Radiation imaging device and radiation imaging system

Abstract

To provide a mechanism capable of avoiding inappropriate radiation stop control from being performed.SOLUTION: A radiation imaging device 100 that performs imaging using radiation 301, comprises: an imaging unit 120 configured to include a dose signal output pixel that outputs an electric signal based on the dose of the incident radiation 301; and a processing unit 130 that performs processing to compare a threshold value and an integrated value of the electrical signal output from the dose signal output pixel included in the imaging unit 120 during a period in which the imaging unit 120 is not irradiated with radiation 301.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a radiation imaging apparatus that performs imaging using radiation, a control method thereof, and a radiation imaging system that includes the radiation imaging apparatus. [Background technology]

[0002] Radiation imaging devices equipped with an imaging unit such as a sensor panel that detects radiation such as X-rays are widely used in fields such as industry and medicine. In recent years, portable radiation imaging devices capable of imaging in multiple imaging modes according to the purpose, such as still image shooting and video shooting, have been considered. In addition, radiation imaging devices capable of performing automatic exposure control (AEC) by detecting the accumulated dose of radiation that has passed through a subject and stopping the irradiation of radiation from a radiation source when the detected accumulated dose reaches an appropriate amount have also been considered.

[0003] Patent Document 1 discloses an example of a radiographic imaging device that detects radiation based on the difference between an electrical signal flowing through a first wiring, which is an electrical signal corresponding to an electric charge generated in a radiation detection sensor unit, and an electrical signal flowing through a second wiring having a wiring pattern substantially identical to that of the first wiring, thereby suppressing the influence of noise and accurately detecting radiation even when noise occurs due to disturbance factors, etc. Patent Document 2 discloses an example of a radiographic imaging system that, when disturbance noise is detected by a detection means in a signal representing a radiation dose, converts the signal into a signal representing a dose less than the radiation dose represented by the signal, thereby accurately performing radiation stop control even when noise occurs and preventing re-imaging due to an insufficient dose. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-52896 A [Patent Document 2] JP 2014-90869 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional techniques including Patent Document 2, for example, there may be cases where inappropriate radiation shutdown control is performed due to deterioration over time of the device that detects the radiation dose or failure due to impact or the like.

[0006] The present invention has been made in consideration of such problems, and has an object to provide a mechanism capable of avoiding inappropriate radiation shutdown control. [Means for solving the problem]

[0007] The radiation imaging device of the present invention is a radiation imaging device that performs imaging using radiation, and has an imaging section that is configured to include dose signal output pixels that output electrical signals based on the dose of the incident radiation, and a processing section that performs processing to compare an integrated value of the electrical signals output from the dose signal output pixels with a threshold value during a period when the radiation is not irradiated to the imaging section. The present invention also includes a method for controlling the above-mentioned radiation imaging apparatus, and a radiation imaging system configured to include the above-mentioned radiation imaging apparatus. Effect of the Invention

[0008] According to the present invention, it is possible to prevent inappropriate radiation shutdown control from being performed. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of a schematic configuration of a radiation imaging system including a radiation imaging apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 illustrates the first embodiment of the present invention and is a diagram showing an example of an internal configuration of an imaging unit illustrated in FIG. [Diagram 3]5 is a timing chart showing an example of a processing procedure in a control method for a radiation imaging system including a radiation imaging apparatus according to the first embodiment of the present invention. [Figure 4] 5 is a flowchart showing an example of a processing procedure in a control method of a radiation imaging apparatus according to the first embodiment of the present invention. [Diagram 5] 10 is a timing chart showing an example of a first process procedure in a control method for a radiation imaging system including a radiation imaging apparatus according to a second embodiment of the present invention. [Figure 6] 10 is a timing chart showing an example of a second process procedure in a control method for a radiation imaging system including a radiation imaging apparatus according to a second embodiment of the present invention. [Figure 7] 10 is a timing chart showing an example of a third process procedure in a control method for a radiation imaging system including a radiation imaging apparatus according to a second embodiment of the present invention. [Figure 8] 10 is a timing chart showing an example of a fourth process procedure in a control method for a radiation imaging system including a radiation imaging apparatus according to the second embodiment of the present invention. [Figure 9] 10 is a timing chart showing an example of a fifth process procedure in a control method for a radiation imaging system including a radiation imaging apparatus according to the second embodiment of the present invention. [Figure 10] 13 is a timing chart showing an example of a sixth process procedure in a control method for a radiation imaging system including a radiation imaging apparatus according to the second embodiment of the present invention. [Figure 11] FIG. 13 illustrates a third embodiment of the present invention and shows an example of an internal configuration of the imaging unit illustrated in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a mode (embodiment) for carrying out the present invention will be described with reference to the drawings. Note that in the embodiment of the present invention described below, radiation includes α-rays, β-rays, and γ-rays, which are beams made of particles (including photons) emitted by radioactive decay, as well as beams having the same or higher energy levels, such as X-rays, particle beams, and cosmic rays.

[0011] (First embodiment) First, a first embodiment of the present invention will be described.

[0012] Fig. 1 is a diagram showing an example of a schematic configuration of a radiation imaging system 10 including a radiation imaging device 100 according to a first embodiment of the present invention. As shown in Fig. 1, the radiation imaging system 10 includes the radiation imaging device 100, an irradiation control device 200, and a radiation source 300. The radiation imaging system 10 is configured to electrically capture an image of a subject H formed by radiation 301 and obtain an electrical radiation image.

[0013] The radiation source 300 irradiates radiation 301 in accordance with an irradiation permission command from the irradiation control device 200. The radiation 301 emitted from the radiation source 300 passes through the subject H and enters the radiation imaging device 100. In addition, the radiation source 300 stops irradiating the radiation 301 in accordance with an irradiation stop command from the irradiation control device 200.

[0014] The irradiation control device 200 controls the irradiation of radiation 301 by the radiation source 300. The irradiation control device 200 may include an irradiation switch 201. For example, the irradiation control device 200 controls the irradiation of radiation 301 by the radiation source 300 based on the operation state of the irradiation switch 201 or various instruction information from the radiation imaging device 100.

[0015] The radiation imaging apparatus 100 is an apparatus for imaging a subject H using radiation 301. The radiation imaging apparatus 100 has an automatic exposure control function (AEC function) for controlling the stop of irradiation of the radiation 301. As shown in FIG. 1, the radiation imaging apparatus 100 includes a computer 110, an imaging section 120, a processing section 130, an input section 140, and a display section 150.

[0016] Radiation 301 emitted from a radiation source 300 (including radiation 301 transmitted through the subject H) is incident on the imaging section 120. The imaging section 120 is configured to include a plurality of image signal output pixels that output image signals related to a radiation image, and a plurality of dose signal output pixels that output dose signals that are electrical signals based on the exposure dose of the incident radiation 301. Note that, in this embodiment, an example in which pixels are used as a configuration for outputting dose signals will be described, but a dedicated sensor or the like may also be used.

[0017] The processing unit 130 performs various processes related to radiation stop control. In the present embodiment, the processing unit 130 performs a process of comparing an integrated value of an electric signal (dose signal) output from a dose signal output pixel of the imaging unit 120 with a threshold value during a period in which the imaging unit 120 is not irradiated with radiation 301 from the radiation source 300. Thereafter, in the present embodiment, if the integrated value described above exceeds the threshold value, the processing unit 130 transmits to the irradiation control device 200 disapproval instruction information for disapproving irradiation of the radiation 301 from the radiation source 300 to the imaging unit 120. Then, when the irradiation control device 200 receives the disapproval instruction information from the processing unit 130, the processing unit 130 transmits an irradiation disapproval command to the radiation source 300 to control the radiation source 300 not to irradiate the radiation 301. On the other hand, in the present embodiment, if the integrated value described above does not exceed the threshold value, the processing unit 130 transmits to the irradiation control device 200 permission instruction information for permitting irradiation of the radiation 301 from the radiation source 300 to the imaging unit 120. When the irradiation control device 200 receives the permission instruction information from the processing unit 130 , it transmits an irradiation permission command to the radiation source 300 and controls the radiation source 300 to irradiate radiation 301 .

[0018] The processing unit 130 may be configured, for example, by a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a general-purpose computer with a program built in. The processing unit 130 may also be configured by a combination of all or part of these.

[0019] The computer 110 comprehensively controls the operation of the radiation imaging apparatus 100 and performs various processes. The computer 110 also communicates with the irradiation control device 200. The computer 110 also processes image signals output from image signal output pixels of the imaging section 120 to generate radiation image data.

[0020] The input unit 140 inputs various types of information to the computer 110 .

[0021] The display unit 150 displays various information and images under the control of the computer 110. For example, when the processing unit 130 transmits non-permission instruction information to the irradiation control device 200, the display unit 150 displays a warning to that effect. Also, for example, the display unit 150 displays a radiation image based on radiation image data generated by the computer 110.

[0022] Next, the internal configuration of the imaging unit 120 shown in FIG. 1 will be described. Fig. 2 shows a first embodiment of the present invention, and is a diagram showing an example of an internal configuration of the imaging unit 120 shown in Fig. 1. Hereinafter, the imaging unit 120 in the first embodiment shown in Fig. 2 will be referred to as "imaging unit 120-1".

[0023] As shown in FIG. 2, the imaging section 120-1 includes a pixel area 121, a bias power supply 122, a shift register 123 which is a drive circuit, a readout circuit 124, a buffer amplifier 125, and an A / D converter 126.

[0024] The pixel region 121 is configured by arranging a plurality of pixels 210 in a matrix on an insulating substrate, for example. Here, in the example shown in Fig. 2, for the sake of simplicity of explanation, the pixel region 121 is shown in which the pixels 210 (specifically, pixels 210-11 to 210-55 shown in Fig. 2) are arranged in 5 rows and 5 columns, but in the actual pixel region 121, many more pixels 210 are arranged. For example, a 17-inch FPD may have approximately 2800 rows and approximately 2800 columns of pixels 210.

[0025] One pixel 210 is configured to include a conversion element S that converts incident radiation 301 into an electric charge, and a switch element T that outputs an electric signal corresponding to the electric charge generated by the conversion element S. In the example shown in Fig. 2, the conversion element S included in the pixel 210-11 in the first row and first column is described as a "conversion element S11," and the switch element T included in the pixel 210-11 in the first row and first column is described as a "switch element T11." Here, to generalize the example shown in Fig. 2 using any natural numbers m and n, the conversion element S included in the pixel 210-mn in the mth row and nth column is described as a "conversion element Smn," and the switch element T included in the pixel 210-mn in the mth row and nth column is described as a "switch element Tmn."

[0026] In this embodiment, the conversion element S may be an indirect type conversion element including, for example, a wavelength converter (for example, a scintillator) that converts the radiation 301 into light detectable by a photoelectric conversion element, and a photoelectric conversion element that converts the light converted by the wavelength converter into an electric charge. In this case, the photoelectric conversion element may be an MIS type photodiode arranged on an insulating substrate such as a glass substrate, and made mainly of amorphous silicon. In addition, the photoelectric conversion element may be a PIN type photodiode arranged on a semiconductor substrate such as silicon. In addition, the conversion element S is not limited to the indirect type conversion element described above, and a direct type conversion element that directly converts the radiation 301 into an electric charge may be used. In this case, for example, amorphous selenium may be used as the main material of the conversion element. The multiple conversion elements S shown in FIG. 2 detect a two-dimensional distribution of the radiation 301 that has reached the imaging unit 120-1.

[0027] For example, a transistor having a control terminal and two main terminals can be used as the switch element T. In this embodiment, the switch element T can be a thin film transistor (TFT).

[0028] One electrode of the conversion element S is electrically connected to one of two main terminals of the switch element T, and the other electrode of the conversion element S is electrically connected to a bias power supply 122 via a common bias wiring. The switch elements T arranged in the row direction (horizontal direction in FIG. 2), for example, the switch elements T11 to T15 in the first row, have a control terminal electrically connected in common to a drive wiring Vg(1). A drive signal for controlling the conductive state of the switch elements T11 to T15 is provided to the switch elements T11 to T15 from the shift register 123 via the drive wiring Vg(1). In addition, the switch elements T arranged in the column direction (vertical direction in FIG. 2), for example, the switch elements T11 to T51 in the first column, have the other main terminal electrically connected to a signal wiring Sig1. While the switch elements T11 to T51 are in a conductive state, a signal according to the charge accumulated in the conversion element S is output to the readout circuit 124 via the signal wiring Sig1. The signal lines Sig1 to Sig5 arranged in the column direction transmit signals output from the pixels 210 connected to the same drive line Vg to the readout circuit 124 in parallel.

[0029] Here, in the present embodiment shown in FIG. 2, the dose signal output pixel and the image signal output pixel included in the imaging unit 120 may be configured as the same pixel 210 in the pixel region 121 of the imaging unit 120-1. In this case, the computer 110 in FIG. 1 controls the shift register 123 to drive the pixel 210 at different timings, thereby causing the pixel to function as the dose signal output pixel or the image signal output pixel. For example, the computer 110 in FIG. 1 may select either a first drive mode in which the pixel 210 functions as a dose signal output pixel or a second drive mode in which the pixel 210 functions as an image signal output pixel, based on information from the input unit 140. Note that, here, a description is given of a mode in which the computer 110 in FIG. 1 performs various controls on the internal configuration of the imaging unit 120, but this embodiment is not limited to this mode, and a mode in which the processing unit 130 in FIG. 1 performs the controls is also applicable to this embodiment.

[0030] The shift register 123 outputs drive signals including a conductive voltage Vcom for turning on the switch element T and a non-conductive voltage Vss for turning off the switch element T to each drive wiring Vg in response to control signals D-CLK, DIO, and OE supplied from the computer 110 in Fig. 1. In this way, the shift register 123 controls the conductive and non-conductive states of the switch element T to drive each pixel 210 in the pixel area 121. Specifically, the control signal D-CLK is a shift clock signal of the shift register 123 used as a drive circuit. The control signal DIO is a pulse signal transferred by the shift register 123. The control signal OE is a signal for controlling the output terminal of the shift register 123. The drive time and the scanning direction are set in this way.

[0031] In the readout circuit 124, an amplifier circuit 242 that amplifies signals output in parallel from the pixels 210 arranged in the pixel region 121 is provided for each signal wiring Sig. The amplifier circuit 242 is configured to include an integral amplifier 2421, a variable amplifier 2422, and a sample-and-hold circuit 2423. The integral amplifier 2421 amplifies the signals output from the pixels 210. More specifically, the integral amplifier 2421 includes an operational amplifier that amplifies and outputs the electric signal read from the pixel 210, an integral capacitance, and a reset switch. The integral amplifier 2421 can change the amplification factor by changing the value of the integral capacitance. In addition, the signal output from the pixel 210 is input to an inverting input terminal of the operational amplifier of the integral amplifier 2421, and a reference voltage Vref is input from the reference power supply 241 to a non-inverting input terminal of the operational amplifier. In addition, the amplified signal is output from an output terminal of the operational amplifier of the integral amplifier 2421. In addition, in the integral amplifier 2421, an integral capacitance is disposed between the inverting input terminal and the output terminal of the operational amplifier. The variable amplifier 2422 amplifies the signal output from the integral amplifier 2421. The sample-and-hold circuit 2423 samples and holds the signals amplified by the integral amplifier 2421 and the variable amplifier 2422. This sample-and-hold circuit 2423 includes a sampling switch and a sampling capacitance. In addition, the readout circuit 124 is configured to include a multiplexer 243 that sequentially outputs signals read out in parallel from the amplifier circuit 242 as a serial electrical signal.

[0032] In this readout circuit 124, the operation of each component is controlled in response to control signals RC, SH, and CLK supplied from the computer 110 in Fig. 1. Specifically, the control signal RC is a signal for controlling the operation of the reset switch of the integral amplifier 2421. Furthermore, the control signal SH is a signal for controlling the operation of the sample-and-hold circuit 2423. Furthermore, the control signal CLK is a signal for controlling the operation of the multiplexer 243.

[0033] The buffer amplifier 125 performs impedance conversion on the electrical signal output from the multiplexer 243 and outputs the signal to the A / D converter 126 .

[0034] The A / D converter 126 converts the analog electrical signal output from the buffer amplifier 125 into a digital electrical signal. For example, in a drive mode in which one or more rows of pixels 210 in the pixel region 121 function as dose signal output pixels, before or during irradiation with radiation 301, a digital electrical signal (dose signal) output from the pixel 210 (dose signal output pixel) via the A / D converter 126 is supplied to, for example, the processing unit 130 in Fig. 1. Also, for example, in a drive mode in which the pixel 210 in the pixel region 121 functions as an image signal output pixel, after irradiation with radiation 301, a digital electrical signal (image signal) output from the pixel 210 (image signal output pixel) via the A / D converter 126 is supplied to, for example, the computer 110 in Fig. 1.

[0035] Next, an operation when, for example, the user operates (turns on) the exposure switch 201 and the exposure control device 200 issues a request for the radiation imaging apparatus 100 to irradiate radiation 301 will be described with reference to FIGS.

[0036] Fig. 3 is a timing chart showing an example of a processing procedure in a control method for a radiation imaging system 10 including a radiation imaging apparatus 100 according to the first embodiment of the present invention. Specifically, Fig. 3 shows, from the top, the irradiation timing of radiation 301 from the radiation source 300, the exposure (accumulation) timing of the imaging section 120, the readout timing of the main image (radiation image) of the imaging section 120, the readout timing of the dose detection lines of the imaging section 120, and the fluctuation timing of the threshold value Th and the integrated value of the dose detection lines. Here, the readout timing of the main image (radiation image) of the imaging section 120 is, for example, the timing of reading out an electrical signal (image signal) from the pixel 210 (image signal output pixel) in the case of a drive mode in which the pixel 210 of the pixel region 121 functions as an image signal output pixel. In addition, the readout timing of the dose detection line of the imaging unit 120 is, for example, the timing of reading out an electrical signal (dose signal) from the dose signal output pixel line in the case of a driving mode in which one or more rows of pixels 210 in the pixel area 121 function as dose signal output pixels.

[0037] 3 shows an example of the operation of the radiation imaging device 100 according to the first embodiment during a period when the imaging section 120 is not irradiated with radiation 301 from the radiation source 300. Specifically, in the case of a drive mode in which, for example, one or more rows of pixels 210 in the pixel region 121 are made to function as dose signal output pixels, an operation of reading out an electric signal (dose signal) from the dose signal output pixel line (dose detection line) is shown. In addition, in FIG. 3, the processing unit 130 performs a process of comparing an integrated value of the read electric signal (dose signal) with a threshold value Th. In the case of FIG. 3, since the integrated value of the electric signal of the dose detection line (dose signal output pixel line) exceeds the threshold value Th, the processing unit 130 transmits, to the irradiation control device, non-permission instruction information that does not permit irradiation of the imaging section 120 with radiation 301 from the radiation source 300. In addition, as in the example shown in Figure 3, when the integrated value of the electrical signal of the dose detection line (dose signal output pixel line) exceeds the threshold value Th, it is possible that an output abnormality is occurring in the dose detection line (dose signal output pixel line) due to, for example, deterioration over time or a breakdown caused by an impact.

[0038] Fig. 4 is a flowchart showing an example of a processing procedure in a control method for the radiation imaging apparatus 100 according to the first embodiment of the present invention. The flowchart shown in Fig. 4 starts in a state in which the imaging section 120 is not irradiated with radiation 301 from the radiation source 300 (a state before irradiation of the radiation 301).

[0039] First, in step S101, the processing unit 130 reads out an electrical signal (dose signal) from a dose signal output pixel line (dose detection line) in a driving mode in which, for example, one or more rows of pixels 210 in the pixel area 121 function as dose signal output pixels.

[0040] Subsequently, in step S102, the processing unit 130 integrates the electrical signals (dose signals) read out from the dose signal output pixel line in step S101 to calculate an integrated value.

[0041] Next, in step S103, the processing unit 130 compares the integrated value calculated in step S102 with a threshold value Th, and determines whether or not the integrated value calculated in step S102 exceeds the threshold value Th.

[0042] As a result of the determination in step S103, when the integrated value calculated in step S102 does not exceed the threshold value Th (S103 / NO), the process proceeds to step S104. In step S104, the processing unit 130 determines that no output abnormality has occurred in, for example, the dose signal output pixel line, and transmits permission instruction information to the irradiation control device 200 to permit irradiation of radiation 301 from the radiation source 300 to the imaging unit 120. When the irradiation control device 200 receives the permission instruction information from the processing unit 130, it transmits an irradiation permission command to the radiation source 300 and controls the radiation source 300 to irradiate radiation 301. After that, when the processing of step S104 ends, the processing of the flowchart in Fig. 4 may end, or the processing may return to step S101 and repeat the processing from step S101 onwards.

[0043] On the other hand, if it is determined in step S103 that the integrated value calculated in step S102 exceeds the threshold value Th (S103 / YES), the process proceeds to step S105. In step S105, the processing unit 130 determines that, for example, an output abnormality has occurred in the dose signal output pixel line, and transmits to the irradiation control device 200 disallowance instruction information for disallowing irradiation of the imaging unit 120 with the radiation 301 from the radiation source 300. When the irradiation control device 200 receives the disallowance instruction information from the processing unit 130, it transmits an irradiation disallowance command to the radiation source 300 and controls the radiation source 300 not to irradiate the radiation 301. Furthermore, since there is a possibility that appropriate radiation stop control cannot be performed due to, for example, an output abnormality has occurred in the dose signal output pixel line, in step S105, a warning is displayed on the display unit 150 indicating, for example, that appropriate dose detection cannot be performed. This allows the user to understand that appropriate radiation stop control cannot be performed because appropriate dose detection cannot be performed.

[0044] In the radiation imaging device 100 according to the first embodiment, the processing unit 130 is configured to compare the integrated value of the electrical signal output from the dose signal output pixel line (dose detection line) with a threshold value Th during a period in which the imaging unit 120 is not irradiated with radiation 301. According to this configuration, when an integrated value of an electrical signal output from a dose signal output pixel line exceeds a threshold value Th, the processing unit 130 can determine that, for example, an output abnormality has occurred in the dose signal output pixel line, and can transmit to the irradiation control device 200 disallowance instruction information for disallowing irradiation of the imaging unit 120 with the radiation 301 from the radiation source 300. This can prevent inappropriate radiation stop control from being performed. Furthermore, unnecessary radiation imaging can be prevented.

[0045] Second embodiment Next, a second embodiment of the present invention will be described. In the following description of the second embodiment, matters common to the first embodiment will be omitted, and only matters different from the first embodiment will be described.

[0046] The schematic configuration of a radiation imaging system including a radiation imaging apparatus according to the second embodiment is similar to the schematic configuration of a radiation imaging system 10 including a radiation imaging apparatus 100 according to the first embodiment shown in Fig. 1. The internal configuration of an imaging section 120 of the radiation imaging apparatus 100 according to the second embodiment is similar to the internal configuration of an imaging section 120-1 in the first embodiment shown in Fig. 2.

[0047] Specifically, the second embodiment relates to various aspects after permission to irradiate radiation 301 has been granted in step S104 of Fig. 4. The radiation imaging apparatus 100 according to the second embodiment has an automatic exposure control function (AEC function) that controls the stopping of irradiation of radiation 301.

[0048] Fig. 5 is a timing chart showing an example of a first process procedure in a control method for a radiation imaging system 10 including a radiation imaging apparatus 100 according to a second embodiment of the present invention. In Fig. 5, elements similar to those shown in Fig. 3 are given the same names, and detailed descriptions thereof will be omitted.

[0049] The timing chart shown in Fig. 5 illustrates an example of a processing procedure after "irradiation permission" of the radiation 301 is given in step S104 of Fig. 4. Specifically, when permission instruction information permitting irradiation of the radiation 301 from the radiation source 300 is transmitted from the processing unit 130 to the irradiation control device 200, the irradiation control device 200 starts irradiating the radiation 301 from the radiation source 300. Here, in this embodiment, it is assumed that the irradiation control device 200 has set a minimum irradiation time 501 and a set irradiation time 502 for radiography of the subject H as the irradiation time of the radiation 301 from the radiation source 300.

[0050] When irradiation of radiation 301 from the radiation source 300 starts, exposure for accumulating electric charge begins in each pixel 210 in the pixel region 121 of the imaging section 120. Then, the processing unit 130 reads out electric signals (dose signals) at regular time intervals from a dose detection line (dose signal output pixel line) configured of, for example, one row or a plurality of rows of pixels 210 in the pixel region 121. At this time, exposure is performed and the electric charge is reset every time an electric signal (dose signal) is read out from the dose detection line (dose signal output pixel line), so the processing unit 130 calculates an integrated value by integrating the electric signals (dose signals) of the read dose detection line (dose signal output pixel line). Hereinafter, the integrated value calculated by integrating the electric signals (dose signals) of the dose detection line (dose signal output pixel line) will be referred to as a "line integrated value."

[0051] Then, the processing unit 130 performs a process of comparing the line integrated value with a threshold value Th at regular time intervals during the period during which the imaging unit 120 is irradiated with the radiation 301 based on the transmitted permission instruction information. In the example shown in FIG. 5, when the line integrated value exceeds the threshold value Th, the processing unit 130 transmits stop instruction information for stopping the irradiation of the radiation 301 to the imaging unit 120, for example, to the irradiation control device 200 and the computer 110. Upon receiving the stop instruction information from the processing unit 130, the irradiation control device 200 transmits an irradiation stop command to the radiation source 300 to stop the irradiation of the radiation 301 from the radiation source 300. Furthermore, upon receiving the stop instruction information from the processing unit 130, the computer 110 stops the exposure operation of each pixel 210 in the pixel region 121 of the imaging unit 120. Next, the computer 110 performs an operation of reading out the electrical signals (image signals) of each pixel 210 (which may include pixels that have been caused to function as pixels of the dose detection line (dose signal output pixels)) that have been accumulated up to that point.

[0052] 5, when the line integrated value exceeds the threshold value Th, appropriate radiation stop control can be performed by stopping the irradiation of the radiation 301 to the imaging unit 120. This allows appropriate automatic exposure control (AEC) to be performed.

[0053] Here, the threshold value Th set in the processing unit 130 will be described. The threshold value Th can be set to a different value depending on the part of the subject H to be examined. For example, in a region to be imaged, such as the lung region of the subject H, which has a large amount of air, the radiation 301 tends to pass through easily, and therefore the dose of the radiation 301 reaching the pixel region 121 is large, and therefore the threshold value Th is set to a high value. Conversely, in a region to be imaged, such as the bones or organs of the subject H, which is difficult for the radiation 301 to pass through, the threshold value Th is set to a low value.

[0054] In the example shown in FIG. 5, appropriate radiation stop control is performed using the above-mentioned threshold value Th within a minimum irradiation time 501 or more and within a set irradiation time 502 selected by a radiologist according to an imaging technique, for example.

[0055] Fig. 6 is a timing chart showing an example of a second processing procedure in the control method for the radiation imaging system 10 including the radiation imaging apparatus 100 according to the second embodiment of the present invention. In Fig. 6, the same elements as those shown in Fig. 3 and Fig. 5 are given the same names, and detailed description thereof will be omitted.

[0056] The timing chart shown in FIG. 6, like that shown in FIG. 5 described above, shows an example of a processing procedure after "permission to irradiate" the radiation 301 in step S104 in FIG.

[0057] 6, when the line integrated value exceeds the threshold Th during the minimum irradiation time 501 of the radiation 301, the processing unit 130 transmits stop instruction information to, for example, the irradiation control device 200 and the computer 110 to stop irradiation of the radiation 301 to the imaging unit 120 when the minimum irradiation time 501 has elapsed. In this Fig. 6, the above-mentioned line integrated value exceeds the threshold Th in a time shorter than the set minimum irradiation time 501, but since the radiation source 300 is controlled by the irradiation control device 200, the radiation 301 irradiated from the radiation source 300 cannot be stopped. Therefore, in Fig. 6, when the minimum irradiation time 501 has elapsed, radiation stop control is performed, and further, an operation of stopping the exposure operation in each pixel 210 in the pixel region 121 of the imaging unit 120 and reading out an electrical signal (image signal) from each pixel 210 is performed. At this time, the computer 110 may perform image correction on the radiation image data generated based on the read image signals, such as decreasing the gain from the time from when the above-mentioned line integrated value exceeds the threshold value Th to when the irradiation is stopped.

[0058] Furthermore, the dose of radiation 301 is expressed as the product of the tube current of the radiation source 300 and the exposure time. For this reason, for example, an appropriate setting value of the tube current may be calculated so as to be equal to or longer than the minimum exposure time 501 based on whether or not stop instruction information is generated within the minimum exposure time 501, the time when the above-mentioned line integrated value exceeds the threshold value Th, and the currently set tube current, and displayed on the display unit 150. However, since the value of the tube current to be set varies depending on the tube voltage of the radiation source 300, the distance between the radiation source 300 and the subject H, and the presence or absence of a grid, a specific numerical value is not shown here.

[0059] Fig. 7 is a timing chart showing an example of a third process procedure in the control method for the radiation imaging system 10 including the radiation imaging apparatus 100 according to the second embodiment of the present invention. In Fig. 7, the same elements as those shown in Fig. 3 and Fig. 5 to Fig. 6 are given the same names, and detailed description thereof will be omitted.

[0060] 7. The timing chart shown in FIG. 7, like that shown in FIG. 5 described above, shows an example of a processing procedure after "permission to irradiate" the radiation 301 in step S104 in FIG.

[0061] 7, if the line integrated value does not exceed the threshold value Th after the minimum irradiation time 501 of the radiation 301 has elapsed and the line integrated value has not increased or decreased by a predetermined amount or more during a certain period 701, the processing unit 130 transmits stop instruction information to stop irradiating the imaging unit 120 with the radiation 301 to, for example, the irradiation control device 200 and the computer 110 when the certain period 701 has elapsed. Specifically, in FIG. 7, in addition to determining whether the above-mentioned line integrated value exceeds the threshold value Th, the processing unit 130 also monitors the above-mentioned increase or decrease (fluctuation) of the line integrated value.

[0062] 7, when the line integrated value does not increase or decrease by a predetermined amount within a certain period 701, even if the line integrated value does not exceed a set threshold Th, the processing unit 130 transmits stop instruction information to stop the irradiation of the radiation 301 to the irradiation control device 200 and the computer 110. As a result, when the certain period 701 has elapsed, the irradiation of the radiation 301 from the radiation source 300 is stopped, and further, the exposure operation of each pixel 210 in the pixel region 121 of the imaging unit 120 is stopped, and an operation of reading out an electrical signal (image signal) from each pixel 210 is performed.

[0063] 7, when there is no increase or decrease in the line integrated value during a certain period 701 and the irradiation of the radiation 301 is stopped when the line integrated value is equal to or less than a set threshold value Th, the radiation image data may be at a level lower than the expected threshold value, for example, when the part of the subject H to be examined contains a material that is difficult for the radiation 301 to transmit. However, by also monitoring the line integrated value, the irradiation of the radiation 301 is not continued, and inadvertent exposure of the subject H to the radiation 301 can be avoided.

[0064] Fig. 8 is a timing chart showing an example of a fourth process procedure in the control method for the radiation imaging system 10 including the radiation imaging apparatus 100 according to the second embodiment of the present invention. In Fig. 8, the same elements as those shown in Fig. 3 and Fig. 5 to Fig. 7 are given the same names, and detailed description thereof will be omitted.

[0065] The timing chart shown in FIG. 8, like that shown in FIG. 5 described above, shows an example of a processing procedure after "permission to irradiate" the radiation 301 in step S104 in FIG.

[0066] 8, if the line integrated value increases or decreases (sudden change) 800 by a predetermined amount or more within a certain period 801 after the minimum irradiation time 501 of the radiation 301 has elapsed, the processing unit 130 transmits stop instruction information to, for example, the irradiation control device 200 and the computer 110 to stop irradiating the imaging unit 120 with the radiation 301 when the certain period 801 has elapsed. Specifically, in FIG. 8, in addition to determining whether the line integrated value described above exceeds the threshold value Th, the increase or decrease (fluctuation) 800 of the line integrated value is also monitored.

[0067] 8 , when the line integrated value increases or decreases (sudden change) 800 by a predetermined amount or more within a certain period 801, the processing unit 130 transmits stop instruction information to stop the irradiation of the radiation 301 to the irradiation control device 200 and the computer 110. As a result, when the certain period 801 has elapsed, the irradiation of the radiation 301 from the radiation source 300 is stopped, and further, the exposure operation of each pixel 210 in the pixel region 121 of the imaging unit 120 is stopped, and an operation of reading out an electrical signal (image signal) from each pixel 210 is performed.

[0068] 8, when the line integrated value increases or decreases (sudden change) 800 by a predetermined amount or more during a certain period 801, control to stop the irradiation of radiation 301 is performed because a problem is expected to occur in the dose signal output pixel or a problem is expected in the irradiation control of radiation 301. In other words, this is because there is a possibility that it is undesirable to continue radiography as is. For this reason, for example, when the line integrated value increases or decreases (sudden change) 800 by a predetermined amount or more during a certain period 801 as shown in this Fig. 8, a warning to that effect may be displayed on the display unit 150 to warn the user.

[0069] Fig. 9 is a timing chart showing an example of a fifth process procedure in the control method for the radiation imaging system 10 including the radiation imaging apparatus 100 according to the second embodiment of the present invention. In Fig. 9, the same elements as those shown in Fig. 3 and Fig. 5 to Fig. 8 are given the same names and detailed description thereof will be omitted.

[0070] The timing chart shown in FIG. 9, like that shown in FIG. 5 described above, shows an example of a processing procedure after "permission to irradiate" the radiation 301 in step S104 in FIG.

[0071] 9, if the line integrated value does not exceed the threshold value Th before the set irradiation time 502 of the radiation 301 has elapsed and the line integrated value continues to increase within a predetermined range, the processing unit 130 transmits, for example, to the irradiation control device 200 and the computer 110, continuation instruction information for continuing irradiation of the imaging unit 120 with the radiation 301 until the line integrated value exceeds the threshold value Th. Specifically, in FIG. 9, in addition to determining whether the line integrated value exceeds the threshold value Th as described above, the processing unit 130 also monitors an increase or decrease (fluctuation) in the line integrated value.

[0072] 9, the line integrated value indicates an increase corresponding to the irradiation dose per unit time, but if the threshold value Th is not reached even after the set irradiation time 502 has elapsed, irradiation of the radiation 301 is continued even after the set irradiation time 502 has elapsed. Then, in the example shown in Fig. 9, if the line integrated value reaches the threshold value Th after the set irradiation time 502 has elapsed, the processing unit 130 transmits stop instruction information to stop the irradiation of the radiation 301 at that time point to the irradiation control device 200 and the computer 110. As a result, when the line integrated value reaches the threshold value Th, the irradiation of the radiation 301 from the radiation source 300 is stopped, and further, the exposure operation in each pixel 210 in the pixel region 121 of the imaging unit 120 is stopped, and an operation of reading out an electrical signal (image signal) from each pixel 210 is performed.

[0073] 9, even after the set irradiation time 502 has elapsed, irradiation of radiation 301 is continued to perform an appropriate exposure operation for each pixel 210 in the pixel region 121. In the example shown in Fig. 9, the difference between the set irradiation time 502 and the time for which radiation 301 was actually irradiated may be displayed on the display unit 150 after radiation imaging. If the actual time for which radiation 301 was irradiated is long, that is, if the imaging time is long, the acquired radiation image data may become unclear due to vibration or shaking of the subject H. For this reason, for example, an appropriate tube current setting value of the radiation source 300 may be displayed on the display unit 150 so that it can be utilized in the next radiation imaging.

[0074] Fig. 10 is a timing chart showing an example of a sixth process procedure in the control method for the radiation imaging system 10 including the radiation imaging apparatus 100 according to the second embodiment of the present invention. In Fig. 10, the same elements as those shown in Fig. 3 and Fig. 5 to Fig. 9 are given the same names, and detailed description thereof will be omitted.

[0075] The timing chart shown in FIG. 10, like that shown in FIG. 5 described above, shows an example of a processing procedure after "permission to irradiate" the radiation 301 in step S104 in FIG.

[0076] 10, if the line integrated value of the radiation 301 does not exceed the threshold value Th before the set irradiation time 502 of the radiation 301 has elapsed, the processing unit 130 transmits stop instruction information to, for example, the irradiation control device 200 and the computer 110 to stop the irradiation of the radiation 301 to the imaging unit 120 when the set irradiation time 502 has elapsed. As a result, when the set irradiation time 502 has elapsed, the irradiation of the radiation 301 from the radiation source 300 is stopped, and further, an operation of reading out an electrical signal (image signal) from each pixel 210 is performed after stopping the exposure operation in each pixel 210 in the pixel region 121 of the imaging unit 120. In the example shown in FIG. 10, since the line integrated value of the radiation 301 does not exceed the threshold value Th before the set irradiation time 502 of the radiation 301 has elapsed, the computer 110 performs gain correction on the acquired radiation image data. In addition, when the gain correction is performed after radiation imaging, the corrected sensitivity and dB may be displayed on the display unit 150.

[0077] As shown in FIG. 10, the irradiation of the radiation 301 is limited by the set irradiation time 502 when, for example, it is desired to limit the amount of radiation 301 to which the subject H is exposed.

[0078] In the second embodiment described with reference to FIGS. 5 to 10, the display unit 150 may display, for example, a predetermined tube current setting value of the radiation source 300, which is calculated from the actual irradiation time for irradiating the radiation 301.

[0079] According to the second embodiment described above, in addition to the effects of the first embodiment described above, appropriate radiation shutdown control can be performed.

[0080] (Third embodiment) Next, a third embodiment of the present invention will be described. In the following description of the third embodiment, matters common to the first and second embodiments will be omitted, and only matters different from the first and second embodiments will be described.

[0081] The schematic configuration of a radiation imaging system including the radiation imaging apparatus according to the third embodiment is similar to the schematic configuration of the radiation imaging system 10 including the radiation imaging apparatus 100 according to the first embodiment shown in FIG.

[0082] Fig. 11 shows a third embodiment of the present invention, and is a diagram showing an example of the internal configuration of the imaging unit 120 shown in Fig. 1. Hereinafter, the imaging unit 120 in the third embodiment shown in Fig. 11 will be referred to as "imaging unit 120-3." In Fig. 11, the same components as those shown in Fig. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0083] As shown in FIG. 11, the imaging section 120-3 includes a pixel area 621, a bias power supply 122, a shift register 623 which is a drive circuit, a readout circuit 124, a buffer amplifier 125, and an A / D converter 126.

[0084] In the above-mentioned first and second embodiments, as shown in Fig. 2, the same pixel 210 is driven at different timings to function as a dose signal output pixel and an image signal output pixel. In contrast, in the third embodiment, the dose signal output pixel and the image signal output pixel are configured as different pixels in a pixel region 621 shown in Fig. 11.

[0085] 11, among the multiple pixels 210 arranged in the pixel region 621, the pixel 210-23 connected to the drive wiring Vg(d1) and the pixel 210-43 connected to the drive wiring Vg(d2) are radiation amount signal output pixels. Also, among the multiple pixels 210 arranged in the pixel region 621, the pixels 210 connected to the drive wirings Vg(1) to Vg(5) are image signal output pixels.

[0086] When the third embodiment is applied to the first embodiment, the processing unit 130 performs a process of comparing an integrated value of electrical signals (dose signals) output from, for example, the dose signal output pixels 210-23 and 210-43 of the imaging unit 120-3 with a threshold value Th during a period in which the imaging unit 120-3 is not irradiated with radiation 301 from the radiation source 300. Thereafter, in the third embodiment, when the integrated value exceeds the threshold value Th, the processing unit 130 transmits to the irradiation control device 200 disallowance instruction information for disallowing irradiation of the imaging unit 120-3 with radiation 301 from the radiation source 300. Then, when the irradiation control device 200 receives the disallowance instruction information from the processing unit 130, it transmits an irradiation disallowance command to the radiation source 300 and controls the radiation source 300 not to irradiate radiation 301. On the other hand, in the third embodiment, when the integrated value does not exceed the threshold value Th, the processing unit 130 transmits permission instruction information to the irradiation control device 200 to permit irradiation of the imaging unit 120-3 with radiation 301 from the radiation source 300. When the irradiation control device 200 receives the permission instruction information from the processing unit 130, it transmits an irradiation permission command to the radiation source 300 and controls the radiation source 300 to irradiate radiation 301.

[0087] Furthermore, when the third embodiment is applied to the second embodiment, the processing unit 130 performs a process of comparing, for example, an integrated value of the electric signals (dose signals) output from the dose signal output pixels 210-23 and 210-43 of the imaging unit 120-3 with a threshold value Th at regular time intervals during a period in which the imaging unit 120-3 is irradiated with radiation 301 based on the transmitted permission instruction information. Furthermore, when the third embodiment is applied to the second embodiment described using Figures 5 to 10, the integrated value of the electric signals (dose signals) output from the dose signal output pixels 210-23 and 210-43 may be applied instead of the line integrated value in the second embodiment.

[0088] In addition, in the example shown in FIG. 11, one dose signal output pixel 210 is connected to each of the drive wiring Vg(d1) and the drive wiring Vg(d2), but multiple dose signal output pixels 210 may be connected to each of them.

[0089] In addition, in the example shown in FIG. 11, the shift register 623 is configured to drive the pixels 210 connected to the drive wirings Vg(1) to Vg(5) and the drive wirings Vg(d1) to Vg(d2) at different drive timings.

[0090] In the third embodiment, as in the first embodiment, it is possible to avoid inappropriate radiation stop control. Furthermore, in the third embodiment, as in the second embodiment, it is possible to perform appropriate radiation stop control.

[0091] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. This program and a computer-readable storage medium storing the program are included in the present invention.

[0092] It should be noted that the above-mentioned embodiments of the present invention are merely illustrative examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0093] 10: radiation imaging system, 100: radiation imaging device, 110: computer, 120: imaging section, 130: processing section, 140: input section, 150: display section, 200: irradiation control device, 201: irradiation switch, 300: radiation source, 301: radiation, H: subject

Claims

1. A radiation imaging device that performs imaging using radiation, an imaging unit configured to include dose signal output pixels that output electrical signals based on the dose of the incident radiation; a processing unit that performs processing to compare an integrated value of the electrical signal output from the dose signal output pixel with a threshold value; and the processing unit performs, based on an instruction to permit the irradiation of radiation, a process of comparing the integrated value of the electrical signals output from the dose signal output pixels during a period when the radiation is not being irradiated with the threshold value, and a process of comparing the integrated value of the electrical signals output from the dose signal output pixels during a period when the radiation is being irradiated with the threshold value, and if the integrated value does not exceed the threshold value after a minimum irradiation time has elapsed, issues an instruction to stop the irradiation of the radiation to the imaging unit.

2. 2. The radiation imaging apparatus according to claim 1, further comprising a display unit that displays a warning when the processing unit issues the stop instruction.

3. 2. The radiation imaging device according to claim 1, wherein the processing unit issues a stop instruction to stop irradiating the imaging unit with the radiation if the integrated value increases or decreases by a predetermined amount or more over a certain period after the minimum irradiation time of the radiation has elapsed.

4. the imaging unit is configured to include a plurality of the dose signal output pixels, 4. The radiation imaging apparatus according to claim 1, wherein the processing unit uses, as the integrated value, an integrated value of the electrical signals output from the plurality of dose signal output pixels.

5. The radiation imaging device according to any one of claims 1 to 4, an irradiation control device that controls the irradiation of the radiation from the radiation source; A radiation imaging system comprising:

Images