Abstract:
A radiation detection device has: a scintillator for converting radiation into fluorescence; a photoelectric conversion unit for converting the fluorescence into an electric signal; and a reset light source unit for exposing reset light to the photoelectric conversion unit. A system control unit has an optical reset disabling unit for, based on a reset disabling instruction, disabling the exposure of the reset light output from the reset light source unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY CLAIM 
     This application is a Continuation of International Application No. PCT/JP2012/076081 filed on Oct. 9, 2012, which was published under PCT Article 21(2) in Japanese, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2011-234412 filed on Oct. 25, 2011, the contents all of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a radiographic image (radiation image) capturing system having a radiation detecting device which includes a scintillator for converting radiation into fluorescence and a photoelectric converting portion for converting the fluorescence into an electric signal, and also to a radiation detecting device. 
     BACKGROUND ART 
     In the medical field, it has been widely practiced to apply radiation from a radiation source to a subject and detect the radiation that has passed through the subject with a radiation detecting device thereby to acquire a radiographic image of the subject (see, for example, Japanese Laid-Open Patent Publication No. 2006-140592). 
     Radiation detecting devices are roughly classified into indirect conversion radiation detecting devices which include a scintillator or the like for converting radiation into visible light and a photodiode or the like for converting the visible light into electric charges, and direct conversion radiation detecting devices which have a semiconductor material for directly absorbing and converting radiation into electric charges. 
     In a case where the above radiation detecting devices are used in high-speed moving image capturing processes such as fluorography and digital subtraction angiography (DSA) or the like, they may cause artifacts or afterimages due to the response of a phosphor (fluorophore) or a photoelectric transducer device, lowering the quality of generated images, immediately after X-rays of high dose are applied at one period of time or continuously. 
     One known solution to such afterimages is disclosed as an X-ray detector in Japanese Patent No. 4150079, for example. The X-ray detector disclosed in Japanese Patent No. 4150079 has a bias radiation source for irradiating a semiconductor device with an electromagnetic radiation thereby to prevent afterimages from being produced without complex corrective calculations. Specifically, it is known that it is effective to remove afterimages to apply resetting light to a photoelectric transducing portion, i.e., to reset the photoelectric transducing portion with light, which converts fluorescence generated by a scintillator into an electric signal. 
     SUMMARY OF INVENTION 
     However, once the photoelectric transducing portion is reset with light, the X-ray detector is unable to perform a radiographic moving image capturing process (fluorography) for a certain period of time that is equal to at least the sum of a period of time to apply the resetting light and a period of time to remove the effect of the applied resetting light, or even on the condition that the X-ray detector is able to perform a radiographic moving image capturing process, images generated in the radiographic moving image capturing process tend to be disrupted. 
     On the condition that the X-ray detector is incorporated in a radiographic image capturing system which allows the operator to recognize in real time how a catheter, for example, enters a subject, then a radiographic moving image capturing process may not be performed or captured images may be disrupted, posing an obstacle to the medical practice, in a case where the catheter should carefully be inserted into the subject. 
     The present invention has been made in view of the above drawbacks. It is an object of the present invention to provide a radiographic image capturing system and a radiation detecting device which are capable of selectively nullifying a light resetting process that is effective to remove afterimages thereby to avoid shortcomings resulting from the light resetting process. 
     Another object of the present invention is to provide a radiographic image capturing system and a radiation detecting device which are capable of preventing images from being disrupted by afterimages in a case where radiographic images need to be observed carefully, by forcibly resetting a photoelectric transducing portion with light in a situation where no obstacle will be posed to the medical practice. 
     [1] According to a first aspect of the present invention, there is provided a radiographic image capturing system comprising a radiographic image capturing apparatus including a radiation applying device having a radiation source and a radiation detecting device for converting radiation emitted from the radiation source and transmitted through a subject into a radiographic image and supplying the radiographic image, and a system control portion for controlling the radiographic image capturing apparatus to perform a radiographic image capturing process at a preset frame rate, wherein the radiation detecting device has a scintillator for converting the radiation into fluorescence, a photoelectric transducing portion for converting the fluorescence into an electric signal, and a resetting light source for irradiating the photoelectric transducing portion with resetting light, and the system control portion has a light resetting nullifying portion for nullifying application of the resetting light from the resetting light source in response to a resetting nullifying command. 
     [2] In the first aspect, the radiographic image capturing system may further comprise a resetting nullifying switch for supplying the resetting nullifying command in response to operator&#39;s input, wherein the light resetting nullifying portion may nullify the application of the resetting light from the resetting light source in response to the resetting nullifying command from the resetting nullifying switch. 
     [3] In the first aspect, the light resetting nullifying portion may nullify the application of the resetting light from the resetting light source only during a period in which the resetting nullifying command is supplied. 
     [4] In the first aspect, the system control portion may further include a resetting nullification commanding portion for supplying the resetting nullifying command based on a result of an analysis of the radiographic image from the radiation detecting device, and the light resetting nullifying portion may nullify the application of the resetting light from the resetting light source in response to the resetting nullifying command. 
     [5] The resetting nullification commanding portion may supply the resetting nullifying command based on a positional relationship between a designated particular image of the subject in the radiographic image from the radiation detecting device and an image of an instrument inserted in the subject. 
     [6] The resetting nullification commanding portion may supply the resetting nullifying command during a period in which the designated particular image of the subject and the image of the instrument inserted in the subject are in a preset positional relationship, and the light resetting nullifying portion may nullify the application of the resetting light from the resetting light source only during a period in which the resetting nullifying command is supplied. 
     [7] The preset positional relationship may be a relationship in which the image of the instrument has a portion placed in the particular image. 
     [8] In the first aspect, the radiographic image capturing system may further comprise a forced light resetting portion for forcibly applying the resetting light from the resetting light source in response to a forced resetting command. 
     [9] The radiographic image capturing system may further comprise a forced resetting switch for supplying the forced resetting command in response to operator&#39;s input, wherein the forced light resetting portion may forcibly apply the resetting light from the resetting light source in response to the forced resetting command from the forced resetting switch. 
     [10] The system control portion may further include a guidance output portion for providing guidance for turning on the forced resetting switch. 
     [11] The guidance may comprise an afterimage phenomenon in the radiographic image. 
     [12] The guidance output portion may include an accumulated dose calculating portion for calculating an accumulated dose that is stored in the radiation detecting device after the radiation detecting device has been irradiated with last resetting light, and the guidance output portion may supply the accumulated dose as representing the afterimage phenomenon in the radiographic image. 
     [13] The guidance may comprise an elapsed time from the application of last resetting light. 
     [14] The forced light resetting portion may forcibly apply the resetting light from the resetting light source in response to the forced resetting command supplied from an external source. 
     [15] The system control portion may further include a forced resetting commanding portion for supplying the forced resetting command based on the result of an analysis of the radiographic image from the radiation detecting device. 
     [16] The forced resetting commanding portion may supply the forced resetting command based on a positional relationship between a designated particular image of the subject in the radiographic image from the radiation detecting device and an image of an instrument inserted in the subject. 
     [17] The forced resetting commanding portion may include a motion vector calculating portion for determining a moving direction and a moving speed of the image of the instrument based on the plurality of radiographic images, and the forced resetting commanding portion may supply the forced resetting command in a case where the moving direction of the image of the instrument is oriented toward the particular image and before the image of the instrument reaches the particular image. 
     [18] The forced resetting commanding portion may supply the forced resetting command in a case where the moving direction of the image of the instrument is oriented toward the particular image and a time required until the image of the instrument reaches the particular image becomes a preset time. 
     [19] According to a second aspect of the present invention, there is provided a radiation detecting device comprising a scintillator for converting radiation into fluorescence, a photoelectric transducing portion for converting the fluorescence into an electric signal, a resetting light source for irradiating the photoelectric transducing portion with resetting light, and a light resetting nullifying portion for nullifying application of the resetting light from the resetting light source in response to a resetting nullifying command. 
     [20] In the second aspect, the radiation detecting device may further comprise a resetting nullifying switch for supplying the resetting nullifying command in response to operator&#39;s input, and the light resetting nullifying portion may nullify the application of the resetting light from the resetting light source in response to the resetting nullifying command from the resetting nullifying switch. 
     [21] The light resetting nullifying portion may nullify the application of the resetting light from the resetting light source only during a period in which the resetting nullifying command is supplied. 
     [22] In the second aspect, the light resetting nullifying portion may nullify the application of the resetting light from the resetting light source only during a period in which the resetting nullifying command is supplied from an external source. 
     [23] In the second aspect, the radiation detecting device may further comprise a forced light resetting portion for forcibly applying the resetting light from the resetting light source in response to a forced resetting command. 
     [24] The radiation detecting device may further comprise a forced resetting switch for supplying the forced resetting command in response to operator&#39;s input, and the forced light resetting portion may forcibly apply the resetting light from the resetting light source in response to the forced resetting command from the forced resetting switch. 
     [25] The radiation detecting device may further comprise a guidance output portion for providing guidance for turning on the forced resetting switch. 
     [26] The guidance may comprise an afterimage phenomenon in the radiographic image. 
     [27] The guidance output portion may include an accumulated dose calculating portion for calculating an accumulated dose that is stored in the radiation detecting device after application of last resetting light, and the guidance output portion may supply the accumulated dose as representing the afterimage phenomenon in the radiographic image. 
     [28] The guidance may comprise an elapsed time from the application of last resetting light. 
     [29] The forced light resetting portion may forcibly apply the resetting light from the resetting light source in response to the forced resetting command supplied from an external source. 
     The radiographic image capturing system and the radiation detecting device according to the present invention are capable of selectively nullifying a light resetting process that is effective to remove afterimages thereby to avoid shortcomings resulting from the light resetting process. Furthermore, the radiographic image capturing system and the radiation detecting device are capable of preventing images from being disrupted by afterimages in a case where radiographic images need to be observed carefully, by forcibly resetting a photoelectric transducing portion with light in a situation where no obstacle will be posed to the medical practice. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view of a radiographic image capturing system according to an embodiment of the present invention; 
         FIG. 2  is a block diagram showing mainly the configurations of a radiation applying device and a radiation detecting device; 
         FIG. 3  is a perspective view of the radiation detecting device; 
         FIG. 4  is an exploded perspective view of the radiation detecting device; 
         FIG. 5  is a cross-sectional view taken along line V-V of  FIG. 4 ; 
         FIG. 6  is a circuit diagram showing mainly a photoelectric transducing portion and a readout circuit; 
         FIG. 7  is a block diagram showing mainly the configuration of a first system control portion; 
         FIG. 8  is a flowchart of a processing sequence of a moving image capturing processing portion of the first system control portion; 
         FIG. 9  is a flowchart of a processing sequence of a light resetting processing portion of the first system control portion; 
         FIG. 10  is a timing chart of a processing sequence of the first system control portion, particularly including operation of a forced light resetting portion; 
         FIG. 11  is a timing chart of a processing sequence of the first system control portion, particularly including operation of a light resetting nullifying portion; 
         FIGS. 12A and 12B  are views showing the manner in which a catheter is inserted into a blood vessel; 
         FIG. 13  is a block diagram showing mainly the configuration of a second system control portion; 
         FIG. 14A  is a block diagram showing the configuration of a guidance output portion according to a first principle; 
         FIG. 14B  is a block diagram showing the configuration of a guidance output portion according to a second principle; 
         FIG. 15  is a block diagram showing mainly the configuration of a third system control portion; 
         FIG. 16  is a flowchart of a processing sequence of a light resetting processing portion of the third system control portion; 
         FIG. 17  is a block diagram showing mainly the configuration of a fourth system control portion; and 
         FIG. 18  is a block diagram showing the configuration of a radiation applying device according to another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Radiation detecting devices and radiographic image capturing systems according to embodiments of the present invention will be described below with reference to  FIGS. 1 through 18 . 
     As shown in  FIG. 1 , a radiographic image capturing system  10  according to an embodiment of the present invention has a radiographic image capturing apparatus  12  and a system control portion  14  for controlling the radiographic image capturing apparatus  12  to capture radiographic images at a preset frame rate which may be in the range from 15 frames per second to 60 frames per second, for example. The system control portion  14  is connected to a console  16  for data communication therewith. The console  16  is connected to a monitor  18  for observing images and diagnosing images, and an input device  20  such as a keyboard, a mouse, etc. for entering operator&#39;s input. The operator of the radiographic image capturing system  10 , such as a doctor or a radiologist, sets a suitable irradiation energy level of radiation, which includes a tube voltage, a tube current, an irradiation time, etc., and a suitable frame rate for capturing images, to current conditions using the input device  20  for surgical operations and catheter inserting processes to be performed while viewing moving images. Data that are entered using the input device  20  and data generated and edited using the console  16  are supplied to the system control portion  14 . Radiographic images that are captured are supplied from the system control portion  14  to the console  16 , which displays the supplied radiographic images on the monitor  18 . 
     The radiographic image capturing apparatus  12  has a radiation applying device  28  for applying radiation  26  with the preset irradiation energy level to a subject  24  on an image capturing table  22 , and a radiation detecting device  30  for converting the radiation  26  that has passed through the subject  24  into a radiographic image and supplying the radiographic image to the system control portion  14 . 
     As shown in  FIG. 2 , the radiation applying device  28  includes a radiation source  34 , a radiation source control portion  36  for controlling the radiation source  34  based on commands from the system control portion  14 , and an automatic collimating portion  38  for increasing or reducing an area that is irradiated with the radiation  26  based on commands from the system control portion  14 . 
     As shown in  FIGS. 3 through 5 , the radiation detecting device  30  has a casing  40  made of a material permeable to the radiation  26 . The casing  40  comprises a first case  42  and a second case  44 . The first case  42  has a first flat plate  46 , which is of a substantially rectangular shape as viewed in plan, for being irradiated with the radiation  26 , and a first side wall  48  extending around the peripheral edges of the first flat plate  46 . The second case  44  has a second flat plate  50 , which is similar in shape to the first flat plate  46 , and a second side wall  52  erected on the peripheral edges of the second flat plate  50 . 
     The first case  42  is detachably mounted on the second case  44 . With the first case  42  mounted on the second case  44 , the casing  40  defines a closed space  54  (see  FIG. 5 ) therein. 
     Each of the first case  42  and the second case  44  of the casing  40  is made of a composite material such as carbon-fiber-reinforced plastics (CFRP) or the like, engineering plastics, a biomass material, aluminum, aluminum alloy, magnesium, magnesium alloy, or resin for reducing the overall weight of the radiation detecting device  30 . The first case  42  and the second case  44  may be made of the same material or different materials. In  FIG. 5 , each of the first case  42  and the second case  44  is made as an integral case of CFRP. 
     The casing  40  houses therein a battery  56  as a power supply of the radiation detecting device  30 , a transceiver  58  for sending signals including radiographic images to the system control portion  14  and receiving signals including radiographic images from the system control portion  14 , a radiation detecting panel  62 , which is of a rectangular shape as viewed in plan, supported by the first flat plate  46  with an intermediate member  60 , to be described later, interposed therebetween, a shield plate  66  having edges disposed in a mounting groove  64  defined in an inner surface of the second side wall  52 , and a cassette control portion  68  disposed between the shield plate  66  and the second flat plate  50 , for controlling the radiation detecting panel  62 . 
     The battery  56  supplies electric energy to the transceiver  58 , the radiation detecting panel  62 , and the cassette control portion  68 . Lead plates that serve as shield plates, not shown, should desirably be disposed between the battery  56  and the first flat plate  46  and between the transceiver  58  and the first flat plate  46 . The lead plates thus positioned are effective to prevent the battery  56  and the transceiver  58  from being unduly deteriorated by the radiation  26 . 
     The radiation detecting panel  62  may comprise an indirect-conversion-type radiation detecting panel  62 , which may be of the ISS (Irradiation Side Sampling) type or the PSS (Penetration Side Sampling) type, for converting the radiation  26  that has passed through the subject  24  into visible light (fluorescence) using a scintillator  70  and then converting the visible light into an analog electric signal using a photoelectric transducing portion  72 . 
     In a case where the radiation detecting panel  62  is of the ISS type, then the photoelectric transducing portion  72  and the scintillator  70  are arranged successively along the direction in which the radiation  26  is applied. In a case where the radiation detecting panel  62  is of the PSS type, then the scintillator  70  and the photoelectric transducing portion  72  are arranged successively along the direction in which the radiation  26  is applied. 
     According to the present embodiment, the radiation detecting panel  62  is of the ISS type. Usually, the scintillator  70  emits more intensive light from its surface irradiated with the radiation  26  than the reverse side thereof. Therefore, the radiation detecting panel  62  of the ISS type has a shorter distance that the light emitted by the scintillator  70  travels before reaching the photoelectric transducing portion  72  than the radiation detecting panel of the PSS type. As the light is less liable to be scattered and dissipated, radiographic images are of a higher resolution. 
     The radiation detecting panel  62  may alternatively comprise a direct-conversion-type radiation detecting panel, instead of an indirect-conversion-type radiation detecting panel for directly converting the dose of the radiation  26  into an electric signal using solid-state detector elements made of amorphous selenium (a-Se). 
     The scintillator  70  is formed by evaporating a columnar crystalline structure of cesium iodide (CsI:Tl), for example, on a base plate according to a vacuum evaporation process. The scintillator  70  thus formed is capable of efficiently detecting the radiation  26  for generating radiographic images of a higher resolution. 
     Alternatively, the scintillator  70  may be formed by evaporating GOS (Gd 2 O 2 S:Tb), for example, on a base plate. The scintillator  70  thus formed is capable of converting the radiation  26  into visible light. The base plate may be made of CFRP, aluminum, aluminum alloy, magnesium, magnesium alloy, or resin. 
     The photoelectric transducing portion  72  is layered on a surface of the scintillator  70  which is closer to the first flat plate  46 . The photoelectric transducing portion  72  comprises a flexible board  74  having a matrix of thin-film transistors (TFTs) made of an oxide semiconductor (IGZO) and a plurality of solid-state detector elements  76  (pixels) of amorphous silicon (a-Si) disposed on the array of TFTs. 
     Since the oxide semiconductor (IGZO) is selectively sensitive to only wavelengths shorter than 460 nm, it is effective to prevent switching noise from being generated by the light emitted from the scintillator  70 . 
     The photoelectric transducing portion  72  and the cassette control portion  68  are electrically connected to each other by flexible cables  78 ,  80 . The flexible cable  78  has a gate IC  82  for energizing the TFTs based on signals from the cassette control portion  68 . The flexible cable  80  has an ASIC  84  (Application Specific Integrated Circuit) for amplifying analog electric signals from the solid-state detector elements  76  and converting the analog electric signals into digital electric signals. The flexible cable  78  is removably connected to a longitudinally extending side edge of the photoelectric transducing portion  72 , and the flexible cable  80  is removably connected to a transversely extending side edge of the photoelectric transducing portion  72 . 
     The shield plate  66  is made of a material, e.g., lead, for absorbing back scattered rays from the radiation detecting panel  62 . Therefore, back scattered rays from the radiation detecting panel  62  are prevented from being applied to the cassette control portion  68  and hence preventing the cassette control portion  68  from deteriorating. The cassette control portion  68  is supported on the shield plate  66  by a plurality of brackets  86  (see  FIG. 5 ). 
     The intermediate member  60 , which is in the form of a plate, is disposed between the first flat plate  46  and the radiation detecting panel  62 . The intermediate member  60  has a main intermediate member body  92  bonded to an inner irradiation surface  90  by an adhesive member  88  and a resetting light source  94 . 
     The resetting light source  94  has a light emission layer  96 , which is of a rectangular shape as viewed in plan, for emitting resetting light, a metal electrode  98  interposed between the light emission layer  96  and the main intermediate member body  92 , a transparent electrode  100  interposed between the light emission layer  96  and the radiation detecting panel  62 , for passing the resetting light therethrough, and a power supply  102  and a switch  104  that are electrically connected to the transparent electrode  100  and the metal electrode  98 , respectively. The battery  56  may double as the power supply  102 , or the power supply  102  may be a dedicated power supply separate from the battery  56 . 
     The light emission layer  96  is made of an organic electroluminescent (EL) material or an inorganic EL material. The metal electrode  98  should preferably be made of a material having a high transmittance for the radiation  26  and a high reflectance for the resetting light. For example, the metal electrode  98  may be made of aluminum or the like, for example. The transparent electrode  100  may be made of ITO or the like, for example. 
     According to the present embodiment, the cassette control portion  68  controls the power supply  102  and the switch  104  of the resetting light source  94  to cause the light emission layer  96  to emit resetting light prior to a radiographic image capturing process. 
     By way of example, the photoelectric transducing portion  72  of the radiation detecting panel  62 , which is of the indirect conversion type, and a readout circuit  106  for the photoelectric transducing portion  72  will be described in detail below with reference to  FIG. 6 . 
     The photoelectric transducing portion  72  has a photoelectric transducing layer  108  including the pixels  76  made of a-Si or the like for converting visible light into an electric signal and disposed on an array of thin-film transistors (TFTs)  110  arranged in rows and columns. Each of the pixels  76  stores an electric charge generated in a case where visible light is converted into an analog electric signal. The electric charges stored in the pixels  76  can be read as an image signal in a case where the TFTs  110  are turned on in the successive rows. 
     The readout circuit  106  has the TFTs  110  connected to the respective pixels  76 , gate lines  112  connected to the TFTs  110  and extending parallel to the rows of the TFTs  110 , and signal lines  114  connected to the columns of the TFTs  110  and extending parallel to the columns of the TFTs  110 . The gate lines  112  are connected to a line scanning driver  116 , whereas the signal lines  114  are connected to a multiplexer  118 . The gate lines  112  are supplied with control signals Von, Voff for turning on and off the TFTs  110  along the rows from the line scanning driver  116 . The line scanning driver  116  includes a plurality of switches SW 1  for switching between the gate lines  112  and a first address decoder  120  for supplying a selection signal for selecting one of the switches SW 1 . The first address decoder  120  is supplied with an address signal from the cassette control portion  68 . 
     The signal lines  114  are supplied with electric charges stored by the pixels  76  through the TFTs  110  arranged in the columns. The electric charges supplied to the signal lines  114  are amplified by charge amplifiers  122 . The charge amplifiers  122  are connected through respective sample and hold circuits  124  to the multiplexer  118 . 
     The electric charges read out from the columns are supplied through the signal lines  114  to the charge amplifiers  122  corresponding to the columns. Each of the charge amplifiers  122  comprises an operational amplifier  126 , a capacitor  128 , and a switch  130 . In a case where the switch  130  is turned off, the charge amplifier  122  converts an electric charge signal applied to an input terminal of the operational amplifier  126  into a voltage signal, and outputs the voltage signal. The charge amplifier  122  amplifies the electric charge signal with a gain set by the cassette control portion  68 . Information (gain setting information) about the gain for the charge amplifier  122  is supplied from the system control portion  14  to the cassette control portion  68 , which sets the gain for the charge amplifier  122  based on the supplied gain setting information. 
     The operational amplifiers  126  have other input terminals grounded, i.e., connected to ground potential (GND). In a case where all the TFTs  110  are turned on and the switches  130  are turned on, the electric charges stored in the capacitors  128  are discharged by closed circuits of the capacitors  128  and the switches  130 , and the electric charges stored in the pixels  76  are drained (swept out) to ground potential (GND) through the switches  130  and the operational amplifiers  126 . The process of discharging the electric charges stored in the capacitors  128  and draining the electric charges stored in the pixels  76  to ground potential (GND) by turning on the switches  130  of the charge amplifiers  122  is referred to as a resetting process (dummy reading process). In particular, a process of draining the electric charges stored in all the pixels to ground potential is referred to as “all-pixel resetting process”. In the resetting process, voltage signals that correspond to the electric charge signals stored in the pixels  76  are not supplied to the multiplexer  118 , but drained. 
     The multiplexer  118  includes a plurality of switches SW 2  for successively switching between the signal lines  114  and a second address decoder  132  for supplying a selection signal for selecting one of the switches SW 2 . The second address decoder  132  is supplied with an address signal from the cassette control portion  68 . The multiplexer  118  has an output terminal connected to an A/D converter  134 . A radiographic image signal is converted by the A/D converter  134  into a digital image signal representing radiographic image information, which is supplied to the cassette control portion  68 . 
     The TFTs  110  which function as switching devices may be combined with another image capturing device such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor or the like. Alternatively, the TFTs  110  may be replaced with a CCD (Charge-Coupled Device) image sensor for shifting and transferring electric charges with shift pulses which correspond to gate signals in the TFTs. 
     As shown in  FIG. 2 , the cassette control portion  68  of the radiation detecting device  30  includes an address signal generating portion  136  for the readout circuit  106  (see  FIG. 6 ), an image memory  138 , and a cassette ID memory  140 . 
     The address signal generating portion  136  supplies address signals to the first address decoder  120  of the line scanning driver  116  and the second address decoder  132  of the multiplexer  118  of the readout circuit  106  shown in  FIG. 6  based on readout control information for radiographic images from the system control portion  14 , for example. The readout control information includes information representing a progressive mode, an interlace mode (an odd-numbered row readout mode, an even-numbered row readout mode, an every third row readout mode, an every fourth row readout mode, etc.), and a binning mode (a 4-pixels-into-1 readout mode, a 6-pixels-into-1 readout mode, a 9-pixels-into-1 readout mode, etc.). In the 4-pixels-into-1 readout mode, for example, two adjacent gate lines  112  are simultaneously energized, i.e., supplied with the control signal Von, and two adjacent signal lines  114  are simultaneously energized, thereby mixing electric charges in four adjacent pixels in two rows and two columns into a single superpixel electric charge to be read. The address signal generating portion  136  generates address signals depending on a mode represented by the readout control information, and supplies the generated address signals to the first address decoder  120  of the line scanning driver  116  and the second address decoder  132  of the multiplexer  118 . The readout control information is generated by the system control portion  14  based on input entered by the operator, for example, and supplied to the cassette control portion  68  of the radiation detecting device  30 . 
     The readout control information supplied from the system control portion  14  includes, in addition to the information about the readout modes (readout mode information) described above, image capturing range information for designating an image capturing range. For example, on the condition that the operator sets an image capturing range for moving images using the input device  20  and the monitor  18 , then the image capturing range information includes the addresses of the gate lines  112  and the addresses of the signal lines  114  included in the image capturing range thus set. The image capturing range information may include start addresses (numbers) and end addresses (numbers) of the gate lines  112  and start addresses (numbers) and end addresses (numbers) of the signal lines  114  included in the image capturing range. On the condition that the readout mode information represents an odd-numbered row readout mode (decimating or thinning mode), for example, then odd-numbered gate lines  112  among the gate lines  112  included in the image capturing range of the radiation detecting panel  62  are successively selected, and signal electric charges from the signal lines  114  included in the image capturing range of the radiation detecting panel  62  are not combined, but successively transferred to the A/D converter  134 . On the condition that the readout mode information represents a 4-pixels-into-1 readout mode (binning mode), for example, then two at a time of the gate lines  112  included in the image capturing range are successively selected, and signal electric charges from adjacent two of the signal lines  114  included in the image capturing range are combined, i.e., signal electric charges from four pixels are combined, and successively transferred to the A/D converter  134 . 
     The image memory  138  stores radiographic image information from the readout circuit  106 . The cassette ID memory  140  stores cassette ID information for identifying the radiation detecting device  30 . 
     The transceiver  58  sends the cassette ID information stored in the cassette ID memory  140  and the radiographic image information stored in the image memory  138  to the system control portion  14  via a wired communication link or a wireless communication link. 
     The radiation detecting device  30  has a switching control portion  142  for turning on and off the switch  104  of the resetting light source  94 . The cassette control portion  68  includes a pulse signal generating portion  144 . The pulse signal generating portion  144  generates a pulse signal having a certain pulse duration in response to an ON signal, i.e., a signal for performing a light resetting process, from the system control portion  14 , and supplies the generated pulse signal to the switching control portion  142 . Based on the supplied pulse signal, the switching control portion  142  turns on the switch  104  for the pulse duration of the pulse signal. The light emission layer  96  now emits resetting light for a period of time that corresponds to the pulse duration, and the emitted resetting light is applied to the photoelectric transducing portion  72 , thereby performing the light resetting process. 
     Specific examples of the system control portion  14  of the radiographic image capturing system  10  will be described below with reference to  FIGS. 7 through 17 . 
     As shown in  FIG. 7 , a system control portion according to a first specific example (hereinafter referred to as “first system control portion  14 A) has a moving image capturing processing portion  146  and a light resetting processing portion  148 . 
     The moving image capturing processing portion  146  has a parameter setting portion  150 , a parameter history storage portion  152 , and a moving image transfer portion  154 . 
     In a case where new parameters including an irradiation energy level, a frame rate, or the like are set based on input from the operator, the parameter setting portion  150  stores them as latest parameters including newly set irradiation energy level, a frame rate, or the like in the parameter history storage portion  152 . Particularly, in a case where a new irradiation energy level is set, the parameter setting portion  150  supplies irradiation energy level setting information Sa including information about the new irradiation energy level, i.e., information of a tube voltage, a tube current, an irradiation time, etc., to the radiation applying device  28 . On the condition that a gain of the charge amplifiers  122  or a readout mode is newly set, then the parameter setting portion  150  supplies readout control information Sb including information about the newly set gain or readout mode to the radiation detecting device  30 . 
     The parameter history storage portion  152  stores irradiation energy levels and frame rates (and the like) that were set over a predetermined period in the past from the present, of the irradiation energy levels and the frame rates (and the like) which have been set so far. 
     The moving image transfer portion  154  receives radiographic images Da successively supplied from the radiation detecting device  30 , and transfers the received radiographic images Da to the console  16 . The console  16  displays the successively transferred radiographic images Da on the monitor  18 . The monitor  18  thus displays the radiographic images Da as a moving image. 
     A resetting nullifying switch  156  and a forced resetting switch  158  are connected to the console  16 . In a case where the operator turns on the resetting nullifying switch  156 , it generates a resetting nullifying command signal Sn which is, e.g., high in level over a period during which the operator turns on the resetting nullifying switch  156 . The resetting nullifying command signal Sn is supplied from the resetting nullifying switch  156  through the console  16  to the first system control portion  14 A. In a case where the operator turns on the forced resetting switch  158 , it generates a forced resetting command signal Sr having a certain pulse duration. The forced resetting command signal Sr is supplied from the forced resetting switch  158  through the console  16  to the first system control portion  14 A. 
     The light resetting processing portion  148  has an ON signal output portion  160 , a light resetting nullifying portion  162 , and a forced light resetting portion  164 . 
     The ON signal output portion  160  generates an ON signal Son at the selected frame interval in the range from 5 to 100 frames, for example, based on the latest frame rate stored in the parameter history storage portion  152 . For example, on the condition that the interval of 50 frames is selected, then the ON signal output portion  160  generates an ON signal Son at the frame interval between the 50nth (n: 1, 2, 3, . . . ) frame and the 50nth+1 frame. In a case where the ON signal Son is supplied to the radiation detecting device  30 , the light resetting process is performed on the radiation detecting device  30 . 
     The forced light resetting portion  164  is supplied with a forced resetting command signal Sr from the forced resetting switch  158 . In a case where the forced light resetting portion  164  is supplied with the forced resetting command signal Sr, the forced light resetting portion  164  generates an ON signal Son having the same attributes (pulse duration, amplitude) as the ON signal Son from the ON signal output portion  160 . 
     The light resetting nullifying portion  162  is supplied with the ON signal Son from the ON signal output portion  160 , the ON signal Son from the forced light resetting portion  164 , and the resetting nullifying command signal Sn from the resetting nullifying switch  156 . While the light resetting nullifying portion  162  is not being supplied with the resetting nullifying command signal Sn, the light resetting nullifying portion  162  supplies the ON signal Son from the ON signal output portion  160  and the ON signal Son from the forced light resetting portion  164 . In a case where the light resetting nullifying portion  162  is supplied with the resetting nullifying command signal Sn, the light resetting nullifying portion  162  does not supply the ON signal Son from the ON signal output portion  160  and the ON signal Son from the forced light resetting portion  164 . Normally, the light resetting process will be performed. However, during a period of time in which the light resetting nullifying portion  162  is supplied with the resetting nullifying command signal Sn, the light resetting nullifying portion  162  does not perform the light resetting process, i.e., nullifies the light resetting process. 
     Processing operation of the radiographic image capturing system  10  which has the first system control portion  14 A will be described below with reference to  FIGS. 8 through 12 . The moving image capturing processing portion  146  and the light resetting processing portion  148  operate in a multitasking mode. 
     First, a processing sequence of the moving image capturing processing portion  146  will be described below with reference to  FIG. 8 . In step S 1  shown in  FIG. 8 , the first system control portion  14 A stores an initial value (=1) in a counter k for counting image capturing events. 
     In step S 2 , the parameter setting portion  150  judges whether new parameters including an irradiation energy level, a frame rate, an image capturing range, and a readout mode, etc. for the radiation  26  has been set or not. On the condition that the operator has set new parameters, then control goes to step S 3  in which the irradiation energy level, the frame rate, etc. that have been newly set are stored as latest parameters in the parameter history storage portion  152 . 
     On the condition that an irradiation energy level has been newly set, then the parameter setting portion  150  supplies irradiation energy level setting information Sa including information about the newly set irradiation energy level, i.e., information of a tube voltage, a tube current, an irradiation time, etc., to the radiation applying device  28  in step S 4 . Based on the irradiation energy level setting information Sa from the first system control portion  14 A, the radiation source control portion  36  of the radiation applying device  28  sets the irradiation energy level of the radiation  26  to be emitted from the radiation source  34  to the newly set irradiation energy level. 
     On the condition that an image capturing range and a readout mode, etc. have been newly set, then the parameter setting portion  150  supplies readout control information Sb including information about the newly set image capturing range and information about the newly set readout mode to the radiation detecting device  30  in step S 5 . The cassette control portion  68  of the radiation detecting device  30  supplies the readout control information Sb to the address signal generating portion  136 . 
     In step S 6 , the first system control portion  14 A judges whether a period of time corresponding to the latest frame rate Fr has elapsed from the start time of the preceding radiographic image capturing event or not. On the condition that the counter k indicates the initial value or the period of time corresponding to the latest frame rate Fr has elapsed from the starting time of the preceding radiographic image capturing event, then control goes to step S 7 . In step S 7 , the first system control portion  14 A supplies an exposure start signal Sc (see  FIG. 10 ) to the radiation applying device  28  at the start time of a kth radiographic image capturing event. Based on the exposure start signal Sc from the first system control portion  14 A, the radiation source control portion  36  of the radiation applying device  28  controls the radiation source  34  to emit the radiation  26  at the set irradiation energy level. 
     In step S 8 , the first system control portion  14 A supplies an operation start signal Sd (see  FIG. 10 ) indicative of storage and readout of electric charges to the radiation detecting device  30 . 
     In step S 9 , based on the operation start signal Sd from the first system control portion  14 A, the radiation detecting device  30  stores and reads out electric charges. Specifically, the radiation  26  that has passed through the subject  24  is converted by the scintillator  70  of the photoelectric transducing portion  72  into visible light, which is then converted by the pixels  76  of the photoelectric transducing portion  72  into electric charges in amounts that depend on the intensity of the visible light. The electric charges are stored in the pixels  76 . 
     In a next readout period, the address signal generating portion  136  generates address signals based on the supplied readout control information Sb (image capturing range information, readout mode information, etc.), and supplies the generated address signals to the first address decoder  120  of the line scanning driver  116  and the second address decoder  132  of the multiplexer  118  of the readout circuit  106 . The readout circuit  106  reads the electric charges from the pixels  76  according to the readout control information Sb, and outputs the read electric charges as radiographic images Da, which will be displayed as a moving image, using the image memory  138  in an FIFO mode, for example. The radiographic images Da from the radiation detecting device  30  are supplied to the first system control portion  14 A. 
     In step S 10 , the first system control portion  14 A transfers the supplied radiographic images Da to the console  16 . The console  16  stores the transferred radiographic images Da in a frame memory, and displays the radiographic image in the kth radiographic image capturing event as a radiographic image in a kth frame on the monitor  18 . 
     In step S 11 , the first system control portion  14 A updates the counter k by +1. 
     In step S 12 , the first system control portion  14 A judges whether there is a request for ending the moving image capturing process or not. On the condition that there is not a request for ending the moving image capturing process, then control goes back to step S 2  to repeat the processing from step S 2 . The monitor  18  now displays a radiographic moving image at the set frame rate. On the condition that there is a request for ending the moving image capturing process in step S 12 , then the moving image capturing process is ended. 
     A processing sequence of the light resetting processing portion  148  will be described below with reference to  FIG. 9 . In step S 101  shown in  FIG. 9 , the light resetting nullifying portion  162  judges whether there is a command for performing the light resetting process or not. Specifically, the light resetting nullifying portion  162  judges whether it is supplied with an ON signal Son from the ON signal output portion  160  or the forced light resetting portion  164  or not. On the condition that the light resetting nullifying portion  162  is supplied with an ON signal Son, i.e., a command for performing the light resetting process, then control goes to step S 102  in which the light resetting nullifying portion  162  judges whether there is a command for nullifying the light resetting process or not. Specifically, the light resetting nullifying portion  162  judges whether it is supplied with a resetting nullifying command signal Sn or not. On the condition that the light resetting nullifying portion  162  is supplied with a resetting nullifying command signal Sn, i.e., a command for nullifying the light resetting process, then control goes to step S 103  in which the supply of the ON signal Son is stopped, nullifying the command for performing the light resetting process. Thereafter, control goes back to step S 101  to repeat the processing from step S 101 . 
     In a case where the light resetting nullifying portion  162  judges that it is supplied with a command for performing the light resetting process in step S 101  and on the condition that the light resetting nullifying portion  162  judges that it is not supplied with a command for nullifying the light resetting process in step S 102 , then control goes to step S 104  in which the light resetting nullifying portion  162  supplies an ON signal Son for performing the light resetting process to the radiation detecting device  30 . In step S 105 , the photoelectric transducing portion  72  is reset by being irradiated with resetting light. 
     On the condition that the light resetting nullifying portion  162  judges that it is not supplied with a command for performing the light resetting process in step S 101  or on the condition that the light resetting process is performed in step S 105 , control goes to step S 106 . In step S 106 , the first system control portion  14 A judges whether there is a request for ending the moving image capturing process or not. On the condition that there is not a request for ending the moving image capturing process, then control goes back to step S 101  to repeat the light resetting process from step S 101 . On the condition that there is a request for ending the moving image capturing process in step S 106 , then the light resetting process is ended. 
     The processing sequences will be described below with reference to an example shown in  FIG. 10 . At start time tn−1 of an (N−1)th (N=2, 3, . . . ) radiographic image capturing event, the first system control portion  14 A supplies an exposure start signal Sc to the radiation applying device  28  and also supplies an operation start signal Sd to the radiation detecting device  30 , whereupon the first system control portion  14 A is supplied with a radiographic image Da captured in the (N−1)th radiographic image capturing event. The first system control portion  14 A transfers the supplied radiographic image Da to the console  16 , which displays the radiographic image Da as a radiographic image in an (N−1)th frame on the monitor  18 . 
     Similarly, at start time tn of an Nth radiographic image capturing event upon elapse of the latest frame rate Fr from the above start time tn−1, the first system control portion  14 A supplies an exposure start signal Sc to the radiation applying device  28  and also supplies an operation start signal Sd to the radiation detecting device  30 , whereupon the first system control portion  14 A is supplied with a radiographic image Da captured in the Nth radiographic image capturing event. The first system control portion  14 A transfers the radiographic image Da to the console  16 , which displays the radiographic image Da as a radiographic image in an Nth frame on the monitor  18 . The above processes are repeated to display a radiographic moving image on the monitor  18 . 
     In a case where an ON signal Son that is periodically generated by the first system control portion  14 A is supplied to the radiation detecting device  30  between the (N−1)th radiographic image capturing event and the Nth radiographic image capturing event, then the light resetting process is carried out based on the ON signal Son. 
     In a case where the forced resetting switch  158  is operated to supply a forced resetting command signal Sr to the first system control portion  14 A between an (N+k)th (k=1, 2, 3, . . . ) radiographic image capturing event and an (N+k+1)th radiographic image capturing event, an ON signal Son is forcibly supplied from the first system control portion  14 A to the radiation detecting device  30 . Now, the light resetting process is forcibly carried out based on the ON signal Son. 
     As shown in  FIG. 11 , in a case where the resetting nullifying switch  156  is operated to supply a resetting nullifying command signal Sn to the first system control portion  14 A prior to the start time of an mth (m=50, for example) radiographic image capturing event after the preceding light resetting process, e.g., prior to start time tn+m of an (N+m)th radiographic image capturing event, then the light resetting nullifying portion  162  stops supplying an ON signal Son from the first system control portion  14 A, which is otherwise supplied periodically. Therefore, the light resetting process is not performed. The light resetting process is nullified during a period Ta in which it is supplied with the resetting nullifying command signal Sn. 
     A mode of use of the radiographic image capturing system  10  will be described below with reference to  FIGS. 12A and 12B . 
     According to one mode of use of the radiographic image capturing system  10 , as shown in  FIGS. 12A and 12B , a doctor inserts a catheter  168  into a blood vessel  166  in the subject  24 , and the doctor visually recognizes the way in which the catheter  168  moves in the blood vessel  166  in real time by observing a radiographic moving image that is being captured by the radiographic image capturing system  10  and displayed on the monitor  18 . In a case where the catheter  168  reaches a branch  170  where the blood vessel  166  is bifurcated, the doctor who is handling the catheter  168  carefully controls the catheter  168  to guide it into one of the blood vessels leading from the branch  170  while observing the radiographic moving image displayed on the monitor  18 . In a case where the doctor is going to position a stent and a balloon in a constricted region  172  of the blood vessel  166  using the catheter  168 , the doctor carefully controls the catheter  168  to guide it into the constricted region  172  while observing the radiographic moving image displayed on the monitor  18 . 
     On the condition that the light resetting process is carried out in the situation described above, then the radiographic image capturing system  10  is unable to capture radiographic images for use as a moving image (fluorography) for a certain period of time that is equal to at least the sum of a period of time in which to apply the resetting light and a period of time in which to remove the effect of the applied resetting light, or even on the condition that the radiographic image capturing system  10  is able to capture radiographic images, the captured radiographic images tend to be disrupted. As a result, the doctor may find it difficult to properly insert the catheter  168  into the blood vessel  166 . 
     In a case where the doctor encounters such a situation in which the light resetting process should not be performed, the doctor turns on the resetting nullifying switch  156  to prevent the light resetting process from being performed. Consequently, the above problems upon light resetting, i.e., the failure to capture radiographic images and the disruption of captured radiographic images, can be avoided in advance in the situation where the doctor needs to move the catheter  168  carefully in the blood vessel  166 . 
     Before the doctor has to move the catheter  168  carefully in the blood vessel  166 , the doctor can turn on the forced resetting switch  158  to forcibly perform the light resetting process on the radiation detecting device  30 . Therefore, in a case where the doctor needs to observe radiographic images carefully, the radiographic images are prevented from being disrupted by afterimages in advance, so that the doctor can insert the catheter  168  while observing a radiographic moving image of good quality. 
     Since the ON signal Son from the forced light resetting portion  164  is supplied to the light resetting nullifying portion  162 , even on the condition that the doctor turns on the forced resetting switch  158  in error in a situation in which the light resetting process should not be performed, the light resetting process will not forcibly be performed. Consequently, the medical practice will not be obstructed by the light resetting process which would otherwise forcibly be carried out. On the condition that the radiographic moving image cannot clearly be seen by afterimages while the tip end of the catheter  168  is about to enter the branch  170  of the blood vessel  166  in the above mode of use, the doctor can turn off the resetting nullifying switch  156  and turn on the forced resetting switch  158  to perform the light resetting process. Thereafter, it is possible for the doctor to control the catheter  168  while seeing a radiographic moving image that is essentially free of afterimages. 
     Some system control portions  14  with better operability, i.e., second through fourth system control portions  14 B through  14 D, according to second through fourth specific examples will be described below with reference to  FIGS. 13 through 17 . 
     As shown in  FIG. 13 , the second system control portion  14 B according to the second specific example is of substantially the same configuration as the first system control portion  14 A described above, but is different therefrom in that it additionally has a guidance output portion  174  for providing guidance or an indication for turning on the forced resetting switch  158 . 
     The guidance output portion  174  displays an objective numerical value, graph, or the like representing the afterimage phenomenon in radiographic images, so that the doctor can confirm the afterimage phenomenon in radiographic images at a glance. 
     The guidance output portion  174  may be configured on two principles, i.e., a first principle and a second principle. As shown in  FIG. 14A , the guidance output portion  174  that is configured on the first principle has an accumulated dose calculating portion  176  for calculating an accumulated dose that is stored in the radiation detecting device  30  after it has been irradiated with the last resetting light. 
     According to the present embodiment, the accumulated dose (accumulated exposure dose) refers to an accumulation of doses in successive radiographic image capturing events, i.e., a radiographic moving image capturing event, under a single image capturing technique. The accumulated dose may be, for example, of a value produced in a case where the maximum values of radiation doses detected by the respective pixels  76  of the photoelectric transducing portion  72 , i.e., maximum pixel values, are accumulated in radiographic moving image capturing events, or of a value produced in a case where the radiation doses detected by a certain one of the pixels  76  of the photoelectric transducing portion  72  are accumulated in radiographic moving image capturing events. 
     The accumulated dose calculating portion  176  includes an integrating register  178 , a pixel value integrating portion  180 , an integrated value resetting portion  182 , and a numerical value converting portion  184 . 
     The pixel value integrating portion  180  reads a maximum pixel value or a particular pixel value from among the pixel values of radiographic images Da successively sent from the radiation detecting device  30 , adds the read pixel value to an integrated value in the integrating register  178 , and stores the sum in the integrating register  178  again. 
     The integrated value resetting portion  182  resets the integrated value in the integrating register  178  to “0” in response to the ON signal Son supplied from the light resetting nullifying portion  162 . Before the moving image capturing process starts, the light resetting nullifying portion  162  is initialized with “0” stored therein. 
     The numerical value converting portion  184  converts the integrated value in the integrating register  178  into a ratio, e.g., a percentage, to a preset maximum value, and supplies the ratio as information representing an accumulated dose to the console  16 . The preset maximum value may be represented by a numerical value that is produced in a case where an upper limit value for pixel values is multiplied by the number of radiographic image capturing events that are carried out in one period of the ON signal Son which is periodically supplied from the ON signal output portion  160 . 
     As shown in  FIG. 14B , the guidance output portion  174  that is configured on the second principle has an elapsed time measuring portion  186  for measuring an elapsed time from the last application of the resetting light, a timing register  188 , a timing resetting portion  190 , and a numerical value converting portion  184 . 
     The elapsed time measuring portion  186  counts reference clock pulses clk and stores the count in the timing register  188 . The timing resetting portion  190  resets the count in the timing register  188  to “0” in response to the ON signal Son supplied from the light resetting nullifying portion  162 . 
     The numerical value converting portion  184  converts the count in the timing register  188  into a ratio, e.g., a percentage, to a preset maximum value, and supplies the ratio as information representing an elapsed time to the console  16 . The preset maximum value may be represented by the time of one period of the ON signal Son which is periodically supplied from the ON signal output portion  160 . 
     The console  16  displays information of the accumulated dose or information of the elapsed time from the guidance output portion  174  on the monitor  18 . Specifically, as shown in  FIG. 12A , the console  16  displays the information of the accumulated dose or the information of the elapsed time as a numerical value  192  on an upper left corner, or an upper right corner, of the screen of the monitor  18 . Alternatively, as shown in  FIG. 12B , the console  16  displays the information of the accumulated dose or the information of the elapsed time as a bar  194  on the upper left corner, or the upper right corner, of the screen of the monitor  18 . 
     In a case where the numerical value  192  shown in  FIG. 12A  or the bar  194  shown in  FIG. 12B  is smaller than 70%, for example, the numerical value  192  or the bar  194  is displayed in green. In a case where the numerical value  192  or the bar  194  exceeds 70%, it is displayed in red. In a case where the numerical value  192  or the bar  194  exceeds 90%, it may be blinked. 
     In the above mode of use of the radiographic image capturing system  10 , the doctor carefully inserts the catheter  168  into the blood vessel  166  while observing a radiographic moving image displayed on the monitor  18  in order to guide the catheter  168  accurately into a route to be followed. In a case where the radiographic moving image is adversely affected by afterimages, then the radiographic moving image tends to defocus, making the doctor suffer eye strain. In a case where the doctor turns on the forced resetting switch  158 , the light resetting process is performed on the radiation detecting device  30  in advance, and the doctor will not be troubled by afterimages. On the other hand, on the condition that afterimages that are occurring are not strong and do not concern the doctor, then the doctor may not need to turn on the forced resetting switch  158 . However, depending on the doctor, or the imaged region, or the level of eye strain, the doctor has to make a subjective judgment as to whether afterimages that are occurring are weak or strong. As a result, the doctor may turn on the forced resetting switch  158  so often that the doctor may possibly find it troublesome to turn on the forced resetting switch  158 . 
     To cope with the above shortcoming, the second system control portion  14 B has the guidance output portion  174  which displays the afterimage phenomenon in radiographic images, i.e., the degree of afterimages, as a numerical value or a bar. The doctor can then confirm at a glance the degree of afterimages by seeing the displayed numerical value or bar, and can use the displayed numerical value or bar as a guidance for turning on the forced resetting switch  158 . In addition, as the degree of afterimages goes higher, the numerical value or bar is displayed in red or blinked. The doctor can then turn on the forced resetting switch  158  depending on the numerical value or bar that is displayed in red or blinked. Accordingly, the doctor does not feel troublesome about turning on the forced resetting switch  158 . 
     The system control portion according to the third specific example, i.e., the third system control portion  14 C, will be described below with reference to  FIGS. 15 and 16 . 
     As shown in  FIG. 15 , the third system control portion  14 C is of substantially the same configuration as the second system control portion  14 B described above, but is different therefrom in that it additionally has a resetting nullification commanding portion  196  for supplying a resetting nullifying command signal Sn based on the result of an analysis of a radiographic image Da from the radiation detecting device  30 , instead of the resetting nullifying switch  156 . 
     The resetting nullification commanding portion  196  supplies a resetting nullifying command signal Sn based on the positional relationship between a designated particular image of the subject  24  and an image of an instrument, e.g., the catheter  168 , inserted in the subject  24 , in the radiographic image Da from the radiation detecting device  30 . 
     Specifically, the resetting nullification commanding portion  196  includes a range command request portion  198 , a particular image setting portion  200 , an instrument image setting portion  202 , and a resetting nullification determining portion  204 . 
     The range command request portion  198  supplies the console  16  with a request signal Se and a message Dm for requesting the doctor to designate the range of a particular image to the console  16 . The console  16  displays the message Dm on the monitor  18 . Based on the message Dm displayed on the monitor  18 , the doctor designates a range, i.e., a particular image, where the light resetting process is not to be carried out, in the radiographic moving image displayed on the monitor  18 . The doctor may designate the range with a displayed surrounding quadrilateral or circular frame that is controlled by drag and drop using the mouse, for example. On the condition that the monitor  18  comprises a touchscreen, then the doctor may designate the range with a displayed circle using a finger or a stylus. 
     Based on the supplied request signal Se, the console  16  returns address information Dad, which represents a first relative address range of the display area of the monitor  18  with respect to the frame memory and a second relative address range of the particular image with respect to the display area of the monitor  18 , to the third system control portion  14 C. The address information Dad is supplied to the particular image setting portion  200 . 
     The particular image setting portion  200  specifies an address range of the image displayed on the monitor  18  in the radiographic image Da from the first relative address range in the address information Dad, and sets an address range of the particular image designated by the doctor in the radiographic image Da from the specified address range and the second relative address range. 
     The instrument image setting portion  202  extracts an image which moves the greatest distance from radiographic images Da in a plurality of frames that are successively supplied, determines an address of a leading tip end of the extracted image, i.e., an address on the latest radiographic image, and uses the determined address as the address of the image of the instrument, i.e., the catheter  168 . The image which moves the greatest distance should preferably be extracted according to a motion vector search which is used in a known interframe prediction process. 
     In a case where the address of the image of the instrument is not included in the address range of the particular image designated by the doctor, then the resetting nullification determining portion  204  does not supply the resetting nullifying command signal Sn. On the condition that the address of the image of the instrument is included in the address range of the particular image designated by the doctor, then the resetting nullification determining portion  204  supplies the resetting nullifying command signal Sn. In particular, the resetting nullification determining portion  204  continues to supply the resetting nullifying command signal Sn during a period Ta in which the address of the image of the instrument is included in the address range of the particular image. 
     In the above mode of use of the radiographic image capturing system  10 , simply in a case where the doctor designates a range, i.e., a particular image, in which the light resetting process is not to be carried out, in the radiographic moving image displayed on the monitor  18  using a mouse or touch panel, the third system control portion  14 C automatically keeps supplying the resetting nullifying command signal Sn during the period Ta after the tip end of the catheter  168  enters the designated range until it leaves the designated range. During the period Ta, therefore, the light resetting process is not carried out. Since the doctor does not need to turn on the resetting nullifying switch  156  during the period Ta, the doctor may give their full attention to controlling the catheter  168 . 
     Since unlike the first system control portion  14 A, the third system control portion  14 C does not make it necessary for the doctor to turn on the resetting nullifying switch  156 , on the condition that the radiographic moving image cannot clearly be seen by afterimages while the tip end of the catheter  168  is about to enter the branch  170  of the blood vessel  166 , the doctor cannot turn off the resetting nullifying switch  156  and turn on the forced resetting switch  158 . To cope with the above problem, the third system control portion  14 C supplies the ON signal Son from the forced light resetting portion  164  directly, not via the light resetting nullifying portion  162 , to the radiation detecting device  30 , thereby forcibly carrying out the light resetting process. Consequently, even though the resetting nullifying command signal Sn is supplied to the light resetting nullifying portion  162 , the light resetting process is forcibly carried out in a case where the doctor turns on the forced resetting switch  158 , and hence the doctor will not be troubled by afterimages. 
     A processing sequence of the light resetting processing portion  148  of the third system control portion  14 C will be described below with reference to  FIG. 16 . In step S 201  shown in  FIG. 16 , the forced light resetting portion  164  judges whether there is a forced light resetting command or not by judging whether there is supplied a forced resetting command signal Sr or not. 
     In a case where the forced light resetting portion  164  judges that there is supplied a forced resetting command signal Sr, then control goes to step S 202  in which the forced light resetting portion  164  supplies an ON signal Son for performing the light resetting process to the radiation detecting device  30 . In step S 203 , the photoelectric transducing portion  72  is reset by being irradiated with resetting light. 
     In a case where the forced light resetting portion  164  judges that there is not a forced light resetting command in step S 201 , then control goes to step S 204  in which the light resetting nullifying portion  162  judges whether there is a command for performing the light resetting process or not. Specifically, the light resetting nullifying portion  162  judges whether it is supplied with an ON signal Son from the ON signal output portion  160  or not. On the condition that the light resetting nullifying portion  162  is supplied with an ON signal Son, i.e., a command for performing the light resetting process, then control goes to step S 205  in which the light resetting nullifying portion  162  judges whether there is a command for nullifying the light resetting process or not. Specifically, the light resetting nullifying portion  162  judges whether it is being supplied with a resetting nullifying command signal Sn or not. On the condition that the light resetting nullifying portion  162  is supplied with a resetting nullifying command signal Sn, i.e., a command for nullifying the light resetting process, then control goes to step S 206  in which the supply of the ON signal Son is stopped, nullifying the command for performing the light resetting process. Thereafter, control goes back to step S 201  to repeat the processing from step S 201 . 
     On the condition that the light resetting nullifying portion  162  judges that it is not supplied with a command for nullifying the light resetting process in step S 205 , then control goes to steps S 202 , S 203  to reset the photoelectric transducing portion  72  by irradiating it with resetting light. 
     On the condition that the light resetting nullifying portion  162  judges that it is not supplied with a command for performing the light resetting process in step S 204  or on the condition that where the photoelectric transducing portion  72  has been reset by being irradiated with resetting light in step S 203 , control goes to step S 207 . In step S 207 , the third system control portion  14 C judges whether there is a request for ending the moving image capturing process or not. On the condition that there is not a request for ending the moving image capturing process, then control goes back to step S 201  to repeat the light resetting process from step S 201 . On the condition that there is a request for ending the moving image capturing process in step S 207 , then the light resetting process is ended. 
     The system control portion according to the fourth specific example, i.e., the fourth system control portion  14 D, will be described below with reference to  FIG. 17 . 
     As shown in  FIG. 17 , the fourth system control portion  14 D is of substantially the same configuration as the third system control portion  14 C described above, but is different therefrom in that it has a forced resetting commanding portion  206  for supplying a forced resetting command signal Sr based on the result of an analysis of a radiographic image Da, instead of the forced resetting switch  158  shown in  FIG. 15 . In  FIG. 17 , the details of the moving image capturing processing portion  146  are omitted from illustration. 
     The forced resetting commanding portion  206  supplies a forced resetting command signal Sr based on the positional relationship between a designated particular image of the subject  24  and an image of an instrument, e.g., the catheter  168 , inserted in the subject  24 , in the radiographic image Da from the radiation detecting device  30 . 
     Specifically, the forced resetting commanding portion  206  includes a motion vector calculating portion  208 , a particular image selecting portion  210 , an arrival time calculating portion  212 , and a forced resetting determining portion  214 . 
     The motion vector calculating portion  208  determines a moving direction and a moving speed of the instrument image based on an address of the instrument image determined by the instrument image setting portion  202  of the resetting nullification commanding portion  196 . The address of the instrument image that is supplied from the instrument image setting portion  202  changes from time to time, frame by frame. Therefore, the motion vector calculating portion  208  determines a moving direction and a moved distance of the instrument image based on the address that changes from time to time, and determines a moving speed of the instrument image based on the moved distance and the latest frame rate. 
     The particular image selecting portion  210  selects an address range of a closest particular image that is present in the moving direction of the instrument image, based on an address range of one or more particular images set by the particular image setting portion  200  of the resetting nullification commanding portion  196 , the address of the instrument image determined by the instrument image setting portion  202 , and the moving direction of the instrument image from the motion vector calculating portion  208 . 
     The arrival time calculating portion  212  calculates a distance up to the particular image selected from the instrument image based on the address of the instrument image and the address range of the selected particular image, and also calculates an arrival time based on the calculated distance and the moving speed of the instrument image from the motion vector calculating portion  208 . 
     The forced resetting determining portion  214  supplies a forced resetting command signal Sr in a case where the arrival time calculated by the arrival time calculating portion  212  reaches a preset time, thereby forcibly performing the light resetting process. The preset time should preferably be at least the sum of a period of time (the pulse duration of a pulse signal) in which the resetting light is applied and a period of time in which the effect of the applied resetting light is removed. 
     In the mode of use of the radiographic image capturing system  10 , before the doctor has to move the catheter  168  carefully in the blood vessel  166 , the fourth system control portion  14 D automatically and forcibly performs the light resetting process simply in a case where the doctor designates a range, i.e., a particular image, in which the light resetting process is not to be carried out, in the radiographic moving image displayed on the monitor  18  using a mouse or touch panel. Therefore, in a case where the doctor needs to observe radiographic images carefully, the radiographic images are prevented from being disrupted by afterimages in advance, so that the doctor can insert the catheter  168  while observing a radiographic moving image of good quality. Since the doctor does not need to turn on the forced resetting switch  158  as well as the resetting nullifying switch  156 , the doctor may give their full attention to controlling the catheter  168 . 
     In the above embodiment, the fight resetting processing portion  148  and the guidance output portion  174  are incorporated in the system control portion  14 . However, as shown in  FIG. 18 , the light resetting processing portion  148  and the guidance output portion  174  may be incorporated in the cassette control portion  68  of the radiation detecting device  30 . 
     Specifically, as shown in  FIG. 18 , the cassette control portion  68  includes the light resetting processing portion  148  and the guidance output portion  174  in addition to the address signal generating portion  136 , the image memory  138 , the cassette ID memory  140 , and the pulse signal generating portion  144 . The radiation detecting device  30  has the resetting nullifying switch  156  and the forced resetting switch  158  that are disposed in the casing  40  or outside the casing  40 . On the condition that the resetting nullifying switch  156  and the forced resetting switch  158  are disposed outside the casing  40 , they are electrically connected to the radiation detecting device  30  via a wired communication link or a wireless communication link. A mobile terminal  216  having a display portion is also electrically connected to the radiation detecting device  30  via a wired communication link or a wireless communication link. 
     The mobile terminal  216  may display radiographic images sent through the console for displaying a radiographic moving image, and may display radiographic images sent directly from the radiation detecting device for displaying a radiographic moving image. The mobile terminal  216  may also display guidance as shown in  FIGS. 12A and 12B . 
     The resetting nullification commanding portion  196  of the third system control portion  14 C or the forced resetting commanding portion  206  of the fourth system control portion  14 D may also be incorporated in the cassette control portion  68 . 
     The radiographic image capturing systems and the radiation detecting devices according to the present invention are not limited to the above embodiments, but may employ various arrangements without departing from the scope of the invention.