JP2011115566A - Imaging area specifying apparatus, radiographic system, imaging area specifying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging area specifying apparatus, radiographic system, and imaging area specifying method, capable of suppressing progress of deterioration at a specific part of a detection area on a radiation detector. <P>SOLUTION: The imaging area specifying apparatus is constituted so that a correlation value correlated with the amount of radiation emitted to each of a plurality of predetermined divided areas 61A divided from a detection region 61 of a radiation detector 60, is stored as correlation information, and an imaging area capable of capturing the radiological image of a predetermined size is specified while preventing variations in the amount of radiation emitted to each of the divided areas 61A in the detection region 61, on the basis of the stored correlation information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging region specifying device, a radiographic imaging system, and an imaging region specifying method.

  In recent years, a radiation sensitive layer is disposed on a TFT (Thin Film Transistor) active matrix substrate, radiation such as irradiated X-rays is detected, and an electric signal indicating a radiation image represented by the detected radiation is output (FPD). Radiation detectors such as Flat Panel Detector have been put into practical use. This radiation detector has the merit that an image can be confirmed immediately and a moving image can be confirmed as compared with a conventional X-ray film or imaging plate.

  A portable radiographic imaging device (hereinafter also referred to as an electronic cassette) that incorporates this radiation detector and stores radiation image data output from the radiation detector has been put into practical use. The electronic cassette is highly portable, so you can shoot a patient while placed on a stretcher or bed and change the position of the electronic cassette, making it easy to adjust the imaging part. Can be dealt with flexibly.

  By the way, in a conventional cassette having a built-in X-ray film or imaging plate (IP), photographing is performed with a cassette containing a film or an imaging plate having a size corresponding to the photographing region and photographing technique. This is because radiography is performed only on the imaging region and the periphery that need to be observed in consideration of the patient's exposure, and it is more reasonable to use a film with the size of the imaging region and the periphery. It is. For this reason, in the conventional cassette, cassettes of a plurality of sizes are prepared.

  On the other hand, an electronic cassette is more expensive than a cassette incorporating an X-ray film or an imaging plate, and digital radiographic image data can be obtained by imaging, and so-called data is valid only in a specific area of the radiographic image data. Trimming can be easily performed. For this reason, the electronic cassette irradiates only the imaging region and the surrounding area that need to be observed using a part of the detection area, or an image of a part of the irradiated area. By performing this trimming, one size of electronic cassette can correspond to a plurality of imaging parts / imaging techniques.

  Japanese Patent Application Laid-Open No. 2004-151561 discloses a technique for dividing a detection region into a plurality of pieces and performing divided shooting.

  Also, in Patent Document 2 and Patent Document 3, when performing fluoroscopic imaging to continuously capture a moving part such as the heart and obtain a moving image, the range of reading pixel information from the radiation detector is changed, There is disclosed a technique for performing fluoroscopic imaging at a high frame rate by narrowing a radiographic image capturing area and limiting a radiation irradiation area according to the radiographic area.

JP 2003-33343 A Japanese Patent No. 2716949 JP 2009-17484 A

  However, the technique disclosed in Patent Document 1 has a problem that deterioration may occur in a specific part of the detection region of the radiation detector.

  In the radiation detector, a region irradiated with radiation deteriorates. For this reason, in the radiation detector, when imaging using a specific part of the detection region is repeated, deterioration of only the part proceeds. For example, as shown in FIG. 16, when there is a display (“+” mark) indicating the center of the detection area, photographing is often performed using the center portion of the detection area. When the used imaging is repeated, deterioration of the central portion proceeds, and the image quality of the radiographic image captured at the central portion deteriorates. Further, when photographing with the whole radiation detector, there is a possibility that a difference in image quality may occur between the central portion and the peripheral portion.

  In particular, fluoroscopic imaging has a large number of shots, and the total amount of radiation irradiated to the radiation detector is greatly increased as compared to normal still image imaging. For this reason, as in Patent Document 2 and Patent Document 3, when the radiographic image capturing area is limited to be narrow and the radiation irradiation area is also limited according to the radiographic area, deterioration of the imaging area portion proceeds. For example, in fluoroscopic imaging, the imaging region is usually limited to the central portion of the radiation detector, but deterioration of the central portion proceeds. However, Patent Document 2 and Patent Document 3 do not disclose measures against such deterioration.

  The present invention has been made in view of the above problems, and provides an imaging region specifying device, a radiographic imaging system, and an imaging region specifying method capable of suppressing the progress of deterioration in a specific part of a detection region of a radiation detector. The purpose is to do.

  In order to achieve the above object, an imaging region specifying device according to claim 1 is a radiation detector that outputs an electrical signal indicating a radiation image represented by radiation irradiated to a detection region for detecting radiation. Based on the correlation information stored in the storage means and storage means for storing a correlation value correlated with the irradiated radiation dose as correlation information for each divided area obtained by dividing the detection area into a plurality of predetermined areas. And specifying means for specifying an imaging region in which a radiographic image of a predetermined size can be acquired while suppressing variations in the radiation dose applied to each segmented region within the detection region.

  According to the first aspect of the present invention, the correlation value correlating with the irradiated radiation dose is stored in the storage means for each divided area obtained by dividing the detection area of the radiation detector into a plurality of predetermined areas. Remember as.

  In the present invention, a radiographic image having a predetermined size is suppressed by the specifying unit based on the correlation information stored in the storage unit while suppressing variations in the radiation dose irradiated to each segmented region in the detection region. An imaging region capable of performing is specified.

  As described above, according to the first aspect of the present invention, the correlation value correlating with the irradiated radiation dose is obtained for each divided region obtained by dividing the detection region of the radiation detector into a plurality of predetermined regions. As the imaging region that can capture a radiographic image of a predetermined size while suppressing variations in the radiation dose irradiated to each segmented region within the detection region is specified based on the stored correlation information By taking a radiographic image using the specified imaging region, it is possible to suppress the deterioration from progressing in a specific part of the detection region of the radiation detector.

  Note that, in the present invention, as in the invention described in claim 2, the storage means stores, for each imaging region of the subject on which a radiographic image is to be captured, an area necessary for imaging the radiographic image of the imaging region. Size information indicating a size is further stored, and acquisition means for acquiring imaging region information indicating an imaging region to be imaged is further provided, and the specifying unit is based on the size information stored in the storage unit, The size of the area necessary for imaging of the imaging region indicated by the imaging region information acquired by the acquisition unit is obtained, and based on the correlation information, variation in the radiation dose irradiated to each segmented region in the detection region is suppressed. However, an imaging region in which a radiographic image of the size can be taken may be specified.

  Further, in the invention according to claim 1 or 2, as in the invention according to claim 3, the specifying unit is configured to detect an area necessary for imaging of the imaging region within the detection area based on the correlation information. For each size range, the sum of the correlation values of the respective divided regions within the range may be obtained, and the range having the smallest total value may be specified as the imaging region.

  Further, in the invention according to claim 1 or 2, as in the invention according to claim 4, the specifying unit is configured to determine an area necessary for imaging of the imaging region within the detection area based on the correlation information. For each size range, the maximum correlation value of each segmented region in the range may be obtained, and the range having the smallest maximum value may be specified as the imaging region.

  Further, the invention according to claims 1 to 4 may further include a presenting means for presenting the imaging region specified by the specifying means, as in the invention according to claim 5.

  Further, according to the first to fifth aspects of the present invention, as in the sixth aspect of the present invention, the specifying means is adapted to the radiation generating apparatus provided with the limiting means for generating radiation and limiting the radiation irradiation area. The image forming apparatus may further include a control unit that controls the restriction unit so that the specified imaging region is irradiated with radiation.

  Further, according to the first to sixth aspects of the present invention, as in the seventh aspect of the present invention, the correlation value is either one of a still image shooting in which shooting is performed once or a fluoroscopic shooting in which shooting is continuously performed. There may be further provided a conversion means for converting the correlation value in the other photographing of the still image photographing or the fluoroscopic photographing into the correlation value in the one photographing as the number of photographing in one photographing or the irradiation time of the radiation.

  On the other hand, a radiographic imaging system according to an eighth aspect of the present invention is a radiographic imaging apparatus having a radiation detector that outputs an electrical signal indicating a radiographic image represented by radiation applied to a detection region for detecting radiation; Storage means for storing a correlation value correlating with the irradiated radiation dose as correlation information for each divided area obtained by dividing the detection area into a plurality of predetermined areas, and the correlation information stored in the storage means Based on the above, an imaging region specifying device having specifying means for specifying an imaging region capable of capturing a radiographic image of a predetermined size while suppressing variation in the radiation dose irradiated to each divided region in the detection region; Presenting means for presenting an imaging region identified by the identifying means.

  Therefore, since this invention acts similarly to invention of Claim 1, it can suppress that deterioration progresses in the specific part of the detection area | region of a radiation detector.

  In the invention according to claim 8, as in the invention according to claim 9, whether or not an imaging region is arranged at a position where a radiographic image is taken in an imaging region specified by the specifying means of the radiation detector. Detecting means for detecting whether or not an imaging region is arranged at a position where a radiographic image is imaged in the imaging area by the detecting means from the radiation generating device that generates radiation to the imaging area And permission means for permitting irradiation of radiation.

  In the invention according to claim 9, as in the invention according to claim 10, the radiation detector converts the radiation into light by a scintillator that converts the radiation into light, and shows a radiation image represented by the light. It is assumed that an electric signal is output, and the scintillator may include a columnar crystal of a phosphor material.

  In the invention described in claim 10, as in the invention described in claim 11, the phosphor material is preferably CsI.

  According to an eleventh aspect of the present invention, as in the twelfth aspect of the present invention, the storage means further stores irradiation information regarding the intensity and irradiation timing of the irradiated radiation for each of the divided regions, and Based on the irradiation information, the sectioned area where the recovery period necessary for the recovery of the sensitivity change has not passed since the irradiation with the intensity of radiation that causes a temporary sensitivity change is outside the imaging area. Alternatively, the imaging region may be specified so that the segmented region does not overlap the region of interest of the imaging region.

    The invention according to claim 12 is the radiation detector according to claim 13, further comprising temperature detecting means for detecting the temperature of the radiation detector, wherein the specifying means detects the radiation detected by the temperature detecting means. The recovery period may be changed shorter as the temperature state of the detector is higher.

  On the other hand, in the imaging region specifying method according to the fourteenth aspect of the present invention, the detection region of the radiation detector that outputs an electrical signal indicating a radiation image represented by radiation applied to the detection region for detecting radiation is predetermined. For each of the divided areas divided into a plurality of areas, a correlation value correlating with the irradiated radiation dose is stored as correlation information in the storage means, and based on the correlation information stored in the storage means, Then, an imaging region in which a radiographic image having a predetermined size can be captured while suppressing variation in the radiation dose irradiated to each segmented region is specified.

  Therefore, since this invention acts similarly to invention of Claim 1, it can suppress that deterioration progresses in the specific part of the detection area | region of a radiation detector.

  According to the present invention, it is possible to obtain an effect that it is possible to suppress the deterioration from progressing in a specific part of the detection region of the radiation detector.

It is a block diagram which shows the structure of the radiation information system which concerns on embodiment. It is a figure which shows the mode of the radiation imaging room where the radiographic imaging system which concerns on embodiment was installed. It is a permeation | transmission perspective view which shows the internal structure of the electronic cassette concerning embodiment. It is a block diagram which shows the detailed structure of the radiographic imaging system which concerns on 1st Embodiment. It is a perspective view which shows schematic structure of the movable aperture_diaphragm | restriction apparatus which concerns on embodiment. It is a cross-sectional schematic diagram which shows schematic structure of the 3 pixel part of the radiation detector which concerns on embodiment. It is sectional drawing which showed roughly the structure of the signal output part of 1 pixel part of the radiation detector which concerns on embodiment. It is a top view which shows an example which divided the detection area of the radiation detector which concerns on embodiment into nine division area. It is a top view which shows an example of the irradiation surface of the electronic cassette concerning 1st Embodiment. It is a schematic diagram which shows an example of the data structure of the correlation information which concerns on embodiment. It is a schematic diagram which shows an example of the data structure of the size information which concerns on embodiment. It is a schematic diagram which shows an example of the data structure of the division area | region combination information which concerns on embodiment. It is a flowchart which shows the flow of a process of the imaging region specific process program which concerns on embodiment. It is a figure which shows an example of the display form which showed the imaging | photography area | region which concerns on embodiment on the display. It is a flowchart which shows the flow of a process of the correlation information update process program which concerns on embodiment. It is a top view which shows an example of the irradiation surface of the electronic cassette concerning 2nd Embodiment. It is a block diagram which shows the detailed structure of the radiographic imaging system which concerns on 2nd Embodiment. It is a flowchart which shows the flow of a process of the imaging | photography site | part arrangement | positioning waiting process program which concerns on 2nd Embodiment. It is a figure which shows an example of the radiation dose and operation | movement condition in fluoroscopic imaging and still image imaging which concern on another form. It is a flowchart which shows the flow of a process of the correlation information update process program which concerns on another form. It is a figure which shows an example of the presentation means which presents the imaging | photography area | region which concerns on another form. It is a figure which shows an example of the presentation means which presents the imaging | photography area | region which concerns on another form. It is a cross-sectional side view for demonstrating the surface reading system and back surface reading system of the radiation to a radiation detector. It is a graph which shows the relationship between the radiation dose with which the scintillator was irradiated, and light emission amount. It is a graph which shows the time-dependent change of variation | change_quantity (DELTA) of the inclination of the sensitivity line of a scintillator.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, the configuration of the radiation information system 10 according to the present embodiment will be described.

In FIG. 1, the radiation information system 10 according to the present embodiment {hereinafter also referred to as “RIS10” (RIS: Radiology Information System). ) Is a block diagram showing each component.

  The RIS 10 is a system for managing information such as medical appointment reservations and diagnosis records in the radiology department, and constitutes a part of a hospital information system (hereinafter referred to as “HIS” (Hospital Information System)). .

  The RIS 10 includes a plurality of radiographic images individually installed in a plurality of imaging request terminal devices 12 (hereinafter also referred to as “terminal devices 12”), an RIS server 14, and a radiographic room (or operating room) in a hospital. An imaging system 18 (hereinafter also referred to as “imaging system 18”) is configured to be connected to an in-hospital network 16 including a wired or wireless LAN (Local Area Network). Has been. The hospital network 16 is also connected to an HIS server (not shown) that manages the entire HIS.

  The terminal device 12 is used by doctors and radiographers to input and browse diagnostic information and facility reservations, and radiographic image capturing requests and imaging reservations are also made via the terminal device 12. Each terminal device 12 includes a personal computer having a display device, and is capable of mutual communication via the RIS server 14 and the hospital network 16.

  On the other hand, the RIS server 14 receives an imaging request from each terminal device 12 and manages a radiographic imaging schedule in the imaging system 18, and includes a database 14A.

  The database 14A includes patient attribute information (name, ID, gender, date of birth, age, blood type, weight, etc.), medical history, medical history, radiation images taken in the past (hereinafter referred to as “patient information”). ), Information relating to the electronic cassette 32 used in the imaging system 18 such as an identification number, model, size, sensitivity, usable imaging site, start date of use, and number of times of use (described later). Hereinafter, it is referred to as “electronic cassette information”), and an environment in which a radiographic image is taken using the electronic cassette 32, that is, an environment in which the electronic cassette 32 is used (for example, a radiographic room or an operating room). It contains information.

  The imaging system 18 captures a radiographic image by an operation of a doctor or a radiographer according to an instruction from the RIS server 14. The imaging system 18 includes a radiation generator 34 that irradiates a patient with a radiation X (see also FIG. 3) that is a dose in accordance with the exposure conditions from a radiation source 130 (see also FIG. 2), and an imaging region of the patient. An electronic cassette 32 having a built-in radiation detector 60 (see also FIG. 3) that generates a charge by absorbing the radiation X transmitted therethrough and generates image information indicating a radiation image based on the generated charge amount; A cradle 40 that charges a battery built in the cassette 32, an electronic cassette 32, a radiation generator 34, and a console 42 that controls the cradle 40 are provided.

  FIG. 2 shows an example of an arrangement state in which the imaging system 18 according to the present embodiment is arranged in the radiation imaging room 44.

  As shown in the figure, in the radiation imaging room 44, a rack 45 for holding the electronic cassette 32 when performing radiography in a standing position, and a patient lying down when performing radiography in a prone position. A bed 46 is provided, and the front space of the rack 45 is used as a patient imaging position 48 when radiography is performed in a standing position, and the space above the bed 46 is used when radiography is performed in a prone position. The patient's imaging position 50 is set.

  Further, in the radiation imaging room 44, the radiation source 130 is arranged around a horizontal axis (see FIG. 5) in order to enable radiation imaging in a standing position and in a standing position by radiation from a single radiation source 130. 2 is provided, and a support moving mechanism 52 is provided which can be rotated in the vertical direction (arrow B direction in FIG. 2) and supported so as to be movable in the horizontal direction (arrow C direction in FIG. 2). It has been. The support moving mechanism 52 includes a drive source that rotates the radiation source 130 around a horizontal axis, a drive source that moves the radiation source 130 in the vertical direction, and a drive source that moves the radiation source 130 in the horizontal direction. (Both not shown).

  The cradle 40 is formed with a housing portion 40 </ b> A capable of housing the electronic cassette 32.

  The electronic cassette 32 is housed in the housing portion 40A of the cradle 40 during standby, and the built-in battery is charged. When a radiographic image is taken, the electronic cassette 32 is taken out from the cradle 40 by a radiographer, and the photographing posture is upright. For example, the position is moved / positioned to a position 49 held by the rack 45, and the position is moved / positioned to a position 51 on the bed 46 if the photographing posture is in the upright position.

  In the imaging system 18 according to the present embodiment, the radiation generator 34 and the console 42 are connected by a cable and various types of information are transmitted / received by wired communication, but the illustration of the cable is omitted in FIG. In the imaging system 18 according to the present embodiment, various information is transmitted and received between the electronic cassette 32 and the console 42 by wireless communication.

  Note that the electronic cassette 32 is not used only in the radiography room or the operating room, but can be used for, for example, examinations and rounds in hospitals because of its portability.

  FIG. 3 shows an internal configuration of the electronic cassette 32 according to the present exemplary embodiment.

  As shown in the figure, the electronic cassette 32 includes a housing 54 made of a material that transmits the radiation X, and has a waterproof and airtight structure. When the electronic cassette 32 is used in an operating room or the like, there is a risk that blood and other germs may adhere. Therefore, one electronic cassette 32 can be used repeatedly by sterilizing and cleaning the electronic cassette 32 as necessary with a waterproof and airtight structure.

  Inside the housing 54 are a grid 58 for removing scattered radiation of the radiation X by the patient from the irradiation surface 56 side of the housing 54 irradiated with the radiation X, and a radiation detector 60 for detecting the radiation X transmitted through the patient. , And a lead plate 62 that absorbs backscattered rays of radiation X is disposed in order. Note that the irradiation surface 56 of the housing 54 may be configured as a grid 58.

  In addition, a case 31 that houses an electronic circuit including a microcomputer and a rechargeable secondary battery is disposed at one end side inside the housing 54. The radiation detector 60 and the electronic circuit are operated by electric power supplied from the secondary battery disposed in the case 31. In order to avoid various circuits housed in the case 31 from being damaged by the radiation X irradiation, it is desirable to arrange a lead plate or the like on the irradiation surface 56 side of the case 31. The electronic cassette 32 according to the present embodiment is a rectangular parallelepiped whose irradiation surface 56 has a rectangular shape, and a case 31 is disposed at one end in the longitudinal direction. A handle 54 </ b> A that is gripped when the electronic cassette 32 is moved is provided at a predetermined position on the outer wall of the housing 54.

  FIG. 4 is a block diagram showing the main configuration of the electrical system of the radiographic imaging system 18 according to the first exemplary embodiment.

  As shown in the figure, the radiation generator 34 is provided with a connection terminal 34 </ b> A for communicating with the console 42. The console 42 is provided with a connection terminal 42 </ b> A for communicating with the radiation generator 34. The connection terminal 34 </ b> A of the radiation generator 34 and the connection terminal 42 </ b> A of the console 42 are connected by a communication cable 35.

  The radiation detector 60 incorporated in the electronic cassette 32 is an indirect conversion method in which radiation is converted into light by a scintillator and then converted into charges by a photoelectric conversion element such as a photodiode, and radiation is converted into charges by a semiconductor layer such as amorphous selenium. Any direct conversion method may be used. The direct conversion type radiation detector 60 is configured by laminating a photoelectric conversion layer that absorbs radiation X and converts it into charges on a TFT active matrix substrate 66. The photoelectric conversion layer is made of amorphous a-Se (amorphous selenium) containing, for example, selenium as a main component (for example, a content rate of 50% or more), and when irradiated with radiation X, a charge corresponding to the amount of irradiated radiation. By generating a certain amount of charge (electron-hole pairs) internally, the irradiated radiation X is converted into a charge. The indirect conversion type radiation detector 60 uses a phosphor material and a photoelectric conversion element (photodiode) indirectly instead of the radiation-charge conversion material that directly converts the radiation X such as amorphous selenium into electric charges. Convert to charge. As phosphor materials, gadolinium sulfate (GOS) and cesium iodide (CsI) are well known. In this case, radiation X-light conversion is performed using a fluorescent material, and light-charge conversion is performed using a photodiode of a photoelectric conversion element.

  Further, on the TFT active matrix substrate 66, a pixel unit 74 provided with a storage capacitor 68 for storing charges generated in the photoelectric conversion layer or photoelectric conversion element and a TFT 70 for reading out the charges stored in the storage capacitor 68. (In FIG. 4, photoelectric conversion layers or photoelectric conversion elements corresponding to the individual pixel portions 74 are schematically shown as sensor portions 72.) A large number of them are arranged in a matrix and radiation X to the electronic cassette 32 The charges generated in the sensor unit 72 in accordance with the irradiation of are accumulated in the storage capacitors 68 of the individual pixel units 74. As a result, the image information carried on the radiation X irradiated to the electronic cassette 32 is converted into charge information and held in the radiation detector 60.

  The TFT active matrix substrate 66 is extended in a certain direction (row direction), a plurality of gate wirings 76 for turning on and off the TFTs 70 of the individual pixel portions 74, and a direction (column) orthogonal to the gate wirings 76. A plurality of data wirings 78 are provided for reading out stored charges from the storage capacitor 68 via the TFT 70 which is turned on and turned on. Individual gate lines 76 are connected to a gate line driver 80, and individual data lines 78 are connected to a signal processing unit 82. When charges are accumulated in the storage capacitors 68 of the individual pixel portions 74, the TFTs 70 of the individual pixel portions 74 are sequentially turned on in units of rows by a signal supplied from the gate line driver 80 via the gate wiring 76. The charges stored in the storage capacitor 68 of the pixel unit 74 in which the TFT 70 is turned on are transmitted as an analog electric signal through the data wiring 78 and input to the signal processing unit 82. Accordingly, the charges accumulated in the storage capacitors 68 of the individual pixel portions 74 are sequentially read out in units of rows.

  Although not shown, the signal processing unit 82 includes an amplifier and a sample-and-hold circuit provided for each data wiring 78. After the charge signal transmitted through each data wiring 78 is amplified by the amplifier, It is held in the sample hold circuit. Further, a multiplexer and an A / D (analog / digital) converter are sequentially connected to the output side of the sample and hold circuit, and the charge signals held in the individual sample and hold circuits are sequentially (serially) input to the multiplexer. The digital image data is converted by an A / D converter.

  An image memory 90 is connected to the signal processing unit 82, and image data output from the A / D converter of the signal processing unit 82 is sequentially stored in the image memory 90. The image memory 90 has a storage capacity capable of storing a predetermined number of image data, and image data obtained by imaging is sequentially stored in the image memory 90 every time a radiographic image is captured.

  The image memory 90 is connected to a cassette control unit 92 that controls the operation of the entire electronic cassette 32. The cassette control unit 92 includes a microcomputer, and includes a CPU (central processing unit) 92A, a memory 92B including a ROM and a RAM, and a nonvolatile storage unit 92C including an HDD, a flash memory, and the like.

  A wireless communication unit 94 is connected to the cassette control unit 92. The wireless communication unit 94 corresponds to a wireless local area network (LAN) standard represented by IEEE (Institute of Electrical and Electronics Engineers) 802.11a / b / g / n, etc. Control the transmission of various information between them. The cassette control unit 92 can wirelessly communicate with the console 42 via the wireless communication unit 94, and can transmit and receive various information to and from the console 42. The cassette control unit 92 stores an exposure condition, which will be described later, received from the console 42 via the wireless communication unit 94, and starts reading out charges based on the exposure condition.

  Further, the electronic cassette 32 is provided with a power supply unit 96, which functions as the above-described various circuits and elements (gate line driver 80, signal processing unit 82, image memory 90, wireless communication unit 94, and cassette control unit 92). The microcomputer is activated by the electric power supplied from the power supply unit 96. The power supply unit 96 incorporates a battery (a rechargeable secondary battery) so as not to impair the portability of the electronic cassette 32, and supplies power from the charged battery to various circuits and elements. In FIG. 4, the power supply unit 96 and wirings for connecting various circuits and elements are omitted.

  On the other hand, the console 42 is configured as a server computer, and includes a display 100 that displays an operation menu, captured radiographic images, and the like, and a plurality of keys, and inputs various information and operation instructions. An operation panel 102.

  The console 42 according to the present embodiment includes a CPU 104 that controls the operation of the entire apparatus, a ROM 106 that stores various programs including a control program in advance, a RAM 108 that temporarily stores various data, and various data. An HDD 110 that stores and retains, a display driver 112 that controls display of various types of information on the display 100, and an operation input detection unit 114 that detects an operation state of the operation panel 102 are provided.

  The console 42 is connected to the connection terminal 42A, and communicates with the radiation generator 34 via the connection terminal 42A and the communication cable 35 to transmit and receive various types of information such as exposure conditions and posture information (described later). I / F) unit 116 and a wireless communication unit 118 that transmits and receives various types of information such as exposure conditions and image data by wireless communication with the electronic cassette 32.

  CPU 104, ROM 106, RAM 108, HDD 110, display driver 112, operation input detection unit 114, communication I / F unit 116, and wireless communication unit 118 are connected to each other via a system bus BUS. Therefore, the CPU 104 can access the ROM 106, RAM 108, and HDD 110, controls display of various information on the display 100 via the display driver 112, and the radiation generator 34 via the communication I / F unit 116. And control of transmission / reception of various information to / from the electronic cassette 32 via the wireless communication unit 118. Further, the CPU 104 can grasp the operation state of the user with respect to the operation panel 102 via the operation input detection unit 114.

  On the other hand, the radiation generator 34 sends various information such as exposure conditions between the radiation source 130 that emits the radiation X, the movable diaphragm 131 that restricts the radiation X irradiation region of the radiation source 130, and the console 42. Controlling the power supply to each drive source provided in the support moving mechanism 52, the communication I / F unit 132 that transmits and receives, the radiation source control unit 134 that controls the radiation source 130 based on the received exposure conditions And a radiation source drive control unit 136 for controlling the operation of the support moving mechanism 52.

  The radiation source control unit 134 is also realized by a microcomputer, and stores the received exposure conditions and posture information. The exposure conditions received from the console 42 include information such as tube voltage, tube current, and irradiation period, and the posture information includes information indicating whether the photographing posture is standing or lying. If the imaging posture designated by the received posture information is in the standing position, the radiation source control unit 134 causes the radiation source 130 to be in the standing position imaging position 53A (see FIG. 2, exit) via the radiation source drive control unit 136. If the imaging posture specified by the received posture information is in the supine position, the support movement mechanism 52 is controlled so that the received radiation is positioned at a position at which the patient positioned at the imaging position 48 is irradiated from the side). The radiation source 130 is positioned at the position 53B for supine imaging (see FIG. 2, the position where the emitted radiation is irradiated from above to the patient positioned at the imaging position 50) via the radiation source drive control unit 136. Thus, the support moving mechanism 52 is controlled. Further, when an exposure start is instructed, the radiation source control unit 134 causes the radiation source 130 to irradiate the radiation X based on the received exposure conditions. The radiation X irradiated from the radiation source 130 passes through the movable diaphragm device 54 and is irradiated to the patient.

  As shown in FIG. 5, the movable diaphragm device 131 is provided with slit plates 135 and 136 and slit plates 137 and 138. The slit plates 135 and 136 and the slit plates 137 and 138 are movable by a driving force of a motor or solenoid (not shown). The movable diaphragm device 131 changes the irradiation region of the radiation X by the radiation source 130 in the X direction by moving the slit plates 135 and 136 individually in one direction (X direction), and the slit plates 137 and 138 in one direction. The irradiation region of the radiation X by the radiation source 130 is changed to the Y direction by individually moving in the intersecting direction (Y direction) with respect to.

  The movable aperture device 131 is provided with an operation panel 131A (see FIG. 4) for instructing movement of the slit plates 135 and 136 and the slit plates 137 and 138. A doctor or a radiographer can change the irradiation region of the radiation X by operating the operation panel 131A and adjusting the arrangement relationship of the slit plates 135 and 136 and the slit plates 137 and 138. The irradiation region of the radiation X is confirmed by the operator by, for example, providing an imaging camera in the vicinity of the radiation source 130, imaging an imaging region captured by the radiation, and displaying the image on the display 100 of the console 42. May be. Further, a visible light lamp that irradiates visible light in the vicinity of the radiation source 130 may be provided, and the operator may be confirmed by irradiating the imaging region of the subject's body.

  Next, the structure of the radiation detector 60 of the indirect conversion system which converts a radiation into an electric charge indirectly using a fluorescent material and a photoelectric conversion element is demonstrated.

  FIG. 6 is a schematic cross-sectional view schematically showing the configuration of the three pixel portions of the indirect conversion type radiation detector 60 according to an embodiment of the present invention.

  In the radiation detector 60, a signal output unit 202, a sensor unit 72, and a scintillator 204 are sequentially stacked on an insulating substrate 200, and a pixel unit is configured by the signal output unit 202 and the sensor unit 72. . A plurality of pixel units are arranged on the substrate 200, and the signal output unit 202 and the sensor unit 72 in each pixel unit are configured to overlap each other.

  The scintillator 204 is formed on the sensor unit 72 via a transparent insulating film 206, and is formed by forming a phosphor that emits light by converting radiation incident from above (opposite the substrate 200) into light. It is. By providing such a scintillator 204, the radiation transmitted through the subject is absorbed and light is emitted.

  The wavelength range of light emitted by the scintillator 204 is preferably in the visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 60, the wavelength range of green is included. Is more preferable.

  Specifically, the phosphor used in the scintillator 204 preferably contains cesium iodide (CsI) when imaging using X-rays as radiation, and has an emission spectrum of 420 nm to 600 nm at the time of X-ray irradiation. It is particularly preferable to use CsI (Tl). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.

  The scintillator 204 may be formed by vapor deposition on a vapor deposition substrate, for example, when it is intended to be formed of columnar crystals such as CsI (Tl). When the scintillator 204 is formed by vapor deposition as described above, an Al plate is often used as the vapor deposition substrate from the viewpoint of X-ray transmittance and cost, but is not limited thereto. When GOS is used as the scintillator 204, the scintillator 204 may be formed by applying GOS to the surface of the TFT active matrix substrate 66 without using a vapor deposition substrate.

  The sensor unit 72 includes an upper electrode 210, a lower electrode 212, and a photoelectric conversion film 214 disposed between the upper and lower electrodes.

Since it is necessary for the upper electrode 210 to cause the light generated by the scintillator 204 to be incident on the photoelectric conversion film 214, it is preferable that the upper electrode 210 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 204. It is preferable to use a transparent conductive oxide (TCO) having a high transmittance for visible light and a small resistance value. Although a metal thin film such as Au can be used as the upper electrode 210, the TCO is preferable because it tends to increase the resistance value when obtaining a transmittance of 90% or more. For example, ITO, IZO, AZO, FTO, SnO ₂ , TiO ₂ , ZnO _{2 and the} like can be preferably used, and ITO is most preferable from the viewpoint of process simplicity, low resistance, and transparency. Note that the upper electrode 210 may have a single configuration common to all pixel portions, or may be divided for each pixel portion.

  The photoelectric conversion film 214 absorbs light emitted from the scintillator 204 and generates electric charge according to the absorbed light. The photoelectric conversion film 214 may be formed of a material that generates an electric charge when irradiated with light. For example, the photoelectric conversion film 214 may be formed of amorphous silicon, an organic photoelectric conversion material, or the like. The photoelectric conversion film 214 containing amorphous silicon has a wide absorption spectrum and can absorb light emitted by the scintillator 204. If the photoelectric conversion film 214 includes an organic photoelectric conversion material, it has a sharp absorption spectrum in the visible range, electromagnetic waves other than light emitted by the scintillator 204 are hardly absorbed by the photoelectric conversion film 214, and radiation such as X-rays. Can be effectively suppressed noise generated by the absorption by the photoelectric conversion film 214.

  The organic photoelectric conversion material constituting the photoelectric conversion film 214 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 204 in order to absorb light emitted by the scintillator 204 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 204, but if the difference between the two is small, the light emitted from the scintillator 204 can be sufficiently absorbed. . Specifically, the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the scintillator 204 is preferably within 10 nm, and more preferably within 5 nm.

  Examples of the organic photoelectric conversion material that can satisfy such conditions include quinacridone organic compounds and phthalocyanine organic compounds. For example, since the absorption peak wavelength of quinacridone in the visible region is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 204, the difference in peak wavelength can be made within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 214 can be substantially maximized.

  Next, the photoelectric conversion film 214 applicable to the radiation detector 60 according to the present embodiment will be specifically described.

  The electromagnetic wave absorption / photoelectric conversion site in the radiation detector 60 according to the present invention includes an organic photoelectric conversion film 214 sandwiched between a pair of lower electrode 212 and upper electrode 210 and the lower electrode 212 and upper electrode 210. It can be composed of layers. More specifically, this organic layer is a part that absorbs electromagnetic waves, a photoelectric conversion part, an electron transport part, a hole transport part, an electron blocking part, a hole blocking part, a crystallization preventing part, an electrode, and an interlayer contact improvement. It can be formed by stacking or mixing parts.

  The organic layer preferably contains an organic p-type compound or an organic n-type compound.

  The organic p-type semiconductor (compound) is a donor organic semiconductor (compound) mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound.

  An organic n-type semiconductor (compound) is an acceptor organic semiconductor (compound) mainly represented by an electron-transporting organic compound and refers to an organic compound having a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound.

  The materials applicable as the organic p-type semiconductor and organic n-type semiconductor and the configuration of the photoelectric conversion film 214 are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, and thus the description thereof is omitted. Note that the photoelectric conversion film 214 may be formed by further containing fullerenes or carbon nanotubes.

  The thickness of the photoelectric conversion film 214 is preferably as large as possible in terms of absorbing light from the scintillator 204. However, when the thickness is more than a certain level, the photoelectric conversion film 214 is generated in the photoelectric conversion film 214 by a bias voltage applied from both ends of the photoelectric conversion film 214. Since electric field strength is reduced and charges cannot be collected, the thickness is preferably 30 nm to 300 nm, more preferably 50 nm to 250 nm, and particularly preferably 80 nm to 200 nm.

  In the radiation detector 60 shown in FIG. 6, the photoelectric conversion film 214 has a single configuration common to all the pixel portions, but may be divided for each pixel portion.

  The lower electrode 212 is a thin film divided for each pixel portion. The lower electrode 212 can be made of a transparent or opaque conductive material, and aluminum, silver, or the like can be suitably used.

  The thickness of the lower electrode 212 can be, for example, 30 nm or more and 300 nm or less.

  In the sensor unit 72, by applying a predetermined bias voltage between the upper electrode 210 and the lower electrode 212, one of charges (holes, electrons) generated in the photoelectric conversion film 214 is moved to the upper electrode 210. The other can be moved to the lower electrode 212. In the radiation detector 60 of the present embodiment, a wiring is connected to the upper electrode 210, and a bias voltage is applied to the upper electrode 210 via this wiring. In addition, the polarity of the bias voltage is determined such that electrons generated in the photoelectric conversion film 214 move to the upper electrode 210 and holes move to the lower electrode 212. However, this polarity is opposite. May be.

  The sensor unit 72 constituting each pixel unit only needs to include at least the lower electrode 212, the photoelectric conversion film 214, and the upper electrode 210. In order to suppress an increase in dark current, the electron blocking film 216 and the hole blocking are included. It is preferable to provide at least one of the films 218, and it is more preferable to provide both.

  The electron blocking film 216 can be provided between the lower electrode 212 and the photoelectric conversion film 214. When a bias voltage is applied between the lower electrode 212 and the upper electrode 210, electrons are transferred from the lower electrode 212 to the photoelectric conversion film 214. It is possible to suppress the dark current from increasing due to the injection of.

  An electron-donating organic material can be used for the electron blocking film 216.

  The material actually used for the electron blocking film 216 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 214, and the like, and 1.3 eV or more from the work function (Wf) of the material of the adjacent electrode. Those having a large electron affinity (Ea) and an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoelectric conversion film 214 are preferable. Since the material applicable as the electron donating organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  The thickness of the electron blocking film 216 is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably, in order to reliably exhibit the dark current suppressing effect and prevent a decrease in the photoelectric conversion efficiency of the sensor unit 72. It is 50 nm or more and 100 nm or less.

  The hole blocking film 218 can be provided between the photoelectric conversion film 214 and the upper electrode 210. When a bias voltage is applied between the lower electrode 212 and the upper electrode 210, the hole blocking film 218 is transferred from the upper electrode 210 to the photoelectric conversion film 214. It is possible to suppress the increase in dark current due to the injection of holes.

  An electron-accepting organic material can be used for the hole blocking film 218.

  The thickness of the hole blocking film 218 is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably, in order to surely exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the sensor unit 72. Is from 50 nm to 100 nm.

  The material actually used for the hole blocking film 218 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 214, etc., and 1.3 eV from the work function (Wf) of the material of the adjacent electrode. As described above, it is preferable that the ionization potential (Ip) is large and the Ea is equal to or larger than the electron affinity (Ea) of the material of the adjacent photoelectric conversion film 214. Since the material applicable as the electron-accepting organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  In the case where the bias voltage is set so that holes move to the upper electrode 210 and electrons move to the lower electrode 212 among the charges generated in the photoelectric conversion film 214, the electron blocking film 216 and the hole blocking are set. The position of the film 218 may be reversed. Further, it is not necessary to provide both the electron blocking film 216 and the hole blocking film 218. If either one is provided, a certain dark current suppressing effect can be obtained.

  A signal output unit 202 is formed on the surface of the substrate 200 below the lower electrode 212 of each pixel unit.

  FIG. 7 schematically shows the configuration of the signal output unit 202.

  Corresponding to the lower electrode 212, a storage capacitor 68 for storing the charge moved to the lower electrode 212, and a TFT 70 for converting the charge stored in the storage capacitor 68 into an electric signal and outputting it are formed. The region where the storage capacitor 68 and the TFT 70 are formed has a portion that overlaps the lower electrode 212 in a plan view. With such a configuration, the signal output unit 202 and the sensor unit 72 in each pixel unit are connected to each other. There will be overlap in the thickness direction. In order to minimize the plane area of the radiation detector 60 (pixel portion), it is desirable that the region where the storage capacitor 68 and the TFT 70 are formed is completely covered by the lower electrode 212.

  The storage capacitor 68 is electrically connected to the corresponding lower electrode 212 through a wiring made of a conductive material penetrating an insulating film 219 provided between the substrate 200 and the lower electrode 212. Thereby, the electric charge collected by the lower electrode 212 can be moved to the storage capacitor 68.

  In the TFT 70, a gate electrode 220, a gate insulating film 222, and an active layer (channel layer) 224 are stacked, and a source electrode 226 and a drain electrode 228 are formed on the active layer 224 at a predetermined interval. The active layer 224 can be formed of, for example, amorphous silicon, amorphous oxide, organic semiconductor material, carbon nanotube, or the like. Note that the material forming the active layer 224 is not limited thereto.

The amorphous oxide that can form the active layer 224 is preferably an oxide containing at least one of In, Ga, and Zn (for example, In—O-based), and at least two of In, Ga, and Zn. Oxides containing one (for example, In—Zn—O, In—Ga—O, and Ga—Zn—O) are more preferable, and oxides including In, Ga, and Zn are particularly preferable. As the In—Ga—Zn—O-based amorphous oxide, an amorphous oxide whose composition in a crystalline state is represented by InGaO ₃ (ZnO) _m (m is a natural number less than 6) is preferable, and InGaZnO is particularly preferable. ₄ is more preferable. Note that the amorphous oxide that can form the active layer 224 is not limited thereto.

  Examples of the organic semiconductor material that can form the active layer 224 include, but are not limited to, phthalocyanine compounds, pentacene, vanadyl phthalocyanine, and the like. In addition, about the structure of a phthalocyanine compound, since it is demonstrated in detail in Unexamined-Japanese-Patent No. 2009-212389, description is abbreviate | omitted.

  If the active layer 224 of the TFT 70 is formed of an amorphous oxide, an organic semiconductor material, or a carbon nanotube, it will not absorb radiation such as X-rays, or even if it absorbs it, it will remain in a very small amount. The generation of noise in 202 can be effectively suppressed.

  When the active layer 224 is formed of carbon nanotubes, the switching speed of the TFT 70 can be increased, and the TFT 70 having a low light absorption in the visible light region can be formed. In addition, when the active layer 224 is formed of carbon nanotubes, the performance of the TFT 70 is remarkably reduced only by mixing a very small amount of metallic impurities into the active layer 224. Therefore, extremely high purity carbon nanotubes are separated by centrifugation or the like.・ It needs to be extracted and formed.

  Here, any of the above-described amorphous oxide, organic semiconductor material, carbon nanotube, and organic photoelectric conversion material can be formed at a low temperature. Therefore, the substrate 200 is not limited to a substrate having high heat resistance such as a semiconductor substrate, a quartz substrate, and a glass substrate, and a flexible substrate such as plastic, aramid, or bionanofiber can also be used. Specifically, flexible materials such as polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, and poly (chlorotrifluoroethylene). A conductive substrate can be used. If such a plastic flexible substrate is used, it is possible to reduce the weight, which is advantageous for carrying around, for example.

  In addition, the substrate 200 is provided with an insulating layer for ensuring insulation, a gas barrier layer for preventing permeation of moisture and oxygen, an undercoat layer for improving flatness or adhesion to electrodes, and the like. May be.

  Since aramid can be applied at a high temperature process of 200 ° C. or more, the transparent electrode material can be cured at a high temperature to reduce the resistance, and can also be used for automatic mounting of a driver IC including a solder reflow process. Moreover, since aramid has a thermal expansion coefficient close to that of ITO (indium tin oxide) or a glass substrate, warping after production is small and it is difficult to crack. In addition, aramid can form a substrate thinner than a glass substrate or the like. Note that the substrate 200 may be formed by stacking an ultrathin glass substrate and aramid.

  Bionanofiber is a composite of cellulose microfibril bundles (bacterial cellulose) produced by bacteria (Acetobacter Xylinum) and a transparent resin. The cellulose microfibril bundle has a width of 50 nm and a size of 1/10 of the visible light wavelength, and has high strength, high elasticity, and low thermal expansion. By impregnating and curing a transparent resin such as an acrylic resin or an epoxy resin in bacterial cellulose, a bio-nanofiber having a light transmittance of about 90% at a wavelength of 500 nm can be obtained while containing 60-70% of the fiber. Bionanofiber has a low coefficient of thermal expansion (3-7ppm) comparable to silicon crystals, and is as strong as steel (460MPa), highly elastic (30GPa), and flexible, compared to glass substrates, etc. The substrate 200 can be formed thinly.

  In this embodiment, the signal output unit 202, the sensor unit 72, and the transparent insulating film 206 are formed in this order on the substrate 200, and the scintillator 204 is pasted on the substrate 200 using an adhesive resin with low light absorption. Thus, the radiation detector 60 is formed. Hereinafter, the substrate 200 formed up to the transparent insulating film 206 is referred to as a TFT active matrix substrate (hereinafter also referred to as “TFT substrate”) 66.

  Next, the overall operation of the RIS 10 according to the present embodiment will be briefly described.

  When capturing a radiographic image, the terminal device 12 (see FIG. 1) accepts an imaging request from a doctor or a radiographer. In the imaging request, the environment in which the electronic cassette 32 is used, the date and time of imaging, the imaging region to be imaged, the imaging posture, the tube voltage, and the radiation dose to be irradiated are specified.

  The terminal device 12 notifies the RIS server 14 of the contents of the accepted imaging request. The RIS server 14 stores the contents of the imaging request notified from the terminal device 12 in the database 14A.

  The console 42 accesses the RIS server 14 to acquire the content of the imaging request from the RIS server 14 and displays the content of the imaging request on the display 100 (see FIG. 4).

  In addition, the console 42 transmits posture information indicating an imaging posture in radiography to be performed from now on to the radiation generation device 34. As a result, the radiation source controller 134 of the radiation generator 34 controls the radiation source drive controller 136 so that the radiation source 130 is positioned at a position corresponding to the imaging posture specified by the received posture information.

  The doctor or the radiographer starts radiographic image capturing based on the content of the imaging request displayed on the display 100.

  For example, when a radiographic image of the patient 50 lying on the bed 46 shown in FIG. 2 is taken, a doctor or a radiographer electronically inserts an electron between the bed 46 and the imaging site of the patient 50 according to the imaging site of the patient 50. A cassette 32 is placed. In addition, a doctor or a radiographer arranges the radiation generator 34 above the imaging region and operates the operation panel 131A of the movable aperture device 131 so that the radiation X is irradiated only to the imaging region and the periphery. The irradiation area is limited. Furthermore, a doctor or a radiographer designates an exposure condition for designating a tube voltage, a tube current, and an irradiation period when irradiating the operation panel 102 of the console 42 with radiation X in accordance with the imaging region and imaging conditions of the patient. Perform the operation.

  By the way, when the imaging | photography using the specific part of the detection area 61 which can detect a radiation is repeated, the radiation detector 60 progresses deterioration of only the said part.

  Therefore, in the present embodiment, as shown in FIG. 8, the detection area 61 of the radiation detector 60 is divided into nine 3 × 3 divided areas 61A, and the radiation dose irradiated to each divided area 61A. Are stored in the HDD 110 as correlation information. In addition, the number (for example, (1)) shown in parentheses in each segmented area 61A indicates an identification number for identifying each segmented area 61A.

  As shown in FIG. 9, the irradiation surface 56 irradiated with the radiation X of the housing 54 of the electronic cassette 32 is divided into regions 56 </ b> A corresponding to the respective divided regions 61 </ b> A of the radiation detector 60. An identification number corresponding to the segmented area 61A of the radiation detector 60 is attached to the periphery of each area 56A except for the area 56A.

  FIG. 10 shows an example of the data structure of correlation information stored in the HDD 110.

  In the present embodiment, for each identification number of the partitioned area 61A, the number of times of photographing using the partitioned area 61A is stored as a correlation value.

  In the present embodiment, size information indicating the size of an area necessary for radiographic image capturing of the radiographic region is stored in the HDD 110 for each radiographic region of the patient whose radiographic image is to be captured.

  FIG. 11 shows an example of the data structure of the size information stored in the HDD 110.

  In the present embodiment, the number of segment areas 61A is stored as numerical values in the vertical direction × horizontal direction as size information necessary for imaging for each imaging region. For example, in the case of photographing a hand as an imaging region, it indicates that a total of four divided areas 61A of 2 × 2 (two in the vertical direction and two in the horizontal direction) are necessary.

  Further, in the present embodiment, for each size of the area necessary for shooting, the partitioned area combination information indicating the combination of the partitioned areas 61A in which the size is obtained in the detection area 61 is stored in the HDD 110.

  FIG. 12 shows an example of the data structure of the group area combination information stored in the HDD 110.

  In the present embodiment, for each area size required for shooting, a combination of identification numbers of the segment area 61A from which the size is obtained is stored. For example, when the size of the area required for photographing is 2 × 2, the identification numbers of the segmented areas 61A are (1, 2, 4, 5), (2, 3, 5, 6), (4, 5, 7, Four combinations of 8) and (5, 6, 8, 9) are stored.

  When a predetermined operation instruction for imaging preparation is given to the operation panel 102, the console 42 can perform radiographic imaging of a radiographic region while suppressing variations in radiation dose to each segmented region 61A of the radiation detector 60. An imaging area specifying process for specifying an area is performed.

  FIG. 13 shows a flowchart showing the flow of processing of the photographing area specifying processing program executed by the CPU 104 according to the present embodiment. The program is stored in advance in a predetermined area of the HDD 110.

  In step S10 in the figure, the size of the segment area 61A corresponding to the target part requested to be imaged by the imaging request is read from the size information stored in the HDD 110.

  In the next step S12, based on the divided area combination information stored in the HDD 110, the combination of the divided areas 61A from which the size read in step S12 is obtained is specified.

  In the next step S14, the number of shootings of each segmented area 61A indicated by the correlation information stored in the HDD 110 is summed for each combination of the segmented areas 61A specified in step S14.

  In the next step S16, the combination of the segmented areas 61A having the smallest total value of the number of times of shooting totaled in step S14 is specified as the shooting area.

  In the next step S18, the segmented area 61A identified as the imaging area in step S16 is displayed on the display 100, and the process ends.

  FIG. 14 shows an example of a display form on the display 100. In FIG. 14, in addition to the segmented area 61A identified as the imaging area, the name of the patient to be imaged, the imaging region, and the imaging conditions are also displayed.

  In the present embodiment, among all the divided areas 61A, the divided area 61A specified as the shooting area is displayed in white, and the identification number of the divided area 61A specified as the shooting area is displayed as the recommended area.

  The doctor or radiographer places the electronic cassette 32 so that the identification number area 56A displayed on the display 100 corresponds to the imaging region, and when imaging preparation is completed, instructs the operation panel 102 of the console 42 to perform imaging. Perform the shooting instruction operation.

  When an imaging instruction operation is performed on the operation panel 102, the console 42 transmits instruction information for instructing the start of exposure to the radiation generator 34 and the electronic cassette 32. Thereby, the radiation source 130 generates and emits radiation at a tube voltage, a tube current, and an irradiation period according to the exposure conditions received by the radiation generator 34 from the console 42.

  As a result, radiation is applied to the segmented area 61 </ b> A identified as the imaging area of the radiation detector 60 and radiographic imaging is performed, so that it is possible to suppress the deterioration of only a specific part of the detection area 61. Is done.

  The cassette control unit 92 of the electronic cassette 32 controls the gate line driver 80 after the elapse of the irradiation period specified by the exposure condition after receiving the instruction information for instructing the start of exposure, and 1 line from the gate line driver 80. An ON signal is sequentially output to each gate wiring 76 one by one, and each TFT 70 connected to each gate wiring 76 is sequentially turned on line by line.

  In the radiation detector 60, when the TFTs 70 connected to the gate wirings 76 are sequentially turned on line by line, the charges accumulated in the storage capacitors 68 sequentially line by line flow out to the data wirings 78 as electric signals. The electric signal flowing out to each data wiring 78 is converted into digital image data by the signal processing unit 82 and stored in the image memory 90.

  The cassette control unit 92 transmits the image information stored in the image memory 90 to the console 42 by wireless communication after the end of photographing.

The console 42 performs various kinds of correction such as shading correction on the received image information, and performs image processing for trimming an image of a portion corresponding to the segmented area 61A identified as the shooting area, and the image information after the image processing Is stored in the HDD 110. The image information stored in the HDD 110 is displayed on the display 100 for confirmation of the captured radiographic image, and is transferred to a server computer constituting a RIS (Radiology Information System) via a network (not shown). It is also stored in the database. Thereby, it becomes possible for a doctor to perform interpretation, diagnosis, and the like of a radiographic image taken.

  The console 42 stores the image information after the image processing in the HDD 110, and then performs correlation information update processing for updating the correlation information stored in the HDD 110.

  FIG. 15 is a flowchart showing the flow of processing of the correlation information update processing program executed by the CPU 104 according to the present embodiment. The program is stored in advance in a predetermined area of the HDD 110.

  In step S40 in the figure, out of the number of times of shooting in each segmented area 61A indicated by the correlation information stored in the HDD 110, the number of times of shooting in the segmented area 61A identified as the shooting area by the processing by the shooting area specifying process program is one. To finish the process.

  As a result, the number of photographing times of each segmented area 61A stored as the correlation information is updated.

  As described above, according to the present embodiment, the correlation value correlated with the irradiated radiation dose is correlated for each of the divided areas 61A obtained by dividing the detection area 61 of the radiation detector 60 into a plurality of predetermined areas. An imaging region that is stored as information and is capable of capturing a radiation image of a predetermined size while suppressing variations in the radiation dose irradiated to each segmented region 61A in the detection region 61 based on the stored correlation information. Since the identification is performed, radiographic images are captured using the identified imaging region, so that it is possible to prevent deterioration from progressing in a specific part of the detection region 61.

  Moreover, according to this Embodiment, since the specified imaging | photography area | region is shown on the display 100, it can introduce | transduce without adding a change to the electronic cassette 32. FIG.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  Since the configuration of the radiation information system 10 according to the second embodiment is the same as that of the first embodiment (see FIGS. 1 and 2), description thereof is omitted here.

  FIG. 16 shows the configuration of the electronic cassette 32 according to the second exemplary embodiment. In addition, the same code | symbol is attached | subjected to the part same as the said 1st Embodiment (FIG. 9), and description is abbreviate | omitted.

  The electronic cassette 32 according to the second exemplary embodiment is provided with a touch panel 57 integrally with the irradiation surface 56. The touch panel 57 may be any of a pressure sensitive method, a resistive film method, a capacitance method, an optical scanning method, an ultrasonic method, and the like. In the present embodiment, one touch panel 57 is provided for the irradiation surface 56, but a separate touch panel 57 may be provided for each region 56A.

  FIG. 17 is a block diagram showing a detailed configuration of the radiographic image capturing system 18 according to the second exemplary embodiment. In addition, the same code | symbol is attached | subjected to the part same as the said 1st Embodiment (FIG. 4), and description is abbreviate | omitted.

  The touch panel 57 is connected to the cassette control unit 92. The cassette control unit 92 can grasp which area 56 </ b> A of the irradiation surface 56 is in contact with the object based on the detection result by the touch panel 57.

  The console 42 performs the above-described shooting area specifying process and notifies the electronic cassette 32 of the identification number of the divided area 61A specified as the shooting area by wireless communication. The console 42 also displays on the display 100 a message that prompts the user to place the imaging region in the imaging area together with the segmented area 61A identified as the imaging area. It should be noted that the console 42 is in a shooting standby state until an exposure permission for permitting irradiation of radiation, which will be described later, is notified from the electronic cassette 32, and the shooting instruction operation is performed even when a shooting instruction operation is performed on the operation panel 102. The instruction information for instructing the start of exposure is not transmitted to the radiation generator 34 and the electronic cassette 32.

  A doctor or a radiographer arranges the electronic cassette 32 so that the divided area 61 </ b> A displayed on the display 100 corresponds to the imaging region.

  When the cassette controller 92 of the electronic cassette 32 is notified from the console 42 of the identification number of the segmented area 61A identified as the imaging area, the cassette control unit 92 is positioned at the position corresponding to the imaging area of the irradiation surface 56 corresponding to the notified identification number. An imaging part arrangement waiting process for detecting whether or not an imaging part is arranged is performed.

  FIG. 18 is a flowchart showing the flow of processing of the imaging part arrangement waiting process program executed by the CPU 92A according to the present embodiment. The program is stored in advance in a predetermined area of the storage unit 92C.

  In step S50 of the figure, based on the detection result by the touch panel 57, the area 56A of the irradiation surface 56 where the object is arranged is specified.

  In the next step S52, the process waits for detection of whether or not an object has been placed in all of the area 56A of the irradiation surface 56 corresponding to the notified identification number. When it becomes determination, it transfers to step S50.

  In step S54, the exposure permission for permitting radiation irradiation is notified to the console 42 by wireless communication, and the process ends.

  Thereby, when an imaging part is arrange | positioned in the position corresponding to the imaging area | region of the irradiation surface 56 of the electronic cassette 32, irradiation of a radiation is permitted.

  When the exposure permission is notified from the electronic cassette 32, the console 42 also displays on the display 100 a message indicating that preparation for imaging is complete. In addition, the console 42 validates the reception of the imaging instruction operation on the operation panel 102, and transmits the instruction information instructing the start of exposure to the radiation generator 34 and the electronic cassette 32 when the imaging instruction operation is received.

  As described above, according to the present embodiment, it is detected whether or not an imaging region is arranged at a position where a radiographic image is captured in the specified imaging area, and the radiographic image is captured in the imaging area. When it is detected that the imaging region is arranged, the radiation generator 34 permits the irradiation of the radiation to the imaging region, so that the radiation is irradiated without the imaging region being arranged in the imaging region. Can be suppressed.

  In the first embodiment, the case where the electronic cassette is applied as a portable radiographic image capturing apparatus has been described. However, the present invention is not limited to this and is applied to a stationary radiographic image capturing apparatus. You may apply.

  In each of the above embodiments, the case where the number of imaging is used as the correlation value correlated with the irradiated radiation dose has been described. However, the present invention is not limited to this. For example, the correlation value may be the radiation dose itself, or the irradiation time of radiation.

  In addition, when the radiographic image capturing device performs still image capturing that captures images one by one and fluoroscopic imaging that continuously captures images to obtain a moving image, when performing still image capturing, and when performing fluoroscopic imaging The amount of radiation generated from the radiation generator 34 is changed, the charge stored in the storage capacitor 68 of each pixel unit 74 of the radiation detector 60 is read, the amplification factor of the charge signal in the signal processing unit 82, etc. There are cases where the operating conditions are changed (for example, Patent Document 2 and Patent Document 3).

  FIG. 19 shows an example of radiation dose and operating conditions in fluoroscopic imaging and still image imaging.

  In still image shooting, a patient is irradiated with radiation only for the time required for shooting. In fluoroscopic shooting, imaging is performed by continuously irradiating the patient with radiation during the shooting period. For this reason, in fluoroscopic imaging, the radiation dose per unit time is reduced from several tenths to one hundredth compared to still image shooting in order to reduce the exposure dose of the patient as much as possible. In fluoroscopic imaging, a maximum of 60 / second to 90 frames / second is required. In order to perform this reading, a high sensitivity of several tens of times and a high speed of several tens of times are required for fluoroscopic imaging compared to still image imaging. On the other hand, in still image shooting, a dynamic range of nearly 4 digits is required to obtain a high-definition image for diagnosis, but in perspective imaging, a dynamic range of about 2 digits is sufficient.

  For example, it is assumed that one-minute fluoroscopic imaging is performed with a frame rate of 30 FPS and a radiation dose per unit time of 0.1 times that for still image shooting. In this case, the radiation dose irradiated by one fluoroscopic imaging is 180 times (0.1 times × 30 FPS × 60 SEC = 180 times) the radiation dose of one still image photographing. On the other hand, the number of times of radiography for 1 minute is 1800 times (30 FPS × 60 SEC = 1800 times).

  Here, for example, when the correlation value is taken as the number of imaging and one frame of fluoroscopic imaging is counted as one, the imaging frequency of fluoroscopic imaging is the amount of radiation irradiated when the same imaging frequency is performed in still image imaging. However, when a series of fluoroscopic imaging is counted as one imaging, the amount of radiation irradiated by one still image imaging is 180 times as much as that.

  Therefore, when using the number of shootings as the correlation value, the number of shootings in one of the still image shooting or fluoroscopic shooting is counted, and the number of shootings in the other shooting is converted to the number of shootings in one shooting. And may be counted. For example, when counting by the number of times of still image shooting, the still image is calculated from the conditions of fluoroscopic shooting (radiation dose per unit time and frame rate for still image shooting) and the shooting period (seconds) of fluoroscopic shooting. By calculating the amount of radiation per unit time for photographing x frame rate x fluoroscopic imaging period (seconds), it can be converted to the number of times of radiography. Further, for example, when counting by the number of times of radiography, the calculation of the number of times of radiographing of still images / 0.1 from the radiation dose per unit time (0.1 times) with respect to the time of still image shooting. By performing this, it can be converted into the number of times of radiography.

  FIG. 20 shows an example of a correlation information update processing program when counting is performed based on the number of shootings in still image shooting. In addition, the same code | symbol is attached | subjected to the part same as the said 1st Embodiment (FIG. 15), and description is abbreviate | omitted.

  In step S30, it is determined whether or not fluoroscopic imaging has been performed. If the determination is affirmative, the process proceeds to step 32. If the determination is negative, the process proceeds to step S40. Thereby, when a still image shooting is performed, the process proceeds to step S40.

In step S32, a conversion process is performed for converting the number of times of radiography to the number of times of still image shooting.

  For example, if the frame rate is 30 FPS, the radiation dose per unit time for still image shooting is 0.1 times, and one-minute fluoroscopic shooting is performed, 0.1 × 30 FPS × 60 seconds = 180 It is converted into 180 shots for image shooting.

  In step S34, out of the number of times of shooting in each segmented area 61A indicated by the correlation information stored in the HDD 110, the number of times of shooting in the segmented area 61A identified as the shooting area by the processing by the shooting area specifying processing program is set in step S32. Add the number of shots converted in step, and end the process.

  Correspondence relationship between fluoroscopic imaging conditions (radiation dose per unit time, frame rate, shooting time (time from the first frame to the end n-th frame)) for still image shooting and the number of still image shootings Is stored in advance in the HDD 110 as correspondence information, and converted in step S32 by obtaining the number of times of still image shooting corresponding to fluoroscopic shooting in which shooting has been performed based on the correspondence information stored in advance in the HDD 110. May be.

  Also, when the irradiation time is used as the correlation value, the irradiation time in one of the still image shooting or fluoroscopic shooting is accumulated, and the irradiation time in the other shooting is converted into the irradiation time in one shooting. May be accumulated. For example, when it is assumed that the irradiation time in still image shooting is to be accumulated, from the conditions for fluoroscopic shooting (radiation dose per unit time for still image shooting) and the shooting period (seconds) for fluoroscopic shooting, By calculating the amount of radiation per unit time x the imaging period (seconds) for fluoroscopic imaging, it can be converted to the irradiation time for still image imaging. In addition, for example, when the accumulation is performed with the irradiation time in fluoroscopic imaging, the irradiation time / 0.1 in the still image shooting is calculated from the radiation dose per unit time (0.1 times) with respect to the still image shooting. By performing the above, it can be converted into an irradiation time in fluoroscopic imaging.

  In fluoroscopic imaging, radiation may be generated from the radiation generator 34 in synchronization with the imaging timing of each frame, and the electronic cassette 32 may be irradiated with radiation in pulses. In such a case, when the irradiation time and the radiation dose are used as the correlation values, it is preferable not to consider the period between the frames during fluoroscopic imaging as the irradiation time.

  In addition, the sensitivity of CsI decreases as the radiation dose irradiated increases. Therefore, when the radiation detector 60 is an indirect conversion method and the scintillator 204 is a CsI columnar crystal, the cumulative radiation dose is calculated for each of the divided areas 61A obtained by dividing the detection area 61 into a plurality of predetermined areas. When the accumulated radiation dose becomes an allowable value, a partial decrease in sensitivity can be prevented by changing the imaging region. In particular, in moving image shooting, the amount of radiation per frame is small, but the number of shots is large, and the total radiation dose increases. For this reason, in moving image shooting, it is preferable to change the shooting area in order to maintain sensitivity.

  Further, the correlation value correlated with the radiation dose may be stored for each photographing date and time, or may be accumulated and stored for each predetermined period such as a day. Moreover, it is good also as what memorize | stores the information regarding the intensity | strength (energy) of the irradiated radiation with a correlation value.

  When CsI is irradiated with high-intensity (high energy) radiation, a temporary sensitivity change (so-called deep trap) occurs. Specifically, as shown in FIG. 24, the slope changes from the straight line A to the straight line B with respect to the amount of radiation emitted in one imaging, and the sensitivity is improved. The amount of change Δ in the slope of the sensitivity line decreases with time over several days as shown in FIG. The degree of recovery in which the amount of change Δ of the slope of the sensitivity line decreases also depends on the temperature of CsI, and the amount of change Δ decreases faster as the temperature of CsI increases. When the recovery factor at normal operating temperature and storage temperature (for example, 25 ° C.) is 1, for example, the recovery factor is 0.5 at 10 ° C. or lower, and the recovery factor 2 is at 40 ° C. or higher.

  For this reason, the electronic cassette 32 is used as an imaging region including a specific part whose sensitivity has changed after a specific part or more of the detection region 61 of the radiation detector 60 is irradiated with radiation having a predetermined intensity or more that causes a sensitivity change. When imaging is performed, the sensitivity of a specific part is changed, and thus an afterimage (so-called ghost) due to sensitivity unevenness occurs in the captured radiographic image.

  Therefore, for each of the divided regions 61A, irradiation information related to the intensity and irradiation timing of the irradiated radiation is further stored in the HDD 110, and based on the irradiation information, radiation having a strength that causes a temporary sensitivity change is irradiated. After that, specify the imaging area so that the segmented area that has not passed the recovery period required for recovery of the sensitivity change is outside the imaging area, or the segmented area does not overlap the region of interest of the imaging site. May be. For example, when radiographing a radiographic image, it is stored for each segmented region 61A as radiation information whether or not radiation having a predetermined intensity or more that causes a change in sensitivity occurs every predetermined period such as daily. In addition, an imaging area is specified except for a segmented area 61A in which a predetermined recovery period (for example, 2 days) necessary for recovery of a temporary sensitivity change has not elapsed, or a segmented area in which the recovery period has not elapsed The imaging region may be specified so that 61A does not overlap with the region of interest that is of high interest among the imaging regions. As a result, the occurrence of an afterimage due to a temporary sensitivity change of CsI can be suppressed, and the photographing performance can be maintained.

  Information on the position of the region of interest may be stored in advance for each imaging region, or may be input by the photographer from the operation panel 102, or received from another server computer via the network. It is good. In addition, by setting multiple thresholds for the intensity of radiation that causes sensitivity changes, and comparing the intensity of irradiated radiation with each threshold, the intensity of irradiated radiation is divided into a plurality of levels, A recovery period may be set according to each level.

  Further, as described above, the recovery period of the CsI sensitivity change also varies depending on the temperature.

  Therefore, a temperature sensor is disposed at the end of the radiation detector 60, the temperature sensor detects the temperature of the radiation detector 60 at any time and stores it together with the detection date and time, and when taking a radiographic image, a predetermined intensity or more is obtained. The recovery period may be changed from the temperature state (average temperature, maximum temperature, minimum temperature, cumulative temperature) of the radiation detector 60 after the irradiation of this radiation. For example, when the average temperature is 10 ° C. compared to the case where the average temperature of the radiation detector 60 after irradiation with radiation of a predetermined intensity or higher is 25 ° C., the recovery period is changed twice or the average temperature is In the case of 40 ° C., the recovery period may be changed to ½ times.

  In each of the above-described embodiments, the case where the size information is stored to correspond to a plurality of imaging regions has been described, but the present invention is not limited to this. For example, when the size of an area necessary for imaging is determined in advance, it is not necessary to store size information for each imaging region.

  In each of the above embodiments, the case where the specified imaging region is displayed on the display 100 has been described, but the present invention is not limited to this. For example, a presentation unit that presents an imaging region on the irradiation surface 56 of the housing 54 of the electronic cassette 32 may be provided. FIG. 21 shows a case where a display lamp 56B such as an LED is provided as a presentation means at the end of each column in the vertical and horizontal directions of the area 56A, and the display of the end of the area 56A that is the shooting area is shown. An imaging region is presented by turning on the lamp 56B. FIG. 22 shows a case where the display unit 56C is provided as a presentation means at the end of the housing 54, and an area 56A that is an imaging region is presented on the display unit 56C. In addition, for example, a visible light lamp, a diaphragm for presenting an imaging region that restricts the irradiation area of light from the visible light lamp, and a restriction device for presenting an imaging region to be limited are provided in the radiation generating apparatus 34, and the electronic cassette is irradiated with light from the visible light lamp. An imaging region may be presented on the irradiation surface 56 of the 32 housings 54. In the case of a stationary radiographic imaging device, the positional relationship between the radiation generating device 34 and the radiographic imaging device is fixed, so the arrangement of the radiation generating device 34 is controlled and the aperture device for presenting the imaging region is controlled. Thus, the shooting area can be presented. In the case of the electronic cassette 32, for example, an imaging device such as a camera is provided in the radiation generator 34, the position and orientation of the electronic cassette 32 is specified from the image captured by the imaging device, and the specified position and orientation of the electronic cassette 32 is specified. The imaging region can be presented by controlling the arrangement of the radiation generator 34 based on the above, or by controlling the diaphragm device for presenting the imaging region. In addition, for example, a display unit may be provided in the cradle 40, and the area 56A that is an imaging region may be presented on the display unit.

  Further, in each of the above embodiments, the number of times of imaging is totaled for each combination of the segmented areas 61A in which the imaging region can be imaged, and the combination of the segmented areas 61A having the smallest total value is specified as the imaging area. Although the case has been described, the present invention is not limited to this. For example, the maximum value of the number of times of imaging of each segmented area 61A is obtained for each combination of the segmented areas 61A that can obtain the size capable of imaging the imaging region, and the combination of the segmented areas 61A having the smallest maximum value is specified as the imaged area. May be.

  In each of the above-described embodiments, the detection area 61 is divided into nine 3 × 3 division areas 61A. However, the present invention is not limited to this. For example, it may be divided into 5 × 4 more finely, and the area corresponding to each pixel unit 74 may be set as a divided area.

  In each of the above embodiments, for each area size required for shooting, a combination of identification numbers of the section area 61A from which the size is obtained is stored in advance as section area combination information. It is not limited to this. For example, a combination of identification numbers of the segmented area 61A that can obtain the size of the area necessary for photographing may be obtained by calculation.

  Further, in each of the above embodiments, the arrangement of the radiation generation device 34 or the movable diaphragm device 131 may be controlled so that radiation is irradiated to the imaging region. In the case of a stationary radiographic image capturing apparatus, the positional relationship between the radiation generating apparatus 34 and the radiographic image capturing apparatus is fixed, so that the imaging region can be controlled by controlling the arrangement of the radiation generating apparatus 34 or the movable diaphragm 131. Can be irradiated with radiation. In the case of the electronic cassette 32, for example, an imaging device such as a camera is provided in the radiation generator 34, the position and orientation of the electronic cassette 32 is specified from the image taken by the imaging device, and the specified electronic cassette 32 is set in the position and orientation. Based on this, it is possible to irradiate the imaging region with radiation by controlling the arrangement of the radiation generator 34 or controlling the movable diaphragm device 131.

  In the second embodiment, the touch panel 57 is provided on the irradiation surface 56 of the electronic cassette 32, and the imaging region is arranged at the position where the radiographic image is captured in the imaging region based on the detection result of the touch panel 57. Although the case where it was detected whether the imaging | photography site | part was arrange | positioned was demonstrated, this invention is not limited to this. For example, the radiation generator 34 is provided with an imaging device such as a camera, and the position and orientation of the electronic cassette 32 is specified from the image captured by the imaging device, and the imaging region is arranged at the position where the radiation image is captured in the imaging region. It may be detected whether or not.

  Further, in the electronic cassette 32 according to each embodiment, the radiation detector 60 may be incorporated so that the radiation X is irradiated from the TFT substrate 66 side.

  Here, as shown in FIG. 23, the radiation detector 60 is irradiated with radiation from the side on which the scintillator 204 is formed, and reads a radiation image by the TFT substrate 66 provided on the back side of the incident surface of the radiation. In the case of the so-called back side scanning method (so-called PSS (Penetration Side Sampling) method), the scintillator 204 emits light more strongly on the upper surface side of the figure (opposite side of the TFT substrate 66), and radiation is irradiated from the TFT substrate 66 side. In the case of a so-called surface reading method (so-called ISS (Irradiation Side Sampling) method) in which a radiation image is read by the TFT substrate 66 provided on the surface side of the radiation incident surface, the radiation transmitted through the TFT substrate 66 is transmitted. The light enters the scintillator 204 and the TFT substrate 66 side of the scintillator 204 emits light more intensely. Electric charges are generated in each sensor portion 72 provided on the TFT substrate 66 by light generated by the scintillator 204. For this reason, since the radiation detector 60 is closer to the light emission position of the scintillator 204 with respect to the TFT substrate 66 when the front surface reading method is used than when the rear surface reading method is used, the resolution of the radiation image obtained by imaging is higher. high.

  In the radiation detector 60, the photoelectric conversion film 214 is made of an organic photoelectric conversion material, and the photoelectric conversion film 214 hardly absorbs radiation. For this reason, the radiation detector 60 according to the present embodiment suppresses a decrease in sensitivity to the radiation X because the amount of radiation absorbed by the photoelectric conversion film 214 is small even when radiation is transmitted through the TFT substrate 66 by the surface reading method. be able to. In the surface reading method, radiation passes through the TFT substrate 66 and reaches the scintillator 204. Thus, when the photoelectric conversion film 214 of the TFT substrate 66 is made of an organic photoelectric conversion material, the radiation in the photoelectric conversion film 214 is obtained. Therefore, it is suitable for the surface reading method.

  Further, the amorphous oxide constituting the active layer 224 of the TFT 70 and the organic photoelectric conversion material constituting the photoelectric conversion film 214 can be formed at a low temperature. For this reason, the substrate 200 can be formed of plastic resin, aramid, or bionanofiber with little radiation absorption. Since the substrate 200 formed in this way has a small amount of radiation absorption, a reduction in sensitivity to the radiation X can be suppressed even when the radiation passes through the TFT substrate 66 by the surface reading method.

  Further, for example, the radiation detector 60 is attached to the irradiation surface 56 portion in the housing 54 so that the TFT substrate 66 is on the irradiation surface 56 side, and the substrate 200 is made of a highly rigid plastic resin, aramid, or bio-nanofiber. When formed, since the radiation detector 60 itself has high rigidity, the irradiation surface 56 portion of the housing 54 can be formed thin. In addition, when the substrate 200 is formed of a highly rigid plastic resin, aramid, or bionanofiber, the radiation detector 60 itself has flexibility, so that even when an impact is applied to the irradiation surface 56, the radiation detector 60 is damaged. It ’s hard.

  In addition, the configuration of the RIS 10 described in the above embodiments (see FIG. 1), the configuration of the radiation imaging chamber 44 (see FIG. 2), and the configuration of the electronic cassette 32 (FIGS. 3, 8, 9, and 16). , FIGS. 21 and 22), the configuration of the movable aperture device 131 (see FIG. 5), the configuration of the radiation detector 60 (see FIGS. 6 and 7), and the configuration of the imaging system 18 (see FIGS. 4 and 17). .) Is an example, and it goes without saying that unnecessary portions can be deleted, new portions can be added, and the connection state can be changed within the scope of the present invention.

  The configuration of the correlation information, size information, and segmented area combination information (see FIGS. 10 to 12) described in the above embodiment is also an example, and unnecessary information is within the scope of the present invention. It goes without saying that can be deleted, new information can be added, and information can be changed.

  Further, the processing flow of the imaging region specifying processing program, the correlation information update processing program, and the imaging part arrangement waiting processing program described in the above embodiment (see FIGS. 13, 15, 18, and 20) is also an example. Needless to say, unnecessary steps can be deleted, new steps can be added, and the processing order can be changed without departing from the gist of the present invention.

18 Radiation imaging system 32 Electronic cassette 34 Radiation generator 42 Console 56B Indicator (presenting means)
56C display unit (presentation means)
57 Touch panel (detection means)
60 Radiation detector 61 Detection area 61A Division area 92 Cassette control unit 92A CPU (permission means, conversion means)
100 display (presentation means)
104 CPU (specifying means, control means)
110 HDD (storage means)
131 Movable throttle device (limitation means)

Claims (14)

Radiation irradiated for each divided region obtained by dividing the detection region of the radiation detector that outputs an electrical signal indicating a radiation image represented by radiation irradiated to the detection region for detecting radiation into a plurality of predetermined regions Storage means for storing a correlation value correlated with the amount as correlation information, and based on the correlation information stored in the storage means, in advance, while suppressing variations in the radiation dose irradiated to each segmented area in the detection area A specifying means for specifying an imaging region capable of capturing a radiographic image of a predetermined size;
An imaging region specifying device comprising: The storage means further stores size information indicating a size of a region necessary for radiographic image capturing of the radiographic region for each radiographic region of the subject where radiographic image capturing is performed,
It further comprises an acquisition means for acquiring imaging part information indicating an imaging part to be imaged,
The specifying unit obtains the size of an area necessary for imaging of the imaging region indicated by the imaging region information acquired by the acquiring unit based on the size information stored in the storage unit, and based on the correlation information The imaging region specifying device according to claim 1, wherein an imaging region capable of capturing a radiographic image of the size is specified while suppressing variation in the radiation dose irradiated to each divided region in the detection region. Based on the correlation information, the specifying means obtains the sum of correlation values of each segmented area in the range for each range that is the size of the area necessary for imaging of the imaging region in the detection area, The imaging region specifying device according to claim 1 or 2, wherein the smallest range is specified as the imaging region. The specifying means obtains the maximum value of the correlation value of each segmented region in the range for each range that is the size of the region necessary for imaging of the imaging region in the detection region based on the correlation information, and the maximum value The imaging region specifying device according to claim 1, wherein the smallest range is specified as the imaging region.   The imaging region specifying device according to claim 1, further comprising a presentation unit that presents the imaging region specified by the specifying unit.   Control means for controlling the restricting means so that radiation is emitted from the radiation generating device provided with the restricting means for restricting the radiation irradiation area to the imaging region specified by the specifying means. The imaging region specifying device according to any one of claims 1 to 5. The correlation value is set as the number of times of imaging or the irradiation time of radiation in either one of still image shooting that performs shooting one by one or fluoroscopic shooting that performs continuous shooting,
The imaging region specifying device according to any one of claims 1 to 6, further comprising conversion means for converting a correlation value in the other imaging of still image imaging or fluoroscopic imaging into a correlation value in one imaging. A radiographic imaging device having a radiation detector that outputs an electrical signal indicating a radiographic image represented by radiation irradiated to a detection region for detecting radiation;
Storage means for storing a correlation value correlating with the irradiated radiation dose as correlation information for each divided area obtained by dividing the detection area into a plurality of predetermined areas, and the correlation information stored in the storage means Based on the above, an imaging region specifying device having specifying means for specifying an imaging region capable of capturing a radiographic image of a predetermined size while suppressing variation in the radiation dose irradiated to each divided region in the detection region;
Presenting means for presenting the imaging region identified by the identifying means;
Radiographic imaging system equipped with. Detecting means for detecting whether or not an imaging part is arranged at a position where a radiographic image is captured in the imaging region specified by the specifying means of the radiation detector;
When the detection unit detects that an imaging region is arranged at a position where a radiographic image is captured in the imaging region, permission unit that permits radiation irradiation to the imaging region from a radiation generator that generates radiation When,
The radiographic imaging system according to claim 8, further comprising: The radiation detector is a scintillator that converts radiation into light, converts the radiation into light, and outputs an electrical signal indicating a radiation image represented by the light,
The radiation image capturing system according to claim 9, wherein the scintillator includes a columnar crystal of a phosphor material. The radiographic imaging system according to claim 10, wherein the phosphor material is CsI. The storage means further stores irradiation information regarding the intensity and irradiation time of the irradiated radiation for each of the divided regions,
Based on the irradiation information, the specifying unit is outside a shooting region if a recovery region necessary for recovery of the sensitivity change has not elapsed since irradiation with radiation having a temporary sensitivity change occurred. The radiographic image capturing system according to claim 11, wherein the imaging region is specified so that the segmented region does not overlap with the region of interest of the imaging region. Temperature detecting means for detecting the temperature of the radiation detector,
The radiographic imaging system according to claim 12, wherein the specifying unit changes the recovery period to be shorter as the temperature state of the radiation detector detected by the temperature detecting unit is higher. Radiation irradiated to each divided region obtained by dividing the detection region of the radiation detector that outputs an electrical signal indicating a radiation image represented by radiation irradiated to the detection region for detecting radiation into a plurality of predetermined regions A correlation value correlated with the quantity is stored in the storage means as correlation information
Based on the correlation information stored in the storage unit, an imaging region that can capture a radiographic image of a predetermined size while suppressing variations in the radiation dose irradiated to each segmented region within the detection region is specified. Yes How to specify the shooting area.