Abstract:
A radiation detection apparatus including a casing, and a radiation detection device accommodated inside the casing, which detects radiation emitted from a radiation source and having passed through a subject, and converts the radiation into radiation image information, and an electronic circuit accommodated inside the casing, further comprising: storage device detachably mounted with respect to the casing, and wherein the electronic circuit includes a data compression circuit, which compresses the radiation image information, to thereby create compressed radiation image information, and herein the storage device stores the compressed radiation image information.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a radiation detection apparatus for irradiating a subject with radiation and capturing a radiation image, as well as to a radiation image capturing system that uses such a radiation detection apparatus. 
         [0003]    2. Description of the Related Art 
         [0004]    In the medical field, a radiation image capturing apparatus, in which radiation is applied to a subject, and radiation that has passed through the subject is directed to a radiation detection device for capturing a radiation image of the subject, has been widely used. 
         [0005]    In this case, as types of radiation detection devices, there are known a radiation film on which a radiation image is exposed and recorded, or a stimulable phosphor panel in which radiation energy is stored as a radiation image in a stimulable phosphor, and when stimulating light is applied thereto, the radiation image can be read out as stimulated light. In such radiation detection devices, the radiation film in which the radiation image has been recorded is supplied to a developing apparatus where an image developing process is carried out, or the stimulable phosphor panel is supplied to a reading apparatus in which the radiation image is acquired as a visible image by performing a reading process thereon. 
         [0006]    On the other hand, in a medical environment such as an operating room or the like, for performing rapid and precise treatments with respect to a patient, it is essential to read out and display the radiation image directly from the radiation detection device. As a radiation detection device capable of responding to such requirements, a radiation detection device has been developed that uses solid state detection elements which convert radiation directly into electrical signals, or which, after the radiation has been converted into visible light by a scintillator, converts the visible light into electrical signals, which are read out. 
         [0007]    In addition, heretofore, various data transmitting methods for transmitting radiation image information to the exterior from a radiation detection device using solid state detecting elements have been proposed. (See, Japanese Laid-Open Patent Publication No. 2004-101195, Japanese Laid-Open Patent Publication No. 2005-296050, Japanese Laid-Open Patent Publication No. 2002-190584 and Japanese Laid-Open Patent Publication No. 2006-267043.) 
         [0008]    In the method disclosed in Japanese Laid-Open Patent Publication No. 2004-101195, image data detected by solid state detecting elements is subjected to thinning processing, converted to wireless signals, and transmitted to the exterior. In the method disclosed in Japanese Laid-Open Patent Publication No. 2005-296050, image data detected by solid state detecting elements is subjected to data compression, and is transmitted to and displayed on a display device through a wireless antenna for enabling confirmation. In Japanese Laid-Open Patent Publication No. 2002-190584, image data from an electronic cassette is recorded in a recording medium, whereupon the image data is read out from the recording medium and supplied to a storage server or the like. In the method disclosed in Japanese Laid-Open Patent Publication No. 2006-267043, radiation image data recorded in a radiation detection device is stored in a detachable image memory, which is then moved to an external apparatus. 
         [0009]    However, in the methods disclosed in Japanese Laid-Open Patent Publication No. 2004-101195 and Japanese Laid-Open Patent Publication No. 2005-296050, due to the influence of electromagnetic waves between the electronic cassette and the external apparatus, problems may be caused in particular with respect to sensitive equipment related to medical procedures. 
         [0010]    In the methods disclosed in Japanese Laid-Open Patent Publication No. 2002-190584 and Japanese Laid-Open Patent Publication No. 2006-267043, problems related to electromagnetic waves can be avoided. However, a large capacity recording medium is needed, leading to an increase in costs. There is also a problem in that the image data cannot be stored quickly in the recording medium. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention, taking into consideration the above-mentioned problems, has the object of providing a radiation detection apparatus and radiation image capturing system, in which adverse effects of electromagnetic radiation are not incurred, and required image information can be swiftly acquired and confirmed. 
         [0012]    A radiation detection apparatus in accordance with a first aspect of the present invention includes a casing, with a radiation detection device accommodated inside the casing, which detects radiation emitted from a radiation source and having passed through a subject, and converts the radiation into radiation image information, and an electronic circuit accommodated inside the casing. The radiation detection apparatus further has a storage device detachably mounted with respect to the casing, and the electronic circuit includes a data compression circuit therein, which compresses the radiation image information to thereby create compressed radiation image information, wherein the storage device stores the compressed radiation image information. 
         [0013]    A radiation image capturing system in accordance with a second aspect of the present invention has a radiation detection apparatus that includes a casing, with a radiation detection device accommodated inside the casing, which detects radiation emitted from a radiation source and having passed through a subject, and converts the radiation into radiation image information, and an electronic circuit accommodated inside the casing. The electronic circuit of the radiation detection apparatus includes a data compression circuit therein, which compresses the radiation image information to thereby create compressed radiation image information. The radiation image capturing system further includes a storage device detachably mounted with respect to the casing of the radiation detection apparatus and in which the compressed radiation image information is stored, and a display device into which the storage device can be loaded when detached from the casing of the radiation detection apparatus, for displaying the compressed radiation image information stored in the storage device. 
         [0014]    According to the present invention, the adverse influence of electromagnetic waves is not imparted to the system, and necessary image information can be quickly acquired and confirmed. 
         [0015]    The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a structural view showing a radiation image capturing system; 
           [0017]      FIG. 2  is an interior structural view of an electronic cassette; 
           [0018]      FIG. 3  is a block diagram of a circuit structure of a radiation detection device accommodated inside the electronic cassette; 
           [0019]      FIG. 4  is a schematic block diagram showing primarily the cassette controller of the electronic cassette; and 
           [0020]      FIG. 5  is a schematic block diagram of the radiation image capturing system. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    A radiation detection device and a radiation image capturing system in accordance with embodiments of the present invention shall be described below with reference to  FIGS. 1 through 5 . 
         [0022]    As shown in  FIG. 1 , the radiation image capturing system  10  according to the present embodiment is equipped with a radiation source  24  for irradiating a patient  22  (subject) with radiation X having a given dose according to image capturing conditions, a radiation source controller  26  for controlling the radiation source  24 , a radiation detection apparatus (hereinafter referred to as an electronic cassette  28 ) containing a radiation detection device  44  that detects radiation X having passed through the patient  22 , a cradle  30  for carrying out a charging process on the electronic cassette  28 , a portable information terminal  32  having an image capturing switch for activating the radiation source  24 , which is carried by a technician for confirming conditions including image capturing operations, and a console  34  (control device) for controlling the radiation source controller  26 , the electronic cassette  28 , the cradle  30  and the portable information terminal  32 , as well as performing transmission and reception of necessary information therebetween. 
         [0023]    The radiation source  24 , the radiation source controller  26  and the cradle  30  are disposed inside an image capturing room  36 , whereas the console  34  is located in an operations room  38  outside of the image capturing room. Further, necessary information may be transmitted and received between the radiation source controller  26 , the portable information terminal  32  and the console  34  by means of wireless communications. 
         [0024]    The electronic cassette  28 , as shown in  FIG. 2 , is equipped with a casing  40  made from a material which is permeable to radiation X. Inside of the casing  40 , a grid  42  for removing radiation X scattered by the patient  22 , a radiation detection device  44  (solid state detector) for detecting radiation X that have passed through the patient  22 , and a lead plate  46  for absorbing backscattered radiation X are arranged in this order from a side surface on which radiation X is irradiated. 
         [0025]    Further, a battery  48 , which serves as a power source for the electronic cassette  28 , a cassette controller  50  that controls driving of the radiation detection device  44 , an image memory  52  for recording therein image information (radiation image information) of radiation X that has been detected by the radiation detection device  44 , and an interface  54  are accommodated in the casing  40 , respectively. Moreover, in order to avoid damage caused by radiation X to the electronic circuits of the cassette controller  50 , the image memory  52  and the interface  54 , etc., it is preferable for a lead plate or the like to be disposed on surface sides of the casing  40  that are subject to being irradiated with radiation X. 
         [0026]    As shown in  FIG. 2 , on one side surface of the casing  40 , a slot  202  is provided for detachably mounting a memory card  200  (storage device). Inside the slot, as shown in  FIG. 3 , a first connection terminal  206  is arranged, to which the external terminal  204  of the memory card  200  is connected. The first connection terminal  206  is connected to the interface  54 . As the memory card, for example, a USB memory or the like, various types of which are available on the market, can be used. 
         [0027]    Further, on the side surface of the casing  40 , a second connection terminal  210  is arranged, to which a cable  208  for connection to the console  34  may be attached. The second connection terminal  210  also is connected to the interface  54 . 
         [0028]    As shown in  FIG. 3 , the radiation detection device  44  includes a structure in which a photoelectric conversion layer  64  made up from an amorphous selenium (a-Se) material, which generates electric charges upon sensing radiation X, is disposed on thin film transistors (TFTs)  66  arrayed in a matrix form. After the generated electric charges are accumulated in storage capacitors  68 , the TFTs  66  are successively turned on one line at a time, and the electric charges are read out as image signals.  FIG. 3  shows the connected relationship of only one of the TFTs  66  and one pixel (image element)  70  made up from a photoelectric conversion layer  64  and a storage capacitor  68 , whereas the structures of other similar pixels  70  have been omitted from illustration for the sake of simplicity. Since when heated to high temperatures, the structure of amorphous selenium changes and the functionality thereof is lowered, amorphous selenium must be used within a prescribed temperature range. Accordingly, it is preferable to provide some means for cooling the radiation detection device  44  inside the electronic cassette  28 . 
         [0029]    Gate lines  72 , which extend in parallel to the direction of the rows, and signal lines  74  which extend in parallel to the direction of the columns, are connected to the TFTs  66 , which are connected respectively to each of the pixels  70 . Each of the gate lines  72  is connected to a line scanning driver  76 , and each of the signal lines  74  is connected to a multiplexer  78  that constitutes a reading circuit. 
         [0030]    Control signals V ON , V OFF  that control ON and OFF states of the TFTs  66  arrayed in the direction of the rows, are supplied from the line scanning driver  76  to the gate lines  72 . In this case, the line scanning driver  76  comprises a plurality of switches SW 1  that switch the gate lines  72  on or off, and a first address decoder  80 , which outputs selection signals for selecting one of the switches SW 1 . Address signals are supplied from the cassette controller  50  to the first address decoder  80 . 
         [0031]    Further, the signal lines  74  are supplied with electric charges, which are stored in the storage capacitors  68  of each of the pixels  70 , through the TFTs  66  arranged in the columns. The electric charges supplied to the signal lines  74  are amplified by amplifiers  82 . The amplifiers  82  are connected through respective sample and hold circuits  84  to the multiplexer  78 . The multiplexer  78  comprises a plurality of switches SW 2  for successively switching between the signal lines  74 , and a second address decoder  86  for outputting a selection signal for selecting one of the switches SW 2  at a time. The second address decoder  86  is supplied with an address signal from the cassette controller  50 . An A/D converter  88  is connected to the multiplexer  78 . A radiation image signal is converted by the A/D converter  88  into a digital image signal representing the radiation image information, which is supplied to the cassette controller  50 . 
         [0032]    As shown in  FIG. 4 , the cassette controller  50  includes a memory control circuit  212  and a data compression circuit  214 . The memory control circuit  212  carries out the following processes. 
         [0033]    (1) Storing “as is” in a first storage region  216   a  of the image memory  52  the radiation image information Da supplied to the cassette controller  50  from the radiation detection device  44 ; and 
         [0034]    (2) Supplying the radiation image information Da supplied to the cassette controller  50  to the data compression circuit  214 , subjecting the radiation image information Da to data compression processing and creating compressed radiation image information Db, and storing the compressed radiation image information Db in a second storage region  216   b  of the image memory  52 . 
         [0035]    The radiation image data Da stored in the first storage region  216   a  of the image memory  52  is supplied to the second connection terminal  210  through the interface  54  under the control of the cassette controller  50 , and is transmitted to the console  34  through the cable  208  connected to the second connection terminal  210 . Accordingly, data transmission of the radiation image information Da to the console  34  is carried out at a stage when the cable  208  is connected to the electronic cassette  28 . 
         [0036]    On the other hand, the compressed radiation image information Db stored in the second storage region  216   b  of the image memory  52  is supplied to the first connection terminal  206  through the interface  54  under the control of the cassette controller  50 , and is transmitted to and stored in the memory card  200 , which is attached to the first connection terminal  206  of the slot  202 . 
         [0037]      FIG. 5  is a schematic block diagram of the radiation image capturing system  10 . The console  34  is connected to a radiology information system (RIS)  90 , which generally manages radiation image information handled by the radiological department of a hospital along with other information. Further, the RIS  90  is connected to a hospital information system (HIS)  92 , which generally manages medical information in the hospital. 
         [0038]    A first controller  110  of the cradle  30  controls a charging processor  112  that carries out a charging process on the battery  48  of the electronic cassette  28 . Information received from the console  34  through a first transceiver  114  is displayed on a first display unit  116 , and as needed, information may be audibly output by a first speaker  118 . 
         [0039]    Further, a first slot  218  is provided on the cradle  30 , in which the memory card  200  can be detachably mounted. Inside the first slot  218 , a connection terminal  220  is arranged, to which the external terminal  204  of the memory card  200  is connected. The connection terminal  220  is connected to the first controller  110  through a non-illustrated interface. Accordingly, when the memory card  200  is mounted in the first slot  218 , the first controller  110  acquires the compressed radiation image information Db stored in the memory card  200 , and displays the image information as a preview image on the first display unit  116 . 
         [0040]    Further, a second controller  124  of the portable information terminal  32  supplies the radiation source controller  26  through a second transceiver  128  with an image capturing signal generated by the image capturing switch  126  that drives the radiation source  24 . The second controller  124  causes information received from the console  34  through the second transceiver  128  to be displayed on a second display unit  130 , and as needed, causes the information to be output audibly by a second speaker  132 . The portable information terminal  32  includes an operating unit  134 , through which various required information can be set. 
         [0041]    Further, a second slot  222  is provided in the portable information terminal  32 , in which the memory card  200  can be detachably mounted. Inside the second slot  222 , a connection terminal  224  is arranged, to which the external terminal  204  of the memory card  200  is connected. The connection terminal  224  is connected to the second controller  124  through a non-illustrated interface. Accordingly, when the memory card  200  is mounted in the second slot  222 , the second controller  124  acquires the compressed radiation image information Db stored in the memory card  200 , and displays the compressed radiation image information Db as a preview image on the second display unit  130 . 
         [0042]    The console  34  includes a third controller  142 , a third transceiver  144  for transmitting and receiving necessary information by wireless communications with respect to the radiation source controller  26 , and the portable information terminal  32 , a patient information setting unit  146  for setting patient information, an image capturing menu setting unit  147  for selecting and setting from an image capturing menu a region to be imaged of the patient  22 , an image capturing conditions setting unit  148  for setting required image capturing conditions for capturing an image by the radiation source controller  26 , an image processor  150  for carrying out image processing with respect to radiation image information transmitted as data from the electronic cassette  28 , an image memory  152  for storing the processed radiation image information, a third display device  154  for displaying the radiation image information, patient information, the image capturing menu, and the like, and a third speaker  156  for audibly outputting warnings when necessary. 
         [0043]    The patient information is defined as information for specifying a patient  22 , such as the name and sex of the patient  22 , a patient ID number, and the like. The image capturing menu serves as a menu for selecting an image capturing region of the patient  22 . As an image capturing region, the head region, a chest region, or regions of the four limbs, etc., may be considered. The image capturing conditions are conditions for determining a supplied tube voltage, tube current, irradiation time, etc., for irradiating an imaging region of the patient  22  with an appropriate dose of radiation X. The patient information and image capturing operating information, including the imaging capturing menu and the image capturing conditions, can be set by the console  34 , or can be supplied externally to the console  34  through the RIS  90 . 
         [0044]    The radiation image capturing system  10  is basically constructed as described above. Next, operations of the radiation image capturing system  10  shall be described. 
         [0045]    When a radiation image is to be captured of the patient  22 , using the patient information setting unit  146  of the console  34 , patient information concerning the patient  22  is set, together with setting required image capturing conditions using the image capturing conditions setting unit  148 . Further, using the image capturing menu setting unit  147 , a desired image capturing region, for example, the head region, a chest region, or a region of the four limbs, etc., is set from the image capturing menu shown on the third display device  154 . 
         [0046]    The set patient information, image capturing conditions and image capturing region are transmitted to the portable information terminal  32  held by the technician and displayed on the second display unit  130  thereof. In this case, the technician confirms the patient information, the image capturing conditions and the image capturing region, which are displayed on the second display unit  130  of the portable information terminal  32 , so that desired preparations for capturing the image can be carried out. 
         [0047]    Next, the technician mounts the memory card  200  in the electronic cassette  28  through the slot  202  thereof. In this condition, the electronic cassette  28  is placed at the desired image capturing region on the patient, which was selected from the image capturing menu. Of course, the memory card  200  may also be mounted after the electronic cassette  28  has been placed at the desired image capturing region. 
         [0048]    Once the electronic cassette  28  has been placed in an appropriate state with respect to the patient  22 , the technician operates the image capturing switch  126  of the portable information terminal  32  in order to carry out capturing of the radiation image. When the image capturing switch  126  is operated, the second controller  124  of the portable information terminal  32  transmits an image capturing initiation signal to the radiation source controller  26  via the second transceiver  128 . The radiation source controller  26 , which has received the image capturing initiation signal, controls the radiation source  24  according to the image capturing conditions supplied beforehand from the console  34 , and thereby irradiates the patient  22  with radiation X. 
         [0049]    Radiation X that has passed through the patient  22 , after scattered rays have been removed by the grid  42  of the electronic cassette  28 , irradiates the radiation detection device  44  and is converted into electric signals by the photoelectric conversion layer  64  of each of the pixels  70  making up the radiation detection device  44 , which are retained as charges in the storage capacitors  68  (see  FIG. 3 ). Next, the electric charge information that forms the radiation image information of the patient  22  stored in each of the storage capacitors  68  is read out in accordance with address signals, which are supplied from the cassette controller  50  to the line scanning driver  76  and the multiplexer  78 . 
         [0050]    More specifically, the first address decoder  80  of the line scanning driver  76  outputs a selection signal based on the address signal supplied from the cassette controller  50 , thereby selecting one of the switches SW 1 , and supplies a control signal VON to the gate of the TFT  66  that is connected to a corresponding gate line  72 . On the other hand, the second address decoder  86  of the multiplexer  78  outputs a selection signal according to the address signal supplied from the cassette controller  50 , and successively switches the switches SW 2 , whereby the radiation image information, which is formed as electric charge information stored in the storage capacitors  68  of each of the pixels (image elements)  70  that are connected to the gate line  72  selected by the line scanning driver  76 , is read out in succession through the signal lines  74 . 
         [0051]    After the radiation image information read from the storage capacitors  68  of the pixels  70  connected to the selected gate line  72  of the radiation detection device  44  has been amplified by the respective amplifiers  82 , the radiation image information is sampled by each of the sample and hold circuits  84 , and supplied to the A/D converter  88  through the multiplexer  78  and converted into digital signals. The radiation image information Da having been converted into digital signals is stored in the first storage region  216   a  of the image memory  52  by the memory control circuit  212  of the cassette controller  50 . Furthermore, the radiation image information Da is subjected to data compression by the memory control circuit  212  and the data compression circuit  214 , and is stored as compressed radiation image information Db in the second storage region  216   b  of the image memory  52 . 
         [0052]    Similarly, the first address decoder  80  of the line scanning driver  76  successively turns on the switches SW 1  according to the address signals supplied from the cassette controller  50 , and reads out the radiation image information Da, which is made up of charge information stored in the storage capacitors  68  of each of the pixels  70  connected respectively to the gate lines  72 , whereupon the radiation image information Da is stored in the first storage region  216   a  of the image memory  52  through the multiplexer  78  and the A/D converter  88 . Furthermore, the compressed radiation image information Db therefrom is stored in the second storage region  216   b.    
         [0053]    The compressed radiation image information Db stored in the second storage region  216   b  of the image memory  52  is stored in the memory card  200  through the cassette controller  50  and the interface  54 . Accordingly, at a stage after the image has been captured, the technician takes out the memory card  200  at once from the slot  202  and mounts the memory card  200  in the second slot  222  of the portable information terminal  32 , whereby the compressed radiation image information Db is displayed as a preview image on the second display unit  130 . Alternatively, the memory card  200  may be mounted in the first slot  218  of the cradle  30 , whereby the compressed radiation image information Db is displayed as a preview image on the first display unit  116 . 
         [0054]    The technician can confirm the compressed radiation information Db displayed on the first display unit  116  or the second display unit  130 , and thereby can determine whether recapturing of the radiation image is necessary or not. In particular, because the amount of information is reduced due to data compression, the compressed radiation image information Db can be displayed quickly. 
         [0055]    The radiation image information Da stored in the first storage region  216   a  of the image memory  52  is transmitted as data to the console  34  through the cassette controller  50  and the interface  54 , at a stage when the electronic cassette  28  is connected to the console  34  through the cable  208 . After image processing has been implemented by the image processor  150  on the radiation image information Da, which has been transmitted as data to the console  34 , the radiation image information Da is stored in the image memory  152  of the console  34  in a state of association with the patient information. Subsequently, the radiation image information Da stored in the image memory  152  is displayed on the third display device  154 . 
         [0056]    In the electronic cassette  28 , for which an image capturing process has been carried out, the battery  48  thereof is consumed. In this case, the electronic cassette  28  is loaded into the cradle  30  so that a charging process can be performed with respect to the battery  48 . 
         [0057]    In this manner, in the radiation image capturing system  10 , the radiation image information Da acquired by the electronic cassette  28  is subjected to data compression and stored in the memory card  200 . Since the memory card  200  is loaded into the cradle  30  or the portable information terminal  32  and an image is displayed thereby, any influence of electromagnetic waves is not incurred, and necessary radiation image information can be acquired and confirmed swiftly. 
         [0058]    In the above-mentioned example, the battery  48  is accommodated inside the casing  40  of the electronic cassette  28 , so that power is supplied to the radiation detection device  44  and the electronic circuits from the battery  48 . However, apart from this technique, electrical power may also be supplied to the radiation detection device  44  and electronic circuits of the electronic cassette  28  from the exterior through a cable, without requiring the battery  48  to be accommodated within the casing  40 . In this case, the electronic cassette  28  can be made lighter in weight. 
         [0059]    Of course, the present invention is not limited to the above-described embodiments, and the invention can be freely modified, within a range that does not deviate from the essence and gist of the present invention. 
         [0060]    For example, the radiation detection device  44  accommodated in the electronic cassette  28  converts the dose of the irradiated radiation X directly into electric signals through the photoelectric conversion layer  64  (direct conversion type). However, in place of this structure, a radiation detection device in which irradiated radiation X is converted initially into visible light by a scintillator, and thereafter, the visible light is converted into electric signals using a solid-state detector element formed from amorphous silicon (a-Si) or the like (indirect conversion type), may also be used (see, Japanese Patent No. 3494683). 
         [0061]    Further, the radiation image information can be obtained using a light readout type of radiation detection device. With such a light readout type of radiation detection device, radiation is irradiated onto respective solid state detection elements arranged in a matrix form, and an electrostatic latent image corresponding to the irradiation dose is stored cumulatively in the solid state detection elements. When the electrostatic latent image is read, reading light is irradiated onto the radiation detection device, and the generated current values are acquired as radiation image information. Further, by irradiating the radiation detection device with erasing light, the radiation image information in the form of a residual electrostatic latent image can be erased and the radiation detection device can be reused (see, Japanese Laid-Open Patent Publication No. 2000-105297). 
         [0062]    Furthermore, a stimulable phosphor panel can also be used as the radiation detection device.