054]    A power supply unit  96  is also provided in the electronic cassette  32 . The above described various circuits and elements (the gate wire driver  80 , the signal processing unit  82 , the image memory  90 , the wireless communication unit  94 , and the microcomputer functioning as the cassette control unit  92 ) are actuated by the power supplied from the power supply unit  96 . The power supply unit  96  contains a battery (a rechargeable secondary cell) so as to maintain the portability of the electronic cassette  32 , and supplies power from the charged battery to the various circuits and elements. In  FIG. 2 , the interconnects that connect the power supply unit  96  to the various circuits and elements are not shown. 
         [0055]    The console  42  includes a display  100  that displays an operation menu, a captured radiation image, and the like, and an operation input unit  102  that is designed to have plural keys and has various kinds of information and operation instructions input therethrough. 
         [0056]    The console  42  further includes: a CPU  104  that controls operations of the entire apparatus; a ROM  106  in which various kinds of programs including a control program are stored in advance; a RAM  108  that temporarily stores various kinds of data; a HDD  110  that stores and holds various kinds of data; a display driver  112  that controls displaying of various kinds of information on the display  100 , and receives operation information from the display  100 ; an operation input detecting unit  114  that detects an operation state of the operation input unit  102 ; an image signal output unit  210  that outputs image signals to the stereo display device  220 ; a communication interface unit  116  that is connected to the connecting terminal  42 A, and exchanges various kinds of information, such as the irradiation conditions, imaging site information, and the status information about the radiation generator  34 , with the radiation generator  34  via the connecting terminal  42 A and the communication cable  35 ; and a wireless communication unit  118  that exchanges various kinds of information such as the irradiation conditions and image information with the electronic cassette  32  through wireless communication. 
         [0057]    The CPU  104 , the ROM  106 , the RAM  108 , the HDD  110 , the display driver  112 , the operation input detecting unit  114 , the image signal output unit  210 , the communication interface unit  116 , and the wireless communication unit  118  are connected to one another via a system bus BUS. Therefore, the CPU  104  may access the ROM  106 , the RAM  108 , and the HDD  110 . Also, the CPU  104  may control the displaying of various kinds of information on the display  100  via the display driver  112 , recognize the operation information from the display  100 , control the image to be displayed on the stereo display device  220  via the image signal output unit  210 , control the exchange of various kinds of information with the radiation generator  34  via the communication interface unit  116 , and control the exchange of various kinds of information with the electronic cassette  32  via the wireless communication unit  118 . Further, the CPU  104  may recognize the user operation state of the operation input unit  102  via the operation input detecting unit  114 . 
         [0058]    The radiation generator  34  includes: the radiation source  130  that outputs a radiation ray; the communication interface unit  132  that exchanges various kinds of information, such as the irradiation conditions, the imaging site information, and the status information about the radiation generator  34 , with the console  42 ; the source control unit  134  that controls the radiation source  130 , based on the received irradiation conditions; and the source drive control unit  136  that controls operations of the ball screw  147  and the gear  145  by controlling the power supply to the motor (not shown) driving the ball screw  147  and the gear  145 . 
         [0059]    The source control unit  134  is also realized by a microcomputer, and stores the received irradiation conditions, imaging site information, and the like. The irradiation conditions received from the console  42  contain information such as tube voltage, tube current, and irradiation time. Based on the received irradiation conditions, imaging site information, and the like, the source control unit  134  controls the C-shaped arm  140  by controlling the motor (not shown) driving the gear  145 . By doing so, the source control unit  134  adjusts the angle at which the X-ray  131  emitted from the radiation source  130  is incident on the cassette  32  and the object  50 . In this manner, the source control unit  134  causes the radiation source  130  to emit the X-ray  131 , based on the received irradiation conditions. 
         [0060]      FIG. 3  illustrates an example structure of the stereo display device  220  according to this exemplary embodiment. 
         [0061]    As shown in the drawing, in the stereo display device  220 , two display units  222  are vertically arranged, and the upper display unit  222  is tilted forward and is fixed. The two display units  222  have display-light polarizing directions perpendicular to each other. The upper display unit  222  is a display unit  222 R that displays an image for the right eye, and the lower display unit  222  is a display unit  222 L that displays an image for the left eye. A beam splitter mirror  224  that transmits the display light emitted from the display unit  222 L and reflects the display light emitted from the display unit  222 R is provided between the display units  222 L and  222 R. The beam splitter mirror  224  is fixed at an angle that is adjusted so that the image displayed on the display unit  222 L and the image displayed on the display unit  222 R overlap with each other when an observer sees the stereo display device  220  from the front. 
         [0062]    As shown in  FIG. 4 , by seeing the stereo display device  220  through polarizing glasses  225  formed by a right lens and a left lens that have polarizing directions perpendicular to each other, the observer may view the image displayed on the display unit  222 L and the image displayed on the display unit  222 R with the right eye and the left eye independently of each other. In this manner, the observer may stereoscopically view an image. 
         [0063]    Next, the functions of the radiation image capturing apparatus  10  according to this exemplary embodiment are described. 
         [0064]    When a radiation image is to be stereoscopically captured, the positional information about the radiation source  130 , the information about the electronic cassette  32 , the irradiation conditions, the imaging site information, and the like are input to the console  42  via the operation input unit  102  in the radiation image capturing apparatus  10 . 
         [0065]    The console  42  transmits the input positional information about the radiation source  130 , the information about the electronic cassette  32 , the exposure conditions such as tube voltage, tube current and irradiation time, the imaging site information, and the like to the radiation generator  34 . 
         [0066]    The console  42  also transmits image capturing control information, such as the irradiation time during which the radiation generator  34  keeps emitting a radiation ray when a radiation image is to be captured, to the electronic cassette  32  through wireless communication. 
         [0067]    The radiation generator  34  adjusts the height of the C-shaped arm  140  so that the height of the center of rotation of the C-shaped arm  140  or the height of the center of rotation of the radiation source  130  becomes equal to the height of the upper surface  32   a  of the electronic cassette  32 . 
         [0068]    The radiation generator  34  then rotates the C-shaped arm  140 , and positions the radiation source  130  at a predetermined angle  01  with respect to a direction  32   b  perpendicular to the surface  32   a  of the electronic cassette  32 , as shown in  FIG. 5 . 
         [0069]    The radiation generator  34  then emits the X-ray  131  from the radiation source  130  under predetermined irradiation conditions. The X-ray  131  emitted from the radiation source  130  carries image information about the object  50  after transmitted through the object  50 , and then reaches the electronic cassette  32  serving as a radiation detector. 
         [0070]    The X-ray  131  carrying the image information is converted into an electrical signal by the electronic cassette  32 , and the electrical signal is stored into the image memory  90 . 
         [0071]    After the image is captured, the cassette control unit  92  transmits the image information stored in the image memory  90  to the console  42  through wireless communication. 
         [0072]    The console  42  performs various kinds of image corrections such as a shading correction on the received first image information, and stores the corrected first image information together with first image capturing information into the HDD  110 . The first image capturing information contains the positional information about the radiation source  130  (such as the angle information (θ 1 ) about the radiation source  130  and the distance D 1  between the radiation source  130  and the electronic cassette  32 ), the information about the electronic cassette  32  (such as the distance D 2  between the electronic cassette  32  and the object  50 , the information as to whether the electronic cassette  32  has a holder, and the type of the holder if the electronic cassette  32  has one), the irradiation conditions such as tube voltage, tube current and irradiation time, the imaging site information and the like. 
         [0073]    The electronic cassette  32  performs a reset operation to stand by for the next image capturing operation. 
         [0074]    To capture a second image at a different parallax angle for stereoscopic viewing by changing the position of the radiation source  130 , the positional information about the radiation source  130 , the irradiation conditions, and the like are input to the console  42  via the operation input unit  102 . In many cases, the irradiation conditions and the like for the second image are the same as those for the first image. 
         [0075]    The console  42  transmits the positional information about the radiation source  130 , the exposure conditions such as tube voltage, tube current, and irradiation time, and the like to the radiation generator  34 . 
         [0076]    The console  42  also transmits image capturing control information, such as the irradiation time during which the radiation generator  34  keeps emitting a radiation ray when a radiation image is to be captured, to the electronic cassette  32  through wireless communication. 
         [0077]    In the case of the second image, the height of the center of rotation of the C-shaped arm  140 , or the height of the center of rotation of the radiation source  130  is the same as the height in the case of the first image. 
         [0078]    The radiation generator  34  then rotates the C-shaped arm  140 , and positions the radiation source  130  at a predetermined angle θ 2  with respect to the direction  32   b  perpendicular to the surface  32   a  of the electronic cassette  32  (or at a parallax angle θ (=θ 1 +θ 2 ) with respect to the angle in the case of the first image capturing), as shown in  FIG. 5 . The distance D 1  between the radiation source  130  and the electronic cassette  32  is maintained. 
         [0079]    The radiation generator  34  then emits the X-ray  131  from the radiation source  130  under predetermined irradiation conditions. The X-ray  131  emitted from the radiation source  130  carries image information about the object  50  after transmitted through the object  50 , and then reaches the electronic cassette  32  serving as a radiation detector. 
         [0080]    The X-ray  131  carrying the image information is converted into an electrical signal by the electronic cassette  32 , and the electrical signal is stored into the image memory  90 . 
         [0081]    After the image is captured, the cassette control unit  92  transmits the image information stored in the image memory  90  to the console  42  through wireless communication. 
         [0082]    The console  42  performs various kinds of image corrections such as a shading correction on the received second image information, and stores the corrected second image information together with second image capturing information into the HDD  110 . The second image capturing information contains the positional information about the radiation source  130  (such as the angle information (θ 1 ) about the radiation source  130  and the distance D 1  between the radiation source  130  and the electronic cassette  32 ), the information about the electronic cassette  32  (such as the distance D 2  between the electronic cassette  32  and the object  50 , the information as to whether the electronic cassette  32  has a holder, and the type of the holder if the electronic cassette  32  has one), the irradiation conditions such as tube voltage, tube current and irradiation time, the imaging site information, and the like. 
         [0083]    At this point, the second image information and image capturing information are stored, together with the first image information and image capturing information, and the parallax difference (θ=θ 1 +θ 2 ) in the first and second image capturing operations, into the HDD  110 . The information is stored as the image information and image capturing information about two stereoscopic viewing images obtained by one image capturing operation. 
         [0084]    Also, as shown in  FIG. 6 , the first radiation image (a perpendicular image) may be captured from a direction perpendicular to the surface  32   a  of the electronic cassette  32 , and the C-shaped arm  140  is then rotated so that the radiation source  130  is positioned at the predetermined angle θ with respect to the direction  32   b  perpendicular to the surface  32   a  of the electronic cassette  32  (or at the same parallax angle θ as in the first image capturing operation). The second radiation image may be then captured. Alternatively, the first image may be captured while the radiation source  130  is positioned at the predetermined angle θ with respect to the direction  32   b  perpendicular to the surface  32   a  of the electronic cassette  32 , and the second image may be captured from a direction perpendicular to the surface  32   a  of the electronic cassette  32 . 
         [0085]    In such a case, the first image information and image capturing information, the second image information and image capturing information, the parallax difference (θ) in the first and second image capturing operations, and the information as to which one of the first and second images is a perpendicular image are stored as the image information and image capturing information about the two stereoscopic viewing images obtained through one image capturing operation, into the HDD  110 . 
         [0086]    The following is a description of a stereo image forming operation to be performed by the console  42  to cause the stereo display device  220  to display a stereo image based on the two radiation images stored as one piece of image capturing information in the HDD  110 . 
         [0087]    When a predetermined stereo image display start instruction is issued to the operation input unit  102 , the console  42  performs the stereo image forming operation to form an image for the right eye and an image for the left eye that may be stereoscopically viewed, and causes the stereo display device  220  to display a stereo image. 
         [0088]    The program for the stereo image forming operation is stored beforehand in a predetermined region in the ROM  106 , and is executed by the CPU  104 . 
         [0089]    The program for the stereo image forming operation is performed to generate three-dimensional information based on the two stored radiation images, form the image for the right eye and the image for the left eye, cause the display unit  222 R to display the image for the right eye, and cause the display unit  222 L to display the image for the left eye. At this point, the image for the right eye and the image for the left eye are positioned, with a predetermined amount of offset being kept in the horizontal direction. 
         [0090]    With this arrangement, an observer such as a physician may stereoscopically interpret radiation images and make a diagnosis from radiation images by viewing the screen of the stereo display device  220  through the polarizing glasses  225 . 
         [0091]    The observer such as a physician inputs information as to which image of the two images was used as a diagnosis confirmation image via the operation input unit  102  or the display  100 . The information is stored as observation information related to the information about the two stereoscopic viewing images obtained through one image capturing operation, into the HDD  110 . 
         [0092]    If the information as to which one of the two images is the diagnosis confirmation image is associated with the stereoscopically-viewed image and is stored in the HDD  110 , it is easy to determine which image was used as the diagnosis confirmation image. 
         [0093]    If one of the two images is used as the diagnosis confirmation image, the other one of the images is used as an auxiliary image for stereoscopic viewing, and therefore, may be lower in resolution than the diagnosis confirmation image. Therefore, the resolution at the time of image capturing may be lowered. As the resolution of the second image is lowered as described above, the occupied capacity in the HDD  110  becomes smaller, and a larger number of images may be stored in the HDD  110 . 
         [0094]    If the image to be used as the diagnosis confirmation image is captured before the other image is captured, a diagnosis may be made based on the first image, and the second image may not need to be captured. 
         [0095]    If the diagnosis confirmation image is an image (a perpendicular image) captured by directing a radiation ray onto the electronic cassette  32  serving as the radiation detector from a perpendicular direction, a diagnosis may be made based on the same image as a regular radiation image that is not stereoscopically viewed. 
         [0096]    Also, the diagnosis confirmation radiation image may be stored as an image obtained by directing a radiation ray onto the electronic cassette  32  serving as the radiation detector from a direction at an angle predetermined for each imaging site. The angle predetermined for each imaging site is recorded beforehand in the HDD  110 , and an angle θ 1  is determined based on imaging site information that is input from the operation input unit  102 . The radiation source  130  is then moved to have that angle, and an image to be used as the diagnosis confirmation image is captured. Alternatively, the predetermined angle may be input from the operation input unit  102  for each imaging site. 
         [0097]    Also, the radiation image for the dominant eye may be stored as the diagnosis confirmation image. Dominant eye information may be set beforehand in accordance with the ID of an observer such as a physician, and be stored in the HDD  110 . Alternatively, every time an image is captured, the dominant eye information may be input from the operation input unit  102 . 
         [0098]    The amount of offset in the horizontal direction between the image for the right eye and the image for the left eye is also stored into the HDD  110 . The amount of offset is stored as observation information related to the information about the two stereoscopic viewing images obtained through one image capturing direction. 
         [0099]    In the above described example, stereoscopic viewing is performed with the polarizing glasses  225 . However, stereoscopic viewing using glasses may be performed in a different manner. Further, glasses-free stereoscopic viewing with the use of a lenticular or the like may be performed with the naked eye. Therefore, the information as to which one of the stereoscopic viewing techniques is used, as well as the above described information, is stored as the observation information about the two stereoscopic viewing images obtained through one image capturing operation, into the HDD  110 . 
         [0100]    In the above described exemplary embodiment, the portable electronic cassette  32  is used as a radiation detector. However, instead of the electronic cassette  32 , a stationary radiation detector may be used. 
         [0101]    In the above described exemplary embodiment, an X-ray is used as a radiation ray. However, the invention is not limited to X-rays, and a y-ray or the like may be used, instead of an X-ray, for example. 
         [0102]    Various exemplary embodiments of the invention have hitherto been described, however, the invention is not limited to the exemplary embodiments. Therefore, the scope of the invention is limited only by the appended claims.