Abstract:
The disclosed radiograph acquisition device has: a selection unit that selects one radiation detection device from among a plurality of radiation detection devices that can convert radiation to radiographs; and an acquisition unit that acquires the radiograph of one radiation detection device when radiation is radiated at a subject, and the radiograph of at least one other radiation detection device aside from the one radiation device among the plurality of radiation detection devices.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a radiographic image capturing system (radiographic imaging system) and a radiographic image capturing method (radiographic imaging method) for applying radiation to a subject and converting radiation that has passed through the subject into a radiographic image with a radiation detecting device. The present invention also concerns a radiographic image acquiring apparatus (radiograph acquisition device) for acquiring a radiographic image from a radiation detecting device. 
       BACKGROUND ART 
       [0002]    In the medical field, it has widely been customary to apply radiation to a subject, to convert radiation that has passed through the subject into a radiographic image with a radiation conversion panel, and to acquire the radiographic image from the radiation conversion panel. One known form of radiation conversion panel is a stimulable phosphor panel for storing radiation energy representing a radiographic image in a phosphor, and retrieving the radiographic image as stimulated light emitted in response to application of stimulating light thereto. The stimulable phosphor panel is supplied to a radiographic image acquiring apparatus, which performs a process of acquiring the radiographic image in order to obtain the radiographic image as a visible image. 
         [0003]    In operating rooms or the like, it is necessary to immediately read radiographic images from radiation conversion panels, which have captured the radiographic images, and to display the radiographic images in order to treat subjects (patients) quickly and properly. Radiation conversion panels that have been developed to meet such requirements include a direct-conversion-type radiation detector, which employs a solid-state detector for converting radiation directly into electric signals, and an indirect-conversion-type radiation detector, which employs a scintillator for converting radiation into visible light and a solid-state detector for converting the visible light into electric signals. 
         [0004]    Certain medical organizations incorporate a radiographic image capturing system having a plurality of radiation detecting devices with radiation conversion panels employed therein (see Japanese Laid-Open Patent Publication No. 2004-073462 and Japanese Laid-Open Patent Publication No. 2009-219586). 
         [0005]    It may be assumed that all of the radiation detecting devices of such a radiographic image capturing system include therein direct-conversion-type or indirect-conversion-type radiation conversion panels (hereinafter referred to as “FPDs” (Flat Panel Detectors)). A process of applying radiation to a subject and acquiring a radiographic image of the subject from such radiation conversion panels will be described below. 
         [0006]    First, a doctor or radiological technician selects one of the radiation detecting devices, and makes the FPD of the selected radiation detecting device ready to store electric signals (electric charges) converted from the radiation. 
         [0007]    Then, the doctor or radiological technician places a subject (patient) between a radiation source and the selected radiation detecting device. When the radiation source applies radiation through the subject to the radiation detecting device, the FPD converts radiation that has passed through the subject into electric charges and stores the electric charges. After radiation has been applied to the radiation detecting device, the radiographic image acquiring apparatus acquires the electric charges stored in the FPD as a radiographic image representative of the subject. 
       SUMMARY OF INVENTION 
       [0008]    With the radiographic image capturing system according to the background art, as described above, one radiation detecting device is selected, radiation is applied from the radiation source through the subject to the selected radiation detecting device, and the radiographic image acquiring apparatus acquires a radiographic image from the selected radiation detecting device. In this manner, the subject and the radiographic image are associated with each other. 
         [0009]    If the selected radiation detecting device is in a certain state (e.g., if the selected radiation detecting device fails, or if the amount of electric power charged in a battery thereof is insufficient to capture a radiographic image, or if the selected radiation detecting device is physically spaced from the subject (in terms of distances, angles, and positions in relation to an image capturing base used in combination therewith) such that the selected radiation detecting device cannot be used, then the selected radiation detecting device is replaced with another radiation detecting device. If radiation is applied from the radiation source through the subject to the other radiation detecting device, the radiographic image generated by the other radiation detecting device is representative of the subject. 
         [0010]    However, if the doctor or radiological technician forgets to indicate to the radiographic image acquiring apparatus that the radiation detecting devices have been changed in order to capture the radiographic image, then the radiographic image acquiring apparatus is likely to acquire the radiographic image from the selected radiation detecting device, and to associate the subject and the acquired radiographic image with each other. As a result, in a case that the radiographic image acquiring apparatus acquires the radiographic image from the selected radiation detecting device, since the acquired radiographic image does not represent the subject, the radiographic image acquiring apparatus judges the image capturing process as a failure, and indicates that a process for capturing a radiographic image of the subject should be applied again. 
         [0011]    Stated otherwise, if a radiation detecting device (another radiation detecting device) having an FPD that is actually irradiated with radiation, and a radiation detecting device (a selected radiation detecting device) having an FPD from which the radiographic image is acquired are not the same as each other, then the radiographic image capturing system according to the background art does not acquire a radiographic image representative of the subject from the other radiation detecting device, but rather, performs another process for capturing a radiographic image of the subject again. Consequently, the radiographic image capturing system tends to expose the subject to radiation unnecessarily. 
         [0012]    The present invention has been made in order to eliminate the above difficulties. It is an object of the present invention to provide a radiographic image acquiring apparatus, a radiographic image capturing system, and a radiographic image capturing method, which are capable of reliably acquiring a radiographic image representative of a subject while preventing the subject from being needlessly exposed to radiation. 
         [0013]    A radiographic image acquiring apparatus according to the present invention comprises a selector for selecting one of a plurality of radiation detecting devices, each of which is capable of converting radiation into a radiographic image, and an acquirer for acquiring a radiographic image from the one radiation detecting device and a radiographic image from at least one other radiation detecting device that differs from the one radiation detecting device, from among the plurality of radiation detecting devices, in a case that a subject is irradiated with radiation. 
         [0014]    A radiographic image capturing system according to the present invention comprises a plurality of radiographic image capturing apparatus including respective radiation sources each of which outputs radiation, and respective radiation detecting devices each of which converts the radiation into a radiographic image, and a radiographic image acquiring apparatus including a selector for selecting the radiation detecting device of one radiographic image capturing apparatus from among the radiation detecting devices of the plurality of radiographic image capturing apparatus, and an acquirer for acquiring a radiographic image from the one radiation detecting device and a radiographic image from at least one other radiation detecting device that differs from the one radiation detecting device, from among the radiation detecting devices of the plurality of radiographic image capturing apparatus, in a case that a subject is irradiated with radiation. 
         [0015]    A method of capturing a radiographic image according to the present invention comprises the steps of selecting, with a selector, one of a plurality of radiation detecting devices, each of which is capable of converting radiation into a radiographic image, applying radiation to the subject, and acquiring, with an acquirer, a radiographic image from the one radiation detecting device and a radiographic image from at least one other radiation detecting device that differs from the one radiation detecting device, from among the plurality of radiation detecting devices. 
         [0016]    According to the above invention, the acquirer acquires both a radiographic image from the one radiation detecting device selected by the selector, and a radiographic image from at least one other radiation detecting device that differs from the one radiation detecting device. 
         [0017]    If radiation is applied through the subject to the one radiation detecting device, then the control device acquires a radiographic image from the one radiation detecting device, thereby acquiring a radiographic image representative of the subject. If radiation is applied through the subject to the other radiation detecting device, then the control device acquires a radiographic image from the other radiation detecting device, thereby acquiring a radiographic image representative of the subject. 
         [0018]    More specifically, in a case that the one image capturing apparatus is changed over to the other image capturing apparatus in order to capture a radiographic image, it is desirable for the selector to select the other image capturing apparatus before the radiographic image has been captured. However, the other image capturing apparatus may not be selected for capturing a radiographic image, and hence, a radiographic image may not be acquired from the other image capturing apparatus. According to the present embodiment, regardless of whether or not the selector has selected the other image capturing apparatus, both a radiographic image from the one radiation detecting device and a radiographic image from the other radiation detecting device are acquired, thereby reliably acquiring a radiographic image representative of the subject. 
         [0019]    According to the present embodiment, therefore, regardless of whether the one radiation detecting device or the other radiation detecting device is used to capture a radiographic image, the acquirer reliably acquires a radiographic image representative of the subject. As a result, the subject is prevented from being exposed to radiation unnecessarily. 
         [0020]    The radiographic image acquiring apparatus may further comprise a judging section for judging whether or not the radiographic image from the one radiation detecting device is a significant radiographic image representative of the subject. 
         [0021]    Therefore, it is possible to determine whether or not the radiographic image from the one radiation detecting device is a significant radiographic image representative of the subject. A significant radiographic image, which is representative of the subject, is a radiographic image represented by digital image data, an average luminance value or a variance luminance value of which is equal to or greater than a prescribed threshold value, for example. 
         [0022]    The radiographic image acquiring apparatus may further comprise an indicating unit for externally indicating a judgment result from the judging section, if the judging section judges that the radiographic image from the one radiation detecting device is not the significant radiographic image. 
         [0023]    Therefore, the doctor or radiological technician can easily recognize that an image capturing process has been carried out without requiring the selector to select the other radiation detecting device. 
         [0024]    The judging section judges whether or not the radiographic image from the other radiation detecting device is the significant radiographic image, if the judging section judges that the radiographic image from the one radiation detecting device is not the significant radiographic image, thereby determining whether or not the radiographic image from the other radiation detecting device is the significant radiographic image. 
         [0025]    The acquirer successively acquires radiographic images from other radiation detecting devices until the judging section has found the significant radiographic image, if the judging section judges that the radiographic image from the one radiation detecting device is not the significant radiographic image. 
         [0026]    The selector selects the one radiation detecting device and designates an imaging method to be carried out upon application of radiation to the subject using the one radiation detecting device, and the acquirer acquires a radiographic image preferentially from a radiation detecting device, from among the other radiation detecting devices, which produces a radiographic image according to the imaging method, or acquires a radiographic image preferentially from another radiation detecting device that is in close proximity to the one radiation detecting device. 
         [0027]    If the one radiation detecting device is not used, but rather another radiation detecting device is used to capture a radiographic image, then it is assumed it is highly likely to have captured a radiographic image using another radiation detecting device, according to the same imaging method as the imaging method (e.g., an upright imaging process or a supine imaging process) of the one radiation detecting device, or to have captured a radiographic image using another radiation detecting device that is closest in proximity to the one radiation detecting device. It is thus possible to acquire a radiographic image preferentially from another radiation detecting device according to the same imaging method, or from another radiation detecting device that is closest in proximity to the one radiation detecting device, thereby making it possible to acquire a significant radiographic image quickly and reliably. 
         [0028]    The radiographic image acquiring apparatus may further comprise a switcher for switching selection of the one radiation detecting device to selection of the other radiation detecting device, if the judging section judges that the radiographic image from the other radiation detecting device is the significant radiographic image. 
         [0029]    Since a next imaging cycle may be carried out using the other radiation detecting device, which has produced a significant radiographic image, the switcher automatically switches from selection of the one radiation detecting device to selection of the other radiation detecting device, thereby preventing the other radiation detecting device from being unselected due to an oversight in a subsequent image capturing cycle. 
         [0030]    The radiographic image acquiring apparatus preferably further comprises an output unit for externally outputting the radiographic image, which the judging section has judged as being the significant radiographic image. 
         [0031]    The doctor can thus interpret a significant radiographic image for facilitating diagnosis. 
         [0032]    In a case that radiation is applied to the subject in an image capturing chamber, the acquirer acquires the radiographic image from the one radiation detecting device and the radiographic image from the other radiation detecting device, which also is present in the image capturing chamber, from among the plurality of radiation detecting devices. 
         [0033]    Inasmuch as a radiographic image is acquired from the radiation detecting device that is present in the image capturing chamber, it is possible to reliably prevent image acquiring processes from being performed needlessly on radiation detecting devices that are present outside of the image capturing chamber, while also efficiently carrying out a process of acquiring radiographic images. 
         [0034]    The radiographic image acquiring apparatus further comprises an identification information storage unit for storing identification information of the plurality of radiation detecting devices that are present in an image capturing chamber in a case that radiation is applied to the subject in the image capturing chamber, wherein the acquirer acquires radiographic images from the plurality of radiation detecting devices that are present in the image capturing chamber based on the identification information stored in the identification information storage unit. 
         [0035]    Inasmuch as radiographic images are acquired only from radiation detecting devices that are present in the image capturing chamber, it is possible to reliably prevent image acquiring processes from being performed in error on radiation detecting devices that are present outside of the image capturing chamber, while also efficiently carrying out the process of acquiring radiographic images. 
         [0036]    Preferably, each of the radiation detecting devices comprises a radiation conversion panel for converting radiation into electric charges, storing the electric charges, and outputting the stored electric charges as an electric signal to an external device. The radiation conversion panel is made ready to store electric charges before radiation is applied to the subject. 
         [0037]    It is not necessary to irradiate the radiation detecting devices with triggering radiation in order to instruct the radiation conversion panel to store electric charges prior to a main image capturing process. Therefore, the arrangement for instructing the storage of electric charges is simplified, and the dose of radiation to which the subject is exposed can be reduced. 
         [0038]    According to the present invention, regardless of whether the one radiation detecting device or the other radiation detecting device is used to capture a radiographic image, the acquirer reliably acquires a radiographic image representative of the subject. As a result, the subject is prevented from being exposed to radiation needlessly. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0039]      FIG. 1  is a block diagram of a radiographic image capturing system according to an embodiment of the present invention; 
           [0040]      FIG. 2  is a schematic view of a radiation detecting device; 
           [0041]      FIG. 3  is a circuit diagram of the radiation detecting device shown in  FIG. 2 ; 
           [0042]      FIG. 4  is a detailed block diagram of the radiographic image capturing system shown in  FIG. 1 ; 
           [0043]      FIG. 5  is a flowchart of an operation sequence of the radiographic image capturing system according to the embodiment; and 
           [0044]      FIG. 6  is a timing chart showing an elapse of time from turning on of an exposure switch to completion of acquisition of a radiographic image. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0045]    A radiographic image capturing system incorporating a radiographic image acquiring apparatus according to an embodiment of the present invention will be described below with reference to  FIGS. 1 through 6 , in relation to a radiographic image capturing method carried out by the radiographic image capturing system. 
         [0046]    As shown in  FIG. 1 , a radiographic image capturing system  10  according to the present embodiment includes a medical information system  12  (HIS: Hospital Information System) for managing medical procedures in a hospital, a radiological information system  14  (RIS) for managing a process of capturing radiographic images in a radiological department, a viewer  16  which a doctor uses to make a diagnosis based on the interpretation of radiographic images, and consoles  24 ,  26 ,  28  disposed in respective processing chambers, which are located respectively adjacent to a plurality of image capturing chambers  18 ,  20 ,  22  of the radiological department, for managing and controlling respective image capturing apparatus  44 ,  46 ,  48  having different specifications. The HIS  12 , the RIS  14 , the viewer  16 , and the consoles  24 ,  26 ,  28  are interconnected via an in-hospital network  30 . In the processing chambers, respective cradles  32 ,  34 ,  36  are disposed for charging radiation detecting devices  52 ,  62 ,  72  connected respectively to the consoles  24 ,  26 ,  28 . 
         [0047]    The image capturing chamber  18  houses therein image capturing apparatus  44 ,  46  for capturing images of subjects  42  in a supine position (supine imaging process), an image capturing apparatus  48  for capturing an image of a subject  42  in an upright position (upright imaging process), and a control device (acquirer)  40  interconnecting the console  24  and the image capturing apparatus  44 ,  46 ,  48 . Each of the other image capturing chambers  20 ,  22  also houses therein the control device  40  and the image capturing apparatus  44 ,  46 ,  48 , although such devices have been omitted from illustration in  FIG. 1 . The consoles  24 ,  26 ,  28  and the corresponding control devices  40  jointly make up a radiographic image acquiring apparatus according to the present embodiment. 
         [0048]    The image capturing apparatus  44  has an image capturing base  50  and a radiation detecting device  52  placed on the image capturing base  50 . The image capturing apparatus  46  has an image capturing base  60  and a radiation detecting device  62  placed in the image capturing base  60 . The image capturing apparatus  48  has an upright image capturing base  70  and a radiation detecting device  72  placed in the image capturing base  70 . The image capturing apparatus  44 ,  46 ,  48  share a single radiation source  54 . When the radiation source  54  applies radiation  56  to the subject  42 , the irradiated radiation detecting device converts the radiation  56 , which has passed through the subject  42 , into a radiographic image representative of the subject  42 , whereas the other two radiation detecting devices produce radiographic images that are not representative of the subject  42 . 
         [0049]    In the image capturing apparatus  44 , the radiation detecting device  52  is not housed in the image capturing base  50 . The image capturing apparatus  44  is not limited to performing the supine imaging process illustrated in  FIG. 1 , but may also capture an image of a desired region (legs or the like) of the subject  42  while the subject  42  sits on the image capturing base  50 , for example. In  FIG. 1 , the control device  40  and the image capturing apparatus  44 ,  46 ,  48  are illustrated as being interconnected by wired links. However, the control device  40  and the image capturing apparatus  44 ,  46 ,  48  may be interconnected via wireless links. In  FIG. 1 , the radiation detecting devices  52 ,  62 ,  72  are disposed respectively in the image capturing apparatus  44 ,  46 ,  48 . According to the present embodiment, however, at least two radiation detecting devices may be disposed in the image capturing apparatus  44 ,  46 ,  48 . In such a case, one of the three image capturing apparatus  44 ,  46 ,  48 , which is free of a radiation detecting device, may utilize the radiation detecting device of one of the other image capturing apparatus. 
         [0050]    As shown in  FIG. 2 , each of the radiation detecting devices  52 ,  62 ,  72  employed by the image capturing apparatus  44 ,  46 ,  48  has a casing  80  made of a material that is permeable to radiation  56 . The casing  80  houses therein a grid  82  for removing scattered rays of radiation  56  from the subject  42  (see  FIG. 1 ), a radiation conversion panel  84  for converting radiation  56  that has passed through the subject  42  into electric image information, and a lead plate  86  for absorbing back scattered rays of radiation  56 . The grid  82 , the radiation conversion panel  84 , and the lead plate  86  are successively arranged from an irradiated surface of the casing  80  toward a bottom surface of the casing  80 . The irradiated surface of the casing  80  may be constructed as the grid  82 . 
         [0051]    The radiation conversion panel  84 , which is in the form of a planar radiation detector (FPD), comprises a direct-conversion-type radiation detector for detecting and converting radiation  56  directly into electric charges and storing the electric charges, or an indirect-conversion-type radiation detector for converting radiation  56  into visible light, converting the visible light into electric charges, and storing the electric charges. It is assumed hereinafter that the radiation conversion panel  84  comprises an indirect-conversion-type radiation detector. 
         [0052]    The casing  80  also houses therein a battery  88 , which serves as a power supply for the radiation conversion panel  84 , a controller  90  for energizing the radiation conversion panel  84  with electric power supplied from the battery  88 , and a transceiver  92  for sending a radiographic image of the subject  42 , which is represented by electric charges stored in the radiation conversion panel  84 , via the control device  40  (see  FIG. 1 ) to the consoles  24 ,  26 ,  28 . The casing  80  has on a side thereof a power supply switch  94  for activating the radiation detecting device  52 ,  62 ,  72 . 
         [0053]    A circuit arrangement inside the radiation detecting device  52 ,  62 ,  72  will be described below with reference to  FIG. 3 . 
         [0054]    The radiation conversion panel  84  comprises an array of TFTs  106  arranged in rows and columns, and a photoelectric conversion layer  101  made of a material such as amorphous silicon (a-Si) or the like, and having solid-state detectors (hereinafter referred to as pixels)  100  provided thereon for converting visible light into electric signals, the photoelectric conversion layer  101  being disposed on the array of TFTs  106 . The pixels  100 , which are supplied with a bias voltage Vb from the battery  88 , store electric charges generated by conversion of visible light into electric signals (analog signals). The TFTs  106  are turned on along each row at a time to read the electric charges as an image signal. 
         [0055]    The TFTs  106  connected to the respective pixels  100  are connected to respective gate lines  102  that extend parallel to the rows, and to respective signal lines  104  that extend parallel to the columns. The gate lines  102  are connected to a line scanning driver  108 , and the signal lines  104  are connected to a multiplexer  110 . The gate lines  102  are supplied with control signals Von, Voff for turning on and off the TFTs  106  along the rows from the line scanning driver  108 . The line scanning driver  108  comprises a plurality of first switches SW 1  for switching between the gate lines  102 , and an address decoder  112  for outputting a selection signal for selecting one of the first switches SW 1  at a time. The address decoder  112  is supplied with an address signal from the controller  90 . 
         [0056]    The signal lines  104  are supplied with electric charges stored in the pixels  100  through the TFTs  106  arranged in the columns. The electric charges supplied to the signal lines  104  are amplified by amplifiers  114 . The amplifiers  114  are connected through respective sample and hold circuits  116  to the multiplexer  110 . The multiplexer  110  comprises a plurality of second switches SW 2  for successively switching between the signal lines  104 , and an address decoder  118  for outputting a selection signal for selecting one of the second switches SW 2  at a time. The address decoder  118  is supplied with an address signal from the controller  90 . The multiplexer  110  is connected to an A/D converter  120 . A radiographic image signal is converted by the A/D converter  120  into a digital image signal, which is supplied to the controller  90 . The controller  90  stores the radiographic image signal as a digital image signal in an image memory  130 , or alternatively, sends the radiographic image signal stored in the image memory  130  through the transceiver  92  to the control device  40 . 
         [0057]    The TFTs  106 , which function as switching elements, may be combined with any of various other image capturing devices such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor, or may be replaced with a CCD (Charge-Coupled Device) image sensor, in which electric charges are shifted and transferred by shift pulses that correspond to gate signals used in the TFTs  106 . 
         [0058]      FIG. 4  is a detailed block diagram of the radiographic image capturing system  10 . Components of the radiographic image capturing system  10 , which have not been described with reference to  FIGS. 1 through 3 , will primarily be described below. 
         [0059]    Each of the radiation detecting devices  52 ,  62 ,  72  has an ID memory  132  storing therein ID information for identifying a particular radiation detecting device. The controller  90  performs a calibration process (a process of correcting brightness, darkness, and defects in the radiographic images) on the radiation conversion panel  84 , either periodically or upon activation of the radiation detecting devices  52 ,  62 ,  72 , and stores various tables generated by the calibration process for brightness, darkness, and defect correction in the image memory  130 . The calibration process that is carried out is a known process (see, for example, Japanese Laid-Open Patent Publication No. 2009-028373). 
         [0060]    The radiation source  54  has a controller  134  for controlling the radiation source  54  to emit radiation  56 , and a transceiver  136  for sending signals to and receiving signals from the control device  40 . 
         [0061]    The control device  40  has a memory  138  for storing the various tables referred to above, and a transceiver  140  for sending signals to and receiving signals from the transceivers  92  of the radiation detecting devices  52 ,  62 ,  72 , the transceiver  136  of the radiation source  54 , and the consoles  24 ,  26 ,  28 . The transceiver  140  sends radiation image signals acquired from the image memory  130  via the controller  90  and the transceiver  92  to the consoles  24 ,  26 ,  28 . 
         [0062]    Each of the consoles  24 ,  26 ,  28  has a controller  142 , a transceiver  144 , an ID memory (identification information storage unit)  146 , an order information storage unit  148 , an image capturing condition setting section  150 , an image processor  152 , an image memory  154 , a display unit (output unit, indicating unit)  156 , an image judging section (judging section, switcher)  157 , a speaker (indicating unit)  158 , an operating unit (selector, switcher)  159 , and an exposure switch  160 . 
         [0063]    The transceiver  144  sends signals to and receives signals from the HIS  12 , the RIS  14 , the viewer  16 , and the other consoles via the in-hospital network  30 , and also sends signals to and receives signals from the control device  40  and the cradles  32 ,  34 ,  36 . 
         [0064]    The controllers  142  of the consoles  24 ,  26 ,  28  control components in each of the respective consoles  24 ,  26 ,  28 . 
         [0065]    Each of the controllers  142  stores image capturing order information acquired from the RIS  14  in the order information storage unit  148 . The controller  142  also stores image capturing conditions for the image capturing apparatus  44 ,  46 ,  48 , which have been acquired from the RIS  14 , or which have been set by the doctor or radiological technician by operating the operating unit  159  such as a keyboard, a mouse, or the like, in the image capturing condition setting section  150 . 
         [0066]    The order information is generated by the doctor using the RIS  14 . The order information includes patient information for identifying the patient, such as the name, age, gender, etc., of the patient, an image capturing apparatus to be used to capture a radiographic image, a body region to be imaged, an imaging method such as a supine imaging process or an upright imaging process, and image capturing conditions. The image capturing conditions refer to conditions for determining a dose of radiation to be applied to the subject  42 , e.g., a tube voltage and a tube current of the radiation source  54 , an irradiation time of the radiation  56 , etc. 
         [0067]    The doctor or radiological technician operates the operating unit  159  in order to select one of the three image capturing apparatus  44 ,  46 ,  48 , which are present in the respective image capturing chambers  18 ,  20 ,  22 , as an image capturing apparatus to be used to capture radiographic images, as well as to select an imaging method for the selected image capturing apparatus, and to enter the ID information (identification information) of a radiation detecting device (one radiation detecting device) to be used by the selected image capturing apparatus. The controller  142  sets the selected image capturing apparatus and the selected imaging method, which are included in the image capturing conditions, in the image capturing condition setting section  150 . 
         [0068]    The doctor or radiological technician operates the operating unit  159  in order to enter, in addition to the ID information of the radiation detecting device used by the selected image capturing apparatus, the ID information of all of the radiation detecting devices  52 ,  62 ,  72  that are present in the image capturing chambers  18 ,  20 ,  22 , as well as the ID information of any radiation detecting devices that are currently being charged by the cradle connected to the selected image capturing apparatus. The entered ID information is stored in the ID memory  146 . In addition to the ID information referred to above, the ID memory  146  may store ID information of all of the radiation detecting devices that are owned by the hospital. Instead of entering ID information through the operating unit  159 , bar codes representative of the ID information may be applied to the respective radiation detecting apparatus, and such bar codes may be read by a bar-code reader, not shown, in order to store the ID information of the radiation detecting apparatus in the ID memory  146 . 
         [0069]    In the event that the doctor or radiological technician turns on the exposure switch  160 , the controller  142  outputs to the control device  40  the image capturing conditions that are set in the image capturing condition setting section  150 , and the ID information, which is stored in the ID memory  146 , of all of the radiation detecting devices  52 ,  62 ,  72  in the selected image capturing chamber. 
         [0070]    In accordance with the image capturing conditions and the ID information, which are input to the control device  40 , the control device  40  activates the radiation detecting devices  52 ,  62 ,  72  of the respective image capturing apparatus  44 ,  46 ,  48  in the selected image capturing chamber, regardless of whether or not the power supply switch  94  has been turned on, thereby supplying the bias voltage Vb from the battery  88  to the radiation conversion panel  84  to ready the pixels  100  for storage of electric charges therein. 
         [0071]    In a state where the radiation conversion panel  84  of each of the radiation detecting devices  52 ,  62 ,  72  of the respective image capturing apparatus  44 ,  46 ,  48  is ready to store electric charges therein, the control device  40  controls the radiation source  54  so as to emit radiation  56 . 
         [0072]    After radiation  56  has been applied to the subject  42  (i.e., after a radiographic image of the subject  42  has been captured), the control device  40  successively acquires radiographic images obtained by the radiation detecting devices  52 ,  62 ,  72 , including the radiographic image obtained by the one radiation detecting device, and sends the acquired radiographic images to the consoles  24 ,  26 ,  28 . 
         [0073]    More specifically, the control device  40  initially acquires a radiographic image obtained by the one radiation detecting device, and outputs the acquired radiographic image to the consoles  24 ,  26 ,  28 . Thereafter, the control device  40  preferentially acquires a radiographic image obtained by another radiation detecting device, which is close in proximity to the one radiation detecting device, and outputs the acquired radiographic image to the consoles  24 ,  26 ,  28 . Alternatively, the control device  40  may acquire a radiographic image obtained by the one radiation detecting device, and send the acquired radiographic image to the consoles  24 ,  26 ,  28 . Thereafter, the control device  40  may preferentially acquire a radiographic image obtained by another radiation detecting device, the imaging method of which is the same as the one radiation detecting device, and sends the acquired radiographic image to the consoles  24 ,  26 ,  28 . 
         [0074]    While the control device  40  is successively acquiring radiographic images obtained by the radiation detecting devices  52 ,  62 ,  72 , if the image judging section  157  finds a significant (effective) radiographic image representative of the subject  42 , then the control device  40  immediately stops the process of acquiring radiographic images. 
         [0075]    While radiographic images are successively being input by the control device  40  from the radiation detecting devices  52 ,  62 ,  72  to the consoles  24 ,  26 ,  28 , the image judging section  157  judges whether or not there is a significant radiographic image representative of the subject  42 . 
         [0076]    More specifically, the image judging section  157  judges whether or not the radiographic image obtained by the one radiation detecting device is a significant radiographic image representative of the subject  42 . A significant radiographic image representative of the subject  42  is typified by a radiographic image, which is represented by digital image data the average luminance value or variance luminance value of which is equal to or greater than a prescribed threshold value, for example. More specifically, if the radiographic image represented by digital image data includes a white area representative of the subject  42  because the subject  42  absorbs a portion of the radiation  56 , then the average luminance value or variance luminance value of the image data is considered to be relatively high. Therefore, the image judging section  157  judges image data, the average luminance value or variance luminance value of which is equal to or greater than the threshold value, as a significant radiographic image representative of the subject  42 . The average luminance value or variance luminance value may be an average or variance value of the entire image data, or an average or variance value of a particular area of the image data that is representative of the subject  42 . 
         [0077]    If the image judging section  157  determines that the radiographic image obtained by the one radiation detecting device is a significant radiographic image, then the image judging section  157  causes the control device  40  to cancel the process of acquiring radiographic images, and outputs the radiographic image obtained by the one radiation detecting device to the image processor  152 . The image processor  152  processes the radiographic image, and the display unit  156  displays the processed radiographic image. 
         [0078]    If the image judging section  157  determines that the radiographic image obtained by the one radiation detecting device is not a significant radiographic image, and further determines that the radiographic image obtained by another radiation detecting device is a significant radiographic image, then the image judging section  157  causes the control device  40  to cancel the process of acquiring radiographic images, and warns (notifies) the doctor or radiological technician via the speaker  158  and/or the display unit  156  that a radiographic image of the subject  42  has been captured using a radiation detecting device (another radiation detecting device) other than the radiation detecting device (one radiation detecting device) set in the image capturing conditions. 
         [0079]    At the same time that the image judging section  157  provides the warning through the speaker  158  and/or the display unit  156 , the image judging section  157  may output the radiographic image obtained by the other radiation detecting device to the image processor  152 , so that the display unit  156  may display the processed radiographic image. 
         [0080]    If the image judging section  157  determines that neither one of the radiographic image obtained by the one radiation detecting device or the radiographic image obtained by another radiation detecting device is a significant radiographic image, then the image judging section  157  judges whether or not the radiographic image obtained by still another radiation detecting device is a significant radiographic image. If the radiographic image is a significant radiographic image, then the image judging section  157  warns the doctor or radiological technician again via the speaker  158  and/or the display unit  156 , and outputs the radiographic image obtained by the still other radiation detecting device to the image processor  152 , whereupon the display unit  156  displays the processed radiographic image. 
         [0081]    In other words, in the case that there are a plurality of other radiation detecting devices in the image capturing chambers  18 ,  20 ,  22 , the control device  40  successively acquires radiographic images from the other radiation detecting devices, and then sends the acquired radiographic images to the consoles  24 ,  26 ,  28  until the image judging section  157  finds a significant radiographic image. 
         [0082]    If the image judging section  157  determines that the radiographic image obtained by another radiation detecting device is a significant radiographic image, then the image judging section  157  assumes that the subject  42  should be irradiated with radiation  56  using the other radiation detecting device in a next imaging cycle, and replaces (switches from) the image capturing conditions, which are presently set in the image capturing condition setting section  150 , including the image capturing apparatus (one radiation detecting device), the imaging method, and the ID information, with (to) the image capturing conditions including the image capturing apparatus, the imaging method, and the ID information, which correspond to the other radiation detecting device. 
         [0083]    It has been described above that the image judging section  157  judges whether or not the image data represent a significant radiographic image representative of the subject  42  based on the average luminance value or variance luminance value of the image data. However, the image judging section  157  may judge whether or not the image data represent a significant radiographic image representative of the subject  42  based on an average density value or variance density value of the image data. More specifically, if a radiographic image, which is represented by image data, includes a white area representative of the subject  42  because the subject  42  absorbs a portion of the radiation  56 , the average density value or variance density value of the image data is considered to be relatively low. Therefore, the image judging section  157  may judge image data, the average density value or variance density value of which is equal to or greater than another threshold value, as a significant radiographic image representative of the subject  42 , rather than judging image data based on the average luminance value or variance luminance value of the image data. The average density value or variance density value may be an average or variance value of the entire image data, or an average or variance value of a particular area of the image data that represents the subject  42 . 
         [0084]    In the event that a radiographic image from the one radiation detecting device and a radiographic image from another radiation detecting device are acquired, the image judging section  157  may compare the two radiographic images (image data) with each other, and judge whether or not the two radiographic images are significant radiographic images representative of the subject  42 . 
         [0085]    Each of the cradles  32 ,  34 ,  36  comprises a controller  162 , a transceiver  164 , a charging processor  166 , a display unit  168 , and an ID memory  170 . 
         [0086]    The controllers  162  of the respective cradles  32 ,  34 ,  36  control components of the cradle  32 ,  34 ,  36  in their entirety. 
         [0087]    The charging processors  166  charge the radiation detecting devices, which are connected to the cradles  32 ,  34 ,  36  outside the image capturing chambers  18 ,  20 ,  22 . The transceivers  164  send signals to and receive signals from the transceivers  144  of the consoles  24 ,  26 ,  28 . 
         [0088]    Each of the controllers  162  stores the ID information of the radiation detecting device, which is currently being charged by the charging processor  166 , in the ID memory  170 . 
         [0089]    Each of the display units  168  displays information (charge level, ID information, etc.) of the radiation detecting device that is currently being charged. In a case that the cradle and radiation detecting device of the radiation detecting device are connected to each other, the controller  162  may read the ID information from the ID memory  132  of the radiation detecting device, and store the read ID information in the ID memory  170 . Alternatively, the controller  162  may read ID information from a cradle thereof from the ID memory  146  of the console that is connected to a cradle of the console, and store the read ID information in the ID memory  170 . 
         [0090]    The radiographic image capturing system  10  according to the present embodiment is basically constructed as described above. Operations (a radiographic image capturing method) of the radiographic image capturing system  10  with an emphasis on the console  24  and the image capturing chamber  18  will be described below with reference to the flowchart shown in  FIG. 5  and the timing chart shown in  FIG. 6 . 
         [0091]    It is assumed that one radiation detecting device and one image capturing apparatus, which have been selected by the doctor or radiological technician in the image capturing chamber  18 , are the radiation detecting device  72  and the image capturing apparatus  48 , respectively, designed for an upright imaging process, whereas the other radiation detecting devices and the other image capturing apparatus are the radiation detecting device  62  and the image capturing apparatus  46 , and the radiation detecting device  52  and the image capturing apparatus  44 , respectively, which are designed for a supine imaging process. It is also assumed that, upon capturing of radiographic images, the power supply switches  94  are not turned on, but rather, the control device  40  activates the radiation detecting devices  52 ,  62 ,  72 . It is further assumed that, after radiographic images have been captured, the control device  40  acquires the radiographic images preferentially from radiation detecting devices that are closer in proximity to the one radiation detecting device  72  (i.e., the control device  40  successively acquires radiographic images from the radiation detecting device  72 , then from the radiation detecting device  62 , and then from the radiation detecting device  52 ). 
         [0092]    In  FIGS. 5 and 6 , it is assumed that the one image capturing apparatus  48  initially performs an upright imaging process normally on the subject  42  according to the image capturing conditions, and thereafter, regardless of the image capturing conditions for the upright imaging process set in the image capturing condition setting section  150 , the image capturing apparatus  46  performs a supine imaging process, instead of the upright imaging process performed by the image capturing apparatus  48 . 
         [0093]    First, operation of the one image capturing apparatus  48  in the image capturing chamber  18  to perform an upright imaging process normally on the subject  42  according to the image capturing conditions will be described below. 
         [0094]    In step S 1 , the transceiver  144  of the console  24  acquires order information from the RIS  14  via the in-hospital network  30 . The acquired order information is stored in the order information storage unit  148 . 
         [0095]    In step S 2 , the doctor or radiological technician operates the operating unit  159  of the console  24  in order to display the order information stored in the order information storage unit  148  on the display unit  156 . Then, while observing the order information displayed on the display unit  156 , the doctor or radiological technician operates the operating unit  159  in order to select the image capturing apparatus  48  to be used in the imaging process, to select an imaging method (upright imaging process) for the image capturing apparatus  48 , and to enter the ID information of the radiation detecting device  72 . The image capturing apparatus  48  and the imaging method that have been selected, the entered ID information, and the information contained within the order information, which corresponds to the selected and entered items of information, are set as image capturing conditions in the image capturing condition setting section  150 . In addition, the doctor or radiological technician operates the operating unit  159  in order to enter ID information of all of the radiation detecting devices  52 ,  62 ,  72  that are present in the image capturing chamber  18 , together with ID information of any radiation detecting devices that are currently being charged by the cradle  32  connected to the console  24 . The entered ID information is stored in the ID memory  146 . 
         [0096]    In step S 3 , the doctor or radiological technician performs a preparatory process for making the selected image capturing apparatus  48  ready to capture radiographic images. 
         [0097]    More specifically, the doctor or radiological technician loads the image capturing base  70  with the radiation detecting device  72 , the battery  88  of which has been charged by the cradle  32 , and then positions the subject  42  with respect to the image capturing base  70 . Further, the doctor or radiological technician orients the radiation source  54  toward the subject  42  and the image capturing base  70 . 
         [0098]    After the foregoing preparatory process has been completed, in step S 4 , the doctor or radiological technician turns on the exposure switch  160  in order to start an upright imaging process on the subject  42 . 
         [0099]    As shown in  FIG. 6 , upon the exposure switch  160  being turned on at time t 0 , the controller  142  sends the image capturing conditions set in the image capturing condition setting section  150 , together with the ID information of the radiation detecting devices  52 ,  62 ,  72  stored in the ID memory  146 , via the transceiver  144  to the transceiver  140  of the control device  40 . The control device  40  stores the image capturing conditions and the ID information received by the transceiver  140  in the memory  138 , and controls the radiation source  54  and the radiation detecting devices  52 ,  62 ,  72  according to the image capturing conditions and the ID information, so as to perform an upright imaging process on the subject  42  (irradiate the subject  42  with radiation  56 ). 
         [0100]    Specifically, at time t 1 , the control device  40  controls the controller  90  via the transceivers  140 ,  92  in order to activate the radiation detecting devices  52 ,  62 ,  72 . Under the control of the control device  40 , the controller  90  supplies a bias voltage Vb from the battery  88  to the radiation conversion panel  84 , thereby readying the pixels  100  for storage of electric charges therein. 
         [0101]    At time t 2 , the control device  40  sends the image capturing conditions via the transceivers  140 ,  136  to the controller  134  of the radiation source  54 . Based on the received image capturing conditions, the controller  134  outputs radiation  56  for a predetermined period (exposure time) from time t 2  to time t 3 . Radiation  56  is applied through the subject  42  to the radiation detecting device  72  in the image capturing base  70 . Then, radiation  56  that has passed through the subject  42  is directed toward the radiation conversion panel  84  in the radiation detecting device  72 . 
         [0102]    If the radiation detecting device  72  is an indirect-conversion-type radiation detecting device, then the scintillator of the radiation conversion panel  84  in the radiation detecting device  72  emits visible light at an intensity that depends on the intensity of the radiation  56 . As described above, since the pixels  100  of the photoelectric conversion layer  101  are ready from time t 1  for storing electric charges under the bias voltage Vb, the pixels  100  convert the visible light into electric signals, and store the electric signals as electric charges. 
         [0103]    At time t 4  when storage of electric charges in the pixels  100  is completed, the controller  90  supplies address signals to the line scanning driver  108  and the multiplexer  110 , so as to start a process of reading the electric charge information representative of a radiographic image of the subject  42 , which is held in the pixels  100 . 
         [0104]    More specifically, the address decoder  112  of the line scanning driver  108  outputs a selection signal according to the address signal supplied from the controller  90 , so as to select one of the switches SW 1 , and the address decoder  112  supplies a control signal Von to the gates of the TFTs  106 , which are connected to the gate line  102  corresponding to the selected switch SW 1 . The address decoder  118  of the multiplexer  110  outputs a selection signal according to the address signal output from the controller  90 , so as to switch from one switch SW 2  to another, and then successively reads, through the signal lines  104 , radiographic images represented by electric charges held in the pixels  100 , which are connected from the gate line  102  selected by the line scanning driver  108 . 
         [0105]    The radiographic images read from the pixels  100  connected to the gate line  102  are amplified by the respective amplifiers  114 , and then are sampled by the sample and hold circuits  116 . The radiographic images thus sampled are supplied through the multiplexer  110  to the A/D converter  120 , which converts the radiographic images into digital signals. Such digital radiographic image signals are stored in the image memory  130  by the controller  90 . 
         [0106]    Similarly, the address decoder  112  of the line scanning driver  108  successively switches to other switches SW 1  according to the address signal supplied from the controller  90 . The radiographic images represented by electric charges held in the pixels  100 , which are connected from the respective gate lines  102 , are read through the signal lines  104  and stored in the image memory  130  through the multiplexer  110 , the A/D converter  120 , and the controller  90 . 
         [0107]    The image memory  130  thus stores a radiographic image which is representative of the subject  42  in an upright position. In step S 4 , the image capturing process of the image capturing apparatus  48  is carried out as has been described above. As with the radiation detecting device  72 , the radiation detecting devices  52 ,  62  of the other image capturing apparatus  44 ,  46  also store electric charges therein and are capable of reading radiographic images. However, since radiation  56  is not applied to the radiation detecting devices  52 ,  62 , the radiographic images read by the radiation detecting devices  52 ,  62  are not representative of the subject  42 . From time t 3  to time t 4 , the console  24  invalidates the function of the exposure switch  160  (inhibits application of radiation  56 ), even if the doctor or radiological technician turns on the exposure switch  160 . Time t 6  indicates a time at which the operation sequence concerning one image capturing cycle, which is represented by the flowchart shown in  FIG. 5 , is completed. 
         [0108]    In step S 5 , after completion of the image capturing process, the control device  40  acquires via the controller  90  and the transceivers  92 ,  140  the radiographic image stored in the image memory  130  of the radiation detecting device  72  and the ID information stored in the ID memory  132 , and sends the acquired radiographic image and ID information to the transceiver  144 . After the radiographic image and the ID information from the radiation detecting device  72  have been sent to the transceiver  144 , the control device  40  sends via the controller  90  and the transceivers  92 ,  140  the radiographic image stored in the image memory  130  of the radiation detecting device  62 , which is close in proximity to the radiation detecting device  72 , and the ID information stored in the ID memory  132  to the transceiver  144 . Therefore, the transceiver  144  successively receives the ID information and the radiographic image from the radiation detecting device  72 , as well as the ID information and the radiographic image from the radiation detecting device  62 , and then stores the respective ID information and the radiographic images in the image memory  154 . 
         [0109]    In step S 6 , the image judging section  157  judges whether or not the radiographic image selected by the doctor or radiological technician from among the two radiographic images stored in the image memory  154  is a significant radiographic image representative of the subject  42 . 
         [0110]    As described above, since the image capturing apparatus  48  has imaged the subject  42  in an upright position and the radiographic image from the radiation detecting device  72  is representative of the subject  42 , the average luminance value or variance luminance value of the radiographic image (image data) is equal to or greater than the threshold value. Inasmuch as the average luminance value or variance luminance value of the image data is equal to or greater than the threshold value, the image judging section  157  judges that the radiographic image from the radiation detecting device  72  is a significant radiographic image (step S 6 : YES), and further judges that the radiographic image from the radiation detecting device  62 , which is stored in the image memory  154 , is unnecessary. 
         [0111]    Since the image judging section  157  has found a significant radiographic image, the image judging section  157  instructs the control device  40  to cancel the process of acquiring radiographic images, and erases the ID information and the radiographic image of the radiation detecting device  62  from the image memory  154 . The image judging section  157  supplies the ID information and the radiographic image (significant radiographic image) of the radiation detecting device  72 , which are stored in the image memory  154 , to the image processor  152 . 
         [0112]    The image processor  152  performs a predetermined image processing routine on the supplied radiographic image from the radiation detecting device  72  (step S 7 ), and displays the processed radiographic image on the display unit  156  (step S 8 ). 
         [0113]    In the period from time t 4  to time t 5 , the process of acquiring radiographic images from the radiation detecting devices  52 ,  62 ,  72  is completed. The radiographic image displayed on the display unit  156  is sent through the in-hospital network  30  to the viewer  16  for interpretation and diagnosis thereof by the doctor. 
         [0114]    An upright imaging process, which is performed normally on the subject  42  by the image capturing apparatus  48 , has been described above. 
         [0115]    A supine imaging process, which is performed by the image capturing apparatus  46  instead of the upright imaging process performed by the image capturing apparatus  48 , regardless of the fact that the doctor or radiological technician has selected the image capturing apparatus  48  and the image capturing conditions for the image capturing apparatus  48  have been set in the image capturing condition setting section  150 , will be described below. 
         [0116]    In one instance, the doctor or radiological technician plans to perform an upright imaging process with the image capturing apparatus  48  according to the image capturing conditions, but due to a failure of the image capturing apparatus  48  or the radiation detecting device  72 , the doctor or radiological technician determines instead to perform a supine imaging process, which is performed by the image capturing apparatus  46 , instead of the upright imaging process performed by the image capturing apparatus  48 . In another instance, if the imaging method is changed and a supine imaging process is performed by the image capturing apparatus  46 , then it is presumed that the doctor or radiological technician should have operated the operating unit  159  to change the image capturing conditions registered in the image capturing condition setting section  150 , but in fact, the doctor or radiological technician forgot to change the set image capturing conditions. 
         [0117]    In step S 3 , the doctor or radiological technician loads the image capturing base  70  with the radiation detecting device  72 , the battery  88  of which has been charged by the cradle  32 . Then, the doctor or radiological technician positions the subject  42  with respect to the image capturing base  60 , and orients the radiation source  54  toward the subject  42  and the image capturing base  60 . 
         [0118]    After completion of this preparatory process, in step S 4 , the doctor or radiological technician turns on the exposure switch  160  to initiate a supine imaging process on the subject  42 . 
         [0119]    Even though the image capturing apparatus  48  indicated by the image capturing conditions set in the image capturing condition setting section  150  and the image capturing apparatus  46  which actually performs the image capturing process are different from each other, and the doctor or radiological technician recognizes that a supine imaging process is to be performed by the image capturing apparatus  46 , since the set image capturing conditions have not been changed, the console  24  recognizes that an image capturing process will be performed under the image capturing conditions (upright imaging process), which are currently set in the image capturing condition setting section  150 . 
         [0120]    As shown in  FIG. 6 , if the exposure switch  160  is turned on at time t 0 , the console  24  sends the image capturing conditions and the ID information of the radiation detecting devices  52 ,  62 ,  72 , which are stored in the ID memory  146 , to the control device  40 . The control device  40  stores the received image capturing conditions and ID information in the memory  138 , and controls the radiation source  54  and the radiation detecting devices  52 ,  62 ,  72  in accordance with the image capturing conditions and the ID information. The control device  40  controls the radiation source  54  and the radiation detecting devices  52 ,  62 ,  72 , while recognizing that an upright imaging process is to be performed based on the image capturing conditions and the ID information. 
         [0121]    At time t 1 , the control device  40  activates the radiation detecting devices  52 ,  62 ,  72 , thereby readying the pixels  100  for storage of electric charges therein. At time t 2 , the control device  40  sends the image capturing conditions to the radiation source  54 . The radiation source  54  irradiates the subject  42  with radiation  56  for a given exposure time from time t 2  to time t 3 . Radiation  56  that has passed through the subject  42  is led to the radiation conversion panel  84  in the radiation detecting device  62 . The scintillator of the radiation conversion panel  84  emits visible light at an intensity that depends on the intensity of the radiation  56 . The pixels  100  convert the visible light into electric signals and store the electric signals as electric charges. 
         [0122]    At time t 4  when storage of electric charges in the pixels  100  is completed, the controller  90  supplies address signals to the line scanning driver  108  and the multiplexer  110  in order to initiate a process of reading the electric charge information held in the pixels  100 , which is representative of a radiographic image of the subject  42 , and the controller  90  stores the read radiation image in the image memory  130 . 
         [0123]    At this time, the image memory  130  of the radiation detecting device  62  stores the radiographic image, which is representative of the subject  42  in a supine position. Therefore, the radiographic image from the radiation detecting device  72 , which has been selected by the doctor or radiological technician, and the radiographic image from the other radiation detecting device  52  are not representative of the subject  42 . 
         [0124]    In step S 5 , the control device  40  acquires the ID information and the radiographic image from the radiation detecting device  72 , and sends the ID information and the radiographic image to the transceiver  144 . Thereafter, the control device  40  acquires the radiographic image and the ID information from the radiation detecting device  62 , and sends the radiographic image and the ID information to the transceiver  144 . 
         [0125]    In step S 6 , the image judging section  157  judges whether or not the radiographic image selected by the doctor or radiological technician from the two radiographic images stored in the image memory  154  is a significant radiographic image representative of the subject  42 . 
         [0126]    As described above, inasmuch as the image capturing apparatus  46  has captured a radiographic image of the subject  42  in a supine position, the radiographic image from the radiation detecting device  72  is not representative of the subject  42 , and hence the average luminance value or variance luminance value of the radiographic image (image data) is smaller than the threshold value. Therefore, the image judging section  157  determines that the radiographic image from the radiation detecting device  72  is not a significant radiographic image (step S 6 : NO). The image judging section  157  then determines whether or not the radiographic image from the radiation detecting device  62  is a significant radiographic image representative of the subject  42 . 
         [0127]    Since the radiographic image from the radiation detecting device  62  is representative of the subject  42 , and hence the average luminance value or variance luminance value of the image data thereof is equal to or greater than the threshold value, the image judging section  157  determines that the radiographic image from the radiation detecting device  72  is a significant radiographic image. In order to indicate to the radiological technician that the radiographic image according to the image capturing conditions (the radiographic image obtained from the image capturing apparatus  48  in the upright imaging process) and the actually produced radiographic image (the radiographic image obtained from the image capturing apparatus  46  in the supine imaging process) do not agree with each other, the image judging section  157  produces an audible speech warning through the speaker  158  and/or displays a visual warning through the display unit  156  (step S 9 ). 
         [0128]    Inasmuch as the radiographic image from the radiation detecting device  62  is a significant radiographic image, the image judging section  157  judges as unnecessary the radiographic image from the radiation detecting device  72 , which is stored in the image memory  154 . Since the image judging section  157  has found the significant radiographic image, the image judging section  157  instructs the control device  40  to cancel the process of acquiring radiographic images, and erases the ID information and the radiographic image of the radiation detecting device  72  from the image memory  154 . The image judging section  157  supplies the ID information and the radiographic image (significant radiographic image) of the radiation detecting device  62  to the image processor  152 . 
         [0129]    The image processor  152  performs a predetermined image processing routine on the supplied radiographic image from the radiation detecting device  62  (step S 7 ), and displays the processed radiographic image on the display unit  156  (step S 8 ). 
         [0130]    The image judging section  157  also is capable of judging whether or not the radiographic image displayed on the display unit  156  is a radiographic image captured by the image capturing apparatus  48  under the image capturing conditions (step S 10 ). As described above, since the radiographic image displayed on the display unit  156  is a radiographic image captured by the image capturing apparatus  46 , which is different from the image capturing apparatus  48  represented by the image capturing conditions (step S 10 : NO), the image judging section  157  changes the image capturing conditions for the image capturing apparatus  48 , which are currently set in the image capturing condition setting section  150 , into image capturing conditions for the image capturing apparatus  46 , based on the assumption that a next radiographic image will be captured by the image capturing apparatus  46  that has captured the radiographic image displayed on the display unit  156  (step S 11 ). As a result, the image capturing apparatus  46  will be selected for capturing a subsequent radiographic image, thereby preventing the image capturing apparatus  46  from being unselected due to an oversight. 
         [0131]    A supine imaging process, which is carried out by the image capturing apparatus  46  instead of the upright imaging process carried out by the image capturing apparatus  48 , has been described above. 
         [0132]    If a supine imaging process is performed using the image capturing apparatus  44  instead of using the image capturing apparatus  46 , then after having issued a warning in step S 9 , the image judging section  157  instructs the control device  40  to acquire the ID information and the radiographic image from the radiation detecting device  52  of the image capturing apparatus  44 . Control then returns to step S 5 , in which the control device  40  is instructed by the image judging section  157  to acquire the ID information and the radiographic image from the radiation detecting device  52 , and the control device  40  sends the ID information and the radiographic image, which have been acquired, to the console  24 . Therefore, the image judging section  157  performs the process from step S 6  again. 
         [0133]    According to the present embodiment, as described above, the control device  40  acquires both the radiographic image from one radiation detecting device (one image capturing apparatus), which is selected by the doctor or radiological technician by operating the operating unit  159 , and the radiographic image from at least one other radiation detecting device (other image capturing apparatus) that differs from the one radiation detecting device, and the control device  40  sends the acquired radiographic images to the consoles  24 ,  26 ,  28 . 
         [0134]    If radiation  56  is applied through the subject  42  to the one radiation detecting device, then the control device  40  acquires a radiographic image from the one radiation detecting device, thereby acquiring a radiographic image representative of the subject  42 . If radiation  56  is applied through the subject  42  to the other radiation detecting device, then the control device  40  acquires a radiographic image from the other radiation detecting device, thereby acquiring a radiographic image representative of the subject  42 . 
         [0135]    More specifically, in a case that the one image capturing apparatus is changed to the other image capturing apparatus in order to capture a radiographic image, it is desirable for the doctor or radiological technician to operate the operating unit  159 , so as to select the other image capturing apparatus before the radiographic image is captured. However, the doctor or radiological technician may possibly fail to select the other image capturing apparatus for capturing a radiographic image, and thus a radiographic image may not be acquired from the other image capturing apparatus. According to the present embodiment, regardless of whether or not the doctor or radiological technician has actively operated the operating unit  159  in order to select the other image capturing apparatus, both the radiographic image from the one radiation detecting device and the radiographic image from the other radiation detecting device are acquired, thereby reliably acquiring a radiographic image representative of the subject  42 . 
         [0136]    According to the present embodiment, therefore, regardless of whether or not the one radiation detecting device or the other radiation detecting device has been used to capture a radiographic image, the control device  40  reliably acquires a radiographic image that is representative of the subject  42 . As a result, the subject  42  is prevented from being exposed to radiation  56  needlessly. 
         [0137]    The image judging section  157  of each of the consoles  24 ,  26 ,  28  judges whether or not the radiographic image from the one radiation detecting device is a significant radiographic image representative of the subject  42 . Therefore, it is possible to determine whether or not the radiographic image from the one radiation detecting device is a significant radiographic image representative of the subject  42 . 
         [0138]    If the image judging section  157  determines that the radiographic image from the one radiation detecting device is not a significant radiographic image, then the image judging section  157  issues a warning through the speaker  158  and/or the display unit  156 . Therefore, the doctor or radiological technician can easily recognize that an image capturing process has been carried out, without being required to operate the operating unit  159  in order to select the other radiation detecting device. 
         [0139]    If the image judging section  157  determines that the radiographic image from the one radiation detecting device is not a significant radiographic image, then the image judging section  157  judges whether or not the radiographic image from the other radiation detecting device is a significant radiographic image. Therefore, it is possible to determine whether or not the radiographic image from the other radiation detecting device is a significant radiographic image. 
         [0140]    If the image judging section  157  determines that the radiographic image from the one radiation detecting device is not a significant radiographic image, then the control device  40  successively acquires radiographic images from the other radiation detecting devices until the image judging section  157  finds a significant radiographic image. Therefore, a significant radiographic image can reliably be acquired. 
         [0141]    According to the present embodiment, in the event that the doctor or radiological technician operates the operating unit  159  in order to select the one radiation detecting device, the doctor or radiological technician also designates an imaging method to be carried out at the time that radiation  56  is applied to the subject  42  using the one radiation detecting device. In this case, the control device  40  acquires a radiographic image preferentially from a radiation detecting device, from among the other radiation detecting devices, which produces a radiographic image according to the imaging method, or acquires a radiographic image preferentially from another radiation detecting device that is close in proximity to the one radiation detecting device. 
         [0142]    If the one radiation detecting device is not used, but rather another radiation detecting device is used to capture a radiographic image, then it is assumed to be highly likely to have captured a radiographic image using another radiation detecting device, according to the same imaging method as the imaging method (e.g., upright imaging process or supine imaging process) of the one radiation detecting device, or to have captured a radiographic image using another radiation detecting device that is closest in proximity to the one radiation detecting device. The control device  40  thus acquires a radiographic image preferentially from another radiation detecting device according to the same imaging method, or from another radiation detecting device that is closest in proximity to the one radiation detecting device. Consequently, it is possible to acquire a significant radiographic image quickly and reliably. 
         [0143]    For example, if radiographic images are to be acquired according to imaging methods, then the radiographic images may be acquired according to the following sequence. 
         [0144]    Assuming that the one radiation detecting device is the radiation detecting device  72 , then radiographic images are acquired according to a sequence in which the radiation detecting device  72  in the upstanding imaging process→the radiation detecting device  62  in the supine imaging process →the radiation detecting device  52  (in the supine imaging process) are selected in this order. Assuming that the one radiation detecting device is the radiation detecting device  62 , then radiographic images are acquired according to a sequence in which the radiation detecting device  62  in the supine imaging process→the radiation detecting device  52  (in the supine imaging process)→the radiation detecting device  72  in the upstanding imaging process are selected in this order. 
         [0145]    If the image judging section  157  determines that the radiographic image from the other radiation detecting device is a significant radiographic image, then the image judging section  157  switches from the image capturing conditions for the one radiation detecting device, which are set in the image capturing condition setting section  150  (selection of the one radiation detecting device), to the image capturing conditions for the other radiation detecting device (selection of the other radiation detecting device). In this case, since it is assumed that a subsequent imaging cycle will be carried out using the other radiation detecting device, which has produced the significant radiographic image, the image judging section  157  automatically switches from selecting the one radiation detecting device to selecting the other radiation detecting device, thereby preventing the other radiation detecting device from being unselected due to an oversight in the next imaging cycle. 
         [0146]    Each of the consoles  24 ,  26 ,  28  displays, on the display unit  156 , the radiographic image that the image judging section  157  has judged as being a significant radiographic image. Accordingly, the doctor can interpret the significant radiographic image for facilitating diagnosis. 
         [0147]    Since the ID memory  146  stores ID information of all of the radiation detecting devices  52 ,  62 ,  72  that are present in the image capturing chambers  18 ,  20 ,  22 , the control device  40  stores the ID information in the ID memory  146  in the memory  138 , and thereafter acquires radiographic images from the radiation detecting devices  52 ,  62 ,  72  that are present in the image capturing chambers  18 ,  20 ,  22  according to such ID information and the image capturing conditions. 
         [0148]    Inasmuch as radiographic images are acquired only from the radiation detecting devices  52 ,  62 ,  72  that are present in the image capturing chambers  18 ,  20 ,  22 , it is possible to reliably prevent an image acquiring process from being performed in error using radiation detecting devices that are present outside of the image capturing chambers  18 ,  20 ,  22 , e.g., radiation detecting devices that are currently being charged by the cradles  32 ,  34 ,  36  and radiation detecting devices in image capturing chambers in which radiographic images are not being captured. Further, the process of acquiring radiographic images can be carried out efficiently. 
         [0149]    Since each radiation conversion panel  84  is made ready to store electric charges before radiation  56  is applied to the subject  42 , it is not necessary to irradiate the radiation detecting devices  52 ,  62 ,  72  with triggering radiation  56  in order to instruct the radiation conversion panel  84  to store electric charges therein prior to the main image capturing process. Therefore, the arrangement for instructing the storage of electric charges is simplified, and the dose of radiation to which the subject  42  is exposed can be reduced. 
         [0150]    In the above description, the control device  40  and the consoles  24 ,  26 ,  28  are separate from each other. However, the control device  40  may be dispensed with, and the function of the control device  40  to acquire radiographic images may be possessed by the controller  142 . 
         [0151]    If the subject  42  to be imaged is thick bodied, then the dose of radiation  56  that reaches the radiation detecting device, which is used to capture a radiographic image, may possibly be smaller than the dose of radiation that leaks to other radiation detecting devices. According to the present embodiment, therefore, correlative data between mAs values together with the thickness of the subject  42 , and patterns of radiographic images produced upon leakage of radiation may be registered in advance in the image capturing condition setting section  150 . In this case, a radiographic image, which is generated from a thick bodied subject, may be corrected using such registered data and patterns. 
         [0152]    It has been described above that a doctor or radiological technician operates the operating unit  159  in order to register an imaging method in the image capturing condition setting section  150 , whereupon the doctor or radiological technician orients the radiation source  54  toward the subject  42  in a preparatory process. However, according to the present embodiment, the present invention is not limited to such details in the preparatory process. Imaging methods and movements of the radiation source  54  may be associated with each other, and in the event that an imaging method is registered in the image capturing condition setting section  150 , the radiation source  54  may be automatically moved in accordance with the imaging method. Alternatively, in the event that the radiation source  54  is moved in the preparatory process, an imaging method, which depends on the moved radiation source  54 , may automatically be registered in the image capturing condition setting section  150 . 
         [0153]    Furthermore, if an imaging method is changed from the image capturing apparatus  48  to the image capturing apparatus  46 , the dose of radiation  56  according to the image capturing conditions may be changed depending on the changed imaging method, and the changed dose of radiation  56  may be output from the radiation source  54 . 
         [0154]    The present invention is not limited to the embodiment described above, but various changes and modifications may be made without departing from the scope of the invention.