Abstract:
A radiation imaging system that can continuously use sections of a radiation imaging device that has not been damaged and a radiation imaging device are provided. The radiation imaging system comprises: a radiation device that applies radiation; and the radiation imaging device with an imaging panel that captures images of the applied radiation. The radiation imaging device comprises: a failure cause detection unit that detects environmental noise or falls that cause failures in the radiation imaging device; a malfunction diagnostic unit that, in a case where a detected environmental noise value reaches a threshold value or in a case where a fall has been detected, diagnoses a malfunction in the radiation imaging device; and a function limiting unit that applies limits to the radiation imaging device functions that are used continuously, in accordance with the diagnosis results of the malfunction diagnostic unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY CLAIMS 
       [0001]    This application is a Continuation of International Application No. PCT/JP2011/069153 filed on Aug. 25, 2011, 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. 2010-191467 filed on Aug. 27, 2010, and No. 2010-191468 filed on Aug. 27, 2010, the contents all of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a radiographic image capturing system (radiation imaging system) and a radiographic image capturing apparatus (radiation imaging device) for capturing a radiographic image of a human body from radiation that has passed through the human body. 
       BACKGROUND ART 
       [0003]    In the medical field, portable radiographic image capturing apparatus (e.g., FPD (Flat Panel Detector)) have been used for capturing a radiographic image of interior portions of a human body by detecting the intensity of radiation that has passed through the human body. Since the user of a portable FPD carries the portable FPD, the user may mistakenly drop the portable FPD or hit the portable FPD against a hard object such as an image capturing base, a door, or the like while handling the portable FPD, which could possibly cause damage to the portable FPD. 
         [0004]    Japanese Laid-Open Patent Publication No. 2005-177379 discloses a portable FPD equipped with an impact sensor. The portable FPD initiates a self-diagnostic process in response to a signal from the impact sensor. If it is decided that the portable FPD has a fault based on the results of the self-diagnostic process, then the portable FPD is prohibited from starting an image capturing process or applying radiation to a target subject. 
       SUMMARY OF INVENTION 
       [0005]    According to Japanese Laid-Open Patent Publication No. 2005-177379, in a case where a portable FPD has suffered from a fault, the portable FPD can no longer be used continuously. If there is only one FPD in a hospital and the FPD is found to be faulty, then medical examination processes in the hospital tend to be adversely affected due to the FPD being out of service. It is quite economically burdensome for the hospital to replace the FPD with a new one, which is highly expensive to purchase, each time that the FPD becomes defective. 
         [0006]    Occasionally, the user drops the FPD inadvertently, however, a defect is not detected in the FPD at that time. In such a case, the FPD may possibly start to deteriorate from the moment it was dropped. According to Japanese Laid-Open Patent Publication No. 2005-177379, however, FPD deterioration that develops over time cannot be properly diagnosed. 
         [0007]    The present invention has been made in view of the above problems of the background art. It is an object of the present invention to provide a radiographic image capturing system and a radiographic image capturing apparatus, which allow an undamaged section of the radiographic image capturing apparatus to be used continuously. Another object of the present invention is to provide a radiographic image capturing system and a radiographic image capturing apparatus, which are capable of accurately diagnosing deterioration that develops over time. 
         [0008]    According to a first invention, there is provided a radiographic image capturing system having a radiation device for applying radiation and a radiographic image capturing apparatus including an image capturing panel for capturing an image from the applied radiation, wherein the radiographic image capturing apparatus comprises a fault factor detector for detecting an environmental disturbance or dropping, which is responsible for a fault of the radiographic image capturing apparatus, a fault diagnosing section for performing a diagnostic process to diagnose the radiographic image capturing apparatus for a fault if the detected environmental disturbance is equal to or greater than a threshold value or dropping is detected, and a function limiter for limiting a function of the radiographic image capturing apparatus, which is in continuous use, depending on the results of the diagnostic process performed by the fault diagnosing section. 
         [0009]    The fault diagnosing section may include a self-diagnosing section for self-diagnosing the radiographic image capturing apparatus, wherein the self-diagnosing section diagnoses an entire image capturing area of the image capturing panel for a first unimageable region in which an image cannot be captured from the radiation, and the function limiter limits a function of the radiographic image capturing apparatus so as not to capture an image in the first unimageable region. 
         [0010]    The self-diagnosing section may include a function to diagnose interconnections, and the function limiter may limit a function of the radiographic image capturing apparatus by preventing current from flowing into an interconnection that is diagnosed as being not normal. 
         [0011]    The fault diagnosing section may include a real-image diagnosing section for diagnosing a second unimageable region in which an image cannot be captured from the radiation based on image data captured by an idle exposure process. The radiation device may apply diagnostic radiation for diagnosing the radiographic image capturing apparatus to the image capturing panel if the environmental disturbance detected by the fault factor detector is equal to or greater than the threshold value or dropping is detected by the fault factor detector. The real-image diagnosing section may diagnose the second unimageable region based on image data generated from the diagnostic radiation in the idle exposure process, and the function limiter may limit a function of the radiographic image capturing apparatus so as not to capture an image in the second unimageable region. 
         [0012]    The radiographic image capturing system may further comprise an indicator for indicating, to a user, the results of the diagnostic process performed by the fault diagnosing section or the function limited by the function limiter. 
         [0013]    The radiation device may inhibit image-capturing radiation from being applied until the diagnostic process performed by the fault diagnosing section is finished. 
         [0014]    The environmental disturbance may comprise any one of an external pressure applied to the image capturing panel, an environmental temperature or a change therein, and an environmental humidity. 
         [0015]    The radiographic image capturing apparatus may comprise a portable radiographic image capturing apparatus. 
         [0016]    The radiographic image capturing apparatus may include a communication unit for sending a signal to and receiving a signal from another device through a wireless link. The self-diagnosing section may diagnose a communication function of the communication unit, and the function limiter may limit the communication function of the communication unit if the self-diagnosing section diagnoses the communication function of the communication unit as being abnormal. 
         [0017]    The radiographic image capturing apparatus may include a storage unit for storing image data generated from the radiation. The self-diagnosing section may diagnose the storage unit, and the function limiter may limit a successive image capturing function if the storage unit has an available storage capacity smaller than a predetermined value. 
         [0018]    The radiographic image capturing apparatus may include a built-in battery. The self-diagnosing section may diagnose the built-in battery, and the function limiter may limit use of the built-in battery if the built-in battery has a remaining stored energy level smaller than a predetermined value or a degree of deterioration greater than a predetermined value. 
         [0019]    According to a second invention, there is provided a radiographic image capturing system having a radiation device for applying radiation, and a radiographic image capturing apparatus including an image capturing panel for capturing an image from the applied radiation, wherein the radiographic image capturing apparatus comprises a fault factor detector for detecting an environmental disturbance or dropping, which is responsible for a fault of the radiographic image capturing apparatus, and a fault diagnosing section for diagnosing an entire image capturing area of the image capturing panel for an unimageable region in which an image cannot be captured from the radiation, if the detected environmental disturbance is equal to or greater than a threshold value or dropping is detected, and wherein the radiographic image capturing system includes an indicator for indicating, to a user, the unimageable region if the unimageable region is diagnosed as being present within the entire image capturing area. 
         [0020]    According to a third invention, there is provided a radiographic image capturing apparatus comprising a fault factor detector for detecting an environmental disturbance or dropping, which is responsible for a fault of the radiographic image capturing apparatus, a fault diagnosing section for performing a diagnostic process to diagnose the radiographic image capturing apparatus for a fault if the detected environmental disturbance is equal to or greater than a threshold value or dropping is detected, and a function limiter for limiting a function of the radiographic image capturing apparatus depending on the results of the diagnostic process performed by the fault diagnosing section. 
         [0021]    According to the first through third inventions, if the environmental disturbance is equal to or greater than a threshold value or if dropping is detected, the radiographic image capturing apparatus is diagnosed for a fault, and a function of the radiographic image capturing apparatus is limited. Therefore, the radiographic image capturing apparatus, which suffers from the fault, can still be used continuously. Since a function of the radiographic image capturing apparatus is limited depending on the fault, the radiographic image capturing apparatus is prevented from becoming unduly heated, and electric power consumption is minimized. 
         [0022]    According to a fourth invention, there is provided a radiographic image capturing system having a radiation device for applying radiation, and a radiographic image capturing apparatus including an image capturing panel for capturing an image from the applied radiation, wherein the radiographic image capturing apparatus comprises a fault diagnosing section for performing a first fault diagnosing process to periodically diagnose the radiographic image capturing apparatus for a fault, and a fault factor detector for detecting an external pressure or dropping of the radiographic image capturing apparatus, wherein if the detected external pressure is equal to or greater than a threshold value or dropping of the radiographic image capturing apparatus is detected, the fault diagnosing section performs the first fault diagnosing process, and periodically performs the first fault diagnosing process at shortened intervals. 
         [0023]    The first fault diagnosing process may include a function to diagnose an entire image capturing area of the image capturing panel for an unimageable region in which an image cannot be captured from the radiation, based on image data generated by an idle exposure process or a blank reading process. The radiation device may apply diagnostic radiation for diagnosing the radiographic image capturing apparatus for a fault in the image capturing panel when the first fault diagnosing process is performed, and the first fault diagnosing process performed by the fault diagnosing section may diagnose the unimageable region based on image data generated from the diagnostic radiation by the idle exposure process. 
         [0024]    If the detected external pressure is equal to or greater than the threshold value or dropping of the radiographic image capturing apparatus is detected, the fault diagnosing section may subsequently periodically perform a second fault diagnosing process along with the first fault diagnosing process. 
         [0025]    The second fault diagnosing process may include a function to diagnose a resolution of an image based on image data generated by the idle exposure process using a resolution test chart. 
         [0026]    The radiographic image capturing system may further comprise an indicator for indicating, to a user, the results of the first fault diagnosing process performed by the fault diagnosing section. 
         [0027]    If the external pressure, an environmental humidity, an environmental temperature, or a change in the environmental temperature is equal to or greater than a predetermined value, or if the number of times that the external pressure, the environmental humidity, the environmental temperature, or a change in the environmental temperature is equal to or greater than the predetermined value exceeds a predetermined number, the fault diagnosing section may periodically perform the first fault diagnosing process at shortened intervals. 
         [0028]    The radiographic image capturing system may further comprise a function limiter for limiting a function of the radiographic image capturing apparatus based on the results of the first fault diagnosing process performed by the fault diagnosing section. 
         [0029]    The radiographic image capturing apparatus may comprise a portable radiographic image capturing apparatus. 
         [0030]    The radiation device may inhibit image-capturing radiation from being applied while the first fault diagnosing process is being performed by the fault diagnosing section. 
         [0031]    According to a fifth invention, there is provided a radiographic image capturing apparatus comprising a fault diagnosing section for performing a first fault diagnosing process to periodically diagnose the radiographic image capturing apparatus for a fault, and a fault factor detector for detecting an external force or dropping of the radiographic image capturing apparatus, wherein the fault diagnosing section performs the first fault diagnosing process, and periodically performs the first fault diagnosing process at shortened intervals if the detected external force is equal to or greater than a threshold value or dropping is detected. 
         [0032]    According to the fourth and fifth inventions, the first fault diagnosing process is periodically performed, and if the external force is equal to or greater than a threshold value or if dropping is detected, then the first fault diagnosing process is performed, and intervals at which the first fault diagnosing process is periodically performed are shortened. Consequently, the degree to which the radiographic image capturing apparatus deteriorates over time can accurately be diagnosed, thereby making it possible to predict a time at which a replacement radiographic image capturing apparatus should be purchased, as well as predicting a time at which parts of the radiographic image capturing apparatus should be replaced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0033]      FIG. 1  is a view showing a configuration of a radiographic image capturing system according to a first embodiment of the present invention; 
           [0034]      FIG. 2  is a perspective view of an electronic cassette shown in  FIG. 1 ; 
           [0035]      FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 2 ; 
           [0036]      FIGS. 4A and 4B  are schematic views of different structures of a radiation detector shown in  FIG. 3 , in which  FIG. 4A  shows a radiation detector with a scintillator formed on an aluminum substrate by vacuum evaporation, and  FIG. 4B  shows a radiation detector with a scintillator formed on a TFT substrate by vacuum evaporation; 
           [0037]      FIG. 5  is an electric block diagram of the electronic cassette shown in  FIG. 1 ; 
           [0038]      FIG. 6  is a diagram showing by way of example an unimageable region diagnosed by a self-diagnosing section; 
           [0039]      FIG. 7  is an electronic block diagram of a console shown in  FIG. 1 ; 
           [0040]      FIG. 8  is a view showing a displayed example of a function that is limited by a function limiter depending on the results of a self-diagnostic process; 
           [0041]      FIG. 9  is a flowchart of an operation sequence of the electronic cassette according to the first embodiment; 
           [0042]      FIG. 10  is a plan view showing the manner in which a radiographic image of a breast is captured by the electronic cassette; 
           [0043]      FIG. 11  is an electric block diagram of an electronic cassette according to a second embodiment of the present invention; 
           [0044]      FIG. 12  is a flowchart of an operation sequence of the electronic cassette according to the second embodiment; 
           [0045]      FIG. 13  is another flowchart of the operation sequence of the electronic cassette according to the second embodiment; 
           [0046]      FIG. 14  is a diagram showing a peripheral edge region of an imageable region, which is not used for image formation; 
           [0047]      FIG. 15  is a flowchart of a first fault diagnosing process according to the second embodiment; and 
           [0048]      FIG. 16  is a view showing a layout structure of a radiation conversion panel of a radiation detector according to a twelfth modification. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0049]    A radiographic image capturing system, which includes therein radiographic image capturing apparatus according to preferred embodiments of the present invention, will be described in detail below with reference to the accompanying drawings. 
       First Embodiment 
       [0050]      FIG. 1  is a view showing a configuration of a radiographic image capturing system  10  according to a first embodiment of the present invention. The radiographic image capturing system  10  includes a radiation device  18  for applying radiation  16  to a patient as a subject  14  lying on an image capturing base  12  such as a bed or the like, an electronic cassette (radiographic image capturing apparatus)  20  for detecting radiation  16  that has passed through the subject  14  and converting the detected radiation into a radiographic image, a console  24  for controlling the radiographic image capturing system  10  in its entirety, and a display device  26  for displaying a captured radiographic image, etc. The console  24  has an input unit for receiving input actions entered by a doctor or a radiological technician (hereinafter referred to as a “user”). 
         [0051]    The console  24 , the radiation device  18 , the electronic cassette  20 , the display device  26 , and a server  32  send and receive signals through a wireless LAN such as UWB (Ultra-Wide Band), IEEE802.11.a/b/g/n, or the like, or through a wireless communication link using milliwaves, or the like. Alternatively, the console  24 , the radiation device  18 , the electronic cassette  20 , the display device  26 , and the server  32  may send and receive signals through a wired communication link including cables. 
         [0052]    The console  24  is connected to a radiology information system (RIS)  28 , which generally manages radiographic image information handled by the radiological department of a hospital, together with other information. The RIS  28  is connected to a hospital information system (HIS)  30 , which generally manages medical information in the hospital. 
         [0053]    The server  32 , which is connected to the console  24  by a wireless communication link, is provided on the premises of a maintenance provider. The console  24  sends the results of a diagnostic process, to be described later, performed on the electric cassette  20  to the server  32 , so that the maintenance provider can grasp the status of the electronic cassette  20 . 
         [0054]    The radiation device  18  has a radiation source  34  for applying radiation  16 , and a radiation controller  36  for controlling the radiation source  34 . The radiation source  34  applies radiation  16  to the electronic cassette  20 . Radiation  16  applied by the radiation source  34  may be in the form of X-rays, α rays, β rays, γ rays, an electron beam, or the like. 
         [0055]      FIG. 2  is a perspective view of the electronic cassette  20  shown in  FIG. 1 , and  FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 2 . The electronic cassette  20  includes a panel unit (image capturing panel)  40 , and a controller  42  disposed on the panel unit  40 . The panel unit  40  is thinner than the controller  42 . 
         [0056]    The panel unit  40  includes a substantially rectangular housing  44  made of a material that is permeable to radiation  16 . The panel unit  40  has an image capturing surface  46 , which is irradiated with radiation  16 . The image capturing surface  46  includes guide lines  48  disposed substantially centrally thereon. The guide lines  48  are indicative of an image capturing area and an image capturing position for the subject  14 . The guide lines  48  include an outer frame representing an imageable region  50 , which indicates an irradiation field to be irradiated with radiation  16 . The guide lines  48  have a central position (where two guide lines  48  cross each other in a crisscross pattern), which serves as the central position of the imageable region  50 . The image capturing surface  46  is marked with area graduations indicative of the image capturing area. The area graduations include numerals (1, 2, . . . ) representing columns, and alphabetical letters (A, B, . . . ) representing rows. A sheet and a seal, which are applied to the image capturing surface  46 , and a storage bag for storing the electronic cassette  20  may also be marked with area graduations. 
         [0057]    The panel unit  40  includes a radiation detector  56  having a scintillator  52  and a radiation conversion panel  54 , and a driver circuit  80  (see  FIG. 5 ) for energizing the radiation conversion panel  54 . The scintillator  52  converts radiation  16  that has passed through the subject  14  into visible phosphorescence that exists within a visible light range. The radiation conversion panel  54  comprises an indirect conversion panel, which converts phosphorescence generated by the scintillator  52  into electric signals. The scintillator  52  and the radiation conversion panel  54  are disposed in the housing  44  so as to be arranged successively from the image capturing surface  46  that is irradiated with radiation  16 . If the radiation conversion panel  54  comprises a direct conversion panel, which converts radiation  16  directly into electric signals, then since the scintillator  52  is not required, the radiation conversion panel  54  itself serves as the radiation detector  56 . 
         [0058]    The controller  42  has a substantially rectangular housing  58  made of a material impermeable to radiation  16 . The housing  58  extends along one end of the image capturing surface  46  so that the controller  42  is disposed outside of the imageable region  50  on the image capturing surface  46 . The housing  58  accommodates therein a cassette controller  84  for controlling the panel unit  40 , a communication unit  88  for sending signals to and receiving signals from the console  24  through a wireless communication link, and a built-in battery  90 , etc. (see  FIG. 5 ). The built-in battery  90  supplies electric power to the cassette controller  84 , the communication unit  88 , etc. The controller  42  has a side surface on one longitudinal end thereof, which includes an input terminal  60  of an AC adapter for charging the built-in battery  90  from an external power supply, and an USB (Universal Serial Bus) terminal  62  that serves as an interface for sending information to and receiving information from an external apparatus (e.g., the console  24  or the like). 
         [0059]      FIGS. 4A and 4B  are schematic views of different structures of the radiation detector  56 .  FIG. 4A  shows a radiation detector  56  including a scintillator  52 , which is formed by vacuum evaporation on an aluminum substrate  70 .  FIG. 4B  shows a radiation detector  56  including a scintillator  52 , which is formed by vacuum evaporation on a TFT substrate. 
         [0060]    As shown in  FIG. 4A , the scintillator  52  has a strip-like columnar crystalline structure  72  made up of cesium iodide (CsI(Tl), which is formed on the aluminum substrate  70  by vacuum evaporation, for example. The radiation conversion panel  54  is disposed on one side of the columnar crystalline structure  72  remote from the aluminum substrate  70 . The scintillator  52  and the radiation conversion panel  54  are held securely against each other. The radiation conversion panel  54  comprises a layer of pixels disposed on a TFT substrate. Since CsI having such a columnar crystalline structure  72  is susceptible to humidity (water) (especially, a non-columnar crystalline section of the scintillator  52  is susceptible to humidity), the scintillator  52  is sealed by a humidity-resistant protector  74 . Relative positions of the scintillator  52  and the radiation conversion panel  54  are secured as a result of being held against each other. However, the scintillator  52  and the radiation conversion panel  54  may be bonded to each other to thereby secure the scintillator  52  and the radiation conversion panel  54 . 
         [0061]    As shown in  FIG. 4B , the scintillator  52  has a strip-like columnar crystalline structure  72  made up of cesium iodide (CsI(Tl)), which is formed on the TFT substrate by vacuum evaporation. The scintillator  52  is sealed by a humidity-resistant protector  74 . Since the columnar crystalline structure  72  is hard and brittle, the columnar crystalline structure  72  is susceptible to external pressure and stress. Therefore, if the electronic cassette  20  is dropped or is subjected to excessive external pressure, then the columnar crystalline structure  72  and the humidity-resistant protector  74  are liable to become cracked, and the columnar crystalline structure  72  is liable to break. Further, since the scintillator  52  and the TFT substrate have different coefficients of thermal expansion, a change in temperature tends to put the scintillator  52  under stress, thereby causing the columnar crystalline structure  72  and the humidity-resistant protector  74  to crack, and causing the columnar crystalline structure  72  to break. If the columnar crystalline structure  72  becomes cracked and the humidity-resistant protector  74  becomes broken, then not only are the image capturing performance and the sensitivity thereof lowered, but also a region is likely to occur in the radiation detector  56  in which radiographic images cannot be captured. 
         [0062]    If the columnar crystalline structure  72  becomes cracked, then since the electronic cassette  20  is subject to stress (i.e., is placed under an external pressure or stress due to different coefficients of thermal expansion upon a temperature change) as a result of usage over time and changes in environmental temperature, the crack will grow over time, thereby causing the columnar crystalline structure  72  to break. Further, if the humidity-resistant protector  74  becomes cracked or fractured, then water enters through such cracks, etc., thereby causing the columnar crystalline structure  72  to deliquesce over time. Therefore, the image capturing performance and resolution of the radiation detector  56  are gradually lowered. 
         [0063]      FIG. 5  is an electric block diagram of the electronic cassette  20  shown in  FIG. 1 . The electronic cassette  20  includes the driver circuit  80 , a fault factor detector  82 , the cassette controller  84 , a memory (storage unit)  86 , the communication unit  88 , the built-in battery  90 , and a light emitter (indicator)  92 . The built-in battery  90  supplies electric power, respectively, to the fault factor detector  82 , the cassette controller  84 , the communication unit  88 , and the light emitter  92 . The cassette controller  84  supplies electric power, which was supplied thereto from the built-in battery  90 , to a bias power supply  108 , gate ICs (pixel drivers)  114 , ASICs (pixel output circuits)  116 , etc., and also judges whether or not the electric power from the built-in battery  90  should be supplied to the fault factor detector  82 , the communication unit  88 , and the light emitter  92 , while controlling the amount of electric power that is supplied thereto. 
         [0064]    The radiation conversion panel  54  comprises an array of TFTs  102 , which are arranged in rows and columns, and a photoelectric conversion layer including plural pixels  104 , which are disposed on the array of TFTs  102 . The pixels  104 , which are supplied with a bias voltage from the bias power supply  108  of the driver circuit  80 , store electric charges therein, which are converted photoelectrically from phosphorescence generated by the scintillator  52 . 
         [0065]    To the TFTs  102 , which are connected respectively to the pixels  104 , gate lines  110  are connected that extend parallel to the rows, and signal lines  112  are connected that extend parallel to the columns. The gate lines  110  are connected to each of the gate ICs  114  of the driver circuit  80 , whereas the signal lines  112  are connected to each of the ASICs  116  of the driver circuit  80 . 
         [0066]    In  FIG. 5 , one gate line  110  is shown as being connected to each of the gate ICs  114 . Actually, however, multiple gate lines  110  are connected to each of the gate ICs  114 . Plural pixels  104  are connected to each of the gate lines  110  through TFTs  102 . In  FIG. 5 , one signal line  112  is shown as being connected to each of the ASICs  116 . Actually, however, multiple signal lines  112  are connected to each of the ASICs  116 . Plural pixels  104  are connected through TFTs  102  to each of the signal lines  112 . 
         [0067]    Each of the gate ICs  114  outputs gate signals to the gate lines  110 . When the gate signals are output to the gate lines  110 , the TFTs  102  connected to the gate lines  110  and to which the gate signals are output are simultaneously turned on, thereby reading electric charges stored in the pixels  104  through the TFTs  102  into the signal lines  112 . Therefore, the electric charges stored in the pixels  104  are read from each row one at a time. 
         [0068]    Upon each of the gate ICs  114  being supplied with a drive signal from the cassette controller  84 , each of the gate ICs  114  successively selects the gate lines  110  connected thereto, and outputs gate signals to the selected gate lines  110 , thereby successively reading electric charges stored in the pixels  104  from each row one at a time. After the gate IC  114  has output the gate signals to all of the gate lines  110  connected thereto, i.e., after the gate IC  114  has read all the electric charges stored in the pixels  104  that are capable of being read, the gate IC  114  outputs an end signal to the cassette controller  84 . 
         [0069]    Each of the ASICs  116  comprises an amplifier for amplifying the read electric charge signals (electric signals), a multiplexer, an A/D converter, etc. After having amplified the electric signals read from the signal lines  112 , each of the ASICs  116  successively selects the amplified electric signals, converts the selected electric signals into digital signals, and outputs the digital signals to the cassette controller  84 . 
         [0070]    The fault factor detector  82  detects an environmental disturbance or dropping of the electronic cassette  20 , which is responsible as a fault factor of the electronic cassette  20 . An environmental disturbance refers to an environmental humidity, an environmental temperature, a change in the environmental temperature, and an external pressure. The environmental humidity, the environmental temperature, and the change in the environmental temperature will collectively be referred to as “environmental stimuli”. If a possibility exists for the electronic cassette  20  to fail due to other disturbances apart from the environmental humidity, the environmental temperature, the change in the environmental temperature, and the external pressure, then the fault factor detector  82  may detect other fault factors. 
         [0071]    More specifically, the fault factor detector  82  comprises a drop detector  120 , including an acceleration sensor, a gyroscope, or the like, for detecting if the electronic cassette  20  is dropped, a humidity detector  122 , including an electric-resistance or an electric-capacitance humidity sensor, for detecting an environmental humidity of the electronic cassette  20 , i.e., the humidity of an environment in which the electronic cassette  20  is placed, a temperature detector  124  including a thermocouple, a thermistor, or an infrared temperature sensor, for detecting an environmental temperature of the electronic cassette  20 , i.e., the temperature of an environment in which the electronic cassette  20  is placed, and a pressure detector  126  including a pressure sensor such as a pressure-sensitive element, which may be a semiconductor diaphragm, an electrostatic capacitance sensor, or a piezoelectric sensor, for detecting an external pressure applied to the electronic cassette  20 . The fault factor detector  82  may be installed at any location within the electronic cassette  20 . The temperature detector  124  may have a function to detect a change in temperature over a certain period of time, e.g., 24 hours, such as a temperature difference between a highest temperature and a lowest temperature, or a temperature difference between a present temperature and a temperature at an earlier time, e.g., 1 hour before the present time. 
         [0072]    The cassette controller  84  includes an image capture controller  130 , a fault diagnosing section  132 , and a function limiter  134 . The image capture controller  130  controls the manner in which an image is captured with radiation  16 . More specifically, the image capture controller  130  controls the timing at which the radiation conversion panel  54  is exposed to radiation  16 , and the time at which images are read from the radiation conversion panel  54 . The image capture controller  130  controls the exposure start timing so as to be in synchronism with the start of application of radiation  16  from the radiation device  18 , and also controls the exposure end timing so as to be in synchronism with the end of application of radiation  16  from the radiation device  18 . The image capture controller  130  synchronizes the exposure start timing and the exposure end timing by way of wireless communications with the radiation device  18  via the console  24 . 
         [0073]    The image capture controller  130  controls reading of an image by selecting a gate IC  114  and outputting a drive signal to the selected gate IC  114 . After outputting the drive signal to the selected gate IC  114  and subsequently receiving an end signal from the selected gate IC  114 , the image capture controller  130  selects a next gate IC  114  and outputs a drive signal to the selected gate IC  114 . In this manner, electric charges stored in all of the pixels  104  of the radiation conversion panel  54  are read successively one row at a time, i.e., an image is read from the radiation conversion panel  54 . The cassette controller  84  stores in the memory  86  digital signals representing image data sent from the ASICs  116 . The communication unit  88  sends the image data stored in the memory  86  as packets to the console  24 . 
         [0074]    The fault diagnosing section  132  includes a self-diagnosing section  140  and a real-image diagnosing section  142 . The self-diagnosing section  140  diagnoses whether or not the bias power supply  108 , the gate ICs  114 , and the ASICs  116  are operating normally or fail to operate. For example, the self-diagnosing section  140  sends a test signal to the gate ICs  114  and the ASICs  116 , and diagnoses whether or not the gate ICs  114  and the ASICs  116  fail to operate based on response signals sent from the gate ICs  114  and the ASICs  116 . 
         [0075]    The self-diagnosing section  140  also diagnoses whether or not interconnections in the electronic cassette  20  are normal, i.e., whether such interconnections are short-circuited, broken, or unstable (i.e., suffering from a contact failure representing a repetition of making and breaking circuits). Further, the self-diagnosing section  140  diagnoses an unimageable region in which a radiographic image cannot be captured from the radiation  16 . 
         [0076]      FIG. 6  is a diagram showing by way of example an unimageable region included within the imageable region  50 , which is diagnosed by the self-diagnosing section  140 . As shown in  FIG. 6 , an uppermost one of the gate ICs  114  and a leftmost one of the ASICs  116  suffer from a failure due to broken or short-circuited interconnections, thereby producing an unimageable region, as shown in hatching. Since the faulty gate IC  114  is unable to output a gate signal to the connected gate lines  110 , the faulty gate IC  114  is unable to read electric charges stored in the pixels  104 , which are connected through the TFTs  102  to the gate lines  110 . The unimageable region contains pixels  104  that are connected through the TFTs  102  to the gate lines  110 , which are connected to the faulty gate IC  114 . 
         [0077]    The faulty ASIC  116  is unable to output electric charge signals sent to the cassette controller  84  from the signal lines  112  that are connected to the faulty ASIC  116 . The unimageable region contains pixels  104  that are connected through the TFTs  102  to the signal lines  112 , which are connected to the faulty ASIC  116 . 
         [0078]    The self-diagnosing section  140  also diagnoses the memory  86 , the communication unit  88 , and the built-in battery  90 . For example, the self-diagnosing section  140  diagnoses the memory  86  for available storage capacity by checking if the memory  86  has any malfunctioning cells. The self-diagnosing section  140  also diagnoses the communication unit  88  for a communication function thereof by performing a communication test on the communication unit  88  for communication with the console  24 . The self-diagnosing section  140  also diagnoses the built-in battery  90  for a remaining stored energy level (capacity) and a degree of deterioration of the built-in battery  90  based on the charged voltage of the built-in battery  90 , which is detected by a voltage sensor combined with the built-in battery  90 . The self-diagnosing section  140  may also carry out a load current test in order to diagnose the built-in battery  90  for the remaining stored energy level and the degree of deterioration thereof. 
         [0079]    The real-image diagnosing section  142  performs a real-image diagnostic process for diagnosing an unimageable region, which is unable to capture an image, based on image data generated by an idle exposure process. In the idle exposure process, the electronic cassette  20  is directly exposed to radiation  16  that actually is applied thereto. More specifically, even if a region of the imageable region  50  is diagnosed as not being an unimageable region by the real-image diagnosing section  142 , the region may not actually be capable of capturing an image. For example, since a region where the columnar crystalline structure  72  of the scintillator  52  is broken is unable to convert radiation  16  into phosphorescence, such a region is incapable of capturing an image from the radiation  16 . Further, if relative positions of the scintillator  52  and the radiation conversion panel  54  are shifted, then the imageable region  50  may contain a region in which the phosphorescence generated by the scintillator  52  is not applied, whereby such a region is not capable of capturing an image from the radiation  16 . The idle exposure process refers to a process in which an image is captured from radiation  16  that is applied from the radiation device  18  to the electronic cassette  20  during a time that a subject  14  is not present between the radiation device  18  and the electronic cassette  20 . 
         [0080]    The real-image diagnosing section  142  may diagnose, as an unimageable region, a region made up of a striped pattern or a web-like pattern of detected values, which are significantly different from those in a surrounding region. Furthermore, since the image capturing conditions for the idle exposure process are predetermined, values of image data generated by the idle exposure process may be expected to fall within a certain range. Therefore, the real-image diagnosing section  142  may diagnose, as an unimageable region, a region that is made up of image data outside of the certain range. More specifically, the radiation device  18  applies diagnostic radiation  16 , and the image capture controller  130  controls capturing of an image with the applied diagnostic radiation  16 . The real-image diagnosing section  142  diagnoses the imageable region  50  for an unimageable region based on image data of the image captured from the diagnostic radiation  16 . If the image capture controller  130  controls capturing of an image with the applied diagnostic radiation  16 , the timing at which the diagnostic radiation  16  starts to be applied and the exposure start timing need not be in synchronism with each other, insofar as an image can be captured from the diagnostic radiation  16 . 
         [0081]    The function limiter  134  limits functions of the electronic cassette  20  during continuous use thereof depending on the results of a fault diagnosing process carried out by the fault diagnosing section  132 . For example, if the self-diagnosing section  140  diagnoses a gate IC  114  or an ASIC  116  as being faulty, then the function limiter  134  inhibits electric power from being supplied to the faulty gate IC  114  or the faulty ASIC  116 . Therefore, the faulty gate IC  114  or the faulty ASIC  116  is prevented from becoming unduly heated, and an unimageable region corresponding to the faulty gate IC  114  or the faulty ASIC  116  is limited, i.e., is prevented from being used in the image capturing process. In addition, the function limiter  134  stops supplying an electric current to an interconnection, which may be broken or short-circuited, which has been diagnosed as malfunctioning by the self-diagnosing section  140 . Thus, the broken or short-circuited interconnection is prevented from generating heat. Since unwanted electric current is not supplied to the broken or short-circuited interconnection, electric power consumption of the electronic cassette  20  is minimized. Further, if a gate IC  114  is diagnosed as malfunctioning, a drive current may be inhibited from being supplied to the malfunctioning gate IC  114 . 
         [0082]    The function limiter  134  also limits functions of the electronic cassette  20  so as not to acquire an image from an unimageable region that has been diagnosed by the real-image diagnosing section  142 . For example, the electric charges stored in pixels  104  that are diagnosed as making up an unimageable region are not read from such pixels  104 . More specifically, electric power is inhibited from being supplied to the gate ICs  114  for reading the stored electric charges from pixels  104  in the unimageable region, or is inhibited from being supplied to the ASICs  116  for outputting electric charges stored in pixels  104  in the unimageable region as digital signals. Further, gate signals are inhibited from being output to the gate lines  110  for reading the electric charges stored in pixels  104  in the unimageable region. Since an image capturing process is not performed in the unimageable region, an image is not acquired from the unimageable region. 
         [0083]    Since each of the gate ICs  114  reads electric charges stored in pixels  104  along a plurality of rows, if such pixels  104  include even one pixel belonging to an unimageable region, then the electric charges stored in all of such pixels  104  along the rows cannot be read. Therefore, if the ratio of the number of pixels  104  in the unimageable region to the number of pixels  104  outside of the unimageable region, from among all of the pixels  104  to be read by a gate IC  114  that reads the electric charges stored in the pixels  104  in the unimageable region, is equal to or greater than a prescribed ratio, electric power may be inhibited from being supplied to the gate IC  114 , thereby preventing electric charges from being read from the pixels  104 . This is because if the ratio of the number of pixels  104  in the unimageable region to the number of pixels  104  outside of the unimageable region is equal to or greater than the prescribed ratio, a good image cannot be acquired from the read electric charges. The same holds true for the ASICs  116 . If the gate lines  110  are connected respectively to the gate ICs  114  whereas the signal lines  112  are connected respectively to the ASICs  116 , then the above problem does not occur. 
         [0084]    Even if the ratio of the number of pixels  104  in an unimageable region to the number of pixels  104  outside the unimageable region, among all of the pixels  104  to be read by a gate IC  114  that reads the electric charges stored in the pixels  104  in the unimageable region, is smaller than the prescribed ratio, electric power may be inhibited from being supplied to the gate IC  114 , thereby preventing electric charges from being read from the pixels  104 , provided that a certain number of pixels  104  or more are disposed in succession in the unimageable region. This is because if a certain number of pixels  104  or more are disposed in succession in the unimageable region, the region in which an image cannot be captured is too large to acquire a good image from the read electric charges. The same also holds true for the ASICs  116 . 
         [0085]    If electric charges stored in the pixels  104  are not inhibited from being read, then an image correcting process such as a pixel interpolation process may be carried out in order to eliminate the unimageable region. Such an image correcting process may be performed by the console  24  or the cassette controller  84 . However, the image correcting process should not be carried out excessively, because if the image correcting process is excessive, then a disease diagnosis based on an image generated by the image correcting process tends to suffer from reduced accuracy. For example, if the shape or size of a lesion in a cancer diagnosis is measured based on an image generated by the electronic cassette  20 , then the prescribed ratio or the certain number referred to above may be reduced in order to provide stricter conditions for inhibiting electric power from being supplied to the gate IC  114 , or to prevent electric charges from being read from the pixels  104 . 
         [0086]    Rather than inhibiting electric power from being supplied to gate ICs  114  or ASICs  116 , image data generated from image capturing radiation  16  may be trimmed in order to remove image data in a diagnosed unimageable region, thereby limiting the image capturing area. Therefore, image data generated from the imaging radiation  16  is free of image data that occurs within the unimageable region. Such trimmed image data may be stored in the memory  86  and sent to the console  24  by way of the communication unit  88 . The image capturing radiation  16  and the diagnostic radiation  16  may have identical or different irradiating conditions, including tube currents, tube voltages, and irradiation times. Since the diagnostic radiation  16  simply is used for diagnostic purposes, the diagnostic radiation  16  may be applied at a smaller dosage (mAs value) than the image capturing radiation  16 . 
         [0087]    If the self-diagnosing section  140  diagnoses the memory  86  as having an available storage capacity that is smaller than a predetermined value, then the function limiter  134  limits a successive image capturing function. If the self-diagnosing section  140  diagnoses the communication unit  88  as malfunctioning, then the function limiter  134  inhibits electric power from being supplied to the communication unit  88  so as to limit the communication function thereof. If the self-diagnosing section  140  diagnoses the built-in battery  90  as having a remaining stored energy level that is smaller than a predetermined value, or as having deteriorated beyond a predetermined degree, then the function limiter  134  limits usage of the built-in battery  90 . The function limiter  134  may not immediately limit usage of the built-in battery  90 , but may limit usage thereof upon elapse of a certain period of time, e.g., 5 minutes. The function limiter  134  may not completely limit usage of the built-in battery  90 , i.e., may not completely stop supplying electric power from the built-in battery  90 , but may limit the amount of electric power that is capable of being supplied from the built-in battery  90 . The function limiter  134  may limit the amount of electric power supplied from the built-in battery  90  by reducing the number of devices or units to which electric power is supplied from the built-in battery  90 . 
         [0088]    If the wireless function of the communication unit  88  is limited, e.g., if electric power is inhibited from being supplied to the communication unit  88 , then the user can connect the USB connector, which is on the tip end of a USB cable that is connected to the console  24 , to the USB terminal  62 , thereby interconnecting the electronic cassette  20  and the console  24  through a wired link. If electric power is inhibited from being supplied to the communication unit  88 , then the malfunctioning communication unit  88  is prevented from becoming unduly heated. If the communication function of the communication unit  88  fails, then data intended to be sent to the console  24  are stored in the memory  86 , and such stored data are sent to the console  24  after the electronic cassette  20  and the console  24  have been connected to each other by way of the USB cable. According to the first embodiment, the USB cable, which also doubles as a power supply cable, is used to establish a wired communication link between the electronic cassette  20  and the console  24 . However, a communication cable, which does not double as a power supply cable, may be used instead of the USB cable. 
         [0089]    If usage of the built-in battery  90  is limited, then the AC connector, which is provided on the tip end of a cable from an external power supply, may be connected to the input terminal  60  for thereby supplying electric power to the electronic cassette  20  from the external power supply. Accordingly, the electronic cassette  20  is protected from a sudden power shortage while it is in use. 
         [0090]    The light emitter  92  emits light to thereby inform the user that certain functions of the communication unit  88  and the built-in battery  90  have been limited. The light emitter  92  includes a plurality of light-emitting elements having different colors, e.g., red, blue, etc. In a case where the function of the communication unit  88  is limited by the function limiter  134 , the cassette controller  84  controls the light emitter  92  to energize the red light-emitting element, for example. In a case where the function of the built-in battery  90  is limited by the function limiter  134 , the cassette controller  84  controls the light emitter  92  to energize the blue light-emitting element, for example. Therefore, the user can recognize which functions, from among the functions of the communication unit  88  and the built-in battery  90 , have been limited. 
         [0091]    The function limiter  134  normally sends information concerning the function that has been limited to the console  24  through the communication unit  88 . However, if the function limiter  134  has limited the function of the communication unit  88 , then the function limiter  134  sends information concerning the limited function to the console  24  after the electronic cassette  20  and the console  24  have been connected to each other by way of the USB cable. 
         [0092]      FIG. 7  is an electronic block diagram of the console  24 . The console  24  includes an input unit  150  for receiving input signals entered by the user, a controller  152  for controlling the console  24  in its entirety, a display unit (indicator)  154 , and a communication unit  156  for sending signals to and receiving signals from the electronic cassette  20 , etc., through a wireless communication link. The controller  152  controls the display unit  154  to display the results of a diagnostic process performed by the fault diagnosing section  132  and to display the functions limited by the function limiter  134 . Thus, the display unit  154  indicates the limited functions to the user. 
         [0093]      FIG. 8  is a view showing a displayed example of a function, which is limited by the function limiter  134  depending on the results of a self-diagnostic process. According to the displayed example shown in  FIG. 8 , an image capturing area and a limitation of the built-in battery are displayed on the display unit  154 . The display unit  154  displays an electronic cassette  20 ′, which simulates the electronic cassette  20  as viewed from above, in a left-hand section of the screen, and also displays an explanation field for describing the limited functions in a right-hand section of the screen. 
         [0094]    The electronic cassette  20 ′, which is displayed on the display unit  154 , has an imageable region  50 ′ including a diagnosed (limited) unimageable region (shown in hatching). The explanation field displays a message “IMAGING REGION OF COLUMN 1 AND ROW A IS AN UNIMAGEABLE REGION.” In this manner, the user can recognize which imaging region has been limited by observing the region graduations marked on the electronic cassette  20 . The explanation field also displays a message “BUILT-IN BATTERY SUFFERS FROM A CAPACITY SHORTAGE. CONNECT CABLE SINCE BUILT-IN BATTERY IS LIMITED.” 
         [0095]    Operations of the electronic cassette  20  according to the first embodiment will be described below with reference to the flowchart shown in  FIG. 9 . The fault factor detector  82  periodically detects dropping of the electronic cassette  20  together with disturbance values (environmental humidity values, environmental temperature values, and external pressure values). 
         [0096]    The fault diagnosing section  132  judges whether or not a detected disturbance value is equal to or greater than a threshold value (step S 1 ). More specifically, the fault diagnosing section  132  judges whether or not any one of an environmental humidity value detected by the humidity detector  122 , an environmental temperature value detected by the temperature detector  124 , and an external pressure value detected by the pressure detector  126  is equal to or greater than a threshold value. Alternatively, the fault diagnosing section  132  may determine an evaluation value from the environmental humidity value detected by the humidity detector  122 , the environmental temperature value detected by the temperature detector  124 , or the external pressure value detected by the pressure detector  126 , and judge whether or not the evaluation value is equal to or greater than a threshold value. Further, alternatively, the fault diagnosing section  132  may judge whether or not a temperature change detected by the temperature detector  124  is equal to or greater than a threshold value. 
         [0097]    If the fault diagnosing section  132  decides that the disturbance value is not equal to or greater than the threshold value in step S 1 , then the fault diagnosing section  132  judges whether or not the drop detector  120  has detected dropping of the electronic cassette  20  or not (step S 2 ). If the fault diagnosing section  132  decides that the drop detector  120  has not detected dropping of the electronic cassette  20 , then control returns to step S 1 . 
         [0098]    If the fault diagnosing section  132  decides that the disturbance value is equal to or greater than the threshold value in step S 1 , or if the fault diagnosing section  132  decides that the drop detector  120  has detected dropping of the electronic cassette  20  in step S 2 , then the self-diagnosing section  140  carries out a self-diagnostic process (step S 3 ). More specifically, the self-diagnosing section  140  diagnoses the gate ICs  114  and the ASICs  116  for a fault, diagnoses the interconnections, and diagnoses the panel unit  40  for an unimageable region. Further, the self-diagnosing section  140  also diagnoses the memory  86 , the communication unit  88 , and the built-in battery  90 . The self-diagnosing section  140  then sends the results of the self-diagnostic process to the console  24  through the communication unit  88 . Until completion of the fault diagnosis (self-diagnostic process and real-image diagnostic process) of the electronic cassette  20 , the cassette controller  84  sends an irradiation inhibition request to the console  24  through the communication unit  88  for inhibiting application of image-capturing radiation  16 . The console  24  then sends an irradiation inhibition command to the radiation device  18 . The radiation device  18  inhibits the radiation source  34  from applying image-capturing radiation  16  until the fault diagnosis is completed. If the communication unit  88  fails to operate, then since the console  24  cannot communicate with the electronic cassette  20  through the wireless communication link, the console  24  diagnoses the communication unit  88  as suffering from a fault, and inhibits image-capturing radiation  16  from being applied. The console  24  may inhibit image-capturing radiation  16  from being applied prior to step S 3 , or may start inhibiting image-capturing radiation  16  from being applied in step S 4 . 
         [0099]    Then, the function limiter  134  limits functions of the electronic cassette  20 , which is in continuous use, depending on the results of the self-diagnostic process in step S 4 . For example, if the self-diagnosing section  140  diagnoses a gate IC  114  or an ASIC  116  as suffering from a fault, then the function limiter  134  stops supplying electric power to the faulty gate IC  114  or to the faulty ASIC  116 . Thus, an image capturing process in the unimageable region is limited. The function limiter  134  also stops supplying electric power to an interconnection, which has been diagnosed as being broken, short-circuited, or unstable. The function limiter  134  sends information to the console  24  through the communication unit  88  concerning the function that was limited depending on the results of the self-diagnostic process. The unimageable region, which is diagnosed by the self-diagnostic process, will be referred to as a first unimageable region. 
         [0100]    Then, the controller  152  of the console  24  controls the display unit  154  to display the function that was limited depending on the results of the self-diagnostic process, as well as the function that was limited depending on the results of the self-diagnostic process (step S 5 ). For example, if a gate IC  114  for reading the electric charges stored in the pixels  104  of the row indicated by a region corresponding to graduation A on the image capturing surface  46 , and an ASIC  116  for reading the electric charges stored in the pixels  104  of the column indicated by a region corresponding to graduation  1  on the image capturing surface  46  are diagnosed as being faulty, then, as shown in  FIG. 8 , the diagnosed first unimageable region in the imageable region  50 ′ of the electronic cassette  20 ′ is displayed in hatching, and the message “IMAGING REGION OF COLUMN 1 AND ROW A IS AN UNIMAGEABLE REGION” is displayed in the explanation field. If the built-in battery  90  is diagnosed as having a remaining stored energy level lower than a predetermined value, then the message “BUILT-IN BATTERY IS SUFFERING FROM A CAPACITY SHORTAGE. CONNECT CABLE SINCE BUILT-IN BATTERY IS LIMITED” is displayed in the explanation field. If the function limiter  134  has limited the functions of the communication unit  88  and the built-in battery  90 , then the function limiter  134  energizes the light emitter  92  to indicate the limited functions to the user. 
         [0101]    Then, the image capture controller  130  performs an idle exposure process using diagnostic radiation  16  (step S 6 ). More specifically, the image capture controller  130  outputs a request signal to the console  24  through the communication unit  88  for requesting application of diagnostic radiation  16 . In response to the request signal, the console  24  outputs a command signal to the radiation device  18  for applying diagnostic radiation  16 . In response to the command signal, the radiation device  18  applies diagnostic radiation  16 . After having output the request signal, the image capture controller  130  controls the radiation conversion panel  54  so as to be exposed to diagnostic radiation  16  for a given period of time, and then reads the electric charges that are stored in the pixels  104  as a result of being exposed to diagnostic radiation  16 . Image data that are converted from the electric charges generated as a result of being exposed to diagnostic radiation  16  are stored in the memory  86 . At this time, image data are produced based on the diagnostic radiation  16 , while the function is limited depending on the results of the self-diagnostic process. 
         [0102]    Then, based on the image data, which are produced from the diagnostic radiation  16 , the real-image diagnosing section  142  performs a real-image diagnostic process for diagnosing the electronic cassette  20  for an unimageable region in which an image cannot be captured (step S 7 ). The unimageable region, which is detected by the real-image diagnosing section  142 , is referred to as a second unimageable region. The real-image diagnosing section  142  sends the results of the real-image diagnostic process to the console  24  through the communication unit  88 . 
         [0103]    Then, the function limiter  134  limits the function of the electronic cassette  20 , which is in continuous use, depending on the results of the real-image diagnostic process (step S 8 ). In other words, the function limiter  134  limits the function of the electronic cassette  20  so that an image will not be acquired from the unimageable region that is detected by the real-image diagnosing section  142 . For example, the function limiter  134  may inhibit electric power from being supplied to gate ICs  114  and ASICs  116 , so as not to read electric charges stored in the pixels  104  that belong to the diagnosed second unimageable region. Alternatively, image data generated based on the radiation  16  may be trimmed to remove image data from the second unimageable region. The function limiter  134  sends information to the console  24  through the communication unit  88  concerning the function that was limited depending on the results of the real-image diagnostic process. 
         [0104]    Then, the controller  152  of the console  24  controls the display unit  154  to display the results of the real-image diagnostic process and the function that was limited depending on the results of the real-image diagnostic process (step S 9 ). The controller  152  may control the display unit  154  to display the second unimageable region diagnosed by the real-image diagnostic process, in the same manner as shown in  FIG. 8 . If an image capturing area is limited by inhibiting electric power from being supplied to the gate ICs  114 , which read the stored electric charges from the pixels  104  in the second unimageable region, then the actually limited image capturing area becomes wider than, and hence is not in agreement with, the second unimageable region. In this case, the actually limited image capturing area, rather than the second unimageable region, is displayed as an unimageable region. The function that was limited depending on the results of the real-image diagnostic process may be displayed along with the function that was limited depending on the results of the self-diagnostic process. For example, the first unimageable region and the second unimageable region may be displayed together. Upon completion of the fault diagnosing process, the cassette controller  84  sends a signal to the console  24  through the communication unit  88  indicating that image-capturing radiation  16  can be applied. The console  24  then sends a signal to the radiation device  18  indicating that image-capturing radiation  16  can be applied, whereby the image-capturing radiation  16  is made capable of applying the image-capturing radiation  16 . 
         [0105]    As described above, if an environmental disturbance value is equal to or greater than a threshold value or if dropping of the electronic cassette  20  is detected, then the electronic cassette  20  is diagnosed for a fault, and a function of the electronic cassette  20  is limited depending on the results of the diagnosis. Therefore, the electronic cassette  20 , which has become faulty, can be used continuously. Since a function is limited depending on the fault, the electronic cassette  20  is prevented from becoming unduly heated, and hence electric power consumption is minimized. 
         [0106]    If an environmental disturbance value is equal to or greater than a threshold value or if dropping of the electronic cassette  20  is detected, then the electronic cassette  20  is self-diagnosed for a first unimageable region in which an image cannot be captured from the radiation  16 , and an image is not captured in the first unimageable region. Accordingly, the electronic cassette  20  is prevented from becoming unduly heated due to an image capturing process in the first unimageable region, and hence electric power consumption of the electronic cassette  20  is minimized. 
         [0107]    If an environmental disturbance value is equal to or greater than a threshold value or if dropping of the electronic cassette  20  is detected, then the interconnections of the electronic cassette  20  are diagnosed, and current is not supplied to defective interconnections, which may be broken, short-circuited, or unstable. Since current is not supplied to defective interconnections, the interconnections are prevented from becoming unduly heated, and hence electric power consumption of the electronic cassette  20  is minimized. 
         [0108]    If an environmental disturbance value is equal to or greater than a threshold value or if dropping of the electronic cassette  20  is detected, then an idle exposure process is carried out, and the electronic cassette  20  is self-diagnosed for a second unimageable region in which an image cannot be captured from the radiation  16 , based on image data generated by the idle exposure process. Therefore, an unimageable region, which cannot be ascertained by an actual image capturing process, can be detected. 
         [0109]    Since a limited function of the electronic cassette  20  is displayed on the display unit  154 , the user can recognize the limited function. If an environmental disturbance value is equal to or greater than a threshold value or if dropping of the electronic cassette  20  is detected, then image-capturing radiation  16  is inhibited from being applied until the fault diagnostic process carried out by the fault diagnosing section  132  is finished. Consequently, the subject  14  is prevented from being unduly exposed to radiation  16 . 
         [0110]    The first embodiment described above can be modified in the following ways. 
       (Modification 1) 
       [0111]    In the first embodiment, if a second unimageable region is diagnosed by the real-image diagnosing section  142 , then in step S 8 , a function of the electronic cassette  20  is limited so as not to produce an image in the second unimageable region. However, it is possible that a function of the electronic cassette  20  may not be limited. If a function of the electronic cassette  20  is not limited, then step S 8  may be dispensed with, and in step S 9 , the diagnosed second unimageable region simply is displayed on the display unit  154 . At this time, the first unimageable region may also be displayed along with the second unimageable region. 
       (Modification 2) 
       [0112]    In the first embodiment, both the self-diagnostic process and the real-image diagnostic process are performed. However, either one of the self-diagnostic process or the real-image diagnostic process may be performed. 
       (Modification 3) 
       [0113]    A display panel, such as a liquid crystal panel or the like, may be disposed on a reverse side of the panel unit  40 , i.e., a surface thereof remote from the image capturing surface  46 , and an unimageable region diagnosed by the self-diagnostic process or the real-image diagnostic process may be displayed on the display panel on the reverse side of the panel unit  40 . Then, simply by turning over the panel unit  40 , the user can intuitively recognize which region is an unimageable region. Light-emitting elements such as LEDs or the like may be placed at positions of the region graduations on the electronic cassette  20 , and the cassette controller  84  may turn the light-emitting elements on and off in order to indicate an unimageable region. 
       (Modification 4) 
       [0114]    In mammography, it is important to capture images of the armpits because cancer often occurs in the armpits. As shown in  FIG. 10 , in mammography, an image of the breast  160  is captured while the breast  160  is placed on the panel unit  40  of the electronic cassette  20 . Among the end areas of the imageable region  50 , one end area  162  near the breast wall serves as a region for capturing an image of the armpit. However, if the end area  162  of the electronic cassette  20  near the breast wall is detected as an unimageable region, then an image of the armpit cannot be captured. If the end area  162  of the imageable region  50  is diagnosed as being an unimageable region by the self-diagnostic process and the real-image diagnostic process, then the function limiter  134  limits a mammographic function. In this case, for example, the user operates the input unit  150  of the console  24  to select an image capturing order from among a plurality of image capturing orders. At this time, the function limiter  134  may limit the types of available image capturing processes, so that a mammographic image capturing order cannot be selected via the console  24 . 
       (Modification 5) 
       [0115]    The real-image diagnosing section  142  diagnoses an unimageable region based on image data generated by the idle exposure process. However, the real-image diagnosing section  142  may diagnose an unimageable region based on image data that is generated by a blank reading process. Such a blank reading process refers to a process in which radiation  16  is not applied to the electronic cassette  20 , and electric signals stored in the pixels  104 , i.e., electric signals representative of dark current, are read. 
       (Modification 6) 
       [0116]    In the first embodiment, the radiation detector  56  includes on a single substrate, e.g., a glass substrate, a single radiation conversion panel  54  including the TFTs  102  and the pixels  104 . According to Modification 6, the radiation detector  56  includes on a substrate a plurality of respective radiation conversion panels  54 , each of which includes a plurality of TFTs  102  and a plurality of pixels  104 . The radiation conversion panels  54 , which are bonded together without gaps therebetween, convert phosphorescence generated by the scintillator  52  into electric signals. The radiation conversion panels  54  collectively are capable of producing a single radiographic image. According to Modification 6, the operation sequence according to the flowchart shown in  FIG. 9  is performed with respect to each of the radiation conversion panels  54 , thereby managing each of the radiation conversion panels  54 . 
       (Modification 7) 
       [0117]    In the first embodiment, the TFTs  102  and the pixels  104  of the radiation conversion panel  54  are disposed on a single substrate, e.g., a glass substrate. According to Modification 7, a single radiation conversion panel  54  is produced by forming a plurality of TFTs  102  and a plurality of pixels  104  on each of a plurality of substrates, i.e., silicon wafers, and thereafter bonding the substrates together. 
       (Modification 8) 
       [0118]    Modifications 1 through 7 may be combined together insofar as they do not counteract one another or operate in a contradictory manner. 
       Second Embodiment 
       [0119]    Parts and features according to a second embodiment, which differ from those according to the first embodiment, will be described below, whereas identical parts and features will not be described. More specifically, the radiographic image capturing system  10 , and the radiation device  18 , the electronic cassette  20 , the console  24 , the display device  26 , the RIS  28 , the HIS  30 , and the server  32  according to the second embodiment are identical to those of the first embodiment, however, the electronic cassette  20  has an electric configuration that differs from that of the electronic cassette  20  according to the first embodiment. 
         [0120]      FIG. 11  is an electric block diagram of the electronic cassette  20  according to the second embodiment. The electronic cassette  20  has a cassette controller  84 , including a fault diagnosing section  132  which differs from the fault diagnosing section  132  according to the first embodiment. According to the second embodiment, the fault diagnosing section  132  periodically performs a first fault diagnosing process. If dropping of the electronic cassette  20  is detected, or if a detected external pressure is equal to or greater than a threshold value, then the fault diagnosing section  132  performs the first fault diagnosing process at reduced intervals, i.e., in reduced periodic cycles. The fault diagnosing section  132  also performs a second fault diagnosing process along with the first fault diagnosing process. The first fault diagnosing process includes a self-diagnostic process and a real-image diagnostic process. The second fault diagnosing process includes a resolution diagnostic process. 
         [0121]    The fault diagnosing section  132  includes a self-diagnosing section  140  that performs a first fault diagnosing process, a real-image diagnosing section  142  that performs a second fault diagnosing process, a resolution diagnosing section  144  that performs a resolution diagnostic process, and a period storage unit  146 , which stores respective periodic cycles of the periodic diagnostic process. The period storage unit  146  stores periods for each of the periodic cycles as default values. The fault diagnosing section  132  periodically performs the first fault diagnosing process in respective periodic cycles, the periods of which have been stored in the period storage unit  146 . Components of the fault diagnosing section, which have the same functions as those according to the first embodiment, are denoted by identical reference characters. 
         [0122]    The resolution diagnosing section  144  diagnoses the resolution of an image based on image data generated by an idle exposure process, in which the radiation  16  that has passed through a resolution test chart, e.g., an MTF chart, is detected and converted into an image. 
         [0123]    Operations of the electronic cassette  20  according to the second embodiment will be described below with reference to the flowcharts shown in  FIGS. 12 and 13 . The fault factor detector  82  periodically detects dropping of the electronic cassette  20 , environmental humidity values, environmental temperature values, and external pressure values. 
         [0124]    The fault diagnosing section  132  judges whether or not the period of each of the periodic cycles of the periodic diagnostic process, which is stored in the period storage unit  146 , has expired (step S 21  of  FIG. 12 ). For example, if the period stored in the period storage unit  146  is 6 months, then the fault diagnosing section  132  judges whether or not 6 months have elapsed from a previous periodic diagnostic process. 
         [0125]    If the fault diagnosing section  132  decides that the period of each of the periodic cycles of the periodic diagnostic process has not arrived in step S 21 , then the fault diagnosing section  132  judges whether or not an external pressure detected by the pressure detector  126  is equal to or greater than a threshold value (step S 22 ). 
         [0126]    If the fault diagnosing section  132  decides that the external pressure is not equal to or greater than the threshold value, then the fault diagnosing section  132  judges whether or not the drop detector  120  has detected dropping of the electronic cassette  20  (step S 23 ). If the fault diagnosing section  132  judges that the drop detector  120  has not detected dropping of the electronic cassette  20  in step S 23 , then control returns to step S 21 . 
         [0127]    If the fault diagnosing section  132  decides that the external pressure is equal to or greater than the threshold value in step S 22 , or if the fault diagnosing section  132  decides that the drop detector  120  has detected dropping of the electronic cassette  20  in step S 23 , then the fault diagnosing section  132  decides that the electronic cassette  20  has malfunctioned or has suffered from a fault (for example, the columnar crystalline structure  72  or the humidity-resistant protector  74  has become broken or cracked, or a gate IC  114  or the like has become broken, or an interconnection is broken or short-circuited). In this case, the fault diagnosing section  132  shortens the period of the periodic diagnostic process by a predetermined period (e.g., 1 month) or a predetermined percent (e.g., 70 percent) (step S 24 ). More specifically, if an external pressure, which is equal to or greater than the threshold value, is detected, or if dropping of the electronic cassette  20  is detected, the electronic cassette  20  is considered to deteriorate quickly. Therefore, the fault diagnosing section  132  shortens the period of the periodic diagnostic process. If the present period of the periodic diagnostic process is 6 months, then after being shortened by 1 month, the period of the periodic diagnostic process becomes 5 months. The shortened period of the periodic diagnostic process is stored in the period storage unit  146 . The fault diagnosing section  132  stores information indicating that an external pressure, which is equal to or greater than the threshold value, has been detected, or that dropping of the electronic cassette  20  has been detected, in a non-illustrated internal memory. 
         [0128]    Then, the fault diagnosing section  132  performs a first fault diagnosing process by carrying out a self-diagnostic process and a real-image diagnostic process (step S 25 ). The fault diagnosing section  132  performs the first fault diagnosing process since functions of the electronic cassette  20  may possibly have become impaired in a case where the external pressure, which was equal to or greater than the threshold value, or dropping of the electronic cassette  20  was detected. The first fault diagnosing process will be described in detail later. 
         [0129]    Then, the image capture controller  130  performs an idle exposure process for capturing an image based on the diagnostic radiation  16  that has passed through a resolution test chart (step S 26 ). More specifically, the image capture controller  130  outputs a request signal to the console  24  through the communication unit  88  for requesting application of diagnostic radiation  16 . In response to the request signal, the console  24  outputs a command signal to the radiation device  18  for applying diagnostic radiation  16 . When the console  24  outputs the command signal, it controls the display unit  154  to display the letters “SET RESOLUTION TEST CHART”, thereby prompting the user to set a resolution test chart. 
         [0130]    In response to the command signal, the radiation device  18  applies diagnostic radiation  16  after the elapse of a given period of time, e.g., 3 minutes. Before the given period of time elapses, the user sets a resolution test chart on the image capturing surface  46  of the electronic cassette  20 . After having output the request signal, the image capture controller  130  controls the pixels  104  so as to be exposed to diagnostic radiation  16  in a predetermined time exposure process after the elapse of the given period of time. Then, the image capture controller  130  reads the electric charges stored in the pixels  104  by the time exposure process. 
         [0131]    After having acquired image data from diagnostic radiation  16  that has passed through the resolution test chart, the fault diagnosing section  132  performs a resolution diagnostic process to thereby carry out a second fault diagnosing process (step S 27 ). More specifically, the resolution diagnosing section  144  diagnoses an image resolution based on the image data captured in step S 26 . In this manner, the image resolution, which may have been lowered due to the scintillator  52  having become broken or cracked, can be detected. The resolution diagnosing section  144  sends the result of the resolution diagnostic process to the console  24  through the communication unit  88 . The console  24  displays the result of the resolution diagnostic process from the resolution diagnosing section  144  on the display unit  154 , thereby indicating the result to the user. After the second fault diagnosing process in step S 27 , control returns to step S 21 . The above operation sequence is repeated until the period of the periodic diagnostic process expires. 
         [0132]    If the fault diagnosing section  132  decides that the period of the periodic diagnostic process has expired in step S 21 , then the fault diagnosing section  132  performs a first fault diagnosing process by carrying out a self-diagnostic process and a real-image diagnostic process (step S 28 ). By periodically performing the first fault diagnosing process, the fault diagnosing section  132  can periodically diagnose the electronic cassette  20  for a fault or malfunction. Since subjects, who are patients, are placed on the electronic cassette  20 , the electronic cassette  20  experiences external pressures and stresses in a case where the electronic cassette  20  is in normal use. Therefore, the electronic cassette  20  tends to suffer from a fault or malfunction under such external pressures and stresses while in continuous use. 
         [0133]    Then, the fault diagnosing section  132  judges whether or not an external pressure equal to or greater than the threshold value, or dropping of the electronic cassette  20  has been detected thus far (step S 29 ). If in step S 29 , the fault diagnosing section  132  decides that an external pressure equal to or greater than the threshold value, or dropping of the electronic cassette  20  has not been detected thus far, control returns to step S 21  of  FIG. 12 . 
         [0134]    If in step S 29 , the fault diagnosing section  132  decides that an external pressure equal to or greater than the threshold value, or dropping of the electronic cassette  20  has been detected thus far, the image capture controller  130  performs an idle exposure process for capturing an image based on diagnostic radiation  16  that has passed through a resolution test chart (step S 30 ). In step S 30 , the image capture controller  130  operates in the same manner as in step S 26 , thereby capturing an image based on diagnostic radiation  16  that has passed through the resolution test chart. 
         [0135]    Thereafter, the fault diagnosing section  132  performs a resolution diagnostic process based on the captured image data to carry out a second fault diagnosing process (step S 31 ). Then, control returns to step S 21  of  FIG. 12 . In this manner, image resolution, which may have become lowered as a result of deliquescing of the scintillator  52 , can be detected. The resolution diagnosing section  144  sends the results of the resolution diagnostic process to the console  24  through the communication unit  88 . The console  24  displays the results of the resolution diagnostic process from the resolution diagnosing section  144  on the display unit  154 , thereby indicating such results to the user. If an external pressure equal to or greater than the threshold value, or dropping of the electronic cassette  20  has been detected thus far, the second fault diagnosing process is added to the periodic diagnostic process, because a sign of deterioration of the electronic cassette  20  due to an excessive external pressure being applied thereto, or as a result of dropping thereof, can accurately be grasped, thereby enhancing the accuracy with which the electronic cassette  20  is diagnosed, and improving the prediction of the time at which the electronic cassette should be replaced. Therefore, if an external pressure equal to or greater than the threshold value has not been applied to the electronic cassette  20 , or the electronic cassette  20  has not been dropped thus far, the humidity-resistant protector  74  is not likely to have cracked or fractured, thereby making it less likely that the scintillator  52  has been exposed to humidity. 
         [0136]    In particular, the columnar crystalline structure  72  is highly subject to deterioration, thus resulting in reduced resolution due to exposure to humidity. Therefore, in the second fault diagnosing process, the idle exposure process is carried out using a resolution test chart. As shown in  FIG. 14 , the second fault diagnosing process may use a peripheral edge region  170  of the imageable region  50 . Electric charges stored in the pixels  104  and belonging to the peripheral edge region  170  are not used for image formation, i.e., are dumped during image formation. However, since the scintillator  52  starts to deteriorate due to humidity from the peripheral edge region thereof, the second fault diagnosing process can make use of the peripheral edge region  170  of the imageable region  50  for quickly grasping a sign of deterioration of the electronic cassette  20 . 
         [0137]    While the fault diagnosing section  132  carries out the first fault diagnosing process and the second fault diagnosing process, the fault diagnosing section  132  sends an irradiation inhibit signal to the console  24  through the communication unit  88  in order to prevent the radiation device  18  from applying image-capturing radiation  16 . In response to the irradiation inhibit signal, the console  24  sends an irradiation inhibit command to the radiation device  18 . Accordingly, while the first fault diagnosing process and the second fault diagnosing process are carried out, the radiation device  18  is inhibited from applying image-capturing radiation  16 . In the event of failure of the communication unit  88 , since the console  24  is unable to communicate wirelessly with the electronic cassette  20 , the console  24  diagnoses the communication unit  88  as failing, and may also inhibit the communication unit  88  from applying image-capturing radiation  16 . When the fault diagnosing section  132  has finished the first fault diagnosing process and the second fault diagnosing process, the fault diagnosing section  132  sends a signal to the console  24  indicating that image-capturing radiation  16  can be applied. In response to such a signal, the console  24  sends information indicating that image-capturing radiation  16  can be applied to the radiation device  18 . Thus, the radiation device  18  is rendered capable of applying image-capturing radiation  16 . 
         [0138]      FIG. 15  is a flowchart of the first fault diagnosing process. When the first fault diagnosing process is started, the self-diagnosing section  140  carries out a self-diagnostic process (step S 51 ). More specifically, the self-diagnosing section  140  diagnoses the gate ICs  114  and the ASICs  116  for a fault, diagnoses the interconnections, and diagnoses the panel unit  40  for an unimageable region. The self-diagnosing section  140  also diagnoses the memory  86 , the communication unit  88 , and the built-in battery  90 . The self-diagnosing section  140  sends the results of the self-diagnostic process to the console  24  through the communication unit  88 . In step S 51 , the self-diagnosing section  140  operates in the same manner as in step S 3  of  FIG. 9 . 
         [0139]    Then, the function limiter  134  limits functions of the electronic cassette  20 , which is in continuous use, depending on the results of the self-diagnostic process in step S 52 . For example, if the self-diagnosing section  140  diagnoses a gate IC  114  or an ASIC  116  as suffering from a fault, then the function limiter  134  stops supplying electric power to the faulty gate IC  114  or to the faulty ASIC  116 . Thus, an image capturing process in the unimageable region is limited. The function limiter  134  also stops supplying electric power to an interconnection, which has been diagnosed as being broken, short-circuited, or unstable. The function limiter  134  sends information to the console  24  through the communication unit  88  concerning the function that was limited depending on the results of the self-diagnostic process. The unimageable region, which is diagnosed by the self-diagnostic process, will be referred to as a first unimageable region. In step S 52 , the function limiter  134  operates in the same manner as in step S 4  of  FIG. 9 . 
         [0140]    Then, the controller  152  of the console  24  controls the display unit  154  to display the results of the self-diagnostic process and the function that was limited depending on the results of the self-diagnostic process (step S 53 ). For example, if a gate IC  114  for reading the electric charges stored in the pixels  104  of the row indicated by a region corresponding to graduation A on the image capturing surface  46 , and an ASIC  116  for reading the electric charges stored in the pixels  104  of the column indicated by a region corresponding to graduation  1  on the image capturing surface  46  are diagnosed as being faulty, then, as shown in  FIG. 8 , the diagnosed first unimageable region in the imageable region  50 ′ of the electronic cassette  20 ′ is displayed in hatching, and the message “IMAGING REGION OF COLUMN 1 AND ROW A IS AN UNIMAGEABLE REGION” is displayed in the explanation field. If the built-in battery  90  is diagnosed as having a remaining stored energy level lower than a predetermined value, then the message “BUILT-IN BATTERY IS SUFFERING CAPACITY SHORTAGE. CONNECT CABLE AS BUILT-IN BATTERY IS LIMITED” is displayed in the explanation field. In step S 53 , the controller  152  operates in the same manner as in step S 5  of  FIG. 9 . 
         [0141]    Then, the image capture controller  130  performs an idle exposure process using diagnostic radiation  16  (step S 54 ). More specifically, the image capture controller  130  outputs a request signal to the console  24  through the communication unit  88  for requesting application of diagnostic radiation  16 . In response to the request signal, the console  24  outputs to the radiation device  18  a command signal for applying diagnostic radiation  16 . In response to the command signal, the radiation device  18  applies diagnostic radiation  16 . After having output the request signal, the image capture controller  130  controls the radiation conversion panel  54  so as to be exposed to diagnostic radiation  16  for a given period of time, and then reads the electric charges that are stored in the pixels  104  as a result of being exposed to diagnostic radiation  16 . Image data, which are converted from the electric charges generated as a result of being exposed to diagnostic radiation  16 , are stored in the memory  86 . At this time, image data are produced based on the diagnostic radiation  16 , while the function is limited depending on the results of the self-diagnostic process. In step S 54 , the image capture controller  130  operates in the same manner as in step S 6  of  FIG. 9 . 
         [0142]    Then, based on the image data produced from the diagnostic radiation  16 , the real-image diagnosing section  142  performs a real-image diagnostic process for diagnosing the electronic cassette  20  for an unimageable region in which an image cannot be captured (step S 55 ). The unimageable region, which is detected by the real-image diagnosing section  142 , is referred to as a second unimageable region. The real-image diagnosing section  142  sends the results of the real-image diagnostic process to the console  24  through the communication unit  88 . In step S 55 , the real-image diagnosing section  142  operates in the same manner as in step S 7  shown in  FIG. 9 . 
         [0143]    Then, the function limiter  134  limits the function of the electronic cassette  20 , which is in continuous use, depending on the results of the real-image diagnostic process (step S 56 ). In other words, the function limiter  134  limits the function of the electronic cassette  20  so that an image will not be acquired from the unimageable region that was detected by the real-image diagnosing section  142 . For example, the function limiter  134  may inhibit electric power from being supplied to gate ICs  114  and ASICs  116 , so as not to read electric charges stored in pixels  104  that belong to the diagnosed second unimageable region. Alternatively, the function limiter  134  may trim the image data generated based on the radiation  16 , so as to remove such image data from the second unimageable region. The function limiter  134  sends information to the console  24  through the communication unit  88  concerning the function that was limited depending on the result of the real-image diagnostic process. In step S 56 , the function limiter  134  operates in the same manner as in step S 8  of  FIG. 9 . 
         [0144]    Then, the controller  152  of the console  24  controls the display unit  154  in order to display the function that was limited depending on the results of the real-image diagnostic process, and the function that was limited depending on the results of the real-image diagnostic process (step S 57 ). In the same manner as shown in  FIG. 8 , the controller  152  may control the display unit  154  to display the second unimageable region that was diagnosed by the real-image diagnostic process. If an image capturing area is limited by inhibiting electric power from being supplied to the gate ICs  114 , which read the stored electric charges from pixels  104  in the second unimageable region, then the actually limited image capturing area becomes wider than, and hence is not in agreement with, the second unimageable region. In this case, the actually limited image capturing area, rather than the second unimageable region, is displayed as an unimageable region. The function that was limited depending on the results of the real-image diagnostic process may be displayed along with the function that was limited depending on the results of the self-diagnostic process. For example, the first unimageable region and the second unimageable region may be displayed together. In step S 57 , the controller  152  operates in the same manner as in step S 9  shown in  FIG. 9 . 
         [0145]    As described above, the first fault diagnosing process is carried out periodically. If an external pressure, which is equal to or greater than the threshold value is detected, or if dropping of the electronic cassette  20  is detected, then the first fault diagnosing process is performed, and the intervals at which the first fault diagnosing process is carried out are shortened periodically. Consequently, the degree to which the electronic cassette  20  deteriorates over time can accurately be diagnosed. The results of the diagnostic process, which are sent from the console  24  to the server  32 , allows the maintenance provider to predict a timing at which a replacement electronic cassette  20  should be purchased, as well as a timing at which parts of the electronic cassette  20  should be replaced. 
         [0146]    If an external pressure, which is equal to or greater than the threshold value, is detected, or if dropping of the electronic cassette  20  is detected, then the second fault diagnosing process for diagnosing image resolution is subsequently carried out along with the first fault diagnosing process. Accordingly, the degree to which the resolution of the electronic cassette  20  has decreased can be diagnosed accurately. 
         [0147]    The results of the diagnostic process are displayed on the display unit  154 , thereby allowing the user to recognize the degree to which the electronic cassette  20  has deteriorated at present. 
         [0148]    Inasmuch as the function of the electronic cassette  20  is limited depending on the results of the diagnostic process, the electronic cassette  20  is prevented from becoming unduly heated, and hence electric power consumption of the electronic cassette  20  is minimized. While the fault diagnosing section  132  is performing a diagnostic process, the radiation device  18  is inhibited from applying image-capturing radiation  16 , so that the subject  14  is prevented from being unduly exposed to radiation  16  during the diagnostic process. 
         [0149]    The second embodiment described above can be modified in the following ways. 
       (Modification 1) 
       [0150]    In the second embodiment, if an external pressure is equal to or greater than the threshold value, or if dropping of the electronic cassette  20  is detected (YES in step S 22  or YES in step S 23  of  FIG. 12 ), control proceeds to step S 24 . However, if either one of a detected external pressure, a detected environmental humidity value, a detected environmental temperature value, and a detected temperature change is equal to or greater than a threshold value, or if dropping of the electronic cassette  20  is detected, then control may proceed to step S 24 . This is because the electronic cassette  20  may possibly be suffering from a fault due to the environmental temperature or the environmental humidity. In this case, in step S 29  of  FIG. 13 , the fault diagnosing section  132  judges whether or not an external pressure, an environmental humidity value, an environmental temperature, or a temperature change is equal to or greater than a threshold value, or if dropping of the electronic cassette  20  has been detected thus far. If the fault diagnosing section  132  decides that an external pressure, an environmental humidity value, an environmental temperature, or a temperature change is equal to or greater than a threshold value, or that dropping of the electronic cassette  20  has been detected, then control proceeds to step S 30 . If the fault diagnosing section  132  decides that an external pressure, an environmental humidity value, an environmental temperature, or a temperature change is not equal to or greater than a threshold value, or that dropping of the electronic cassette  20  has not been detected, then control returns to step S 21  of  FIG. 21 . 
       (Modification 2) 
       [0151]    In the second embodiment, if an external pressure is equal to or greater than the threshold value, or if dropping of the electronic cassette  20  is detected, then the fault diagnosing section  132  performs the first fault diagnosing process and the second fault diagnosing process (step S 25  and step S 27  of  FIG. 12 ). However, the fault diagnosing section  132  need not necessarily perform the second fault diagnosing process. If the fault diagnosing section  132  does not perform the second fault diagnosing process, then control goes from step S 25  back to step S 21 . In this case, steps S 26 , S 27  are no longer required, since image resolution is highly likely not to have decreased significantly immediately after an external pressure was detected, which is equal to or greater than the threshold value, or immediately after dropping of the electronic cassette  20  was detected. 
       (Modification 3) 
       [0152]    In the second embodiment, if an external pressure is equal to or greater than the threshold value, or if dropping of the electronic cassette  20  is detected (YES in step S 22  or YES in step S 23  of  FIG. 12 ), the period of the periodic diagnostic process is shortened. However, if the present period of the periodic diagnostic process is equal to or smaller than a predetermined amount (e.g., 1 month, 15 days, or the like), then the period of the periodic diagnostic process may not be shortened further. Since the electronic cassette  20  cannot be used during the periodic diagnostic process, the above limitation on shortening of the period is effective to prevent patient diagnoses from being adversely affected by overly frequent repetitions of the periodic diagnostic process, e.g., ones that are performed each day. 
       (Modification 4) 
       [0153]    In the second embodiment, if an external pressure equal to or greater than the threshold value, or dropping of the electronic cassette  20  has been detected thus far, the second fault diagnosing process is carried out as part of the periodic diagnostic process along with the first fault diagnosing process (steps S 29  through S 31  of  FIG. 13 ). However, even if an external pressure equal to or greater than the threshold value, or dropping of the electronic cassette  20  has been detected thus far, the second fault diagnosing process may not be carried out. If the second fault diagnosing process is not carried out, then steps S 29  through S 31  are no longer required, and control goes from step S 28  back to step S 21  of  FIG. 12 . The resolution diagnostic process may be included as part of the first fault diagnosing process. 
       (Modification 5) 
       [0154]    According to Modification 5, if a detected external pressure, environmental humidity, environmental temperature, or temperature change is equal to or greater than a predetermined value, or if the fault diagnosing section  132  counts the number of times that the detected external pressure, the environmental humidity, the environmental temperature, or the temperature change is equal to or greater than the predetermined value, and the counted number exceeds a predetermined number, then the fault diagnosing section  132  shortens the period of the periodic diagnostic process. In such a situation, since the electronic cassette  20  is considered to deteriorate quickly, the period of the periodic diagnostic process is shortened. 
         [0155]    The fault diagnosing section  132  may operate according to Modification 5 after having detected an external pressure equal to or greater than the threshold value, or after having detected dropping of the electronic cassette  20 . Alternatively, the fault diagnosing section  132  may operate according to Modification 5 regardless of whether an external pressure equal to or greater than the threshold value or dropping of the electronic cassette  20  has been detected. 
       (Modification 6) 
       [0156]    In the second embodiment, the image capture controller  130  captures two images based on application of diagnostic radiation  16  for performing a real-image diagnosis and a resolution diagnosis, respectively. However, the image capture controller  130  may capture only a single image from the diagnostic radiation  16 . If the image capture controller  130  captures a single image from the diagnostic radiation  16 , then the fault diagnosing section  132  performs a real-image diagnosis and a resolution diagnosis using image data of the captured signal image. More specifically, the fault diagnosing section  132  captures an image from the fault diagnosing section  132  that has been passed through a resolution test chart, and the fault diagnosing section  132  performs both real-image diagnosis and resolution diagnosis using the image data of the captured image. 
       (Modification 7) 
       [0157]    In the second embodiment, both a self-diagnostic process and a real-image diagnostic process are carried out as the first fault diagnosing process. However, either one of a self-diagnostic process and a real-image diagnostic process may be carried out. Alternatively, a different diagnostic process, other than a self-diagnostic process and a real-image diagnostic process, may be carried out as the first fault diagnosing process. Although according to the second embodiment, a resolution diagnostic process is carried out as the second fault diagnosing process, another diagnostic process may be carried out in addition to or instead of the resolution diagnostic process. 
       (Modification 8) 
       [0158]    In the second embodiment, if the real-image diagnosing section  142  diagnoses a second unimageable region, then the function of the electronic cassette  20  is limited in step S 56  of  FIG. 15  so as not to produce an image in the second unimageable region. However, the function of the electronic cassette  20  may not be limited. If the function of the electronic cassette  20  is not limited, then steps S 56 , S 57  are dispensed with, and instead of steps S 56  and S 57 , the second unimageable region is displayed on the display unit  154 . 
       (Modification 9) 
       [0159]    A display panel such as a liquid crystal panel or the like may be disposed on the reverse side of the panel unit  40 , i.e., a surface thereof remote from the image capturing surface  46 , and an unimageable region diagnosed by the self-diagnostic process or the real-image diagnostic process may be displayed on the display panel, which is provided on the reverse side of the panel unit  40 . Thus, the user can intuitively recognize which region is an unimageable region simply by turning the panel unit  40  over. Light-emitting elements, such as LEDs or the like, may be placed at positions corresponding to the region graduations on the electronic cassette  20 , and the cassette controller  84  may turn such light-emitting elements on and off in order to indicate an unimageable region. 
       (Modification 10) 
       [0160]    The real-image diagnosing section  142  diagnoses an unimageable region based on image data generated by the idle exposure process. However, the real-image diagnosing section  142  may diagnose an unimageable region based on image data that is generated by a blank reading process. Such a blank reading process refers to a process in which radiation  16  is not applied to the electronic cassette  20 , and electric signals stored in the pixels  104 , i.e., electric signals representative of dark current, are read. 
       (Modification 11) 
       [0161]    In mammography, it is important to capture images of the armpits because cancer often occurs in the armpits. As shown in  FIG. 10 , in mammography, an image of the breast  160  is captured while the breast  160  is placed on the panel unit  40  of the electronic cassette  20 . Among the end areas of the imageable region  50 , one end area  162  near the breast wall serves as a region for capturing an image of the armpit. However, if the end area  162  of the electronic cassette  20  near the breast wall is detected as an unimageable region, then an image of the armpit cannot be captured. If the end area  162  of the imageable region  50  is diagnosed as being an unimageable region by the self-diagnostic process and the real-image diagnostic process, then the function limiter  134  limits a mammographic function. In this case, for example, the user operates the input unit  150  of the console  24  to select an image capturing order from among a plurality of image capturing orders. At this time, the function limiter  134  may limit the types of available image capturing processes, so that a mammographic image capturing order cannot be selected via the console  24 . 
       (Modification 12) 
       [0162]    In the second embodiment, the radiation detector  56  includes on a single substrate, e.g., a glass substrate, a single radiation conversion panel  54  including the TFTs  102  and the pixels  104 . According to Modification 12, as shown in  FIG. 16 , the radiation detector  56  includes on a substrate a plurality of respective radiation conversion panels  54 , each of which includes a plurality of TFTs  102  and a plurality of pixels  104 . The radiation conversion panels  54 , which are bonded together without gaps therebetween, convert phosphorescence generated by the scintillator  52  into electric signals. The radiation conversion panels  54  collectively are capable of producing a single radiographic image. According to Modification 12, the operation sequence according to the flowchart shown in  FIGS. 12 and 13  is performed with respect to each of the radiation conversion panels  54 , thereby managing each of the radiation conversion panels  54 . 
       (Modification 13) 
       [0163]    In the second embodiment, the TFTs  102  and the pixels  104  of the radiation conversion panel  54  are disposed on a single substrate, e.g., a glass substrate. According to Modification 13, a single radiation conversion panel  54  is produced by forming a plurality of TFTs  102  and a plurality of pixels  104  on each of a plurality of substrates, i.e., silicon wafers, and thereafter bonding the substrates together. 
       (Modification 14) 
       [0164]    Modifications 1 through 13 may be combined together insofar as they do not counteract one another or operate in a contradictory manner. 
         [0165]    Although various embodiments of the present invention have been described above, the technical scope of the present invention is not limited by the scope of the respective embodiments. It will be obvious to those skilled in the art that various changes or improvements can be made to each of the above embodiments. It is also apparent from the scope of the patent claims that such changes and improvements are included within the technical scope of the present invention.