Radiographic imaging apparatus, control method and program for radiographic imaging apparatus

Abstract

In a radiography system that performs radiographic imaging of a subject without synchronization with a radiation generator, the aim is to acquire correction data that allows for appropriate correction of the radiographic image. [Solution] The system includes a non-irradiation period setting unit 1216 that sets a non-irradiation period of radiation R based on the end time of irradiation in a first irradiation period of radiation R and the start time of irradiation in a second irradiation period of radiation R; a correction data acquisition period setting unit 1217 that sets a correction data acquisition period based on the start time of acquisition of correction data determined based on the end time of irradiation of radiation R and the non-irradiation period of radiation R, for acquiring correction data to correct a radiation image obtained by photographing a subject H using radiation R during a period when radiation R is not irradiated; and a correction data acquisition unit 1218 that acquires correction data using a correction image obtained from photography during the correction data acquisition period.

Description

Technical Field

[0001] The present invention relates to a radiation imaging apparatus, a control method thereof, and a program.

Background Art

[0002] There is a radiation imaging apparatus that performs fluoroscopic imaging by continuously irradiating radiation from a radiation generator without synchronization with the radiation generator. For example, in a substrate inspection apparatus that applies a substrate as a subject and inspects the substrate by radiation imaging using radiation, when the substrate as the subject flows in and is set at the imaging position while fluoroscopic imaging is being performed, radiation imaging of the substrate is performed. Then, in this substrate inspection apparatus, when the radiation imaging ends, the radiation irradiation is stopped, and the irradiation and irradiation stop of radiation (hereinafter, described as "non-irradiation" as necessary) are repeated periodically, such as when the next substrate as the subject flows in.

[0003] Patent Document 1 describes a technique of using one or more images acquired at a timing before detecting radiation exposure as offset correction images even when a radiation imaging apparatus and a radiation generator cannot be synchronized.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technique described in Patent Document 1, it is not always clear whether the acquired correction image (offset correction image) is, for example, an image acquired during a radiation non-irradiation period. Therefore, the technique described in Patent Document 1 is an insufficient technique from the viewpoint of obtaining correction data for appropriately correcting a radiation image.

[0006] This invention has been made in view of the above problems, and aims to enable the acquisition of correction data that can be used to perform appropriate corrections on a radiographic imaging device that performs radiographic imaging of a subject without synchronization with a radiation generator. [Means for solving the problem]

[0007] The present invention provides a radiography apparatus that photographs a subject using radiation irradiated from a radiation generator without synchronization with the radiation generator, comprising: a start time acquisition means for acquiring the start time of radiation irradiation; an end time acquisition means for acquiring the end time of radiation irradiation; a non-irradiation period setting means for setting a non-irradiation period of radiation based on the end time of irradiation in a first irradiation period of radiation and the start time of irradiation in a second irradiation period which is the irradiation period following the first irradiation period of radiation; a correction data acquisition period for acquiring correction data for correcting a radiographic image obtained by photographing the subject using the radiation during a period when radiation is not irradiated, comprising: an acquisition period setting means for setting the correction data acquisition period based on the start time of acquisition of the correction data determined based on the end time of radiation irradiation and the non-irradiation period of radiation; and a correction data acquisition means for acquiring the correction data using a correction image obtained from photography during the correction data acquisition period. [Effects of the Invention]

[0008] According to the present invention, in a radiography apparatus that performs radiographic imaging of a subject without synchronization with a radiation generator, it is possible to acquire correction data that allows for appropriate correction of the radiographic image. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a schematic configuration of a radiography system according to the first embodiment. [Figure 2]This figure shows an example of a schematic configuration of the radiation detection unit shown in Figure 1. [Figure 3] This flowchart shows an example of a processing procedure in the control method for a radiography apparatus according to the first embodiment. [Figure 4] This is a timing chart showing an example of a processing procedure in the control method for a radiography apparatus according to the first embodiment. [Figure 5] Figure 3 is a flowchart showing an example of a detailed processing procedure during the data acquisition period in step S101. [Figure 6] This flowchart shows an example of a detailed processing procedure during the data processing period in step S102 of Figure 3. [Figure 7] Figure 3 is a flowchart showing an example of a detailed processing procedure during the correction data update period in step S103. [Figure 8] This is a timing chart showing an example of a processing procedure in the control method for a radiography apparatus according to the second embodiment. [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 each embodiment of the present invention described below, X-rays are preferably used as the radiation, but the present invention is not limited to X-rays and may include, for example, alpha rays, beta rays, gamma rays, particle beams, and cosmic rays.

[0011] (First Embodiment) First, let me describe the first embodiment.

[0012] <Outline configuration of a radiography system> Figure 1 is a diagram showing an example of the schematic configuration of a radiography system 10 according to the first embodiment. As shown in Figure 1, the radiography system 10 includes a radiography device 100 and a radiation generator 300.

[0013] The radiation generator 300 and the radiation imaging apparatus 100 are not electrically connected, and do not transmit or receive synchronization signals such as irradiation start notification, irradiation end notification, or notification of irradiation possible timing of radiation.

[0014] As shown in FIG. 1, the radiation generator 300 includes a radiation generation control unit 310, a radiation source 320, and an operation UI 330. Based on, for example, an operation input from the operation UI 330, the radiation generation control unit 310 controls whether to irradiate radiation R from the radiation source 320. Based on the control of the radiation generation control unit 310, the radiation source 320 irradiates or does not irradiate the radiation R. The operation UI 330 inputs, for example, an operation input from the user to the radiation generation control unit 310. Here, examples of the operation input include setting input of irradiation conditions of the radiation R and instruction input of irradiation / non-irradiation of the radiation R.

[0015] The radiation imaging apparatus 100 is a radiation imaging apparatus that performs radiation imaging of the subject H using the radiation R irradiated from the radiation source 320 of the radiation generator 300 without synchronizing with the radiation generator 300. Here, examples of the subject H include a substrate, but in this embodiment, it is not limited to the substrate, and other subjects such as a human body are also applicable. As shown in FIG. 1, the radiation imaging apparatus 100 includes a radiation detection unit 110 and a control unit 120.

[0016] The radiation detection unit 110 is a radiation detection means that detects the incident radiation R as an electrical signal related to a radiation image or the like of the subject H. The control unit 120 performs various controls to comprehensively control the operation of the radiation imaging apparatus 100 and also performs various processes. For example, the control unit 120 controls imaging by the radiation detection unit 110 and communication operations. Further, the control unit 120 may control the operation of the radiation imaging apparatus 100 by a control circuit such as an ASIC, or may control the operation of the radiation imaging apparatus 100 by both a control program and a control circuit.

[0017] As shown in FIG. 1, the control unit 120 includes a drive control unit 121, an image processing unit 122, a storage unit 123, a communication control unit 124, and an internal clock 125.

[0018] The drive control unit 121 performs drive control of the radiation detection unit 110, image acquisition control from the radiation detection unit 110, acquisition control of correction data (in this embodiment, offset correction data) for correcting a radiation image, and the like. As shown in FIG. 1, the drive control unit 121 includes an image acquisition control unit 1211, an irradiation dose measurement unit 1212, and a frame rate management unit 1213. Further, as shown in FIG. 1, the drive control unit 121 includes an irradiation start time acquisition unit 1214, an irradiation end time acquisition unit 1215, a non-irradiation period setting unit 1216, a correction data acquisition period setting unit 1217, and a correction data acquisition unit 1218.

[0019] The image acquisition control unit 1211 is an image acquisition control means that controls the radiation detection unit 110 to acquire various images from the radiation detection unit 110. For example, the image acquisition control unit 1211 performs control to acquire a radiation image in a state where radiation R is being irradiated, and also performs control to acquire a correction image for correcting a radiation image (in this embodiment, offset correction) in a state where radiation R is not being irradiated.

[0020] The irradiation dose measurement unit 1212 is an irradiation dose measurement means that measures the dose (irradiation dose) of radiation R irradiated from the radiation source 320 to the radiation detection unit 110.

[0021] The frame rate management unit 1213 is a frame rate management means that manages the frame rate, which is the imaging cycle of fluoroscopy. The frame rate managed by the frame rate management unit 1213 is registered, for example, before performing fluoroscopy with the radiation imaging apparatus 100. The method for registering the frame rate at this time may be, for example, receiving and registering the frame rate from a control device, which is an external device, or providing an operation UI on the radiation imaging apparatus 100 and registering the frame rate input from the operation UI.

[0022] The irradiation start time acquisition unit 1214 is an irradiation start time acquisition means that acquires the irradiation start time of radiation R from the radiation source 320 to the radiation detection unit 110. Specifically, the irradiation start time acquisition unit 1214 acquires the irradiation start time of radiation R without using the dose of radiation R detected using the detection pixels (detection pixels 204 in Figure 2, described later) provided in the radiation detection unit 110. More specifically, the irradiation start time acquisition unit 1214 acquires the irradiation start time of radiation R based on the value of the bias current flowing through the bias line (bias line 213 in Figure 2, described later) provided in the radiation detection unit 110.

[0023] The irradiation end time acquisition unit 1215 is an irradiation end time acquisition means that acquires the irradiation end time of radiation R from the radiation source 320 to the radiation detection unit 110. Specifically, the irradiation end time acquisition unit 1215 acquires the irradiation end time of radiation R using the dose of radiation R detected using the detection pixels (detection pixels 204 in Figure 2, described later) provided in the radiation detection unit 110.

[0024] The non-irradiation period setting unit 1216 is a non-irradiation period setting means for setting the non-irradiation period of radiation R from the radiation source 320 to the radiation detection unit 110. Specifically, the non-irradiation period setting unit 1216 sets the non-irradiation period of radiation R based on the end time of irradiation in the first irradiation period of radiation R and the start time of irradiation in the second irradiation period, which is the irradiation period following the first irradiation period of radiation R.

[0025] The correction data acquisition period setting unit 1217 is an acquisition period setting means that sets a correction data acquisition period for acquiring correction data to correct a radiation image obtained by photographing a subject H using radiation R during a period when radiation R is not being applied. Specifically, the correction data acquisition period setting unit 1217 sets the correction data acquisition period based on the start time of acquisition of correction data determined based on the end time of radiation R irradiation and the non-irradiation period of radiation R set by the non-irradiation period setting unit 1216. In this embodiment, the correction data acquisition period setting unit 1217 sets an offset correction data acquisition period for acquiring offset correction data to offset correct the radiation image.

[0026] The correction data acquisition unit 1218 is a correction data acquisition means that acquires correction data using at least one correction image obtained from imaging during the correction data acquisition period set by the correction data acquisition period setting unit 1217. For example, if multiple correction images are taken during the correction data acquisition period set by the correction data acquisition period setting unit 1217, the correction data acquisition unit 1218 averages the multiple correction images to acquire correction data. The number of correction images taken is managed as correction image count information in the correction data update parameter 1238 of the storage unit 123. In this embodiment, the correction data acquisition unit 1218 acquires offset correction data using an offset correction image obtained from imaging during the offset correction data acquisition period set by the correction data acquisition period setting unit 1217. In this embodiment, the correction data acquisition unit 1218 describes a form in which it acquires offset correction data for offset correction of a radiographic image, but the present invention is not limited to this form, and forms for acquiring correction data for other image corrections are also applicable to the present invention.

[0027] The image processing unit 122 is an image processing means that performs predetermined image processing on the image acquired from the radiation detection unit 110. For example, the image processing unit 122 performs image correction (offset correction in this embodiment) on the radiation image acquired from the radiation detection unit 110 using correction data acquired by the correction data acquisition unit 1218.

[0028] The memory unit 123 is a storage means for storing various types of information (including data). The memory unit 123 stores various images acquired from the radiation detection unit 110 by the image acquisition control unit 1211 as image data 1231. The memory unit 123 also stores the dose of radiation R measured by the irradiation dose measurement unit 1212 as dose information 1232. The memory unit 123 also stores the irradiation start time of radiation R acquired by the irradiation start time acquisition unit 1214 as irradiation start time information 1233. The memory unit 123 also stores the irradiation end time of radiation R acquired by the irradiation end time acquisition unit 1215 as irradiation end time information 1234. The memory unit 123 also stores the irradiation end period of radiation R, which is determined based on the period between two consecutive irradiation end times in time series, as irradiation end period information 1235. Furthermore, the storage unit 123 stores the non-irradiation period for radiation R set by the non-irradiation period setting unit 1216 as non-irradiation period information 1236. The storage unit 123 also stores the correction data (offset correction data in this embodiment) acquired by the correction data acquisition unit 1218 as correction data 1237. The storage unit 123 also stores correction data update parameters 1238, which include update cycle information, correction image count information, correction data update start time information, and update image capture frame rate information. Here, the correction image count information included in the correction data update parameters 1238 indicates the number of correction images taken during the correction data acquisition period set by the correction data acquisition period setting unit 1217.

[0029] The communication control unit 124 is a communication control means that controls communication with external devices.

[0030] The internal clock 125 is a timing device that measures various times, elapsed time, etc.

[0031] Next, the general configuration of the radiation detection unit 110 will be described. Figure 2 shows an example of the schematic configuration of the radiation detection unit 110 shown in Figure 1. In Figure 2, the same reference numerals are used for components that are the same as those shown in Figure 1, and their detailed explanations are omitted.

[0032] As shown in Figure 2, the radiation detection unit 110 includes an imaging area 210, a drive circuit 220, a power supply circuit 230, and a readout circuit 240.

[0033] The imaging area 210 is configured with multiple pixels to form multiple rows and multiple columns. The multiple pixels configured in the imaging area 210 include multiple imaging pixels 201 used to acquire a radiation image and one or more detection pixels 204 used to monitor the radiation dose R. The imaging pixel 201 includes a conversion element 202 that converts radiation R into an electrical signal (charge) related to the radiation image, and a switch element 203 for outputting the electrical signal accumulated in the conversion element 202 to a signal line 214. The detection pixel 204 includes a conversion element 205 that converts radiation R into an electrical signal related to the dose of radiation R, and a switch element 206 for outputting the electrical signal accumulated in the conversion element 205 to a signal line 214. In this embodiment, the detection pixel 204 has the same pixel configuration as the imaging pixel 201 and is arranged in the imaging area 210 to be included in the rows and columns configured by the multiple imaging pixels 201. In Figure 2, the imaging pixel 201 and the detection pixel 204 are distinguished by applying different hatching patterns to the conversion elements 202 and 205.

[0034] The conversion elements 202 and 205 may be composed of a scintillator that converts radiation R into light and a photoelectric conversion element that converts light into an electrical signal. In this case, the scintillator is generally formed in a sheet shape so as to cover the imaging area 210 and is shared by multiple pixels. Alternatively, the conversion elements 202 and 205 may be composed of a conversion element that directly converts radiation R into an electrical signal, instead of the scintillator and photoelectric conversion element configuration described above. Furthermore, the switch elements 203 and 206 may include thin-film transistors (TFTs) in which the active region is composed of a semiconductor material such as amorphous silicon or polycrystalline silicon.

[0035] Furthermore, multiple drive lines 211 are connected in the row direction of the pixels in the imaging area 210. In Figure 2, a drive line 211 connected to at least one detection pixel 204 is shown as a detection drive line 212. In addition, multiple bias lines 213 and multiple signal lines 214 are connected in the column direction of the pixels in the imaging area 210. Each of the multiple drive lines 211 (including the detection drive line 212) corresponds to any one pixel row. Each of the multiple bias lines 213 corresponds to any one pixel column. Each of the multiple signal lines 214 corresponds to any one pixel column. Among the multiple signal lines 214, some imaging pixels 201 are connected to the same signal line 214 as the detection pixels 204.

[0036] The drive circuit 220 is a driving means configured to supply a drive signal to the pixel to be driven through a plurality of drive lines 211 (including the detection drive line 212) according to a control signal from the drive control unit 121. When a drive signal is supplied from the drive circuit 220 to the pixel to be driven, the electrical signal accumulated in the conversion element included in the pixel to be driven becomes readable to the readout circuit 240 via the signal line 214. The drive control unit 121 controls the imaging pixel 201 to the state of electrical signal (charge) accumulation, and continuously and repeatedly reads out the electrical signal only from each pixel connected to the detection drive line 212, including the detection pixel 204, thereby monitoring changes in the radiation dose R. Specifically, the radiation dose measurement unit 1212 of the drive control unit 121 can determine an increase or decrease in the radiation dose R based on the repeatedly read-out electrical signals related to the radiation dose R.

[0037] The power supply circuit 230 is a power supply means that includes a bias power supply that supplies bias current (which may be understood as bias voltage) to each pixel of the imaging area 210 (including the imaging pixel 201 and the detection pixel 204) via a plurality of bias lines 213. In addition to the bias power supply described above, the power supply circuit 230 also has a refresh power supply and a radiation detection means that detects the irradiation of radiation R by detecting a change in the bias current when radiation R is irradiated. Based on the control of the drive control unit 121, the power supply circuit 230 is driven to detect the irradiation of radiation R by detecting a change in the bias current when radiation R is irradiated using the radiation detection means. The radiation irradiation information of radiation R detected by the radiation detection means of the power supply circuit 230 is then notified to the drive control unit 121 of the control unit 120.

[0038] The readout circuit 240 is a readout means configured to read electrical signals from each pixel of the imaging area 210 through a plurality of signal lines 214. As shown in Figure 2, the readout circuit 240 is composed of a plurality of amplification units 241, a multiplexer 242, and an analog-to-digital converter (hereinafter referred to as "AD converter") 243. Each signal line in the plurality of signal lines 214 is connected to a corresponding amplification unit among the plurality of amplification units 241 in the readout circuit 240. That is, one signal line 214 corresponds to one amplification unit 241. The multiplexer 242 selects the plurality of amplification units 241 in a predetermined order and supplies the electrical signals from the selected amplification units 241 to the AD converter 243. The AD converter 243 converts the analog electrical signals supplied from the multiplexer 242 into digital electrical signals. The image data obtained by converting it into a digital electrical signal is then stored as image data 1231 in the storage unit 123 via the image acquisition control unit 1211 shown in Figure 1. The image acquisition control unit 1211 in Figure 1 reads the image data of the radiation image based on the electrical signals accumulated in each pixel of the imaging area 210 during radiation R irradiation from the radiation detection unit 110 and stores it in the storage unit 123. By continuously performing this operation, it is possible to perform motion picture imaging of radiation.

[0039] When performing video radiography, if radiation R is irradiated at a time when the radiography device 100 cannot acquire an image, it results in ineffective exposure of the subject H to radiation R, which is harmful. Therefore, video radiography becomes possible by periodically and alternately repeating the irradiation of radiation R to acquire a radiographic image and the reading out of the electrical signal (charge) related to the radiographic image. In video radiography, the irradiation of radiation R and the reading out of the electrical signal (charge) described above constitute one frame, and it is necessary to periodically maintain frame processing during the irradiation of radiation R and to start and end this series of alternating operations. Regarding frame processing, the frame rate in video radiography is managed by the frame rate management unit 1213.

[0040] <Control method for radiography equipment> Figure 3 is a flowchart showing an example of a processing procedure in the control method of the radiography apparatus 100 according to the first embodiment. Figure 4 is a timing chart showing an example of a processing procedure in the control method of the radiography apparatus 100 according to the first embodiment.

[0041] In step S101 of Figure 3, the radiography apparatus 100 performs the processing during the data acquisition period shown in Figure 4.

[0042] Next, in step S102 of Figure 3, the radiography apparatus 100 performs the processing shown in Figure 4 during the data processing period.

[0043] Next, in step S103 of Figure 3, the radiography apparatus 100 performs the processing during the correction data update period shown in Figure 4. Once the processing in step S103 of Figure 3 is completed, the process returns to step S101 of Figure 3, and the processing from step S101 onwards of Figure 3 is repeated.

[0044] Next, a detailed example of the process in step S101 in Figure 3 will be described. Figure 5 is a flowchart showing an example of a detailed processing procedure during the data acquisition period in step S101 of Figure 3.

[0045] First, in step S201 of Figure 5, when power is supplied to the radiography device 100, the drive control unit 121 activates (ON) the radiation detection of radiation R using the radiation detection means of the power supply circuit 230.

[0046] Next, in step S202 of Figure 5, the drive control unit 121 uses the radiation detection means of the power supply circuit 230 to determine whether or not the start of irradiation of radiation R from the radiation source 320 to the radiation detection unit 110 has been detected. If, in step S202 of Figure 5, the drive control unit 121 determines that the start of irradiation of radiation R has not been detected (S202 / NO), it waits in step S202 of Figure 5 until the start of irradiation of radiation R is detected.

[0047] Furthermore, in step S202 of Figure 5, if the drive control unit 121 determines that the start of radiation R has been detected (S202 / YES), the process proceeds to step S203. When the process proceeds to step S203 in Figure 5, the irradiation start time acquisition unit 1214 acquires the irradiation start time of radiation R via the internal clock 125. In this embodiment, in step S203 in Figure 5, the irradiation start time acquisition unit 1214 acquires the irradiation start time Ta1 of radiation R during the data acquisition period shown in Figure 4. The irradiation start time acquisition unit 1214 then stores the acquired irradiation start time Ta1 of radiation R in the storage area of ​​the irradiation start time information 1233 of the storage unit 123.

[0048] Next, in step S204 of Figure 5, the drive control unit 121 stops (turns off) the radiation detection of radiation R using the radiation detection means of the power supply circuit 230.

[0049] Next, in step S205 of Figure 5, the drive control unit 121 enables (ON) the radiation dose measurement of radiation R by the irradiation dose measurement unit 1212 using the detection pixel 204 (or detection drive line 212). At the same time, the drive control unit 121 starts fluoroscopic imaging of the subject H using radiation R.

[0050] Next, in step S206 of Figure 5, the drive control unit 121 determines whether the end of radiation irradiation of radiation R has been detected, depending on whether the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold. That is, in step S206 of Figure 5, it is determined that the end of radiation irradiation of radiation R has been detected if the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold. The predetermined threshold for the decrease used in step S206 of Figure 5 may be a fixed value or a variable value. In step S206 of Figure 5, if the drive control unit 121 determines that the end of radiation irradiation of radiation R has not been detected (S206 / NO), it waits in step S206 of Figure 5 until the end of radiation irradiation of radiation R is detected.

[0051] Furthermore, in step S206 of Figure 5, if the drive control unit 121 determines that the end of radiation R irradiation has been detected (S206 / YES), the process proceeds to step S207. When the process proceeds to step S207 in Figure 5, the irradiation end time acquisition unit 1215 acquires the irradiation end time of radiation R via the internal clock 125. In this embodiment, in step S207 in Figure 5, the irradiation end time acquisition unit 1215 acquires the irradiation end time Tb1 of radiation R during the data acquisition period shown in Figure 4. The irradiation end time acquisition unit 1215 then stores the acquired irradiation end time Tb1 of radiation R in the storage area of ​​the irradiation end time information 1234 of the storage unit 123.

[0052] Next, in step S208 of Figure 5, the drive control unit 121 stops (turns off) the radiation dose measurement of radiation R by the irradiation dose measurement unit 1212 using the detection pixel 204 (or detection drive line 212).

[0053] Next, in step S209 of Figure 5, the drive control unit 121 activates (ON) the radiation detection of radiation R using the radiation detection means of the power supply circuit 230.

[0054] Next, in step S210 of Figure 5, the drive control unit 121 uses the radiation detection means of the power supply circuit 230 to determine whether or not the start of irradiation of radiation R from the radiation source 320 to the radiation detection unit 110 has been detected. If, in step S210 of Figure 5, the drive control unit 121 determines that the start of irradiation of radiation R has not been detected (S210 / NO), it waits in step S210 of Figure 5 until the start of irradiation of radiation R is detected.

[0055] Furthermore, in step S210 of Figure 5, if the drive control unit 121 determines that the start of radiation R has been detected (S210 / YES), the process proceeds to step S211. When the process proceeds to step S211 in Figure 5, the irradiation start time acquisition unit 1214 acquires the irradiation start time of radiation R via the internal clock 125. In this embodiment, in step S211 in Figure 5, the irradiation start time acquisition unit 1214 acquires the irradiation start time Ta2 of radiation R during the data acquisition period shown in Figure 4. The irradiation start time acquisition unit 1214 then stores the acquired irradiation start time Ta2 of radiation R in the storage area of ​​the irradiation start time information 1233 of the storage unit 123.

[0056] Next, in step S212 of Figure 5, the drive control unit 121 stops (turns off) the radiation detection of radiation R using the radiation detection means of the power supply circuit 230.

[0057] Next, in step S213 of Figure 5, the drive control unit 121 enables (ON) the measurement of radiation R by the irradiation dose measurement unit 1212 using the detection pixel 204 (or detection drive line 212).

[0058] Next, in step S214 of Figure 5, the drive control unit 121 determines whether the end of radiation R irradiation has been detected based on whether the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold. That is, in step S214 of Figure 5, if the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold, it is determined that the end of radiation R irradiation has been detected. In step S214 of Figure 5, if the drive control unit 121 determines that the end of radiation R irradiation has not been detected (S214 / NO), it waits in step S214 of Figure 5 until the end of radiation R irradiation is detected.

[0059] Furthermore, in step S214 of Figure 5, if the drive control unit 121 determines that the end of radiation R irradiation has been detected (S214 / YES), the process proceeds to step S215. When the process proceeds to step S215 in Figure 5, the irradiation end time acquisition unit 1215 acquires the irradiation end time of radiation R via the internal clock 125. In this embodiment, in step S215 of Figure 5, the irradiation end time acquisition unit 1215 acquires the irradiation end time Tb2 of radiation R during the data acquisition period shown in Figure 4. The irradiation end time acquisition unit 1215 then stores the acquired irradiation end time Tb2 of radiation R in the storage area of ​​the irradiation end time information 1234 of the storage unit 123.

[0060] When the process in step S215 of Figure 5 is completed, the process in the flowchart shown in Figure 5 is completed. Then, when the process in the flowchart shown in Figure 5 is completed, the process in the data acquisition period of step S101 of Figure 3 is completed.

[0061] Next, a detailed example of the process in step S102 of Figure 3 will be described. Figure 6 is a flowchart showing an example of a detailed processing procedure during the data processing period in step S102 of Figure 3.

[0062] In step S301 of Figure 6, the non-irradiation period setting unit 1216 first obtains the irradiation end time Tb1 for the first irradiation period of radiation R, which was stored in S207 of Figure 5, from the storage area of ​​the irradiation end time information 1234 in the storage unit 123. Next, the non-irradiation period setting unit 1216 obtains the irradiation start time Ta2 for the second irradiation period, which is the irradiation period following the first irradiation period of radiation R, which was stored in S211 of Figure 5, from the storage area of ​​the irradiation start time information 1233 in the storage unit 123. Then, based on the obtained irradiation end time Tb1 and irradiation start time Ta2, the non-irradiation period setting unit 1216 calculates and sets the non-irradiation period of radiation R. In this embodiment, in step S301 of Figure 6, the non-irradiation period setting unit 1216 calculates the N-2 non-irradiation period during the data acquisition period shown in Figure 4, and stores and sets it in the storage area of ​​the non-irradiation period information 1236 of the storage unit 123. In this embodiment, the number N represents the number of irradiations of radiation R, and in Figure 4, the number N can be any natural number of 3 or more.

[0063] Next, in step S302 of Figure 6, the drive control unit 121 stops (turns off) the radiation dose measurement of radiation R by the irradiation dose measurement unit 1212 using the detection pixel 204 (or detection drive line 212).

[0064] Next, in step S303 of Figure 6, the drive control unit 121 enables (ON) the radiation detection of radiation R using the radiation detection means of the power supply circuit 230.

[0065] Next, in step S304 of Figure 6, the drive control unit 121 uses the radiation detection means of the power supply circuit 230 to determine whether or not the start of irradiation of radiation R from the radiation source 320 to the radiation detection unit 110 has been detected. If, in step S304 of Figure 6, the drive control unit 121 determines that the start of irradiation of radiation R has not been detected (S304 / NO), the process returns to step S302 of Figure 6.

[0066] Furthermore, in step S304 of Figure 6, if the drive control unit 121 determines that the start of radiation R has been detected (S304 / YES), the process proceeds to step S305. When the process proceeds to step S305 in Figure 6, the irradiation start time acquisition unit 1214 acquires the irradiation start time of radiation R via the internal clock 125. In this embodiment, in step S305 in Figure 6, the irradiation start time acquisition unit 1214 acquires the irradiation start time Ta3 of radiation R during the data processing period shown in Figure 4. The irradiation start time acquisition unit 1214 then stores the acquired irradiation start time Ta3 of radiation R in the storage area of ​​the irradiation start time information 1233 of the storage unit 123.

[0067] Next, in step S306 of Figure 6, the drive control unit 121 stops (turns off) the radiation detection of radiation R using the radiation detection means of the power supply circuit 230.

[0068] Next, in step S307 of Figure 6, the drive control unit 121 enables (ON) the radiation dose measurement of radiation R by the irradiation dose measurement unit 1212 using the detection pixel 204 (or detection drive line 212).

[0069] Next, in step S308 of Figure 6, the drive control unit 121 determines whether the end of radiation R irradiation has been detected based on whether the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold. That is, in step S308 of Figure 6, if the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold, it is determined that the end of radiation R irradiation has been detected. In step S308 of Figure 6, if the drive control unit 121 determines that the end of radiation R irradiation has not been detected (S308 / NO), it waits in step S308 of Figure 6 until the end of radiation R irradiation is detected.

[0070] Furthermore, in step S308 of Figure 6, if the drive control unit 121 determines that the end of radiation R irradiation has been detected (S308 / YES), the process proceeds to step S309. When the process proceeds to step S309 in Figure 6, the irradiation end time acquisition unit 1215 acquires the irradiation end time of radiation R via the internal clock 125. In this embodiment, in step S309 in Figure 6, the irradiation end time acquisition unit 1215 acquires the irradiation end time Tb3 of radiation R during the data processing period shown in Figure 4. The irradiation end time acquisition unit 1215 then stores the acquired irradiation end time Tb3 of radiation R in the storage area of ​​the irradiation end time information 1234 of the storage unit 123.

[0071] Next, in step S310 of Figure 6, the non-irradiation period setting unit 1216 first obtains the irradiation end time Tb2 for the second irradiation period of radiation R, which was stored in S215 of Figure 5, from the storage area of ​​the irradiation end time information 1234 in the storage unit 123. Then, the non-irradiation period setting unit 1216 obtains the irradiation start time Ta3 for the third irradiation period of radiation R, which was stored in S305 of Figure 6, from the storage area of ​​the irradiation start time information 1233 in the storage unit 123. Then, the non-irradiation period setting unit 1216 calculates and sets the non-irradiation period of radiation R based on the obtained irradiation end time Tb2 and irradiation start time Ta3. In this embodiment, in step S301 of Figure 6, the non-irradiation period setting unit 1216 calculates the N-1 non-irradiation period shown in Figure 4 and stores and sets it in the storage area of ​​the non-irradiation period information 1236 in the storage unit 123.

[0072] Next, in step S311 in Figure 6, the drive control unit 121 calculates the N-1th irradiation completion period based on the irradiation completion time Tb2 stored in S215 in Figure 5 and the irradiation completion time Tb3 stored in S309 in Figure 6. Then, the drive control unit 121 calculates the N-2nd irradiation completion period based on the irradiation completion time Tb1 stored in S207 in Figure 5 and the irradiation completion time Tb2 stored in S215 in Figure 5. Finally, the drive control unit 121 stores the calculated N-1st and N-2nd irradiation completion periods in the storage area of ​​the irradiation completion period information 1235 in the storage unit 123.

[0073] Next, in step S312 of Figure 6, the drive control unit 121 determines whether the difference between the N-2 irradiation end period and the N-1 irradiation end period is within a predetermined range, and whether the difference between the N-2 non-irradiation period and the N-1 non-irradiation period is within a predetermined range. If, in step S312 of Figure 6, the drive control unit 121 determines that at least one of the irradiation end periods and non-irradiation periods is not the same between the N-2 and N-1 irradiations (S312 / NO), the process returns to step S302 of Figure 6.

[0074] Furthermore, in step S312 of Figure 6, if the drive control unit 121 determines that the irradiation end cycle and non-irradiation period are the same for the N-2th and N-1st irradiations (S312 / YES), the process proceeds to step S313. The process proceeds to step S313 when it is possible to perform periodic imaging at approximately the same intervals. When the process proceeds to step S313 in Figure 6, the correction data acquisition period setting unit 1217 first sets the acquisition start time Tc1, which is the time to start acquiring correction data during the correction data update period shown in Figure 4. Specifically, the correction data acquisition period setting unit 1217 sets the acquisition start time Tc1 based on the N-1 irradiation end cycle (for example, irradiation end times Tb2 and Tb3) calculated in step SS311 and the N-1 non-irradiation period calculated in step S310. In this case, the acquisition start time Tc1 may be, for example, the irradiation end time Tb3 in the N-1 irradiation end cycle, or it may be the time when 50% of the N-1 non-irradiation period has elapsed from the irradiation end time Tb3. That is, in this embodiment, the correction data acquisition period setting unit 1217 sets the acquisition start time of correction data based on the irradiation end time of radiation R and the non-irradiation period of radiation R. In this embodiment, assuming a period during which the data cannot be updated due to afterimages, the acquisition start time Tc1 is set to the time when 50% of the N-1 non-irradiation period has elapsed from the irradiation end time Tb3, as shown in Figure 4. In this invention, the acquisition start time of the correction data acquisition period is not limited to the time described herein. The correction data acquisition period setting unit 1217 then stores the set acquisition start time Tc1 in the storage area of ​​the correction data update start time information in the correction data update parameter 1238 of the storage unit 123. Next, as shown in Figure 4, the correction data acquisition period setting unit 1217 sets the period from the acquisition start time Tc1 to the end time Td1 of the Nth non-irradiation period, which is assumed to be from the N-1 non-irradiation period, as the correction data acquisition period 410. In this embodiment, the entire period from the acquisition start time Tc1 to the end time Td1 of the Nth non-irradiation period is set as the correction data acquisition period 410, but only a part of that period may be set as the correction data acquisition period.

[0075] Next, in step S314 of Figure 6, the correction data acquisition unit 1218 calculates the number of correction images to be taken based on the correction data acquisition period 410 set in step S313 and the frame rate of the radiographic image. In this embodiment, the frame rate of the radiographic image corresponds to, for example, the updated image shooting frame rate information stored in the correction data update parameter 1238 of the storage unit 123. Here, in this embodiment, the number of correction images to be taken is set to the maximum number that can be taken within the correction data acquisition period 410, but the present invention is not limited to this form, and for example, it may be set to a number that fits within the correction data acquisition period 410 in powers of 2.

[0076] Next, in step S315 of Figure 6, the correction data acquisition unit 1218 determines the correction data update period based on the irradiation end period calculated in step S311. In this case, the correction data update period may be the same as the irradiation end period calculated in step S311, or it may be an integer multiple such as 2 or 3 times the irradiation end period calculated in step S311.

[0077] When the process in step S315 in Figure 6 is completed, the process in the flowchart shown in Figure 6 is completed. Then, when the process in the flowchart shown in Figure 6 is completed, the processing in the data processing period of step S102 in Figure 3 is completed.

[0078] Next, a detailed example of the process in step S103 of Figure 3 will be described. Figure 7 is a flowchart showing an example of a detailed processing procedure during the correction data update period in step S103 of Figure 3.

[0079] First, in step S401 in Figure 7, the drive control unit 121 determines whether or not it has reached the correction data update time corresponding to the acquisition start time Tc1 in the correction data update cycle determined in step S315 in Figure 6. If the drive control unit 121 determines in step S401 in Figure 7 that it has not yet reached the correction data update time (S401 / NO), it waits in step S401 until it reaches the correction data update time.

[0080] In step S401 of Figure 7, if the drive control unit 121 determines that it is time to update the correction data (S401 / YES), the process proceeds to step S402. When the process proceeds to step S402 in Figure 7, the correction data acquisition unit 1218 first acquires correction images for the number of images calculated in step S314 of Figure 6 during the correction data acquisition period 410 set in step S313 of Figure 6. Figure 4 shows an example in which three correction images 411, for which multiple images have been taken, are acquired during the correction data acquisition period 410. In this case, the correction data acquisition unit 1218 generates and acquires correction data for correcting the radiation image using the three acquired correction images 411. Specifically, in this embodiment, the correction data acquisition unit 1218 generates and acquires correction data by averaging the three acquired correction images 411. Then, the correction data acquisition unit 1218 stores the correction data acquired in this step in the correction data 1237 storage area of ​​the storage unit 123 and updates the correction data.

[0081] Next, in step S403 of Figure 7, the drive control unit 121 determines whether or not a periodic fluctuation has been confirmed, as the period at the end of irradiation of radiation R, which is continuously acquired by the irradiation end time acquisition unit 1215, has fallen outside a predetermined range.

[0082] In step S403 of Figure 7, if the drive control unit 121 determines that the period at the end of radiation R irradiation has fallen outside a predetermined range and that a periodic fluctuation has been confirmed (S403 / YES), the process proceeds to step S404. When the process proceeds to step S404 in Figure 7, the drive control unit 121 determines whether the end of radiation R irradiation has been detected based on whether the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold. That is, in step S404 in Figure 7, if the decrease in the radiation dose of radiation R measured by the radiation dose measurement unit 1212 is above a predetermined threshold, it is determined that the end of radiation R irradiation has been detected. If the drive control unit 121 determines in step S404 in Figure 7 that the end of radiation R irradiation has not been detected (S404 / NO), it waits in step S404 in Figure 7 until the end of radiation R irradiation is detected.

[0083] Furthermore, in step S404 of Figure 7, if the drive control unit 121 determines that the end of radiation R irradiation has been detected (S404 / YES), the process proceeds to step S405. When the process proceeds to step S405 in Figure 7, the irradiation end time acquisition unit 1215 acquires the irradiation end time of radiation R via the internal clock 125. In this embodiment, in step S405 in Figure 7, the irradiation end time acquisition unit 1215 acquires the irradiation end time Tbn of radiation R. The irradiation end time acquisition unit 1215 then stores the acquired irradiation end time Tbn of radiation R in the storage area of ​​the irradiation end time information 1234 of the storage unit 123.

[0084] Next, in step S406 of Figure 7, the drive control unit 121 determines whether the difference between the irradiation end time Tbn stored in S405 and the irradiation end time estimated from the irradiation end cycle information 1235 stored in the storage unit 123 matches within a predetermined range.

[0085] In step S406 of Figure 7, if the drive control unit 121 determines that the difference between the irradiation end time Tbn and the irradiation end time estimated from the irradiation end period information 1235 is within a predetermined range (S406 / YES), the process proceeds to step S407. Also, in step S403 of Figure 7, if the drive control unit 121 determines that no periodic variation was observed in the irradiation end time of radiation R (S403 / NO), the process proceeds to step S407. When the process proceeds to step S407 in Figure 7, the drive control unit 121 determines whether or not it has reached the correction data update time corresponding to the acquisition start time in the correction data update cycle determined in step S315 in Figure 6.

[0086] In step S407 of Figure 7, if the drive control unit 121 determines that it is not yet time to update the correction data (S407 / NO), it waits in step S407 until it is time to update the correction data. Also, in step S407 of Figure 7, if the drive control unit 121 determines that it is now time to update the correction data (S407 / YES), it returns to step S402 and repeats the processing from step S402 onwards.

[0087] Furthermore, in step S406 of Figure 7, if the drive control unit 121 determines that the difference between the irradiation end time Tbn and the irradiation end time estimated from the irradiation end cycle information 1235 does not match within a predetermined range (S406 / NO), the process proceeds to step S408. When the process proceeds to step S408 in Figure 7, the drive control unit 121 stops updating the correction data and restarts the processing from the data acquisition period by stopping (turning off) the radiation dose measurement by the irradiation dose measurement unit 1212 using the detection pixel 204 (or detection drive line 212).

[0088] When the process in step S408 in Figure 7 is completed, the process in the flowchart shown in Figure 7 is completed. Then, when the process in the flowchart shown in Figure 7 is completed, the process in the correction data update period in step S103 in Figure 3 is completed. After that, the process returns to step S101 in Figure 3, and the process in the data acquisition period (S101 in Figure 3), the process in the data processing period (S102 in Figure 3), and the process in the correction data update period (S103 in Figure 3) are performed again.

[0089] Furthermore, the confirmation of periodic fluctuations at the end of radiation R irradiation time in step S403 of Figure 7 only needs to be performed once for each of the multiple correction data updates. However, the present invention is not limited to this embodiment, and the confirmation of periodic fluctuations at the end of radiation R irradiation time in step S403 of Figure 7 may be performed each time the correction data is updated.

[0090] Furthermore, in this embodiment, in order to clarify the content of the present invention, the processing when each operation is periodic with each irradiation of radiation R has been described, but the processing when multiple irradiations of radiation constitute one set and each operation is periodic may also be described.

[0091] Furthermore, in this embodiment, an example was described in which the start of radiation R irradiation is detected by radiation detection using the radiation detection means of the power supply circuit 230, and the end of radiation R irradiation is detected using the radiation dose of radiation R measured by the radiation dose measurement unit 1212. In this case, detecting the start of radiation R irradiation using radiation detection using the radiation detection means of the power supply circuit 230 can reduce power consumption compared to using the radiation dose of radiation R measured by the radiation dose measurement unit 1212. However, the present invention is not limited to this embodiment. For example, only the detection of the start of radiation R irradiation at the beginning of imaging may be performed using radiation detection using the radiation detection means of the power supply circuit 230, and all subsequent detections of the start of radiation R irradiation may be performed using the radiation dose of radiation R measured by the radiation dose measurement unit 1212. Alternatively, both the detection of the start of radiation R irradiation and the detection of the end of radiation R irradiation may be performed using the radiation dose of radiation R measured by the radiation dose measurement unit 1212.

[0092] The radiography apparatus 100 according to the first embodiment described above is a radiography apparatus that takes images of a subject H using radiation R irradiated from a radiation generator 300 without synchronization with the radiation generator 300. Specifically, the radiography apparatus 100 according to the first embodiment has the following configuration. The radiography apparatus 100 has an irradiation start time acquisition unit 1214 that acquires the irradiation start time of radiation R, and an irradiation end time acquisition unit 1215 that acquires the irradiation end time of radiation R. The radiography apparatus 100 also has a non-irradiation period setting unit 1216 that sets a non-irradiation period for radiation R based on the irradiation end time in the first irradiation period of radiation R and the irradiation start time in the second irradiation period, which is the irradiation period following the first irradiation period of radiation R. The radiography apparatus 100 also has a correction data acquisition period setting unit 1217 that sets a correction data acquisition period for acquiring correction data to correct the radiographic image obtained by taking images of the subject H using radiation R during a period when radiation R is not irradiated. In this case, the correction data acquisition period setting unit 1217 sets the correction data acquisition period based on the start time for acquiring correction data determined based on the end time of radiation R irradiation and the non-irradiation period of radiation R. The radiography apparatus 100 also has a correction data acquisition unit 1218 that acquires correction data for correcting the radiographic image using the correction image obtained during the correction data acquisition period. According to the configuration of the radiography apparatus 100 in this first embodiment, when radiography of the subject H is performed without synchronization with the radiation generator 300, correction data that can be used to perform appropriate corrections on the radiographic image can be acquired.

[0093] Furthermore, in the first embodiment, until the irradiation start time acquisition unit 1214 acquires the irradiation start time of radiation R (e.g., S203 in Figure 5), the bias current value is detected (e.g., S201 in Figure 5), and the detection of the radiation dose of radiation R by the detection pixel 204 is stopped. After the irradiation start time acquisition unit 1214 acquires the irradiation start time of radiation R, the radiation image is acquired, the radiation dose of radiation R is detected by the detection pixel 204, and the detection of the bias current value is stopped (e.g., S204, S205 in Figure 5). Furthermore, after the irradiation end time acquisition unit 1215 acquires the irradiation end time of radiation R, the bias current value is detected, and the detection of the radiation dose of radiation R by the detection pixel 204 is stopped (e.g., S208, S209 in Figure 5).

[0094] Furthermore, in the first embodiment, if the period at the end of radiation R irradiation time acquired by the irradiation end time acquisition unit 1215 falls outside a predetermined range (S403 / NO ​​in Figure 7) and a negative judgment is made in S403 in Figure 7, the processing in the correction data update period ends. After that, the processing in the data acquisition period (S101 in Figure 3), the processing in the data processing period (S102 in Figure 3), and the processing in the correction data update period (S103 in Figure 3) are performed again. That is, in this case, the irradiation end time acquisition unit 1215 acquires the end of radiation R irradiation time again, the non-irradiation period setting unit 1216 sets the non-irradiation period for radiation R again, and the correction data acquisition period setting unit 1217 sets the correction data acquisition period again. Then, in this case, the correction data acquisition unit 1218 acquires the correction data again. This makes it possible to automatically reset the timing of the correction data update and respond even when a periodic fluctuation occurs at the end of radiation R irradiation time.

[0095] Furthermore, in the first embodiment, the correction data acquisition unit 1218 calculates the number of correction images to be captured based on the correction data acquisition period 410 and the frame rate of the radiographic image. This makes it possible to generate correction data with a good signal-to-noise ratio according to the shooting conditions.

[0096] (Second embodiment) Next, a second embodiment 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 explained.

[0097] The schematic configuration of the radiography system according to the second embodiment is the same as the schematic configuration of the radiography system 10 according to the first embodiment shown in Figure 1. Furthermore, the schematic configuration of the radiation detection unit 110 according to the second embodiment is the same as the schematic configuration of the radiation detection unit 110 according to the first embodiment shown in Figure 2. Also, the processing procedure in the control method for the radiography apparatus 100 according to the second embodiment is the same as the processing procedure in the control method for the radiography apparatus 100 according to the first embodiment shown in Figure 3 (including Figures 5 to 7).

[0098] In the first embodiment described above, an example was explained in which the correction data acquisition period setting unit 1217 sets the start time for acquiring correction data based on the end time of radiation R and the non-irradiation period of radiation R.

[0099] In contrast, the second embodiment differs from the first embodiment described above in how the start time for acquiring correction data is set. In the second embodiment, the correction data acquisition period setting unit 1217 sets the start time for acquiring correction data based on the end time of radiation R irradiation, the dose information of radiation R when photographing the subject H, and the emission time of the residual electrical signal of the radiation detection unit 110. This second embodiment is a configuration that takes into account the period during which the correction data cannot be updated due to afterimages (more specifically, the period during which it is unsuitable for updating due to afterimages) in the correction data update period shown in Figure 4.

[0100] The case where Figure 4 is applied to the second embodiment will be described below. In the second embodiment, the correction data acquisition period setting unit 1217 sets the correction data acquisition start time Tc1 based on the radiation R irradiation end time Tb3, the radiation R dose information when photographing the subject H, and the emission time of the residual electrical signal of the radiation detection unit 110. This makes it possible to set the correction data acquisition start time Tc1 to a period within the Nth non-irradiation period that excludes the period in which the data cannot be updated due to afterimages (more specifically, the period in which the data is unsuitable for updating due to afterimages) within the correction data update period shown in Figure 4. In this second embodiment, the storage unit 123 stores information on the emission time (disappearance time) of the residual electrical signal of the radiation detection unit 110 in relation to the radiation R irradiation dose. In this second embodiment, the irradiation dose measurement unit 1212 acquires the radiation dose at the radiation R irradiation end time Tb3 as radiation R dose information and stores this in the dose information storage area 1232 of the storage unit 123.

[0101] However, in the second embodiment, since the acquisition start time Tc1 is set based on the dose information of radiation R and the emission time of the residual electrical signal of the radiation detection unit 110, it is conceivable that if the radiation dose of radiation R becomes excessive, the acquisition start time Tc1 may fall outside the range of the non-irradiation period.

[0102] Figure 8 is a timing chart showing an example of a processing procedure in the control method of the radiography apparatus 100 according to the second embodiment. In Figure 8, components similar to those shown in Figure 4 are denoted by the same reference numerals, and their detailed explanation is omitted.

[0103] Figure 8 shows a case where the radiation dose R is excessive when photographing subject H, compared to the case shown in Figure 4. In this case, the period without radiation R is a period during which the image cannot be updated due to afterimages (more specifically, a period unsuitable for updating due to afterimages).

[0104] Therefore, in the second embodiment, the correction data acquisition period setting unit 1217 sets the start time for acquiring correction data and the correction data acquisition period as follows.

[0105] The example shown in Figure 4 is when the start time Tc1 for acquiring correction data, which is set based on the end time Tb3 of radiation R irradiation, the dose information of radiation R when photographing the subject H, and the emission time of the residual electrical signal of the radiation detection unit 110, is included in the Nth non-irradiation period. In this Figure 4, the correction data acquisition period setting unit 1217 sets the start time Tc1 for acquiring correction data, similar to the first embodiment, and sets the period from the start time Tc1 to the end time Td1 of the Nth non-irradiation period as the correction data acquisition period 410.

[0106] The example shown in Figure 8 is when the start time for acquiring correction data, which is set based on the end time Tb3 of radiation R irradiation, the dose information of radiation R when photographing the subject H, and the emission time of the residual electrical signal of the radiation detection unit 110, is not included in the Nth non-irradiation period. In this Figure 8, the correction data acquisition period setting unit 1217 sets the period a predetermined amount prior to the end time Td1 of the Nth non-irradiation period as the correction data acquisition period 810. In this Figure 8, the correction data acquisition period setting unit 1217 sets the start time of the correction data acquisition period 810 as the start time Tc2 of acquiring correction data and stores it in the storage area of ​​the correction data update start time information of the storage unit 123. In this Figure 8, an example is shown in which the correction data acquisition unit 1218 acquires three correction images 811, which are multiple images, during the correction data acquisition period 810. In this case, the correction data acquisition unit 1218 generates and acquires correction data by averaging, for example, three correction images 811, and stores the acquired correction data in the correction data storage area 1237 of the storage unit 123 to update the correction data. Although Figure 8 shows an example in which three correction images 811 are acquired, similar to the correction image 411 shown in Figure 4, it is also possible to shorten the correction data acquisition period 810 and acquire two or fewer correction images 811.

[0107] In the case of Figure 8, the correction data acquisition period 810 is set to the latter half of the Nth non-irradiation period, rather than the first half. By setting the latter half of the Nth non-irradiation period as the correction data acquisition period 810, it is possible to obtain a correction image 811 with less afterimage influence than the first half of the Nth non-irradiation period.

[0108] In the second embodiment, a configuration was described that considers the emission time (disappearance time) of the residual electrical signal of the radiation detection unit 110 in relation to the radiation dose R. However, the present invention is not limited to this configuration. For example, a configuration that considers the time required for the effects of the sensor saturation characteristics of the pixels in the radiation detection unit 110 and other electrical characteristics to disappear after irradiation with radiation R is also applicable to the present invention.

[0109] According to the second embodiment, correction data can be acquired using a correction image in which the afterimage effect after irradiation with radiation R has been eliminated or reduced, making it possible to acquire correction data with minimal influence from the preceding radiographic imaging.

[0110] (Third embodiment) Next, a third embodiment 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.

[0111] The schematic configuration of the radiography system according to the third embodiment is the same as the schematic configuration of the radiography system 10 according to the first embodiment shown in Figure 1. Furthermore, the schematic configuration of the radiation detection unit 110 according to the third embodiment is the same as the schematic configuration of the radiation detection unit 110 according to the first embodiment shown in Figure 2. Also, the processing procedure in the control method for the radiography apparatus 100 according to the third embodiment is the same as the processing procedure in the control method for the radiography apparatus 100 according to the first embodiment shown in Figure 3 (including Figures 5 to 7).

[0112] In the first embodiment described above, the irradiation completion period was calculated for each irradiation of radiation R, but the present invention is not limited to this form. In the third embodiment, the storage area of ​​the irradiation completion period information 1235 of the storage unit 123 is capable of storing information for at least three or more irradiation completion periods.

[0113] Furthermore, in the first embodiment described above, an example was given in which the (N-1)th irradiation completion period is calculated based on the (N-1)th irradiation completion time Tb2 and the (N)th irradiation completion time Tb3, and stored in the storage area of ​​the irradiation completion period information 1235 of the storage unit 123. The present invention is not limited to this embodiment. In the third embodiment, an irradiation completion period is also calculated by setting two irradiation completion periods for the (N-1)th and (N-2)th irradiations based on the (N-2)th irradiation completion time Tb1 and the (N)th irradiation completion time Tb3. In this embodiment, when determining whether the irradiation completion period has been determined, a comparison and determination are performed for each irradiation completion period, including one and two irradiation completion periods set together. Here, an example of calculating an irradiation completion period set together with two irradiation completion periods has been described, but for example, an irradiation completion period set together with three irradiation completion periods or an irradiation completion period set together with four or more irradiation completion periods may also be calculated.

[0114] In this third embodiment, the correction data acquisition unit 1218 updates and acquires correction data for each of multiple irradiation end cycles in the radiation R irradiation end cycle, which is determined based on the period between two consecutive irradiation end times in time series.

[0115] According to the third embodiment, since the irradiation end cycle can be determined for each of the multiple irradiations of radiation R, the correction data can be updated and acquired as a single set for each of the multiple irradiations of radiation R.

[0116] (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.

[0117] 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.

[0118] This embodiment includes the following configurations, methods, and programs. [Configuration 1] A radiography apparatus that takes images of a subject using radiation emitted from a radiation generator without synchronizing with the radiation generator, A start time acquisition means for acquiring the start time of the radiation irradiation, An end time acquisition means for acquiring the end time of the radiation irradiation, Non-irradiation period setting means for setting a non-irradiation period of radiation based on the end time of irradiation in the first irradiation period of the radiation and the start time of irradiation in the second irradiation period, which is the irradiation period following the first irradiation period of the radiation; A correction data acquisition period during which the subject is not irradiated with radiation, and during which correction data is acquired for correcting the radiation image obtained by photographing the subject using the radiation, An acquisition period setting means for setting the correction data acquisition period based on the start time for acquiring the correction data determined based on the end time of the radiation irradiation, and the non-irradiation period of the radiation, A correction data acquisition means that acquires the correction data using the correction images obtained from the shooting during the correction data acquisition period, A radiography apparatus characterized by having the following features. [Configuration 2] The correction data acquisition means calculates the number of correction images to be taken based on the correction data acquisition period and the frame rate of the radiographic image, and acquires the correction data using that number of correction images. The radiography apparatus according to configuration 1, characterized by the above. [Configuration 3] The correction images for the aforementioned number of shots are multiple correction images, The correction data acquisition means acquires the correction data by averaging the plurality of correction images. The radiography apparatus according to configuration 2, characterized in that it is a radiographic apparatus. [Structure 4] The acquisition period setting means sets the acquisition start time of the correction data based on the end time of radiation irradiation and the non-irradiation period of radiation. A radiography apparatus according to any one of configurations 1 to 3, characterized by the features described herein. [Composition 5] The system further includes radiation detection means for detecting the aforementioned radiation as an electrical signal related to the aforementioned radiation image, The acquisition period setting means sets the acquisition start time of the correction data based on the end time of radiation irradiation, the dose information of the radiation when the subject is photographed, and the emission time of the residual electrical signal of the radiation detection means. A radiography apparatus according to any one of configurations 1 to 3, characterized by the features described herein. [Composition 6] The acquisition period setting means sets the period from the start time of acquisition of the correction data to the end time of the non-irradiation period of the radiation, if the start time of acquisition of the correction data falls within the non-irradiation period of the radiation, as the correction data acquisition period. A radiography apparatus according to any one of configurations 1 to 5, characterized by the features described herein. [Composition 7] The acquisition period setting means sets the acquisition period for the correction data to a predetermined period prior to the end time of the non-irradiation period of the radiation, if the start time of acquisition of the correction data is not included in the non-irradiation period of the radiation. A radiography apparatus according to any one of configurations 1 to 5, characterized by the features described herein. [Structure 8] The radiation detection means further includes an imaging pixel for detecting the radiation as an electrical signal relating to the radiation image, and a detection pixel for detecting the dose of the radiation. The start time acquisition means acquires the irradiation start time of the radiation without using the radiation dose detected using the detection pixel, The termination time acquisition means acquires the termination time of radiation irradiation using the radiation dose detected using the detection pixels. A radiography apparatus according to any one of configurations 1 to 7, characterized by the above. [Composition 9] The system further includes a power supply means that supplies a bias current to the imaging pixel and the detection pixel via a bias line, The start time acquisition means acquires the irradiation start time of the radiation based on the value of the bias current. The radiography apparatus according to configuration 8, characterized by the above. [Configuration 10] Until the start time acquisition means acquires the irradiation start time of the radiation, the value of the bias current is detected, and the detection of the radiation dose by the detection pixel is stopped. After the start time acquisition means acquires the irradiation start time of the radiation, the radiation image is acquired and the radiation dose is detected by the detection pixels, and the detection of the bias current value is stopped. After the termination time acquisition means acquires the termination time of the radiation irradiation, the value of the bias current is detected, and the detection of the radiation dose by the detection pixel is stopped. The radiography apparatus according to configuration 9, characterized by the features described herein. [Composition 11] If the period of the radiation at the end of irradiation time, as obtained by the end time acquisition means, falls outside a predetermined range, The means for obtaining the end time acquires the end time of the radiation irradiation again, The non-irradiation period setting means resets the non-irradiation period for the radiation, The acquisition period setting means resets the correction data acquisition period, The correction data acquisition means acquires the correction data again. A radiography apparatus according to any one of configurations 1 to 10, characterized by the above. [Composition 12] The correction data acquisition means updates and acquires the correction data for each of the multiple irradiation end cycles in the radiation irradiation end cycle, which is determined based on the period between two consecutive irradiation end times in time series. A radiography apparatus according to any one of configurations 1 to 11, characterized by the features described herein. [Method 1] A control method for a radiographic imaging apparatus that uses radiation emitted from a radiation generator to photograph a subject without synchronizing with the radiation generator, A start time acquisition step to acquire the start time of the radiation irradiation, A step to obtain the end time of the radiation irradiation, A non-irradiation period setting step, which sets a non-irradiation period for the radiation based on the end time of irradiation in the first irradiation period of the radiation and the start time of irradiation in the second irradiation period, which is the next irradiation period after the first irradiation period of the radiation; A correction data acquisition period during which the subject is not irradiated with radiation, and during which correction data is acquired for correcting the radiation image obtained by photographing the subject using the radiation, An acquisition period setting step in which the acquisition period for the correction data is set based on the start time for acquiring the correction data determined based on the end time of the radiation irradiation, and the non-irradiation period of the radiation, A correction data acquisition step in which correction data is acquired using correction images obtained during the correction data acquisition period, A method for controlling a radiography apparatus, characterized by having the following features. [Program 1] A program for causing a computer to perform each step in the method for controlling a radiographic apparatus described in Method 1. [Explanation of symbols]

[0119] 10: Radiography system, 100: Radiography device, 110: Radiation detection unit, 120: Control unit, 121: Drive control unit, 1211: Image acquisition control unit, 1212: Irradiation dose measurement unit, 1213: Frame rate management unit, 1214: Irradiation start time acquisition unit, 1215: Irradiation end time acquisition unit, 1216: Non-irradiation period setting unit, 1217: Correction data acquisition period setting unit, 1218: Correction data acquisition unit, 122: Image processing unit, 123: Memory unit, 124: Communication control unit, 125: Internal clock, 300: Radiation generator, 310: Radiation generation control unit, 320: Radiation source, 330: Operation UI, H: Subject, R: Radiation

Claims

1. A radiography apparatus that takes images of a subject using radiation emitted from a radiation generator without synchronizing with the radiation generator, A start time acquisition means for acquiring the start time of the radiation irradiation, An end time acquisition means for acquiring the end time of the radiation irradiation, Non-irradiation period setting means for setting a non-irradiation period of radiation based on the end time of irradiation in the first irradiation period of the radiation and the start time of irradiation in the second irradiation period, which is the irradiation period following the first irradiation period of the radiation; A correction data acquisition period for acquiring correction data to correct a radiation image obtained by photographing the subject using the radiation during a period when the radiation is not being applied, comprising an acquisition period setting means for setting the correction data acquisition period based on a start time for acquiring the correction data determined based on the end time of radiation irradiation and the period when the radiation is not being applied, A correction data acquisition means that acquires the correction data using the correction images obtained from the shooting during the correction data acquisition period, A radiography apparatus characterized by having the following features.

2. The correction data acquisition means calculates the number of correction images to be taken based on the correction data acquisition period and the frame rate of the radiographic image, and acquires the correction data using that number of correction images. The radiography apparatus according to feature 1.

3. The correction images for the aforementioned number of shots are multiple correction images, The correction data acquisition means acquires the correction data by averaging the plurality of correction images. The radiography apparatus according to feature 2.

4. The acquisition period setting means sets the acquisition start time of the correction data based on the end time of radiation irradiation and the non-irradiation period of radiation. The radiography apparatus according to feature 1.

5. The system further includes radiation detection means for detecting the aforementioned radiation as an electrical signal related to the aforementioned radiation image, The acquisition period setting means sets the acquisition start time of the correction data based on the end time of radiation irradiation, the dose information of the radiation when the subject is photographed, and the emission time of the residual electrical signal of the radiation detection means. The radiography apparatus according to feature 1.

6. The acquisition period setting means sets the period from the start time of acquisition of the correction data to the end time of the non-irradiation period of the radiation, if the start time of acquisition of the correction data falls within the non-irradiation period of the radiation, as the correction data acquisition period. The radiography apparatus according to feature 1.

7. The acquisition period setting means sets the acquisition period for the correction data to a predetermined period prior to the end time of the non-irradiation period of the radiation, if the start time of acquisition of the correction data is not included in the non-irradiation period of the radiation. The radiography apparatus according to feature 1.

8. The radiation detection means further includes an imaging pixel for detecting the radiation as an electrical signal relating to the radiation image, and a detection pixel for detecting the dose of the radiation. The start time acquisition means acquires the irradiation start time of the radiation without using the radiation dose detected using the detection pixel, The termination time acquisition means acquires the termination time of radiation irradiation using the radiation dose detected using the detection pixels. The radiography apparatus according to feature 1.

9. The system further includes a power supply means that supplies a bias current to the imaging pixel and the detection pixel via a bias line, The start time acquisition means acquires the irradiation start time of the radiation based on the value of the bias current. The radiography apparatus according to Feature 8.

10. Until the start time acquisition means acquires the irradiation start time of the radiation, the value of the bias current is detected, and the detection of the radiation dose by the detection pixel is stopped. After the start time acquisition means acquires the irradiation start time of the radiation, the radiation image is acquired and the radiation dose is detected by the detection pixels, and the detection of the bias current value is stopped. After the termination time acquisition means acquires the termination time of the radiation irradiation, the value of the bias current is detected, and the detection of the radiation dose by the detection pixel is stopped. The radiography apparatus according to feature 9.

11. If the period of the radiation at the end of irradiation time, as obtained by the end time acquisition means, falls outside a predetermined range, The means for obtaining the end time acquires the end time of the radiation irradiation again, The non-irradiation period setting means resets the non-irradiation period for the radiation, The acquisition period setting means resets the correction data acquisition period, The correction data acquisition means acquires the correction data again. The radiography apparatus according to feature 1.

12. The correction data acquisition means updates and acquires the correction data for each of the multiple irradiation end cycles in the radiation irradiation end cycle, which is determined based on the period between two consecutive irradiation end times in a time series. The radiography apparatus according to feature 1.

13. A control method for a radiographic imaging apparatus that uses radiation emitted from a radiation generator to photograph a subject without synchronizing with the radiation generator, A start time acquisition step to acquire the start time of the radiation irradiation, A step to obtain the end time of the radiation irradiation, A non-irradiation period setting step, which sets a non-irradiation period for the radiation based on the end time of irradiation in the first irradiation period of the radiation and the start time of irradiation in the second irradiation period, which is the irradiation period following the first irradiation period of the radiation; A correction data acquisition period for acquiring correction data to correct a radiation image obtained by photographing the subject using the radiation during a period when the radiation is not being applied, comprising an acquisition period setting step of setting the correction data acquisition period based on a start time for acquiring the correction data determined based on the end time of radiation irradiation and the period when the radiation is not being applied, A correction data acquisition step in which correction data is acquired using correction images obtained during the correction data acquisition period, A method for controlling a radiography apparatus, characterized by having the following features.

14. A program for causing a computer to perform each step in the control method of a radiography apparatus described in claim 13.

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