WO2013031666A1

WO2013031666A1 - Radiation imaging system and radiation imaging method

Info

Publication number: WO2013031666A1
Application number: PCT/JP2012/071387
Authority: WO
Inventors: 北野浩一; 大田恭義; 岩切直人; 西納直行; 中津川晴康
Original assignee: 富士フイルム株式会社
Priority date: 2011-08-29
Filing date: 2012-08-24
Publication date: 2013-03-07

Abstract

Provided are a radiation imaging system and radiation imaging method, wherein a system control unit comprises: a radiation imaging trial unit which, if a gradation value is different from a predicted result, exercises control by varying the irradiated energy of a radiation irradiation system so as to perform radiation imaging once; and an abnormality inferring unit which, if there is no change between the gradation value obtained from the radiation image on this one occasion and the preceding gradation value, infers that there is an abnormality in the radiation image output system and, if there is a change between the gradation value obtained from the radiation image on this one occasion and the preceding gradation value, infers that there is an abnormality in the radiation irradiation system.

Description

Radiographic imaging system and radiographic imaging method

The present invention relates to a radiographic image capturing system and a radiographic image capturing method capable of obtaining a moving image of a radiographic image by executing radiography at a set frame rate using a radiographic image capturing apparatus.

In recent times, during surgery, during contrast imaging, or during treatment of fractures, etc., radiation image information can be read and displayed immediately from the radiation detector after imaging in order to quickly and accurately treat the patient. is required. As a radiation detector capable of meeting such demands, a solid-state detection element (referred to as a pixel) that converts radiation directly into an electrical signal, or converts radiation into visible light with a scintillator and then converts it into an electrical signal for reading. A radiation detector referred to as a flat panel detector (FPD) using the above has been developed.

In particular, an X-ray diagnostic imaging device is proposed in which a radiographic image is displayed on a monitor by executing radiography at a set frame rate, so that, for example, the catheter entry status with respect to the subject can be grasped in real time. Has been.

Conventionally, in such an X-ray diagnostic imaging apparatus, a method for detecting a structural change due to body movement of a subject with a difference between two frames has been proposed (see JP 2007-82908 A).

Also, conventionally, an X-ray diagnostic imaging apparatus using automatic brightness control (Automatic Brightness Control (ABC)) for controlling X-ray irradiation energy during imaging has been proposed (see JP 2011-98009 A).

Further, conventionally, there has been proposed a technique for detecting an abnormality in communication with an operation unit for X-ray irradiation and applying a safe parameter according to an imaging region (see JP 2009-297304 A). .

However, the method described in Japanese Patent Application Laid-Open No. 2007-82908 is carried out to prevent re-imaging due to improper imaging, but detection of exposure failure due to radiation source / generator malfunction and detection of exposure failure. It does not take into account the correspondence of the case, and does not include the concept of the difference between the gray values between the two frames.

The method described in Japanese Patent Application Laid-Open No. 2011-98009 uses a technique related to automatic brightness control (ABC). From the description in paragraphs [0015] and [0019], etc. Only one frame of computation is included. For this reason, it is not possible to carry out abnormality detection using a difference in gray value between a plurality of frames under automatic luminance control.

The method described in Japanese Patent Application Laid-Open No. 2009-297304 has automatic brightness control as an auxiliary means, and when communication is abnormal, exposure is continued by any means including automatic brightness control. With this technology, it is not possible to cope with poor exposure due to malfunction of the tube, radiation source, and generator, and the exposure continues and excessive exposure increases.

As described above, with the techniques described in Japanese Patent Application Laid-Open Nos. 2007-82908 and 2011-98009, it is impossible to detect an exposure failure using the difference in gray value between a plurality of frames in automatic luminance control. In the techniques described in JP 2007-82908 A, JP 2011-98009 A, and JP 2009-297304 A, measures for reducing the risk related to the X-ray irradiation dose are taken in response to detection of defects. I can't.

That is, the automatic brightness control obtains the gray value (average of QL value, etc.) of the region of interest for each frame, determines whether it is higher or lower than the gray value expected from the imaging region and imaging conditions, This is a method of raising and lowering the X-ray irradiation energy in the next radiography. If any abnormality occurs and the gray value decreases, control for increasing the X-ray irradiation energy is performed without detecting the abnormality. If such control is left unattended, there is a risk of subjecting a subject (such as a patient) to high energy exposure despite the occurrence of an abnormality in the system and the X-ray irradiation control system.

The present invention has been made in consideration of such problems, and at the time of occurrence of an error or abnormality, a radiographic imaging system capable of estimating the cause of the error or abnormality and quickly recovering from the error state or abnormality state And it aims at providing a radiographic imaging method.

[1] The radiographic imaging system according to the first aspect of the present invention includes a radiation irradiation system that irradiates radiation toward a subject with set irradiation energy, and irradiation energy that controls irradiation energy irradiated from the radiation irradiation system. A radiographic imaging apparatus having a control unit, a radiographic image output system that converts radiation image information transmitted through the subject into radiographic image information, and outputs the radiographic image information. A system control unit that controls to perform radiation imaging at a rate, and the irradiation energy control unit increases the irradiation energy of the next radiation when the grayscale value of the radiation image information is lower than a reference value. The system control unit controls to reduce the irradiation energy of the next radiation when the gray value is higher than the reference value. A radiation imaging trial unit that controls to perform one radiography by changing the irradiation energy of the radiation irradiation system when the gray value is different from an expected result; When there is no change between the gray value obtained by the first radiography and the previous gray value, it is estimated that the radiation image output system is abnormal, and the gray value obtained by the first radiography and the previous gray value And an abnormality estimating unit that estimates that the radiation irradiation system is abnormal when there is a change between the two.

The irradiation energy control unit increases the irradiation energy of the next radiation when the gray value of the radiation image information is lower than a reference value, and sets the irradiation energy of the next radiation when the gray value is higher than the reference value. It is controlled to decrease.

The first aspect of the present invention uses the control in the irradiation energy control unit, and when the gray value is different from the expected result, the irradiation energy of the radiation irradiation system is changed, Control is performed so that one radiography is performed, and when there is no change between the gray value and the previous gray value by the one radiography, it is estimated that the radiation image output system is abnormal, When there is a change between the gray value of the previous radiography and the previous gray value, it is assumed that the radiation irradiation system is abnormal, so the processing to recover from the abnormal state after that is appropriate In addition, it is possible to perform the process quickly, and the time from the occurrence of abnormality to the return can be greatly shortened. This leads to a reduction in the interruption time of radiography associated with the occurrence of an abnormality during surgery or catheter insertion operation while observing the moving image display in the region of interest of the subject.

[2] In the first aspect of the present invention, the system control unit includes a gray level difference acquisition unit that acquires a gray level difference of radiation image information based on at least two times of radiography, and the gray level difference is near a specified value. In the case where the above change has occurred, an error notification unit may be provided that notifies the error that the gray value is different from the expected result.

[3] In [2], the error notification unit, when the gray value of the radiation image information based on the current radiation imaging is lower than the specified value near the gray value of the radiation image information based on the previous radiation imaging. , An error notification indicating a drop in gray value is performed, and the radiation imaging trial unit increases the irradiation energy of the radiation irradiation system based on the input of an error notification indicating a drop in the gray value. You may make it control so that radiography may be performed.

[4] In [2], the error notification unit, when the gray value of the radiographic image information based on the current radiography is higher than the gray value of the radiographic image information based on the previous radiography more than the specified value , An error notification indicating an increase in the gray value, and the radiation imaging trial unit reduces the irradiation energy of the radiation irradiation system based on the input of the error notification indicating the increase in the gray value. You may make it control so that radiography may be performed.

[5] In the first aspect of the present invention, the system control unit controls the radiation image output system to execute a reset process when it is estimated that the radiation image output system is abnormal, and the radiation When it is estimated that there is an abnormality in the irradiation system, the irradiation from the radiation irradiation system may be stopped and the radiation irradiation system may be restarted.

[6] The radiographic imaging system according to the second aspect of the present invention includes a radiation irradiation system that irradiates radiation toward a subject with set irradiation energy, and an irradiation energy that controls irradiation energy irradiated from the radiation irradiation system. A radiographic image capturing apparatus comprising: a control unit; and a radiation image output system that converts radiation from the radiation irradiation system that has passed through the subject into radiation image information through an amplifier and outputs the radiation image information. A system control unit that performs control so as to execute radiation imaging at a set frame rate, and the irradiation energy control unit performs the next radiation irradiation when the grayscale value of the radiation image information is lower than a reference value. Control to increase the energy, and to reduce the irradiation energy of the next radiation when the gray value is higher than the reference value, The stem control unit, when the gray value is different from an expected result, the gain of the amplifier is changed, and a radiography trial unit that controls to perform one radiography, and When there is no change between the gray value obtained by one radiography and the previous gray value, it is estimated that the radiation image output system is abnormal, and the gray value obtained by the first radiography and the previous gray value are obtained. And an abnormality estimation unit that estimates that the radiation irradiation system is abnormal.

The second aspect of the present invention uses the control in the irradiation energy control unit to change the gain of the amplifier and change the gain of the amplifier when the gray value is different from the expected result. Control is performed to perform imaging, and when there is no change between the gray value and the previous gray value of the one radiography, it is estimated that the radiation image output system is abnormal, and the one radiography When there is a change between the gray value and the previous gray value, the radiation irradiation system is assumed to be abnormal, so that the processing for recovering from the abnormal state after that is appropriate, and It is possible to carry out quickly, and the time from the occurrence of an abnormality to recovery can be greatly shortened. This leads to a reduction in the interruption time of radiography associated with the occurrence of an abnormality during surgery or catheter insertion operation while observing the moving image display in the region of interest of the subject.

[7] In the second aspect of the present invention, the system control unit includes a density difference acquisition unit that acquires a difference in density values of radiographic image information based on at least two times of radiography, and the difference between the density values is near a specified value. In the case where the above change has occurred, an error notification unit may be provided that notifies the error that the gray value is different from the expected result.

[8] In [7], the error notifying unit determines that the gray value of the radiation image information based on the current radiography is lower than the gray value of the radiological image information based on the previous radiography by the vicinity of the specified value or more. , An error notification indicating a drop in gray value is performed, and the radiation imaging trial unit increases the gain of the amplifier based on the input of the error notification indicating a decrease in gray value, and performs the one radiography. You may make it control so that it may perform.

[9] In [7], the error notification unit, when the gray value of the radiation image information based on the current radiation exposure is higher than the specified value near the gray value of the radiation image information based on the previous radiation imaging And an error notification indicating an increase in gray value, and the radiation imaging trial unit reduces the gain of the amplifier based on an error notification indicating an increase in the gray value, and performs the one radiography. You may make it control so that it may perform.

[10] In the second aspect of the present invention, the system control unit controls the radiation image output system to execute a reset process when it is estimated that the radiation image output system is abnormal, and the radiation When it is estimated that there is an abnormality in the irradiation system, the irradiation from the radiation irradiation system may be stopped and the radiation irradiation system may be restarted.

[11] In [8], when it is estimated that the radiation image output system is abnormal, the system control unit performs a reset process on the radiation image output system, and the radiation imaging trial unit Based on the notification of completion of the reset process, control is performed so that the second radiography is performed in a state where the gain of the amplifier is increased, and the abnormality estimation unit is configured to obtain a gray value obtained by the second radiography, When there is no change between the grayscale values obtained by the one-time radiography, it may be estimated that the radiation irradiation system is abnormal.

[12] In [11], when it is estimated that the radiation irradiation system is abnormal, the system control unit stops the radiation irradiation from the radiation irradiation system and restarts the radiation irradiation system. You may make it control.

[13] In the first and second aspects of the present invention, the radiation imaging trial unit may perform control so that the radiation imaging is performed by narrowing a radiation irradiation area on the subject.

[14] In the radiographic imaging method according to the third aspect of the present invention, a radiation irradiation system for irradiating a subject with radiation at a set irradiation energy, and an irradiation energy for controlling the irradiation energy irradiated from the radiation irradiation system. A radiographic imaging apparatus having a control unit and a radiographic image output system that converts the radiation from the radiation irradiation system that has passed through the subject into radiation image information and outputs the radiation image information, and performs radiation imaging at a set frame rate In the radiographic image capturing method controlled as described above, the irradiation energy control unit increases the irradiation energy of the next radiation when the grayscale value of the radiographic image information is lower than a reference value, and the grayscale value is greater than the reference value. If the value is too high, control is performed to reduce the irradiation energy of the next radiation, and the gray value is different from the expected result. Between the step of controlling to perform one radiography by changing the irradiation energy of the radiation irradiation system, and the gray value and the previous gray value by the one radiography. When there is no change, it is estimated that the radiation image output system is abnormal, and when there is a change between the gray value obtained by the one radiography and the previous gray value, the radiation irradiation system is abnormal. And a step of estimating.

[15] In the radiographic imaging method according to the fourth aspect of the present invention, a radiation irradiation system for irradiating a subject with a set irradiation energy and an irradiation energy for controlling the irradiation energy irradiated from the radiation irradiation system A radiation image capturing apparatus comprising: a control unit; and a radiation image output system that converts radiation from the radiation irradiation system that has passed through the subject into radiation image information through an amplifier and outputs the radiation image information. In the radiographic image capturing method for performing control so as to perform imaging, the irradiation energy control unit increases the irradiation energy of the next radiation when the gray value of the radiographic image information is lower than a reference value, and the gray value is When it is higher than the reference value, control is performed to reduce the irradiation energy of the next radiation, and the gray value is expected. When the result becomes, the step of controlling to perform one radiography by changing the gain of the amplifier, and between the gray value obtained by the single radiography and the previous gray value If there is no change in the radiation image output system, it is estimated that there is an abnormality in the radiation image output system. And a step of estimating.

[16] In the third and fourth aspects of the present invention, when it is estimated that the radiation image output system is abnormal, a reset process is performed on the radiation image output system to estimate that the radiation irradiation system is abnormal. In such a case, the radiation irradiation from the radiation irradiation system may be stopped and the radiation irradiation system may be restarted.

As described above, according to the radiographic image capturing system and radiographic image capturing method according to the present invention, when an error or abnormality occurs, it is possible to estimate the cause of the error or abnormality and quickly return from the error state or abnormal state. Can do.

It is a block diagram which shows the radiographic imaging system (1st radiographic imaging system) which concerns on 1st Embodiment. It is a block diagram which mainly shows the structure of the radiation apparatus and radiation detection apparatus of a 1st radiographic imaging system. It is a circuit diagram which shows the structure of a radiation detection apparatus, and shows the structure of a radiation detector especially. It is a block diagram which mainly shows the structure of the system control part of a 1st radiographic imaging system. It is a flowchart (the 1) which shows the processing operation of a 1st radiographic imaging system. It is a flowchart (the 2) which shows the processing operation of a 1st radiographic imaging system. It is a flowchart (the 3) which shows the processing operation of a 1st radiographic imaging system. It is a time chart which shows the case where the irradiation energy of a radiation irradiation system is raised, one radiography is performed, the abnormality of a radiographic image output system is estimated, and abnormality handling is performed after that. It is a time chart which shows the case where the irradiation energy of a radiation irradiation system is raised, one radiography is performed, the abnormality of a radiation irradiation system is estimated, and abnormality handling is performed after that. It is a time chart which shows the case where the irradiation energy of a radiation irradiation system is reduced, one radiography is performed, the abnormality of a radiographic image output system is estimated, and then abnormality handling is performed. It is a time chart which shows the case where the irradiation energy of a radiation irradiation system is reduced, one radiography is performed, the abnormality of a radiation irradiation system is estimated, and then abnormality handling is performed. It is a block diagram which shows the radiographic imaging system (2nd radiographic imaging system) which concerns on 2nd Embodiment. It is a flowchart which extracts and shows the processing operation of a 2nd radiographic imaging system. It is a time chart which shows the case where the gain of a charge amplifier is raised, one radiography is performed, the abnormality of a radiographic image output system is estimated, and after that, abnormality handling is performed. It is a time chart which shows the case where the gain of a charge amplifier is raised, one radiography is performed, the abnormality of a radiation irradiation system is estimated, and then abnormality handling is performed. It is a time chart which shows the case where the gain of a charge amplifier is reduced, the radiation imaging is performed once, the abnormality of the radiation image output system is estimated, and then the abnormality is dealt with. It is a time chart which shows the case where the gain of a charge amplifier is reduced, the radiation imaging is performed once, the abnormality of the radiation irradiation system is estimated, and then the abnormality is dealt with. It is a time chart which shows the case where radiography is performed twice for abnormality estimation. It is a figure which shows roughly the structure for 3 pixels of the radiation detector which concerns on a modification. FIG. 20 is a schematic configuration diagram of a TFT and a charge storage unit shown in FIG. 19.

Hereinafter, embodiments of a radiographic image capturing system, a radiographic image capturing method, and a radiographic image capturing system according to the present invention will be described with reference to FIGS.

First, as shown in FIG. 1, a radiographic imaging system (hereinafter referred to as a first radiographic imaging system 10 </ b> A) according to the first embodiment includes a radiographic imaging apparatus 12 and a radiographic imaging apparatus 12. And a system control unit 14 that performs control so as to perform radiation imaging at a set frame rate. A console 16 is connected to the system control unit 14 so that data communication with the console 16 is possible. Connected to the console 16 are a monitor 18 for image observation and diagnostic imaging, and an input device 20 (keyboard, mouse, etc.) for operation input. An operator (physician or radiographer) uses the input device 20 to set the radiation irradiation energy and the radiographic frame rate suitable for the current situation in surgery or catheter insertion work while observing a moving image. Data input using the input device 20 and data created and edited by the console 16 are input to the system control unit 14. Further, radiation image information and the like from the system control unit 14 is supplied to the console 16 and displayed on the monitor 18.

The radiographic image capturing apparatus 12 converts a radiation irradiation system 28 that irradiates a radiation 26 toward the subject 24 on the imaging table 22 with the set irradiation energy, and converts the radiation 26 transmitted through the subject 24 into radiation image information. A radiation image output system 29 for outputting to the control unit 14; The radiation image output system 29 includes a radiation detection device 30 that converts radiation 26 transmitted through the subject 24 into radiation image information with a set gain, and data such as radiation image information between the radiation detection device 30 and the system control unit 14. A detection device control unit 32 that performs transmission and reception and controls the radiation detection device 30 based on an instruction from the system control unit 14 (including movement drive).

The movement detection of the radiation detection apparatus 30 is performed when a relatively wide range is imaged, for example, a moving image of the spine or a moving image of the catheter entry position. That is, in such imaging, a movement control signal based on an operation input from an operator (doctor or radiographer) is output from the system control unit 14 and input to the detection device control unit 32. Based on the movement control signal from the system control unit 14, the detection device control unit 32 controls the movement drive mechanism (not shown) to move the radiation detection device 30.

As shown in FIG. 2, the radiation irradiation system 28 is based on a radiation source 34, a radiation source controller 36 that controls the radiation source 34 based on an instruction from the system controller 14, and an instruction from the system controller 14. And an automatic collimator unit 38 that widens or narrows the irradiation area of the radiation 26.

The radiation detector 30 includes a radiation detector 40, a battery 42 as a power source, a cassette control unit 44 that drives and controls the radiation detector 40, and a signal including radiation image information from the radiation detector 40. A transmitter / receiver 46 for transmitting and receiving data is accommodated. The radiation image information output from the transceiver 46 is input to the system control unit 14 and the console 16 via the detection device control unit 32 and is displayed on the monitor 18. That is, radiation image information based on radiation imaging at a set frame rate is sequentially input to the system control unit 14, and thus a moving image of the radiation image information is displayed on the monitor 18 in real time.

The cassette control unit 44 and the transceiver 46 are provided with lead plates or the like on the irradiation surface side of the cassette control unit 44 and the transceiver 46 in order to avoid damage due to the radiation 26 being irradiated. Is preferred.

As the radiation detector 40, for example, the radiation 26 that has passed through the subject 24 is once converted into visible light by a scintillator, and the converted visible light is a solid-state detection element (hereinafter referred to as “a-Si”). An indirect conversion type radiation detector (including a front side reading method and a back side reading method) that converts to an electric signal can also be used. An ISS (Irradiation Side Sampling) type radiation detector, which is a surface reading method, has a configuration in which a solid detection element and a scintillator are sequentially arranged along the irradiation direction of the radiation 26. A PSS (Penetration Side Sampling) type radiation detector, which is a back side reading method, has a configuration in which a scintillator and a solid state detection element are sequentially arranged along the radiation 26 irradiation direction. Further, as the radiation detector 40, in addition to the above-described indirect conversion type radiation detector, direct conversion in which the dose of the radiation 26 is directly converted into an electric signal by a solid detection element made of a substance such as amorphous selenium (a-Se). A type of radiation detector can be employed.

Next, as an example, the circuit configuration of the radiation detection apparatus 30 when the indirect conversion type radiation detector 40 is employed will be described in detail with reference to FIG.

The radiation detector 40 has a photoelectric conversion layer 52 in which each pixel 50 made of a material such as a-Si that converts visible light into an electrical signal is formed on an array of matrix thin film transistors (hereinafter referred to as TFTs 54). It has the structure arranged in. In this case, in each pixel 50, the charge generated by converting visible light into an electrical signal (analog signal) is accumulated, and the charge can be read out as an image signal by sequentially turning on the TFT 54 for each row. .

A gate line 56 extending in parallel with the row direction and a signal line 58 extending in parallel with the column direction are connected to the TFT 54 connected to each pixel 50. Each gate line 56 is connected to a line scan driver 60, and each signal line 58 is connected to a multiplexer 62. Control signals Von and Voff for controlling on / off of the TFTs 54 arranged in the row direction are supplied from the line scan driving unit 60 to the gate line 56. In this case, the line scan driving unit 60 includes a plurality of switches SW1 for switching the gate lines 56, and a first address decoder 64 for outputting a selection signal for selecting the switches SW1. An address signal is supplied from the cassette control unit 44 to the first address decoder 64.

Further, the charge held in each pixel 50 flows out to the signal line 58 via the TFTs 54 arranged in the column direction. This charge is amplified by the charge amplifier 66. A multiplexer 62 is connected to the charge amplifier 66 through a sample and hold circuit 68.

That is, the read charge of each column is input to the charge amplifier 66 of each column via each signal line 58. Each charge amplifier 66 includes an operational amplifier 70, a capacitor 72, and a switch 74. When the switch 74 is off, the charge amplifier 66 converts the charge signal input to one input terminal of the operational amplifier 70 into a voltage signal and outputs the voltage signal. The charge amplifier 66 amplifies and outputs the electrical signal with the gain set by the cassette control unit 44. Information relating to the gain of the charge amplifier 66 (gain setting information) is supplied from the system control unit 14 to the cassette control unit 44 via the detection device control unit 32. The cassette control unit 44 sets the gain of the charge amplifier 66 based on the supplied gain setting information.

The other input terminal of the operational amplifier 70 is connected to GND (ground potential) (ground). When all the TFTs 54 are turned on and the switch 74 is turned on, the charge accumulated in the capacitor 72 is discharged by the closed circuit of the capacitor 72 and the switch 74, and the charge accumulated in the pixel 50 is closed. It is swept out to GND (ground potential) via the switch 74 and the operational amplifier 70. The operation of turning on the switch 74 of the charge amplifier 66 to discharge the charge accumulated in the capacitor 72 and sweeping out the charge accumulated in the pixel 50 to GND (ground potential) is a reset operation (empty reading operation). Call it. In particular, the operation of sweeping out charges of all pixels to GND is referred to as an all-pixel reset operation. That is, in the reset operation, the voltage signal corresponding to the charge signal stored in the pixel 50 is discarded without being output to the multiplexer 62.

The multiplexer 62 includes a plurality of switches SW2 for switching the signal line 58 and a second address decoder 76 for outputting a selection signal for selecting the switch SW2. An address signal is supplied from the cassette control unit 44 to the second address decoder 76. An A / D converter 78 is connected to the multiplexer 62, and radiation image information converted into a digital signal by the A / D converter 78 is supplied to the cassette control unit 44.

The TFT 54 functioning as a switching element may be realized in combination with another imaging element such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor. Furthermore, it can be replaced with a CCD (Charge-Coupled Device) image sensor that transfers charges while shifting the charges with a shift pulse corresponding to a gate signal referred to as a TFT.

The cassette control unit 44 of the radiation detection apparatus 30 includes an address signal generation unit 80, an image memory 82, and a cassette ID memory 84, as shown in FIG.

For example, the address signal generator 80 sends an address signal to the first address decoder 64 of the line scan driver 60 and the second address decoder 76 of the multiplexer 62 shown in FIG. 3 based on the read control information from the system controller 14. Supply. The read control information includes, for example, progressive mode, interlace mode (odd row read mode, even row read mode, second row read mode, third row read mode, etc.), binning mode (1 pixel / 4 pixel read mode, 1 pixel / 6-pixel readout mode, 1-pixel / 9-pixel readout mode, etc.) are included. For example, in the 1-pixel / 4-pixel readout mode, two adjacent gate lines are simultaneously activated (set to Von), and two adjacent signal lines are selected at the same time. In this mode, charges for pixels are mixed and read as one pixel. The address signal generator 80 generates an address signal corresponding to the mode indicated by the read control information, and outputs the address signal to the first address decoder 64 of the line scan driver 60 and the second address decoder 76 of the multiplexer 62. The read control information is created by the system control unit 14 based on an operation input from an operator, for example, and is input to the cassette control unit 44 of the radiation detection apparatus 30.

The image memory 82 stores radiation image information detected by the radiation detector 40. The cassette ID memory 84 stores cassette ID information for specifying the radiation detection apparatus 30. The transceiver 46 transmits the cassette ID information stored in the cassette ID memory 84 and the radiation image information stored in the image memory 82 to the system control unit 14 via the detection device control unit 32 by wired communication or wireless communication.

Then, the system control unit 14 of the first radiographic image capturing system 10A calculates the gray value Da of the region of interest of the radiological image information and stores it in the gray value storage unit 100 as shown in FIG. 102 and an irradiation energy control unit 104 that performs the same control as the automatic luminance control.

The irradiation energy control unit 104 includes a reference value generation unit 106 that generates a reference value Db corresponding to the imaging region, and an irradiation energy control signal (hereinafter referred to as a control signal Sa) corresponding to the difference between the current gray value Da and the reference value Db. The control signal generator 108 that generates and outputs the radiation signal to the radiation irradiation system 28, the control signal Sa in the normal operation period Ta, the error processing period Tb, and the return monitoring period Tc (see FIG. 8). A switching unit 110 that switches between the first control signal Sa1 and the second control signal Sa2.

The error processing period Tb indicates a period from the time ta when an error notification Sb described later is performed to the time when the return processing in the return processing unit 124 described later starts, and the return monitoring period Tc is from the start of the recovery processing. A predetermined time (for example, 5 to 10 seconds) is indicated. A period other than the error processing period Tb and the return monitoring period Tc is the normal operation period Ta.

As the gray value Da, an average value of the pixel values (QL values) of all the pixels included in the region of interest is used. The gray value Da is the same concept as the luminance value.

The control signal Sa1 output from the control signal generation unit 108 corresponds to the reference value Db with the upper limit signal value Vmax corresponding to the upper limit value of the irradiation energy and the lower limit signal value Vmin corresponding to the lower limit value of the irradiation energy as dynamic ranges. This is a signal form in which the reference signal value is Vo and the signal value corresponding to the difference between the gray value Da and the reference value Db is V, and may be an analog signal or a digital signal. 0 may be used as the reference signal value Vo.

Then, in the normal operation period Ta, the control signal generation unit 108 generates and outputs a signal value (Vo + V) for increasing the irradiation energy of the next radiation imaging when the current gray value Da is lower than the reference value Db. When the current gray value Da is higher than the reference value Db, a signal value (Vo-V) for reducing the irradiation energy of the next radiography is generated and output.

Therefore, in the normal operation period Ta, the irradiation energy control unit 104 increases the next irradiation energy when the gray value Da of the region of interest is lower than the reference value Db, and the gray value Da of the region of interest is higher than the reference value Db. When it is high, control is performed so as to reduce the next irradiation energy.

In addition, the system control unit 14 includes a control signal storage unit 112, a shading difference acquisition unit 114, an error notification unit 116, a radiation imaging trial unit 118, an abnormality estimation unit 120, an abnormality handling instruction unit 122, and a return process. Part 124.

The control signal storage unit 112 stores signal values generated in a predetermined period in the past from the present time among the signal values (control signal Sa) generated by the control signal generation unit 108 of the irradiation energy control unit 104.

The density difference acquisition unit 114 acquires the difference ΔD of the density value Da of the region of interest based on radiation irradiation at least twice.

The error notification unit 116 performs error notification (Sb1, Sb2), assuming that an error has occurred when the obtained grayscale value is different from the expected result. The result different from the expected result is that normally, in the irradiation energy control, the radiation irradiation system 28 is feedback-controlled so that the difference d between the obtained gray value Da and the reference value Db is reduced. The value Da is generally a value approximate to the reference value Db. For example, when the maximum value of the gray value Da is set to +128, the result is expected to be within ± 10 with respect to the reference value Db. is there. In such a case, when the gray value Da suddenly becomes 0 or almost 0, or becomes the maximum value or almost the maximum value, the gray value Da is different from the expected result. This is considered to be based on an abnormality in the radiation irradiation system 28, an exposure failure due to a malfunction of the generator, or an abnormality in the radiation image output system 29.

Therefore, the error notification unit 116 sets the specified value Dc in advance to determine whether or not the obtained gray value Da is a result different from the expected result, and the gray value difference ΔD is determined. An error notification (Sb1, Sb2) is made assuming that an error has occurred when the value changes in the vicinity of the specified value Dc. The vicinity of the specified value Dc refers to, for example, a range from the specified value Dc × (1.0−coefficient Kc) to the specified value Dc × (1.0 + coefficient Kc). Here, the coefficient Kc is 0 <Kc <1.0, and is set in advance by simulation or experiment. In the present embodiment, for example, a range of 0.1 to 0.2 can be used as the coefficient Kc.

In the present embodiment, the difference ΔD between the gray values without using the difference d between the gray value Da and the reference value Db is based on the fact that the radiographic image information between frames has high correlation. . For example, in the catheter insertion operation, even when the region of interest moves from, for example, a region having a generally low gray value to a region having a high gray value, the gray value difference ΔD is substantially constant. By comparing the value difference ΔD with the specified value, an error or an abnormality can be reliably detected.

The radiation imaging trial unit 118 controls to perform one radiation imaging by changing the irradiation energy of the radiation irradiation system 28 when the error notification (Sb1, Sb2) is performed.

The abnormality estimation unit 120 estimates that there is an abnormality in the radiation image output system 29 when there is no change between the gray value obtained by one radiography and the gray value before error notification, and the gray value obtained by one radiography. And the gray value before the error notification are estimated to be abnormal in the radiation irradiation system 28.

The abnormality handling command unit 122 outputs a restart command signal Sd for restarting the radiation irradiation system 28 to the radiation irradiation system 28 when the radiation irradiation system 28 is estimated to be abnormal. The radiation source control unit 36 of the radiation irradiation system 28 stops the radiation irradiation from the radiation source 34 based on the input of the restart command signal Sd, and restarts the radiation irradiation system 28. The radiation irradiation system 28 outputs a completion signal Sg to the system control unit 14 when the restart is completed.

Also, the abnormality handling instruction unit 122 outputs a reset instruction signal Se for performing reset processing to the radiation image output system 29 when the radiation image output system 29 is estimated to be abnormal. Based on the input of the reset command signal Se, the detection device control unit 32 of the radiation image output system 29 outputs an all-pixel reset signal Sf to the radiation detection device 30 and performs a digital reset. The radiation detection apparatus 30 performs the all-pixel reset operation described above based on the input of the all-pixel reset signal Sf. The radiation detection device 30 outputs a completion signal Sg to the detection device control unit 32 when the all-pixel reset operation is completed. The detection device control unit 32 outputs a completion signal Sg (completion notification) to the system control unit 14 when the digital reset is completed and a completion signal is received from the radiation detection device 30.

The return monitoring period Tc is started when the completion signal Sg from the radiation irradiation system 28 or the completion signal Sg from the detection device control unit 32 is input to the system control unit 14.

The restoration processing unit 124 performs radiation imaging for restoration until the restoration monitoring period Tc ends at the stage where an abnormality is dealt with in response to an instruction from the abnormality handling instruction unit 122 (start of the restoration process). In this case, the return processing unit 124 performs control so as to perform radiation imaging with preset irradiation energy.

Specifically, the error notification unit 116 determines that the gray value Da (current gray value) of the region of interest based on the current radiography is greater than the gray value Da (previous gray value) of the region of interest based on the previous radiography. Is also lower than the specified value Dc, an error notification Sb1 indicating a decrease in the gray value is performed, and an error notification indicating an increase in the gray value is obtained when the current gray value is higher than the previous gray value by the specified value Dc. Sb2 is performed. As the prescribed value Dc, a value of 25% or more, preferably 30% or more of 1/2 of the maximum density value (maximum density value) can be used. Further, regarding the relationship between the radiation exposure amount to the radiation detector 40 and the gray value Da of the radiation image, the gray value Da decreases as the exposure amount to the radiation detector 40 decreases. Therefore, the fact that the current gray value Da is lower than the previous gray value Da by the vicinity of the specified value Dc indicates that the region of interest based on the current radiography is an almost white image. On the contrary, the fact that the current gray value Da is higher than the previous gray value Da by the vicinity of the specified value Dc indicates that the region of interest based on the current radiography is almost a black image. These are considered to be based on an irradiation failure due to an abnormality in the radiation irradiation system 28, a malfunction of the generator, or an abnormality in the radiation image output system 29.

The radiation imaging trial unit 118 includes a first switching signal output unit 126A and a first control signal setting unit 128A. Further, the return processing unit 124 includes a second switching signal output unit 126B and a second control signal setting unit 128B. The first switching signal output unit 126A and the second switching signal output unit 126B will be described later.

The first control signal setting unit 128A adds a predetermined signal value to the latest signal value stored in the control signal storage unit 112 based on the input of the first error notification Sb1 indicating a drop from the error notification unit 116. Then, a signal value for anomaly estimation is set and output as the first control signal Sa1 only once. In this case, the upper limit signal value Vmax may be set as a signal value for estimating an abnormality. Further, based on the input of the error notification Sb2 indicating an increase from the error notification unit 116, a predetermined signal value is subtracted from the latest signal value to set a signal value for estimating the abnormality, and the first control signal Sa1 is 1 Output only once. In this case, the lower limit signal value Vmin may be set as a signal value for estimating an abnormality.

The second control signal setting unit 128B of the return processing unit 124 sets the latest signal value stored in the control signal storage unit 112 as the signal value for return after the output of the first control signal Sa1, The control signal Sa2 is output until the return monitoring period Tc ends.

The first switching signal output unit 126A of the radiation imaging trial unit 118 outputs the first switching signal Sc1 when receiving the error notification Sb1 or Sb2.

The second switching signal output unit 126B of the return processing unit 124 outputs the second switching signal Sc2 at the start of the return processing, and outputs the third switching signal Sc3 to the switching unit 110 at the end of the return monitoring period Tc.

When the system is activated, the switching unit 110 sets the signal path of the control signal to the control signal generation unit 108 side of the irradiation energy control unit 104, and the first control signal Sa1 from the control signal generation unit 108 is set to the radiation irradiation system 28. However, based on the input of the first switching signal Sc1 from the first switching signal output unit 126A based on the error notification Sb1 or Sb2, the signal path of the control signal is changed to the first of the radiation imaging trial unit 118. By switching to the 1 control signal setting unit 128A side, the first control signal Sa1 from the first control signal setting unit 128A is supplied to the radiation irradiation system 28. In addition, the switching unit 110 changes the signal path of the control signal based on the input of the second switching signal Sc2 from the second switching signal output unit 126B based on the start of the restoration process, and the second control signal setting unit of the restoration processing unit 124. By switching to the 128B side, the second control signal Sa2 from the second control signal setting unit 128B is supplied to the radiation irradiation system 28. Further, the switching unit 110 re-controls the signal path of the control signal based on the input of the third switching signal Sc3 from the second switching signal output unit 126B based on the end of the return monitoring period Tc, and the control signal of the irradiation energy control unit 104 Switch to the generation unit 108 side.

Here, the processing operation of the first radiographic imaging system 10A will be described with reference to the flowcharts of FIGS. 5 to 7 and the time chart of FIG.

First, in step S1 of FIG. 5, the system control unit 14 stores an initial value (= 1) in the counter k of the number of times of shooting at normal times.

In step S2, the control signal generation unit 108 of the irradiation energy control unit 104 sets the signal value V to the reference signal value Vo. For example, 0 is used as the reference signal value Vo.

In step S3, the system control unit 14 determines whether a time corresponding to the latest frame rate has elapsed since the start of the previous radiation imaging. When the value of the counter k is an initial value or when the time corresponding to the latest frame rate has elapsed since the start of the previous radiation imaging, the process proceeds to the next step S4, and the control signal generator 108 determines the current signal value. V is stored in the control signal storage unit 112 as the latest signal value.

In step S5, the control signal generation unit 108 outputs the current signal value V to the radiation irradiation system 28 via the switching unit 110. The radiation source control unit 36 of the radiation irradiation system 28 changes the tube voltage, the tube current, the imaging time, etc. of the radiation source 34 based on the signal value V from the irradiation energy control unit 104 to irradiate the radiation source 34. Set the energy to the new irradiation energy.

In step S6, the system control unit 14 outputs an exposure start signal Sh to the radiation irradiation system 28 at the start of the k-th radiation imaging. The radiation source control unit 36 of the radiation irradiation system 28 controls the radiation source 34 based on the input of the exposure start signal Sh from the system control unit 14, and emits radiation with the irradiation energy set from the radiation source 34. Irradiate.

In step S <b> 7, the system control unit 14 outputs an exposure notification Si indicating that the radiation irradiation system 28 has started exposure to the radiation detection device 30 via the detection device control unit 32.

In step S8, the radiation detection apparatus 30 performs charge accumulation and charge reading based on the input of the exposure notification Si. That is, the radiation 26 that has passed through the subject 24 is once converted into visible light by the scintillator, and the visible light is photoelectrically converted in each pixel 50 to accumulate an amount of electric charge corresponding to the amount of light. Then, a synchronization signal (for example, a vertical synchronization signal) is output at the start of the reading period and input to the detection device control unit 32. The detection device controller 32 synchronizes the reception timing of the radiation image information with the output timing of the radiation image information from the radiation detection device 30 based on the input of the synchronization signal.

In the subsequent readout period, the radiation detection apparatus 30 reads out charges in accordance with currently set readout control information (information indicating progressive mode, interlace mode, and binning mode), and uses the image memory 82, for example, in a FIFO manner. Outputs radiation image information. Radiation image information from the radiation detection device 30 is supplied to the system control unit 14 via the detection device control unit 32.

In step S <b> 9, the gray value acquisition unit 102 calculates the gray value Da of the region of interest (for example, the average value of the pixel values (QL values) of all the pixels included in the region of interest) in the radiographic image information. Store in the storage unit 100.

In step S10, the system control unit 14 transfers the supplied radiation image information to the console 16. The console 16 stores the transferred radiation image information in the frame memory, and displays it on the monitor 18 as a radiation image obtained by the k-th radiation imaging, that is, a radiation image of the k-th frame in the normal operation period.

In step S11, the value of the counter k is updated by +1.

In step S12, the light / dark difference obtaining unit 114 obtains the light / dark value Da of the region of interest based on the radiation irradiation twice. For example, when the latest density value (the density value based on the current radiography) stored in the density value storage unit 100 is Da1, and the latest previous density value (the density value based on the previous radiography) is Da2. The difference ΔD = Da1−Da2 is calculated.

In step S13, the error notification unit 116 determines whether or not the gray value Da1 has changed by more than the vicinity of the specified value Dc from the gray value Da2. The error notification unit 116 outputs the first error notification Sb1 if the difference ΔD is negative and the absolute value | difference ΔD | ≧ Dc, and if the difference ΔD is positive and the absolute value | difference ΔD | ≧ Dc, the first error notification Sb1 is output. 2 Output error notification Sb2.

If no error notification is made from the error notification unit 116, that is, if | ΔD | is less than the specified value Dc, the process proceeds to step S14, and the control signal generation unit 108 of the irradiation energy control unit 104 determines the current gray value Da. And the difference between the reference value Db. That is, the difference d = Da−Db is calculated.

In step S15, the control signal generation unit 108 determines whether or not the difference d <0. If the difference d is negative, the process proceeds to step S16, and the signal value V is increased according to the difference d. On the contrary, if the difference d is positive, the process proceeds to step S17, and the signal value V is decreased according to the difference d.

In step S18, the system control unit 14 determines whether or not there is a system termination request. If there is no system termination request, the process returns to step S3, and the processes after step S3 are repeated. In step S13, the operations of steps S3 to S18 are repeated until it is determined that the gray value Da1 has changed by more than the specified value Dc from the gray value Da2, and the monitor 18 is operated at the set frame rate. A moving image of the radiation image is displayed.

When it is determined in step S13 described above that the gray value Da1 has changed by more than the specified value Dc from the gray value Da2, the process proceeds to step S19 in FIG. 6 and the first switching signal output unit 126A The first switching signal Sc1 is output to the switching unit 110. As a result, the signal path of the control signal is switched to the first control signal setting unit 128 </ b> A side of the radiation imaging trial unit 118.

In step S20, the system control unit 14 determines whether or not a time corresponding to the latest frame rate has elapsed since the start of the previous radiation imaging. The process proceeds to the next step S21 when the time has elapsed since the start of the previous radiation imaging, and the first control signal setting unit 128A determines whether the gray value Da1 is lower than the gray value Da2 by more than the specified value Dc. Is determined. This determination is made based on whether or not the error notification from the error notification unit 116 is the first error notification Sb1.

If the error notification is the first error notification Sb1, the process proceeds to step S22, and the first control signal setting unit 128A adds a predetermined signal value to the latest signal value stored in the control signal storage unit 112, and abnormally occurs. Set the signal value for estimation.

If the error notification is the second error notification Sb2, the process proceeds to step S23, and the first control signal setting unit 128A subtracts a predetermined signal value from the latest signal value to set a signal value for abnormality estimation. Note that the signal value for abnormality estimation set in steps S22 and S23 is not stored in the control signal storage unit 112.

When the processing in step S22 or step S23 is completed, the process proceeds to the next step S24, and the first control signal setting unit 128A sends the set signal value V to the radiation irradiation system 28 only once via the switching unit 110. Output. The radiation source control unit 36 of the radiation irradiation system 28 changes the tube voltage, tube current, imaging time, etc. of the radiation source 34 based on the signal value V from the radiation imaging trial unit 118, and irradiates the radiation source 34. Set the energy to the new irradiation energy.

In step S25, the system control unit 14 outputs an exposure start signal Sh to the radiation irradiation system 28 at the start of the k-th radiation imaging. The radiation source control unit 36 of the radiation irradiation system 28 controls the radiation source 34 based on the input of the exposure start signal Sh from the system control unit 14, and emits radiation with the irradiation energy set from the radiation source 34. Irradiate.

In step S26, the system control unit 14 outputs an exposure notification Si indicating that the radiation irradiation system 28 has started exposure to the radiation detection device 30 via the detection device control unit 32.

In step S27, the radiation detection apparatus 30 performs charge accumulation and charge reading based on the input of the exposure notification Si. Since this operation is the same as the operation in step S8 described above, a duplicate description thereof is omitted here.

In step S28, the gray value acquisition unit 102 calculates the gray value Da of the region of interest and stores it in the gray value storage unit 100.

In step S29, the system control unit 14 transfers the supplied radiation image information to the console 16. The console 16 stores the transferred radiation image information in the frame memory, and displays it on the monitor 18 as a radiation image obtained by the k-th radiation imaging, that is, a radiation image of the k-th frame in the normal operation period.

In step S30, the value of the counter k is updated by +1.

In step S31, the light / dark difference obtaining unit 114 obtains the light / dark value Da of the region of interest based on the radiation irradiation twice. That is, in step S12, the latest gray value when it is determined that the difference ΔD has changed by the vicinity of the specified value Dc and the gray value acquired by one radiography for estimating an abnormality (obtained in step S28). The difference from the shade value) is calculated.

In step S32 of FIG. 7, it is determined whether or not the gray value has changed. This determination is made based on whether or not the difference ΔD is 0 or almost 0 (for example, within ± 0.1 to 0.5%).

If there is no change in the gray value, the process proceeds to step S33, and the abnormality estimation unit 120 estimates that the radiation image output system 29 is abnormal. In accordance with this estimation, in step S34, the abnormality handling command unit 122 outputs a reset command signal Se for performing a reset process to the radiation image output system 29. Based on the input of the reset command signal Se, the detection device control unit 32 of the radiation image output system 29 outputs an all-pixel reset signal Sf to the radiation detection device 30 and performs a digital reset. The radiation detection apparatus 30 performs the all-pixel reset operation described above based on the input of the all-pixel reset signal Sf. The radiation detection device 30 outputs a completion signal Sg to the detection device control unit 32 when the all-pixel reset operation is completed. The detection device control unit 32 outputs a completion signal Sg to the system control unit 14 when the digital reset is completed and the completion signal Sg is received from the radiation detection device 30.

On the other hand, if it is determined in step S32 that there is a change in the gray value, the process proceeds to step S35, and the abnormality estimation unit 120 estimates that the radiation irradiation system 28 is abnormal. In accordance with this estimation, in step S36, the abnormality handling command unit 122 outputs a restart command signal Sd for restarting the radiation irradiation system 28 to the radiation irradiation system 28. The radiation source control unit 36 of the radiation irradiation system 28 stops the radiation irradiation from the radiation source 34 based on the input of the restart command signal Sd, and restarts the radiation irradiation system 28. The radiation irradiation system 28 outputs a completion signal Sg to the system control unit 14 when the restart is completed.

When the processing in step S34 or step S36 is completed, the process proceeds to the next step S37, and the second switching signal output unit 126B of the return processing unit 124 outputs the second switching signal Sc2 to the switching unit 110. As a result, the signal path of the control signal is switched to the second control signal setting unit 128B side of the return processing unit 124.

In step S38, the system control unit 14 determines whether a time corresponding to the latest frame rate has elapsed since the start of the previous radiation imaging. The process proceeds to the next step S39 when the time has elapsed since the start of the previous radiation imaging, and the second control signal setting unit 128B of the return processing unit 124 updates the latest signal value stored in the control signal storage unit 112. Is set as a signal value for recovery.

In step S40, the second control signal setting unit 128B outputs the set signal value V to the radiation irradiation system 28 via the switching unit 110. The radiation source control unit 36 of the radiation irradiation system 28 changes the tube voltage, tube current, imaging time, etc. of the radiation source 34 based on the signal value V from the return processing unit 124, and the irradiation energy of the radiation source 34. Is set to a new irradiation energy.

In step S41, the system control unit 14 outputs an exposure start signal Sh to the radiation irradiation system 28 at the start of the k-th radiation imaging. The radiation source control unit 36 of the radiation irradiation system 28 controls the radiation source 34 based on the input of the exposure start signal Sh from the system control unit 14, and emits radiation with the irradiation energy set from the radiation source 34. Irradiate.

In step S42, the system control unit 14 outputs, via the detection device control unit 32, an exposure notification Si indicating that the radiation irradiation system 28 has started exposure to the radiation detection device 30.

In step S43, the radiation detection apparatus 30 performs charge accumulation and charge readout based on the input of the exposure notification Si. Since this operation is the same as the operation in step S8 described above, a duplicate description thereof is omitted here.

In step S44, the system control unit 14 transfers the supplied radiation image information to the console 16. The console 16 stores the transferred radiation image information in the frame memory, and displays it on the monitor 18 as a radiation image obtained by the k-th radiation imaging, that is, a radiation image of the k-th frame in the normal operation period.

In step S45, the value of the counter k is updated by +1.

In step S46, the return processing unit 124 determines whether or not the return monitoring period Tc has elapsed. If the return monitoring period Tc has not elapsed, the process returns to step S38, and the processes after step S38 are repeated. As a result, the operations in steps S38 to S46 are repeated until the return monitoring period Tc elapses, and the moving image of the radiation image at the set frame rate is displayed on the monitor 18.

In step S46, when it is determined that the return monitoring period Tc has elapsed, the process proceeds to step S47, and the second switching signal output unit 126B outputs the third switching signal Sc3 to the switching unit 110. As a result, the signal path of the control signal is switched again to the control signal generation unit 108 side of the irradiation energy control unit 104. Then, it returns to step S3 of FIG. 5, and transfers to normal operation after step S3.

In step S18 described above, when it is determined that there is a system termination request, the processing in the first radiographic image capturing system 10A is terminated.

In the example of FIG. 8, for example, radiation imaging is performed at the start time tn + 1 of the (N + 1) th radiation imaging in the normal operation period Ta, so that the radiation image information D (N + 1) by the N + 1th radiation imaging is transmitted to the system control unit 14. ) Is supplied. The system control unit 14 transfers the supplied radiation image information D (N + 1) to the console 16 and displays it on the monitor 18 as a radiation image of the (N + 1) th frame. In addition, the system control unit 14 calculates a difference ΔD between the previous (Nth) gray value and the current (N + 1) gray value. Since the difference ΔD (for convenience, indicated by “ΔDn + 1”) is not a value that has decreased more than around the specified value Dc, the normal operation is continued as it is, and the system control unit 14 determines whether the region of interest has a gray value Da and a reference value Db. The signal value V of the control signal Sa corresponding to the difference d is calculated and output to the radiation irradiation system 28. The radiation irradiation system 28 sets the irradiation energy of the radiation source 34 to an amount corresponding to the signal value V (for convenience, indicated by “Vn + 1”) for the next N + 2th radiography.

Then, the density value Da of the region of interest obtained by the N + 2th radiography is approximately 0, for example, and the difference ΔD between the previous (N + 1th) density value and the current (N + 2th) density value ΔD (for convenience, “ΔDmin”). ) Is a value that has been reduced by the vicinity of the prescribed value Dc or more, the process proceeds to the process (error processing period Tb) in the radiation imaging trial unit 118, and after steps S21, S22, and S24 in FIG. A predetermined signal value is added to the previous signal value (Vn + 1) to set a signal value (Vn + 2) for anomaly estimation and output to the radiation irradiation system 28. Thereby, radiation imaging for abnormality estimation is performed only once. Note that Vmax may be used as the signal value.

If there is no change between the gray value of the radiation image information D (N + 3) obtained by the radiography for estimating the abnormality and the gray value by the previous radiography (N + 2), step S32 in FIG. Through S33 and step S34, it is estimated that the radiation image output system 29 is abnormal, and the reset process of the radiation image output system 29 is performed based on this estimation. When the reset process is completed, the error processing period Tb ends, and then the process proceeds to the return process (return monitoring period Tc). In the return processing, the latest signal value stored in the control signal storage unit 112, here, the signal value Vn + 1 based on the gray value obtained by the (N + 1) th radiography is reset, and radiography is performed at the latest frame rate. Will be performed.

Then, normal radiation imaging is performed again after the return monitoring period Tc has elapsed.

On the other hand, as shown in FIG. 9, if there is a change between the gray value of the radiographic image information D (N + 3) obtained by radiography for estimating an abnormality and the gray value of the previous radiography (N + 2). Through steps S32, S35, and S36 in FIG. 7, it is estimated that the radiation irradiation system 28 is abnormal, assuming that the radiation irradiation energy in the (N + 2) th radiography is abnormal. Based on this estimation, the radiation irradiation system 28 is restarted.

Further, as shown in FIG. 10, the density value Da of the region of interest obtained by the N + 2th radiography is, for example, approximately the maximum value, and the difference between the previous (N + 1) density value and the current (N + 2) density value. If ΔD (indicated by “ΔDmax” for the sake of convenience) is a value that has increased by more than the specified value Dc, a predetermined value from the previous signal value (Vn + 1) is obtained through steps S21, S23, and S24 in FIG. A signal value (Vn + 2) for abnormality estimation is set by subtracting the signal value and output to the radiation irradiation system 28. Thereby, radiation imaging for abnormality estimation is performed only once. Note that Vmin may be used as the signal value.

If there is no change between the gray value of the radiographic image information D (N + 3) obtained by the radiography for estimating the abnormality and the gray value of the previous radiography (N + 2), as in the case of FIG. Through steps S32, S33, and S34 of FIG. 7, it is estimated that the radiation image output system 29 is abnormal, and the reset processing of the radiation image output system 29 is performed based on this estimation.

On the contrary, as shown in FIG. 11, there is a change between the gray value of the radiographic image information D (N + 3) obtained by radiography for estimating the abnormality and the gray value of the previous radiography (N + 2). For example, similarly to the case of FIG. 9, it is estimated that the radiation irradiation system 28 is abnormal through the steps S32, S35 and S36 of FIG. 7, and the radiation irradiation system 28 is restarted based on this estimation.

As described above, in the first radiographic image capturing system 10A, when the difference between the grayscale values of the radiographic image information based on at least two radiographs is acquired and the grayscale value difference ΔD changes by more than the specified value Dc, When an error occurs, error notifications Sb1 and Sb2 are performed. Then, when error notifications Sb1 and Sb2 are performed, the irradiation energy of the radiation irradiation system 28 is changed and control is performed so that one radiation imaging is performed, and the gray value and error notification by this one radiation imaging are controlled. When there is no change between the previous gray value and the radiation image output system 29 is estimated to be abnormal, and there is a change between the gray value obtained by one radiography and the gray value before error notification. Since the radiation irradiation system 28 is estimated to be abnormal, it is possible to appropriately and quickly perform the process for recovering from the abnormal state thereafter, and the time until the recovery from the occurrence of the abnormality is greatly increased. Can be shortened. This leads to shortening of the radiography interruption time associated with the occurrence of an abnormality during surgery or catheter insertion operation while observing the moving image display in the region of interest of the subject 24.

Further, the radiographic imaging trial unit 118 controls to increase the irradiation energy of the radiation irradiation system 28 based on the input of the first error notification Sb1 indicating a decrease in the gray value, and to perform one radiography, Based on the input of the second error notification Sb2 indicating an increase in the gray value, the irradiation energy of the radiation irradiation system 28 is reduced and control is performed so that one radiography is performed. The cause of the abnormality can be easily estimated by referring to the photographing result (lightness value).

And when it is estimated that the radiation image output system 29 is abnormal, the radiation image output system 29 is controlled to execute a reset process, and when it is estimated that the radiation irradiation system 28 is abnormal, the radiation irradiation system Since the irradiation from the radiation 28 is stopped and the radiation irradiation system 28 is controlled to be restarted, it is possible to appropriately and quickly perform a process for recovering from the abnormal state thereafter. The time from occurrence to return can be greatly shortened.

By the way, even if it recovers from an abnormal state, it may not be recovered completely (an error may remain). Therefore, the risk that the abnormality occurs again by setting the signal value V in the return monitoring period Tc to a signal value lower than the latest signal value and performing the radiography by the return processing unit 124. May be reduced.

When setting to a low signal value, for example, it is set to 1/3 to 2/3 of the latest signal value stored in the control signal storage unit 112. Of course, other ratios (for example, 1/5 to 4/5) may be set. Alternatively, the frame rate may be set to 1/3 to 2/3 of the latest frame rate with the signal value V set to the latest signal value. Of course, other ratios (for example, 1/5 to 4/5) may be set.

Note that, prior to radiation imaging for anomaly estimation, the system control unit 14 may output an instruction to narrow the irradiation area to the automatic collimator unit 38 to narrow the irradiation area. Thereby, the burden caused by the exposure of the subject 24 can be further reduced.

Next, a radiographic image capturing system according to the second embodiment (hereinafter referred to as a second radiographic image capturing system 10B) will be described with reference to FIGS.

The second radiographic imaging system 10B has substantially the same configuration as the first radiographic imaging system 10A described above, but differs in that the radiographic imaging trial unit 118 has a gain setting unit 130 as shown in FIG.

The gain setting unit 130 receives a first gain setting signal Sj1 for increasing the gain of the charge amplifier 66 via the detection device control unit 32 based on the input of the first error notification Sb1 indicating a drop from the error notification unit 116. The second gain setting signal Sj2 for decreasing the gain of the charge amplifier 66 based on the second error notification Sb2 indicating the increase from the error notification unit 116 and output to the radiation detection device 30 is detected by the detection device control unit 32. And output to the radiation detection apparatus 30.

The radiation detection apparatus 30 increases the gains of all the charge amplifiers 66 by a predetermined amount (may be increased to the maximum gain) based on the input of the first gain setting signal Sj1, and inputs the second gain setting signal Sj2. Based on the above, the gains of all the charge amplifiers 66 are reduced by a predetermined amount (may be reduced to the minimum gain).

Also in the second radiographic imaging system 10B, the abnormality estimation unit 120 outputs a radiographic image when there is no change between the gray value obtained by one radiography for abnormality estimation and the gray value before error notification. The system 29 is estimated to be abnormal, and when there is a change between the gray value obtained by one radiographing and the gray value before error notification, it is estimated that the radiation irradiation system 28 is abnormal.

Here, the processing operation of the second radiation image capturing system 10B will be described.

The second radiographic imaging system 10B performs processing operations similar to those of the first radiographic imaging system 10A described above, but differs in the following respects.

That is, as shown in FIG. 13, when it is determined in step S21 that the gray value Da1 is lower than the gray value Da2 by the vicinity of the specified value Dc, the process proceeds to step S101 and the gain setting of the radiation imaging trial unit 118 is performed. The unit 130 outputs a first gain setting signal Sj1 indicating an increase in gain to the radiation detection apparatus 30 via the detection apparatus control unit 32. On the other hand, when it is determined in step S21 that the gray value Da1 is higher than the gray value Da2 by the vicinity of the specified value Dc, the process proceeds to step S102, and the gain setting unit 130 of the radiation imaging trial unit 118 A second gain setting signal Sj2 indicating a decrease in the output is output to the radiation detection apparatus 30 via the detection apparatus control unit 32.

In the next step S103, the first control signal setting unit 128A outputs the latest signal value stored in the control signal storage unit 112. Subsequent processing operations after step S25 are the same as those of the first radiographic imaging system 10A described above.

In the example of FIG. 14, for example, radiation imaging is performed at the start time tn + 1 of the (N + 1) th radiation imaging in the normal operation period Ta, so that the radiation image information D (N + 1) obtained by the N + 1th radiation imaging is transmitted to the system control unit 14. ) Is supplied. The system control unit 14 transfers the supplied radiation image information D (N + 1) to the console 16 and displays it on the monitor 18 as a radiation image of the (N + 1) th frame. In addition, the system control unit 14 calculates a difference ΔD between the previous (Nth) gray value and the current (N + 1) gray value. Since the difference ΔD (for convenience, indicated by “ΔDn + 1”) is not a value that has decreased more than around the specified value Dc, the normal operation is continued as it is, and the system control unit 14 determines whether the region of interest has a gray value Da and a reference value Db. The signal value V of the control signal Sa corresponding to the difference d is calculated and output to the radiation irradiation system 28. The radiation irradiation system 28 sets the irradiation energy of the radiation source 34 to an amount corresponding to the signal value V (for convenience, indicated by “Vn + 1”) for the next N + 2th radiography. The gain of the charge amplifier 66 is set to the latest gain (denoted by “Gn + 1” for convenience).

Then, the density value Da of the region of interest obtained by the N + 2th radiography is approximately 0, for example, and the difference ΔD between the previous (N + 1th) density value and the current (N + 2th) density value ΔD (for convenience, “ΔDmin”). Is a value that has decreased by more than the prescribed value Dc, the process proceeds to the process (error processing period Tb) in the radiation imaging trial unit 118, and after steps S21, S101, and S103 in FIG. A first gain setting signal Sj1 indicating an increase in gain is output to the radiation detection apparatus 30 via the detection apparatus control unit 32. The radiation detection apparatus 30 sets the gain of the charge amplifier 66 to a gain Ga that is higher than the current gain Gn + 1 by a predetermined gain based on the input of the first gain setting signal Sj1. Of course, the maximum gain Gmax may be set. Then, the latest signal value is output to the radiation irradiation system 28. Thereby, radiation imaging for abnormality estimation is performed only once.

If there is no change between the gray value of the radiation image information D (N + 3) obtained by the radiography for estimating the abnormality and the gray value by the previous radiography (N + 2), step S32 in FIG. Through S33 and step S34, it is estimated that the radiation image output system 29 is abnormal. Based on this estimation, a reset process of the radiation image output system is performed. When the reset process is completed, the error processing period Tb ends, and then the process proceeds to the return process (return monitoring period Tc). In the return processing, the latest signal value stored in the control signal storage unit 112, here, the signal value Vn + 1 based on the gray value obtained by the (N + 1) th radiography is reset, and radiography is performed at the latest frame rate. Will be performed.

On the other hand, as shown in FIG. 15, if there is a change between the gray value of the radiographic image information D (N + 3) obtained by radiography for estimating an abnormality and the gray value of the previous radiography (N + 2). Through steps S32, S35, and S36 in FIG. 7, it is estimated that the radiation irradiation system 28 is abnormal, assuming that the radiation irradiation energy in the (N + 2) th radiography is abnormal. Based on this estimation, the radiation irradiation system 28 is restarted.

Further, as shown in FIG. 16, the density value Da of the region of interest obtained by the N + 2th radiography is, for example, approximately the maximum value, and the difference between the previous (N + 1) density value and the current (N + 2) density value. When ΔD (for convenience, indicated by “ΔDmax”) is a value that has increased by more than the specified value Dc, the second gain setting signal indicating a decrease in gain is obtained through steps S21, S102, and S103 in FIG. Sj2 is output to the radiation detection apparatus 30 via the detection apparatus control unit 32. The radiation detection apparatus 30 sets the gain of the charge amplifier 66 to a gain Gb that is lower than the current gain Gn + 1 by a predetermined gain based on the input of the second gain setting signal Sj2. Of course, the minimum gain Gmin may be set. Then, the latest signal value is output to the radiation irradiation system 28. Thereby, radiation imaging for abnormality estimation is performed only once.

If there is no change between the gray value of the radiation image information D (N + 3) obtained by the radiography for estimating the abnormality and the gray value by the previous radiography (N + 2), the same as in the case of FIG. Through steps S32, S33, and S34 of FIG. 7, it is estimated that the radiation image output system 29 is abnormal, and the reset processing of the radiation image output system 29 is performed based on this estimation.

On the contrary, as shown in FIG. 17, there is a change between the gray value of the radiographic image information D (N + 3) obtained by radiography for estimating the abnormality and the gray value of the previous radiography (N + 2). For example, similarly to the case of FIG. 15, it is estimated that the radiation irradiation system 28 is abnormal through the steps S32, S35 and S36 of FIG. 7, and the radiation irradiation system 28 is restarted based on this estimation.

As described above, in the second radiographic image capturing system 10B, when the difference between the grayscale values of the radiographic image information based on at least two radiographs is acquired and the grayscale value difference ΔD changes by more than the specified value Dc, When an error occurs, error notifications Sb1 and Sb2 are performed. Then, when error notifications Sb1 and Sb2 are performed, the gain of the charge amplifier 66 in the radiation image output system 29 is changed to control to perform one radiation imaging, and the density by this one radiation imaging is controlled. When there is no change between the value and the gray value before the error notification, it is estimated that the radiation image output system 29 is abnormal, and there is a change between the gray value obtained by one radiography and the gray value before the error notification. In such a case, since it is estimated that the radiation irradiation system 28 is abnormal, it is possible to appropriately and quickly perform a process for recovering from the subsequent abnormal state until the recovery from the occurrence of the abnormality. This time can be greatly shortened. This leads to shortening of the radiography interruption time associated with the occurrence of an abnormality during surgery or catheter insertion operation while observing the moving image display in the region of interest of the subject 24.

Further, the radiation imaging trial unit 118 controls to increase the gain of the charge amplifier 66 based on the input of the first error notification Sb1 indicating a decrease in the gray value, and to perform one radiography, and the gray value Since the gain of the charge amplifier 66 is decreased and control is performed so that one radiography is performed on the basis of the input of the error notification Sb2 indicating an increase in the value, the result of the one radiography (the gray value) ), It is possible to easily estimate the cause of the abnormality.

By the way, even if it recovers from an abnormal state, it may not be recovered completely (an error may remain). Therefore, also in the second radiographic imaging system 10B, the return processing unit 124 controls the radiographic imaging by setting the signal value V in the return monitoring period Tc to a signal value lower than the latest signal value. By doing so, the risk that an abnormality will occur again may be reduced.

In the second radiographic imaging system 10B, as shown in FIG. 14, the gray value of the radiographic image information D (N + 3) obtained by one radiographic imaging for estimating an abnormality and the previous radiographic imaging (N + 2). ), It is estimated that the radiation image output system 29 is abnormal. However, as a rare case, the radiation irradiation system 28 may be abnormal. That is, even if the irradiation start signal Sh is output to the radiation irradiation system 28, no radiation is irradiated from the radiation irradiation system 28. In order to deal with such a case, as shown in FIG. 18, two radiographs may be performed for abnormality estimation.

Specifically, when there is no change between the gray value of the radiation image information D (N + 3) obtained by the first radiography for estimating the abnormality and the gray value of the previous radiography (N + 2). Once, it is estimated that the radiation image output system is abnormal, and the radiation image output system 29 is reset. After that, the second radiography for estimating the abnormality is performed while the gain of the charge amplifier 66 is increased. If there is no change between the gray value of the radiation image information D (N + 4) obtained by the second radiography and the gray value of the radiation image information D (N + 3) obtained by the first radiography, this time, the radiation irradiation is performed. It is estimated that the system 28 is abnormal, and the radiation irradiation system 28 is restarted.

As a result, an abnormality can be estimated even in a rare case where the radiation 26 is not irradiated from the radiation irradiation system 28, and a process for recovering from the abnormal state can be performed appropriately and quickly. Thus, the time from the occurrence of abnormality to recovery can be greatly reduced.

The radiographic image capturing system and the radiographic image capturing method according to the present invention are not limited to the above-described embodiments, and can of course have various configurations without departing from the gist of the present invention.

For example, the radiation detector 40 may be the radiation detector 600 according to the modification shown in FIGS. 19 and 20. FIG. 19 is a schematic cross-sectional view schematically showing the configuration of three pixel portions of the radiation detector 600 according to the modification.

In the radiation detector 600, as shown in FIG. 19, a signal output unit 604, a sensor unit 606 (photoelectric conversion unit), and a scintillator 608 are sequentially stacked on an insulating substrate 602, and the signal output unit 604 and A pixel unit is configured by the sensor unit 606. A plurality of pixel portions are arranged in a matrix on the substrate 602, and the signal output portion 604 and the sensor portion 606 in each pixel portion are configured to overlap each other.

The scintillator 608 is formed on the sensor unit 606 with a transparent insulating film 610 interposed therebetween. The scintillator 608 converts the radiation 26 incident from above (the side opposite to the side where the substrate 602 is located) into light and emits light. The body is formed into a film. The wavelength range of light emitted by the scintillator 608 is preferably the visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 600, the wavelength range of green is included. Is more preferable.

Specifically, the phosphor used in the scintillator 608 preferably contains cesium iodide (CsI) when imaging using X-rays as the radiation 26, and the emission spectrum upon X-ray irradiation is 420 nm to 700 nm. It is particularly preferred to use some CsI (Tl) (cesium iodide with thallium added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.

The scintillator 608 may be formed, for example, by vapor-depositing CsI (Tl) having a columnar crystal structure on a vapor deposition base. When the scintillator 608 is formed by vapor deposition as described above, Al is often used as the vapor deposition substrate from the viewpoint of X-ray transmittance and cost, but is not limited thereto. Note that in the case where GOS is used as the scintillator 608, the scintillator 608 may be formed by applying GOS to the surface of the TFT active matrix substrate without using a vapor deposition substrate. Alternatively, after the GOS is applied to the resin base to form the scintillator 608, the scintillator 608 may be bonded to the TFT active matrix substrate. As a result, the TFT active matrix substrate can be preserved even if GOS application fails.

The sensor unit 606 includes an upper electrode 612, a lower electrode 614, and a photoelectric conversion film 616 disposed between the upper electrode 612 and the lower electrode 614.

Since the upper electrode 612 needs to make the light generated by the scintillator 608 incident on the photoelectric conversion film 616, it is preferable that the upper electrode 612 is made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 608. It is preferable to use a transparent conductive oxide (TCO) having a high transmittance for visible light and a low resistance value. Note that although a metal thin film such as Au can be used as the upper electrode 612, a resistance value tends to increase when the transmittance of 90% or more is obtained, so that the TCO is preferable. 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 612 may have a single configuration common to all the pixel portions, or may be divided for each pixel portion.

The photoelectric conversion film 616 includes an organic photoconductor (OPC: Organic Photo Conductors), absorbs light emitted from the scintillator 608, and generates a charge corresponding to the absorbed light. If the photoelectric conversion film 616 includes an organic photoconductor (organic photoelectric conversion material), the photoelectric conversion film 616 has a sharp absorption spectrum in the visible light region, and electromagnetic waves other than light emitted by the scintillator 608 are almost absorbed by the photoelectric conversion film 616. In addition, noise generated when the radiation 26 is absorbed by the photoelectric conversion film 616 can be effectively suppressed. Note that the photoelectric conversion film 616 may be configured to include amorphous silicon instead of the organic photoconductor. In this case, it has a wide absorption spectrum and can efficiently absorb light emitted by the scintillator 608.

The organic photoconductor constituting the photoelectric conversion film 616 preferably has a peak wavelength closer to the emission peak wavelength of the scintillator 608 in order to absorb light emitted by the scintillator 608 most efficiently. Ideally, the absorption peak wavelength of the organic photoconductor coincides with the emission peak wavelength of the scintillator 608. However, if the difference between the two is small, the light emitted from the scintillator 608 can be sufficiently absorbed. . Specifically, the difference between the absorption peak wavelength of the organic photoconductor and the emission peak wavelength of the scintillator 608 with respect to the radiation 26 is preferably within 10 nm, and more preferably within 5 nm.

Examples of organic photoconductors that can satisfy such conditions include quinacridone organic compounds and phthalocyanine organic compounds. For example, since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoconductor and CsI (Tl) is used as the material of the scintillator 608, the difference between the peak wavelengths can be within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 616 can be substantially maximized.

The sensor unit 606 is a stack of 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 prevention part, an electrode, an interlayer contact improvement part, or the like. An organic layer formed by mixing is included. The organic layer preferably contains an organic p-type compound (organic p-type semiconductor) or an organic n-type compound (organic n-type semiconductor).

An organic p-type semiconductor is a donor organic semiconductor (compound) typified 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.

Organic n-type semiconductors are acceptor organic semiconductors (compounds) typified mainly by electron-transporting organic compounds and refer to organic compounds that have the 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, any organic compound can be used as the acceptor organic compound as long as it is an electron-accepting organic compound.

Since the materials applicable as the organic p-type semiconductor and organic n-type semiconductor and the configuration of the photoelectric conversion film 616 are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted. Note that the photoelectric conversion film 616 may be formed by further containing fullerenes or carbon nanotubes.

The thickness of the photoelectric conversion film 616 is preferably as large as possible in terms of absorbing light from the scintillator 608. However, when the thickness is larger than a certain level, the photoelectric conversion film 616 is generated in the photoelectric conversion film 616 by a bias voltage applied from both ends of the photoelectric conversion film 616. 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.

The photoelectric conversion film 616 has a single configuration common to all pixel portions, but may be divided for each pixel portion. The lower electrode 614 is a thin film divided for each pixel portion. However, the lower electrode 614 may have a single configuration common to all the pixel portions. The lower electrode 614 can be made of a transparent or opaque conductive material, and aluminum, silver, or the like can be preferably used. The thickness of the lower electrode 614 can be, for example, 30 nm or more and 300 nm or less.

In the sensor unit 606, by applying a predetermined bias voltage between the upper electrode 612 and the lower electrode 614, one of charges (holes, electrons) generated in the photoelectric conversion film 616 is moved to the upper electrode 612. The other can be moved to the lower electrode 614. In the radiation detector 600 according to this modification, a wiring is connected to the upper electrode 612, and a bias voltage is applied to the upper electrode 612 via the wiring. In addition, the polarity of the bias voltage is determined so that electrons generated in the photoelectric conversion film 616 move to the upper electrode 612 and holes move to the lower electrode 614, but this polarity is opposite. May be.

The sensor unit 606 constituting each pixel unit only needs to include at least the lower electrode 614, the photoelectric conversion film 616, and the upper electrode 612. In order to suppress an increase in dark current, the electron blocking film 618 and the hole blocking are included. It is preferable to provide at least one of the films 620, and it is more preferable to provide both.

The electron blocking film 618 can be provided between the lower electrode 614 and the photoelectric conversion film 616. When a bias voltage is applied between the lower electrode 614 and the upper electrode 612, electrons are transferred from the lower electrode 614 to the photoelectric conversion film 616. 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 618. The material actually used for the electron blocking film 618 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 616, 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 616 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 618 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 606. It is good to set it to 50 nm or more and 100 nm or less.

The hole blocking film 620 can be provided between the photoelectric conversion film 616 and the upper electrode 612. When a bias voltage is applied between the lower electrode 614 and the upper electrode 612, the hole blocking film 620 is applied from the upper electrode 612 to the photoelectric conversion film 616. 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 620. The thickness of the hole blocking film 620 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 photoelectric conversion efficiency of the sensor unit 606. Is preferably 50 nm to 100 nm.

The material actually used for the hole blocking film 620 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 616, and the like, 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 616. 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.

Note that, among the charges generated in the photoelectric conversion film 616, when a bias voltage is set so that holes move to the upper electrode 612 and electrons move to the lower electrode 614, the electron blocking film 618 and the hole blocking are set. The position of the film 620 may be reversed. Further, it is not necessary to provide both the electron blocking film 618 and the hole blocking film 620. If either one is provided, a certain dark current suppressing effect can be obtained.

As shown in FIG. 20, the signal output unit 604 is provided on the surface of the substrate 602 corresponding to the lower electrode 614 of each pixel unit, and the storage capacitor 622 that accumulates the electric charge moved to the lower electrode 614, The TFT 624 converts the electric charge accumulated in the accumulation capacitor 622 into an electric signal and outputs the electric signal. The region where the storage capacitor 622 and the TFT 624 are formed has a portion that overlaps with the lower electrode 614 in plan view. With such a structure, the signal output unit 604 and the sensor unit 606 in each pixel unit are connected to each other. There will be overlap in the thickness direction. If the signal output unit 604 is formed so as to completely cover the storage capacitor 622 and the TFT 624 with the lower electrode 614, the plane area of the radiation detector 600 (pixel unit) can be minimized.

The storage capacitor 622 is electrically connected to the corresponding lower electrode 614 through a wiring made of a conductive material that penetrates an insulating film 626 provided between the substrate 602 and the lower electrode 614. Thereby, the charge collected by the lower electrode 614 can be moved to the storage capacitor 622.

In the TFT 624, a gate electrode 628, a gate insulating film 630, and an active layer (channel layer) 632 are stacked, and a source electrode 634 and a drain electrode 636 are formed on the active layer 632 with a predetermined interval. The active layer 632 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 632 is not limited thereto.

The amorphous oxide that can form the active layer 632 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 (eg, In—Zn—O, In—Ga—O, and Ga—Zn—O) are more preferred, and oxides containing In, Ga, and Zn are particularly preferred. 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 of less than 6) is preferable, and in particular, InGaZnO. ₄ is more preferable. Note that the amorphous oxide that can form the active layer 632 is not limited thereto.

Examples of the organic semiconductor material that can form the active layer 632 include, but are not limited to, phthalocyanine compounds, pentacene, vanadyl phthalocyanine, and the like. The configuration of the phthalocyanine compound is described in detail in Japanese Patent Application Laid-Open No. 2009-212389, so that the description thereof is omitted.

If the active layer 632 of the TFT 624 is formed of an amorphous oxide, an organic semiconductor material, or a carbon nanotube, the radiation 26 such as X-rays is not absorbed, or even if it is absorbed, a very small amount remains. Generation of noise in the unit 604 can be effectively suppressed.

Further, when the active layer 632 is formed of carbon nanotubes, the switching speed of the TFT 624 can be increased, and a TFT 624 having a low light absorption in the visible light region can be formed. In addition, when the active layer 632 is formed of carbon nanotubes, the performance of the TFT 624 is remarkably deteriorated only by mixing a very small amount of metallic impurities into the active layer 632, so that 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 photoconductor can be formed at a low temperature. Therefore, the substrate 602 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 substrates such as polyesters such as polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, polychlorotrifluoroethylene, etc. 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 photoelectric conversion film 616 is formed from an organic photoconductor, and the TFT 624 is formed from an organic semiconductor material, whereby the photoelectric conversion film 616 and the TFT 624 are formed at a low temperature on a plastic flexible substrate (substrate 602). It is possible to reduce the thickness and weight of the radiation detector 600 as a whole. Thereby, the radiation detection apparatus 30 that accommodates the radiation detector 600 can be made thinner and lighter, and convenience in use outside the hospital is improved. In addition, since the base material of the photoelectric conversion portion is made of a material having flexibility different from that of general glass, it is possible to improve damage resistance when the device is carried or used.

In addition, the substrate 602 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 to a high temperature process of 200 degrees or more, the transparent electrode material can be cured at a high temperature to reduce the resistance, and it 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 manufacturing 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 602 may be formed by stacking an ultrathin glass substrate and an aramid.

Bionanofiber is a composite of a cellulose microfibril bundle (bacterial cellulose) produced by bacteria (acetobacterium 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 acrylic resin or epoxy resin into 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. Thus, a thin substrate 602 can be formed.

In this modification, a signal output unit 604, a sensor unit 606, and a transparent insulating film 610 are sequentially formed on a substrate 602, and a scintillator 608 is attached to the substrate 602 using an adhesive resin having low light absorption. Thus, the radiation detector 600 is formed.

In the radiation detector 600 according to the above-described modification, the photoelectric conversion film 616 is made of an organic photoconductor, and the active layer 632 of the TFT 624 is made of an organic semiconductor material. Therefore, the photoelectric conversion film 616 and the signal output unit 604 are used. Therefore, the radiation 26 is hardly absorbed. Thereby, the fall of the sensitivity with respect to the radiation 26 can be suppressed.

Both the organic semiconductor material constituting the active layer 632 of the TFT 624 and the organic photoconductor constituting the photoelectric conversion film 616 can be formed at a low temperature. Therefore, the substrate 602 can be formed of a plastic resin, aramid, or bionanofiber that absorbs less radiation 26. Thereby, the fall of the sensitivity with respect to the radiation 26 can be suppressed further.

Further, for example, when the radiation detector 600 is attached to a portion of the irradiation surface in the housing and the substrate 602 is formed of a highly rigid plastic resin, aramid, or bionanofiber, the rigidity of the radiation detector 600 itself may be increased. Therefore, the irradiation surface portion of the housing can be formed thin. In addition, when the substrate 602 is formed of a highly rigid plastic resin, aramid, or bionanofiber, the radiation detector 600 itself has flexibility, so that even when an impact is applied to the irradiated surface, the radiation detector 600 is not easily damaged. .

The radiation detector 600 described above may be configured as follows.

(1) The photoelectric conversion film 616 may be formed of an organic photoelectric conversion material, and the TFT layer 638 using a CMOS sensor may be formed. In this case, since only the photoelectric conversion film 616 is made of an organic material, the TFT layer 638 including the CMOS sensor may not have flexibility.

(2) The photoelectric conversion film 616 may be formed of an organic photoelectric conversion material, and the flexible TFT layer 638 may be realized by a CMOS circuit including a TFT 624 made of an organic material. In this case, pentacene may be adopted as the material of the p-type organic semiconductor used in the CMOS circuit, and copper fluoride phthalocyanine (F ₁₆ CuPc) may be adopted as the material of the n-type organic semiconductor. Thus, a flexible TFT layer 638 that can have a smaller bending radius can be realized. In addition, by configuring the TFT layer 638 in this way, the gate insulating film can be significantly reduced, and the driving voltage can be lowered. Furthermore, the gate insulating film, the semiconductor, and each electrode can be manufactured at room temperature or 100 ° C. or lower. Furthermore, a CMOS circuit can be directly formed over the flexible substrate 602. Moreover, the TFT 624 made of an organic material can be miniaturized by a manufacturing process in accordance with a scaling law. Note that when the polyimide precursor is applied to a thin polyimide substrate by a spin coat method and heated, the polyimide precursor is changed to polyimide, so that a flat substrate without unevenness can be realized.

(3) Applying a self-alignment placement technique (Fluidic Self-Assembly method) that places a plurality of micron-order device blocks at specified positions on a substrate 602, a photoelectric conversion film 616 and a TFT 624 made of crystalline Si are formed on a resin substrate You may arrange | position on the board | substrate 602 which consists of. In this case, the photoelectric conversion film 616 and TFT 624 as micro device blocks of micron order are fabricated in advance on another substrate and then separated from the substrate, and the photoelectric conversion film 616 and TFT 624 in the liquid are placed on the substrate 602 as the target substrate. Sprinkle on and place statistically. The substrate 602 is processed in advance to be adapted to the device block, and the device block can be selectively placed on the substrate 602. Therefore, an optimal device block (photoelectric conversion film 616 and TFT 624) made of an optimal material can be integrated on an optimal substrate (semiconductor substrate, quartz substrate, glass substrate, etc.), and is not a crystal. It is also possible to integrate device blocks (photoelectric conversion film 616 and TFT 624) optimum for a substrate (flexible substrate such as plastic).

In the radiation detector 600 according to the above-described modification, the light emitted from the scintillator 608 is converted into charges by the sensor unit 606 (photoelectric conversion film 616) located on the side opposite to the side where the radiation source 34 is located. Although it is configured as a so-called back side scanning method (PSS (Penetration Side Sampling) method) for reading an image, it is not limited to this configuration.

For example, the radiation detector may be configured as a so-called surface reading system (ISS (Irradiation Side Sampling) system). In this case, the substrate 602, the signal output unit 604, the sensor unit 606, and the scintillator 608 are laminated in this order along the irradiation direction of the radiation 26, and the light emitted from the scintillator 608 is sensor unit on the side where the radiation source 34 is located. At 606, the radiation image is read after being converted into electric charges. In general, the scintillator 608 emits light more strongly on the irradiation surface side of the radiation 26 than on the back side. Therefore, in the radiation detector configured by the front surface reading method, the scintillator is compared with the radiation detector configured by the back surface reading method. The distance until the light emitted in 608 reaches the photoelectric conversion film 616 can be shortened. Thereby, since the diffusion / attenuation of the light can be suppressed, the resolution of the radiation image can be increased.

Claims

A radiation irradiation system (28) that irradiates the subject (24) with radiation (26) at a set irradiation energy, and an irradiation energy control unit (104) that controls the irradiation energy of the radiation irradiation system (28); A radiographic image capturing apparatus (12) having a radiographic image output system (29) that converts the radiation (26) from the radiation irradiation system (28) that has passed through the subject (24) into radiographic image information and outputs the radiographic image information. )When,
A system control unit (14) for controlling the radiographic imaging device (12) to perform radiographic imaging at a set frame rate;
The irradiation energy control unit (104)
Controls to increase the irradiation energy of the next radiation when the gray value of the radiation image information is lower than the reference value, and to decrease the irradiation energy of the next radiation when the gray value is higher than the reference value. ,
The system control unit (14)
When the gray value is different from the expected result, a radiation imaging trial unit (118) that controls to perform one radiation imaging by changing the irradiation energy of the radiation irradiation system (28). )When,
When there is no change between the gray value obtained by the first radiography and the previous gray value, it is estimated that the radiation image output system (29) is abnormal, and the gray value obtained by the one radiography and its A radiographic imaging system comprising: an abnormality estimation unit (120) that estimates that the radiation irradiation system (28) is abnormal when there is a change between the previous gray value and the previous gray value.
In the radiographic imaging system of Claim 1,
The system control unit (14)
A density difference acquisition unit (114) for acquiring a difference in density values of radiation image information based on at least two times of radiography;
And an error notification unit (116) for performing error notification (Sb) as a result of the difference in the gray value being different from an expected result when the difference in the gray value changes by more than a predetermined value. A featured radiographic imaging system.
The radiographic imaging system according to claim 2,
The error notification unit (116) decreases the gray value when the gray value of the radiographic image information based on the current radiography is lower than the gray value of the radiographic image information based on the previous radiography by the vicinity of the specified value or more. Error notification (Sb1) indicating
The radiation imaging trial unit (118) increases the irradiation energy of the radiation irradiation system (28) based on the input of the error notification (Sb1) indicating the decrease in the gray value, and performs the one radiation imaging. A radiographic imaging system characterized by being controlled to perform.
The radiographic imaging system according to claim 2,
The error notification unit (116) increases the gray value when the gray value of the radiographic image information based on the current radiography is higher than the gray value of the radiographic image information based on the previous radiography by the vicinity of the specified value or more. Error notification (Sb2) indicating
The radiation imaging trial unit (118) reduces the irradiation energy of the radiation irradiation system (28) based on the input of the error notification (Sb2) indicating the increase in the gray value, and performs the one radiation imaging. A radiographic imaging system characterized by being controlled to perform.
The radiographic imaging system according to any one of claims 1 to 4,
The system control unit (14)
When it is estimated that the radiation image output system (29) is abnormal, the radiation image output system (29) is controlled to perform a reset process,
When it is estimated that the radiation irradiation system (28) is abnormal, the irradiation (26) from the radiation irradiation system (28) is stopped and the radiation irradiation system (28) is restarted. A radiographic imaging system characterized by:
A radiation irradiation system (28) that irradiates the subject (24) with radiation (26) at a set irradiation energy, and an irradiation energy control unit (104) that controls the irradiation energy of the radiation irradiation system (28); A radiation image output system (29) for converting the radiation (26) from the radiation irradiation system (28) transmitted through the subject (24) into radiation image information via an amplifier (66) and outputting the radiation image information. A radiographic imaging device (12) having;
A system control unit (14) for controlling the radiographic imaging device (12) to perform radiographic imaging at a set frame rate;
The irradiation energy control unit (104)
Controls to increase the irradiation energy of the next radiation when the gray value of the radiation image information is lower than the reference value, and to decrease the irradiation energy of the next radiation when the gray value is higher than the reference value. ,
The system control unit (14)
A radiography trial unit (118) that controls to perform one radiography by changing the gain of the amplifier (66) when the gray value is different from an expected result;
When there is no change between the gray value obtained by the first radiography and the previous gray value, it is estimated that the radiation image output system (29) is abnormal, and the gray value obtained by the one radiography and its A radiographic imaging system comprising: an abnormality estimation unit (120) that estimates that the radiation irradiation system (28) is abnormal when there is a change between the previous gray value and the previous gray value.
In the radiographic imaging system of Claim 6,
The system control unit (14)
A density difference acquisition unit (114) for acquiring a difference in density values of radiation image information based on at least two times of radiography;
And an error notification unit (116) for performing error notification (Sb) as a result of the difference in the gray value being different from an expected result when the difference in the gray value changes by more than a predetermined value. A featured radiographic imaging system.
In the radiographic imaging system of Claim 7,
The error notification unit (116) decreases the gray value when the gray value of the radiographic image information based on the current radiography is lower than the gray value of the radiographic image information based on the previous radiography by the vicinity of the specified value or more. Error notification (Sb1) indicating
The radiation imaging trial unit (118) increases the gain of the amplifier (66) based on the input of the error notification (Sb1) indicating the drop in the gray value, and performs the one radiation imaging. A radiographic imaging system characterized by controlling.
In the radiographic imaging system of Claim 7,
The error notification unit (116) increases the gray value when the gray value of the radiation image information based on the current radiation exposure is higher than the gray value of the radiation image information based on the previous radiation imaging by more than the specified value. Error notification (Sb2) indicating
The radiation imaging trial unit (118) performs the one-time radiography by reducing the gain of the amplifier (66) based on the input of the error notification (Sb2) indicating the increase in the gray value. A radiographic imaging system characterized by controlling.
The radiographic imaging system according to any one of claims 6 to 9,
The system control unit (14)
When it is estimated that the radiation image output system (29) is abnormal, the radiation image output system (29) is controlled to perform a reset process,
When it is estimated that the radiation irradiation system (28) is abnormal, the irradiation (26) from the radiation irradiation system (28) is stopped and the radiation irradiation system (28) is restarted. A radiographic imaging system characterized by:
The radiographic imaging system according to claim 8, wherein
When it is estimated that the radiation image output system (29) is abnormal, the system control unit (14) performs a reset process on the radiation image output system (29),
The radiation imaging trial unit (118) controls to perform the second radiation imaging in a state where the gain of the amplifier (66) is increased based on the notification of completion of the reset process,
The abnormality estimation unit (120) estimates that there is an abnormality in the radiation irradiation system (28) when there is no change between the gray value obtained by the second radiography and the gray value obtained by the first radiography. A radiographic imaging system characterized by:
The radiographic imaging system according to claim 11, wherein
The system control unit 14)
When it is estimated that the radiation irradiation system (28) is abnormal, the irradiation (26) from the radiation irradiation system (28) is stopped and the radiation irradiation system (28) is restarted. A radiographic imaging system characterized by:
The radiographic imaging system according to any one of claims 1 to 12,
The radiation imaging trial unit (118) controls to perform the radiation imaging by narrowing an irradiation region of the radiation (26) on the subject (24).
A radiation irradiation system (28) that irradiates the subject (24) with radiation (26) at a set irradiation energy, and an irradiation energy control unit (104) that controls the irradiation energy of the radiation irradiation system (28); A radiographic image capturing apparatus (12) having a radiographic image output system (29) that converts the radiation (26) from the radiation irradiation system (28) that has passed through the subject (24) into radiographic image information and outputs the radiographic image information. ) In a radiographic imaging method for controlling to perform radiography at a set frame rate,
The irradiation energy control unit (104) increases the irradiation energy of the next radiation when the gray value of the radiation image information is lower than a reference value, and the next radiation when the gray value is higher than the reference value. Control to reduce the irradiation energy of
A step of changing the irradiation energy of the radiation irradiation system (28) when the gray value is different from an expected result, and controlling to perform one radiography;
When there is no change between the gray value obtained by the first radiography and the previous gray value, it is estimated that the radiation image output system (29) is abnormal, and the gray value obtained by the one radiography and its And a step of estimating that there is an abnormality in the radiation irradiation system (28) when there is a change between the previous gray value and the previous gray value.
A radiation irradiation system (28) that irradiates the subject (24) with radiation (26) at a set irradiation energy, and an irradiation energy control unit (104) that controls the irradiation energy of the radiation irradiation system (28); A radiation image output system (29) for converting the radiation (26) from the radiation irradiation system (28) transmitted through the subject (24) into radiation image information via an amplifier (66) and outputting the radiation image information. In a radiographic imaging method for controlling a radiographic imaging device (12) having a radiographic imaging to execute at a set frame rate,
The irradiation energy control unit (104) increases the irradiation energy of the next radiation when the gray value of the radiation image information is lower than a reference value, and the next radiation when the gray value is higher than the reference value. Control to reduce the irradiation energy of
A step of changing the gain of the amplifier (66) to perform one radiography when the gray value is different from an expected result;
When there is no change between the gray value obtained by the first radiography and the previous gray value, it is estimated that the radiation image output system (29) is abnormal, and the gray value obtained by the one radiography and its And a step of estimating that there is an abnormality in the radiation irradiation system (28) when there is a change between the previous gray value and the previous gray value.
The radiographic image capturing method according to claim 14 or 15,
When it is estimated that the radiation image output system (29) is abnormal, a reset process is performed on the radiation image output system (29),
When it is estimated that the radiation irradiation system (28) is abnormal, the radiation (26) of the radiation irradiation system (28) is stopped and the radiation irradiation system (28) is restarted. Radiation imaging method to do.