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

[0004] , , ,

[0001] The present invention relates to a radiation imaging apparatus that performs imaging using radiation, and a radiation imaging system configured to include the radiation imaging apparatus. Placement, and

Background Art

[0002] Radiation imaging apparatuses provided 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 apparatuses that can perform imaging in a plurality of imaging modes according to the purpose, such as still image shooting and moving image shooting, have been studied. In addition, radiation imaging apparatuses that can perform automatic exposure control (Automatic Exposure Control: AEC) by detecting the integrated irradiation amount of radiation that has passed through a subject and stopping the irradiation of radiation by a radiation source when the detected integrated irradiation amount reaches an appropriate amount have also been studied.

[0003] Patent Document 1 discloses an example of a radiation image imaging apparatus that performs radiation detection based on the difference between an electrical signal corresponding to the charge generated in a sensor unit for radiation detection and flowing through a first wiring and an electrical signal flowing through a second wiring having substantially the same wiring pattern as the first wiring, so that even when noise occurs due to disturbance factors or the like, radiation can be detected accurately while suppressing the influence of the noise. And Patent Document 2 discloses an example of a radiation imaging system that accurately performs radiation stop control and prevents reshooting due to insufficient dose by converting a signal indicating the dose of radiation detected by a detection means into a signal indicating a dose less than the dose of radiation represented by the signal when the occurrence of disturbance noise is detected in the signal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, in the conventional technology, including Patent Document 2, there is a possibility that inappropriate radiation shutdown control may occur due to, for example, aging deterioration or failure of the radiation dose detection device due to impact.

[0006] This invention has been made in view of these problems, and aims to provide a mechanism that can avoid inappropriate radiation shutdown control. [Means for solving the problem]

[0007] The present invention relates to a radiation imaging apparatus that performs imaging using radiation, comprising an imaging unit configured to include a dose signal output pixel that outputs an electrical signal based on the dose of the incident radiation, and ,before It includes a processing unit that performs a process of comparing the integrated value of the electrical signal output from the recorded dose signal output pixel with a threshold value. The processing unit, based on the permission instruction to permit irradiation of the radiation, performs the following processes: comparing the integrated value of the electrical signal output from the dose signal output pixel during the period when the radiation is not being irradiated with the threshold value; and comparing the integrated value of the electrical signal output from the dose signal output pixel during the period when the radiation is being irradiated with the threshold value. If the integrated value does not exceed the threshold value after the minimum irradiation time has elapsed, the processing unit issues a stop instruction to stop the irradiation of the radiation to the imaging unit. . [Effects of the Invention]

[0008] According to the present invention, it is possible to avoid inappropriate radiation shutdown control. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a schematic configuration of a radiation imaging system including a radiation imaging device according to the first embodiment of the present invention. [Figure 2] This figure shows an example of the internal configuration of the imaging unit shown in Figure 1, illustrating a first embodiment of the present invention. [Figure 3] This is a timing chart showing an example of a processing procedure in a control method for a radiation imaging system including a radiation imaging device according to a first embodiment of the present invention. [Figure 4]This flowchart shows an example of a processing procedure in a control method for a radiation imaging device according to the first embodiment of the present invention. [Figure 5] This is a timing chart showing an example of a first processing step in a control method for a radiation imaging system including a radiation imaging device according to a second embodiment of the present invention. [Figure 6] This is a timing chart showing an example of a second processing step in a control method for a radiation imaging system including a radiation imaging device according to a second embodiment of the present invention. [Figure 7] This is a timing chart showing an example of a third processing step in a control method for a radiation imaging system including a radiation imaging device according to a second embodiment of the present invention. [Figure 8] This is a timing chart showing an example of a fourth processing step in a control method for a radiation imaging system including a radiation imaging device according to a second embodiment of the present invention. [Figure 9] This is a timing chart showing an example of a fifth processing step in a control method for a radiation imaging system including a radiation imaging device according to a second embodiment of the present invention. [Figure 10] This is a timing chart showing an example of a sixth processing step in a control method for a radiation imaging system including a radiation imaging device according to a second embodiment of the present invention. [Figure 11] This figure shows a third embodiment of the present invention, illustrating an example of the internal configuration of the imaging unit shown in Figure 1. [Modes for carrying out the invention]

[0010] The embodiments for carrying out the present invention will be described below with reference to the drawings. In the embodiments of the present invention described below, radiation includes alpha rays, beta rays, and gamma rays, which are beams created by particles (including photons) emitted by radioactive decay, as well as beams with energy of equal or greater energy, such as X-rays, particle beams, and cosmic rays.

[0011] (First Embodiment) First, the 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 apparatus 100 according to the first embodiment of the present invention. As shown in FIG. 1, the radiation imaging system 10 includes a radiation imaging apparatus 100, an irradiation control apparatus 200, and a radiation source 300. This radiation imaging system 10 is configured to electrically image 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 apparatus 200. The radiation 301 emitted from the radiation source 300 enters the radiation imaging apparatus 100 through the subject H. Further, the radiation source 300 stops irradiating the radiation 301 in accordance with an irradiation stop command from the irradiation control apparatus 200.

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

[0015] The radiation imaging apparatus 100 is an apparatus that images a subject H using radiation 301. This 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, this radiation imaging apparatus 100 includes a computer 110, an imaging unit 120, a processing unit and an input unit 140, and a display unit 150.

[0016] Radiation 301 emitted from the radiation source 300 (including radiation 301 that has passed through the subject H) is incident on the imaging unit 120. The imaging unit 120 is configured to include a plurality of image signal output pixels that output image signals related to radiation images, and a plurality of dose signal output pixels that output dose signals, which are electrical signals based on the irradiation dose of the incident radiation 301. In this embodiment, an example in which pixels are used as the configuration for outputting dose signals is 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 this embodiment, the processing unit 130 compares the integrated value of the electrical signal (dose signal) output from the dose signal output pixel of the imaging unit 120 with a threshold value during periods when the imaging unit 120 is not irradiated with radiation 301 from the radiation source 300. Subsequently, in this embodiment, if the integrated value exceeds the threshold value, the processing unit 130 transmits a disallowance instruction to the irradiation control device 200, which prohibits irradiation of the imaging unit 120 with radiation 301 from the radiation source 300. When the irradiation control device 200 receives the disallowance instruction from the processing unit 130, it transmits an irradiation disallowance command to the radiation source 300, controlling it so that radiation 301 is not irradiated from the radiation source 300. On the other hand, in this embodiment, if the integrated value does not exceed the threshold value, the processing unit 130 transmits an permission instruction to the irradiation control device 200, which permits irradiation of the imaging unit 120 with radiation 301 from the radiation source 300. When the irradiation control device 200 receives permission instruction information from the processing unit 130, it sends an irradiation permission command to the radiation source 300 and controls the radiation source 300 to irradiate with radiation 301.

[0018] This processing unit 130 may be configured, for example, by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a general-purpose computer with a program installed. Alternatively, the processing unit 130 may be configured by a combination of all or some of these.

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

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

[0021] The display unit 150 displays various information and images based on the control of the computer 110. For example, if the processing unit 130 transmits a disallowance instruction to the irradiation control device 200, the display unit 150 displays a warning indicating that fact. 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 Figure 1 will be described. Figure 2 shows a first embodiment of the present invention and illustrates an example of the internal configuration of the imaging unit 120 shown in Figure 1. Hereinafter, the imaging unit 120 in this first embodiment shown in Figure 2 will be referred to as "imaging unit 120-1".

[0023] As shown in Figure 2, the imaging unit 120-1 is configured to include a pixel area 121, a bias power supply 122, a drive circuit consisting of a shift register 123, a readout circuit 124, a buffer amplifier 125, and an A / D converter 126.

[0024] The pixel region 121 is constructed, for example, by arranging multiple pixels 210 in a matrix on an insulating substrate. In the example shown in Figure 2, for the sake of simplicity, a pixel region 121 with 5 rows x 5 columns of pixels 210 (specifically, pixels 210-11 to 210-55 shown in Figure 2) is shown, but an actual pixel region 121 will have many more pixels 210. For example, a 17-inch FPD may have approximately 2800 rows x 2800 columns of pixels 210.

[0025] Each pixel 210 is composed of a conversion element S that converts incident radiation 301 into electric charge, and a switch element T that outputs an electrical signal corresponding to the charge generated by the conversion element S. In the example shown in Figure 2, the conversion element S contained in the first row, first column pixel 210-11 is described as "conversion element S11", and the switch element T contained in the first row, first column pixel 210-11 is described as "switch element T11". Now, generalizing the example shown in Figure 2 using arbitrary natural numbers m and n, the conversion element S contained in the m row, n column pixel 210-mn is described as "conversion element Smn", and the switch element T contained in the m row, n column pixel 210-mn is described as "switch element Tmn".

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

[0027] The switching element T may be, for example, a transistor having a control terminal and two main terminals. In this embodiment, the switching element T may be a thin-film transistor (TFT).

[0028] One electrode of the conversion element S is electrically connected to one of the two main terminals of the switch element T, and the other electrode of the conversion element S is electrically connected to the bias power supply 122 via a common bias wire. The switch elements T arranged in the row direction (horizontal direction in Figure 2), for example, the switch elements T11 to T15 in the first row, have their control terminals electrically connected in common to the drive wire Vg(1). These switch elements T11 to T15 are supplied with a drive signal from the shift register 123 via the drive wire Vg(1) to control the conduction state of the switch elements T11 to T15. In addition, the switch elements T arranged in the column direction (vertical direction in Figure 2), for example, the switch elements T11 to T51 in the first column, have their other main terminals electrically connected to the signal wire Sig1. While the switch elements T11 to T51 are in a conduction state, a signal corresponding to the charge accumulated in the conversion element S is output to the readout circuit 124 via the signal wire Sig1. The signal wirings Sig1 to Sig5, arranged in a column direction, transmit signals output from the pixel 210 connected to the same drive wiring Vg to the readout circuit 124 in parallel.

[0029] In this embodiment shown in Figure 2, the dose signal output pixels and image signal output pixels included in the imaging unit 120 may be configured as the same pixel 210 in the pixel area 121 of the imaging unit 120-1. In this case, the computer 110 in Figure 1 controls the shift register 123 to make the timing of driving the pixel 210 different from that of the other, thereby causing the pixel to function as either a dose signal output pixel or an image signal output pixel. For example, the computer 110 in Figure 1 may select either a first driving mode in which the pixel 210 functions as a dose signal output pixel, or a second driving mode in which the pixel 210 functions as an image signal output pixel, based on information from the input unit 140. Here, we will describe how the computer 110 in Figure 1 performs various controls on the internal configuration of the imaging unit 120, but this embodiment is not limited to this embodiment, and the methods performed by the processing unit 130 in Figure 1 are also applicable to this embodiment.

[0030] The shift register 123 outputs a drive signal to the respective drive wiring Vg, which includes a conduction voltage Vcom to make the switch element T conduct and a non-conduction voltage Vss to make it non-conductive, in response to the control signals D-CLK, DIO, and OE supplied from the computer 110 in Figure 1. In this way, the shift register 123 controls the conduction and non-conduction states of the switch element T and drives each pixel 210 of the pixel region 121. Specifically, the control signal D-CLK is the 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 that controls the output terminal of the shift register 123. The drive time and scanning direction are set accordingly.

[0031] The readout circuit 124 includes an amplification circuit 242 for each signal line Sig, which amplifies the signals output in parallel from the pixels 210 located in the pixel region 121. The amplification circuit 242 comprises 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, an integral capacitor, and a reset switch that amplify and output the electrical signals read from the pixels 210. The amplification factor of the integral amplifier 2421 can be changed by changing the value of the integral capacitor. The signal output from the pixels 210 is input to the inverting input terminal of the operational amplifier of the integral amplifier 2421, and the reference voltage Vref from the reference power supply 241 is input to the forward input terminal of the operational amplifier of the integral amplifier 2421. The amplified signal is output from the output terminal of the operational amplifier of the integral amplifier 2421. Furthermore, in the integrating amplifier 2421, the integrating capacitor is positioned between the inverting input terminal and the output terminal of the operational amplifier. The variable amplifier 2422 amplifies the signal output from the integrating amplifier 2421. The sample-and-hold circuit 2423 samples and holds the signals amplified by the integrating amplifier 2421 and the variable amplifier 2422. This sample-and-hold circuit 2423 includes a sampling switch and a sampling capacitor. The readout circuit 124 also includes a multiplexer 243 that sequentially outputs the signals read out in parallel from the amplification circuit 242 as a series electrical signal.

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

[0033] The buffer amplifier 125 converts the impedance of the electrical signal output from the multiplexer 243 and outputs it 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 area 121 function as dose signal output pixels, the digital electrical signal (dose signal) output from the pixel 210 (dose signal output pixel) via the A / D converter 126 before or during irradiation with radiation 301 is supplied to the processing unit 130 in Figure 1, for example. Also, for example, in a drive mode in which the pixels 210 of the pixel area 121 function as image signal output pixels, the digital electrical signal (image signal) output from the pixel 210 (image signal output pixel) via the A / D converter 126 after irradiation with radiation 301 is supplied to the computer 110 in Figure 1, for example.

[0035] Next, we will explain, using Figures 3 and 4, the operation when, for example, the irradiation switch 201 is operated (turned on) by the user and the irradiation control device 200 requests the radiation imaging device 100 to irradiate with radiation 301.

[0036] Figure 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 device 100 according to a first embodiment of the present invention. Specifically, Figure 3 shows, from top to bottom, the irradiation timing of radiation 301 from the radiation source 300, the exposure (accumulation) timing of the imaging unit 120, the readout timing of the main image (radiation image) from the imaging unit 120, the readout timing of the dose detection line from the imaging unit 120, and the timing of the change in the threshold Th and the integrated value of the dose detection line. Here, the readout timing of the main image (radiation image) from the imaging unit 120 is, for example, the timing at which an electrical signal (image signal) is read out from the pixel 210 (image signal output pixel) in a drive mode in which the pixel 210 of the pixel region 121 functions as an image signal output pixel. Furthermore, the readout timing of the dose detection line of the imaging unit 120 is, for example, the timing at which an electrical signal (dose signal) is read out from the dose signal output pixel line in a drive mode in which a certain row or a certain number of rows of pixels 210 in the pixel area 121 are to function as dose signal output pixels.

[0037] Here, Figure 3 shows an example of the operation of the radiation imaging device 100 according to the first embodiment during a period when the imaging unit 120 is not irradiated with radiation 301 from the radiation source 300. Specifically, Figure 3 shows the operation of reading an electrical signal (dose signal) from the dose signal output pixel line (dose detection line) in a drive mode in which, for example, one or more rows of pixels 210 in the pixel area 121 are used as dose signal output pixels. In Figure 3, the processing unit 130 performs a process of comparing the integrated value obtained by accumulating the read electrical signal (dose signal) with a threshold Th. In the case of Figure 3, since the integrated value of the electrical signal on the dose detection line (dose signal output pixel line) exceeds the threshold Th, the processing unit 130 transmits a disallowance instruction to the irradiation control device, which disallows irradiation of the imaging unit 120 with radiation 301 from the radiation source 300. Furthermore, as shown in the example in Figure 3, if the integrated value of the electrical signal from the dose detection line (dose signal output pixel line) exceeds the threshold Th, it is possible that an output abnormality is occurring due to, for example, a malfunction in the dose detection line (dose signal output pixel line) caused by aging or impact.

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

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

[0040] Next, in step S102, the processing unit 130 calculates an integrated value by integrating the electrical signals (dose signals) read from the dose signal output pixel line in step S101.

[0041] Next, in step S103, the processing unit 130 compares the integrated value calculated in step S102 with the threshold Th and determines whether the integrated value calculated in step S102 exceeds the threshold Th.

[0042] If, as a result of the judgment in step S103, the cumulative value calculated in step S102 does not exceed the threshold Th (S103 / NO), proceed to step S104. When the process proceeds to step S104, the processing unit 130 determines, for example, that there is no output abnormality in the dose signal output pixel line, and transmits permission instruction information to the irradiation control device 200 to permit the irradiation of the imaging unit 120 with radiation 301 from the radiation source 300. When the irradiation control device 200 receives permission instruction information from the processing unit 130, it transmits an irradiation permission command to the radiation source 300 and controls it to irradiate with radiation 301 from the radiation source 300. After the processing of step S104 is completed, the process of the flowchart in Figure 4 may be terminated, or the process may be returned to step S101 and the processing from step S101 onwards may be repeated.

[0043] On the other hand, if the result of the judgment in step S103 is that the cumulative value calculated in step S102 exceeds the threshold Th (S103 / YES), proceed to step S105. When the system proceeds to step S105, the processing unit 130 determines, for example, that an output abnormality has occurred in the dose signal output pixel line, and transmits a disallowance instruction to the irradiation control device 200, which prohibits irradiation of the imaging unit 120 with radiation 301 from the radiation source 300. When the irradiation control device 200 receives the disallowance instruction from the processing unit 130, it transmits an irradiation disallowance command to the radiation source 300, controlling it so that radiation 301 is not irradiated from the radiation source 300. In addition, for example, because an output abnormality has occurred in the dose signal output pixel line, which may prevent proper radiation stop control, in step S105, the display unit 150 displays a warning, for example, that proper dose detection cannot be performed. This allows the user to understand that proper radiation stop control cannot be performed because proper dose detection cannot be performed.

[0044] In the radiation imaging apparatus 100 according to the first embodiment, the processing unit 130 compares the integrated value of the electrical signal output from the dose signal output pixel line (dose detection line) with a threshold Th during periods when the imaging unit 120 is not irradiated with radiation 301. With this configuration, the processing unit 130 can determine, for example, that an output abnormality has occurred in the dose signal output pixel line if the integrated value of the electrical signal output from the dose signal output pixel line exceeds a threshold Th, and can transmit a disallowance instruction to the irradiation control device 200, which prohibits the irradiation of the imaging unit 120 with radiation 301 from the radiation source 300. This prevents inappropriate radiation shutdown control. Furthermore, it prevents unnecessary radiation imaging.

[0045] (Second embodiment) Next, a second embodiment of the present invention will be described. In the description of the second embodiment below, matters common to the first embodiment described above will be omitted, and matters that differ from the first embodiment described above will be described.

[0046] The schematic configuration of the radiation imaging system including the radiation imaging device according to the second embodiment is the same as the schematic configuration of the radiation imaging system 10 including the radiation imaging device 100 according to the first embodiment shown in Figure 1. Furthermore, the internal configuration of the imaging unit 120 of the radiation imaging device 100 according to the second embodiment is the same as the internal configuration of the imaging unit 120-1 in the first embodiment shown in Figure 2.

[0047] Specifically, the second embodiment relates to various configurations after permission for irradiation with radiation 301 is granted in step S104 of Figure 4. The radiation imaging device 100 according to this second embodiment has an automatic exposure control (AEC) function that controls the stopping of irradiation with radiation 301.

[0048] Figure 5 is a timing chart showing an example of a first processing step in a control method for a radiation imaging system 10 including a radiation imaging device 100 according to a second embodiment of the present invention. In Figure 5, elements similar to those shown in Figure 3 are given the same names, and their detailed explanations are omitted.

[0049] The timing chart shown in Figure 5 illustrates an example of the processing procedure after "permission for irradiation" of radiation 301 is given in step S104 of Figure 4, as shown in Figure 5. Specifically, when permission instruction information for irradiation of 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 irradiation of radiation 301 from the radiation source 300. In this embodiment, the irradiation control device 200 is assumed to have set the minimum irradiation time 501 and the set irradiation time 502 for radiography of the subject H as the irradiation time of radiation 301 from the radiation source 300.

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

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

[0052] As shown in Figure 5, when the line cumulative value exceeds the threshold Th, the irradiation of radiation 301 to the imaging unit 120 is stopped, thereby enabling appropriate radiation stop control. This allows for appropriate automatic exposure control (AEC).

[0053] Here, we will explain the threshold Th set in the processing unit 130. The threshold Th can be set to a different value depending on the part of the subject H being examined. For example, in areas with a large amount of air, such as the lungs of subject H, radiation 301 tends to pass through easily, resulting in a higher dose of radiation 301 reaching the pixel area 121. Therefore, the threshold Th to be set will be a high value. Conversely, in areas of subject H that do not easily transmit radiation 301, such as bones or organs, the threshold Th to be set will be a low value.

[0054] In the example shown in Figure 5, appropriate radiation shutdown control using the threshold Th described above is implemented within a minimum irradiation time of 501 or more, and within a set irradiation time of 502, for example, selected by the radiologic technologist according to the imaging procedure.

[0055] Figure 6 is a timing chart showing an example of a second processing step in a control method for a radiation imaging system 10 including a radiation imaging device 100 according to a second embodiment of the present invention. In Figure 6, elements similar to those shown in Figures 3 and 5 are given the same names, and their detailed explanations are omitted.

[0056] The timing chart shown in Figure 6, similar to Figure 5 above, illustrates an example of the processing procedure after "permission for irradiation" of radiation 301 is given in step S104 of Figure 4.

[0057] In Figure 6, if the line integration value exceeds the threshold Th within the minimum irradiation time 501 of the radiation 301, the processing unit 130 sends stop instruction information to, for example, the irradiation control device 200 and the computer 110 to stop the irradiation of radiation 301 to the imaging unit 120 when the minimum irradiation time 501 has elapsed. In Figure 6, the line integration value exceeds the threshold Th in a time shorter than the set minimum irradiation time 501, but because 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 Figure 6, when the minimum irradiation time 501 has elapsed, radiation stop control is performed, and further, the exposure operation at each pixel 210 of the pixel area 121 of the imaging unit 120 is stopped, and then electrical signals (image signals) are read from each pixel 210. In this case, the computer 110 may perform image correction on the radiation image data generated based on the read-out image signal, such that the gain is reduced from the time from when the line integration value described above exceeds the threshold Th to the time when 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 irradiation time. For this reason, for example, an appropriate setting value for the tube current may be calculated from whether or not stop instruction information is generated within the minimum irradiation time 501, the time at which the line integrated value described above exceeds the threshold Th, and the currently set tube current, and displayed on the display unit 150 so that the irradiation time is 501 or longer. However, the value of the tube current to be set will change 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, so specific numerical values ​​will not be shown here.

[0059] Figure 7 is a timing chart showing an example of a third processing step in a control method for a radiation imaging system 10 including a radiation imaging device 100 according to a second embodiment of the present invention. In Figure 7, elements similar to those shown in Figures 3 and 5 to 6 are given the same names, and their detailed explanations are omitted.

[0060] The timing chart shown in Figure 7, similar to Figure 5 described above, shows an example of the processing procedure after "permission for irradiation" of radiation 301 is given in step S104 of Figure 4.

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

[0062] In the example shown in Figure 7, the processing unit 130 transmits a stop instruction to the irradiation control device 200 and the computer 110 to stop the irradiation of radiation 301, even if it does not exceed a set threshold Th, if the line integrated value has not increased or decreased by more than a predetermined amount for a certain period 701. As a result, when a certain period 701 has elapsed, the irradiation of radiation 301 from the radiation source 300 is stopped, and furthermore, the exposure operation in each pixel 210 of the pixel area 121 of the imaging unit 120 is stopped, and electrical signals (image signals) are read from each pixel 210.

[0063] As shown in Figure 7, the process of stopping radiation 301 irradiation when the line cumulative value remains unchanged for a certain period and falls below a set threshold Th may result in radiation image data at a lower level than the expected threshold, for example, if the area of ​​the subject H being examined contains a substance that does not easily penetrate radiation 301. However, by monitoring the line cumulative value, it is possible to avoid unintentional exposure of the subject H to radiation 301 without continuing the irradiation.

[0064] Figure 8 is a timing chart showing an example of a fourth processing step in a control method for a radiation imaging system 10 including a radiation imaging device 100 according to a second embodiment of the present invention. In Figure 8, elements similar to those shown in Figures 3 and 5 to 7 are given the same names, and their detailed explanations are omitted.

[0065] The timing chart shown in Figure 8, similar to Figure 5 described above, shows an example of the processing procedure after "permission for irradiation" of radiation 301 is given in step S104 of Figure 4.

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

[0067] In the example shown in Figure 8, the processing unit 130 transmits stop instruction information to the irradiation control device 200 and the computer 110 to stop the irradiation of radiation 301 if the line integrated value increases or decreases by more than a predetermined amount (rapid change) 800 over a certain period 801. As a result, when a certain period 801 has elapsed, the irradiation of radiation 301 from the radiation source 300 is stopped, and furthermore, the exposure operation at each pixel 210 of the pixel area 121 of the imaging unit 120 is stopped, and electrical signals (image signals) are read from each pixel 210.

[0068] As shown in Figure 8, if the line integrated value increases or decreases (changes rapidly) by more than a predetermined amount over a certain period of time, the radiation 301 irradiation stop control is performed because a malfunction in the dose signal output pixel or a malfunction in the radiation 301 irradiation control is expected. In other words, it may not be desirable to continue the radiation imaging as is. For this reason, for example, as shown in Figure 8, if the line integrated value increases or decreases (changes rapidly) by more than a predetermined amount over a certain period of time, a warning may be displayed on the display unit 150 to warn the user.

[0069] Figure 9 is a timing chart showing an example of a fifth processing step in a control method for a radiation imaging system 10 including a radiation imaging device 100 according to a second embodiment of the present invention. In Figure 9, elements similar to those shown in Figures 3 and 5 to 8 are given the same names, and their detailed explanations are omitted.

[0070] The timing chart shown in Figure 9, similar to Figure 5 described above, shows an example of the processing procedure after "permission for irradiation" of radiation 301 is given in step S104 of Figure 4.

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

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

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

[0074] Figure 10 is a timing chart showing an example of a sixth processing step in a control method for a radiation imaging system 10 including a radiation imaging device 100 according to a second embodiment of the present invention. In Figure 10, elements similar to those shown in Figures 3 and 5 to 9 are given the same names, and their detailed explanations are omitted.

[0075] The timing chart shown in Figure 10, similar to Figure 5 described above, shows an example of the processing procedure after "permission for irradiation" of radiation 301 is given in step S104 of Figure 4.

[0076] In Figure 10, the processing unit 130, if the line integrated value of the radiation 301 does not exceed the threshold Th before the set irradiation time 502 has elapsed, 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 radiation 301 from the radiation source 300 is stopped, and furthermore, the exposure operation at each pixel 210 of the pixel area 121 of the imaging unit 120 is stopped, and electrical signals (image signals) are read from each pixel 210. In the example shown in Figure 10, since the line integrated value of the radiation 301 did not exceed the threshold Th before the set irradiation time 502 had elapsed, the computer 110 performs gain correction on the acquired radiation image data. If 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 Figure 10, limiting the irradiation of radiation 301 at a set irradiation time of 502 is done, for example, when it is desired to limit the amount of radiation 301 exposed to subject H.

[0078] Furthermore, in the second embodiment described with reference to Figures 5 to 10, the display unit 150 may display, for example, a predetermined tube current setting value of the radiation source 300 calculated from the actual irradiation time related to the irradiation of 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 description of the third embodiment below, matters common to the first and second embodiments described above will be omitted, and matters that differ from the first and second embodiments described above will be explained.

[0081] The schematic configuration of the radiation imaging system including the radiation imaging device according to the third embodiment is similar to the schematic configuration of the radiation imaging system 10 including the radiation imaging device 100 according to the first embodiment shown in Figure 1.

[0082] Figure 11 shows a third embodiment of the present invention and illustrates an example of the internal configuration of the imaging unit 120 shown in Figure 1. Hereinafter, the imaging unit 120 in this third embodiment shown in Figure 11 will be referred to as "imaging unit 120-3". In Figure 11, components similar to those shown in Figure 2 are denoted by the same reference numerals, and their detailed explanations are omitted.

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

[0084] As shown in Figure 2, the first and second embodiments described above were configured to make the same pixel 210 function as a dose signal output pixel and an image signal output pixel by making the timing of their driving different from each other. In contrast, the third embodiment is configured in which the dose signal output pixel and the image signal output pixel are different pixels in the pixel region 621 shown in Figure 11.

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

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

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

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

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

[0090] In the third embodiment, as in the first embodiment described above, it is possible to avoid inappropriate radiation shutdown control. Furthermore, in the third embodiment, as in the second embodiment described above, appropriate radiation shutdown control can be performed.

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

[0092] The embodiments of the present invention described above are merely examples of how the invention can be implemented, and the technical scope of the invention should not be interpreted as being limited by them. In other words, the present invention can be implemented in various forms without departing from its technical concept or its main features. [Explanation of Symbols]

[0093] 10: Radiation imaging system, 100: Radiation imaging device, 110: Computer, 120: Imaging unit, 130: Processing unit, 140: Input unit, 150: Display unit, 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 comprising a dose signal output pixel that outputs an electrical signal based on the dose of the incident radiation, A processing unit that performs a comparison between the integrated value of the electrical signal output from the dose signal output pixel and a threshold value, It has, The processing unit, based on a permission instruction to permit irradiation of the radiation, performs the following processes: comparing the integrated value of the electrical signal output from the dose signal output pixel during a period when the radiation is not being irradiated with the threshold value; and comparing the integrated value of the electrical signal output from the dose signal output pixel 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 the minimum irradiation time has elapsed, it issues a stop instruction to stop irradiating the imaging unit with the radiation.

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

3. The radiation imaging apparatus according to claim 1, characterized in that, after the minimum radiation irradiation time has elapsed, if the accumulated value has increased or decreased by a predetermined amount over a certain period of time, the processing unit issues a stop instruction to stop the irradiation of the radiation to the imaging unit.

4. The imaging unit is configured to include a plurality of dose signal output pixels, The radiation imaging apparatus according to any one of claims 1 to 3, characterized in that the processing unit uses the integrated value of electrical signals output from the plurality of dose signal output pixels as the integrated value.

5. A radiation imaging apparatus according to any one of claims 1 to 4, An irradiation control device for controlling the irradiation of radiation in a radiation source, A radiation imaging system characterized by having the following features.

Images