Radiation imaging apparatus, radiation imaging system, and method and program for controlling radiation imaging apparatus

Abstract

To provide a technique advantageous for improvement of accuracy of AEC in a radiation imaging apparatus.SOLUTION: A radiation imaging apparatus comprises: an imaging region in which a plurality of conversion elements used for an imaging operation of acquiring a radiation image according to the incidence of a radiation are arranged; a plurality of detection units in which elements for detection for detecting a radiation dose incident on the imaging region are arranged; and a control unit. The control unit is configured to perform an offset readout operation of reading out offset signals of the elements for detection from the plurality of detection units in such a state that the radiation is not irradiated before the imaging operation, perform detection of the radiation dose incident on the imaging region by using signals output from the elements for detection during the irradiation of the radiation and the offset signals in the imaging operation, and be able to change an order of reading out the offset signals from the plurality of detection units according to an imaging condition in the imaging operation during a period of the offset readout operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a radiation imaging apparatus, a radiation imaging system, and a method and program for controlling a radiation imaging apparatus. [Background technology]

[0002] In medical image diagnosis and non-destructive testing, radiation imaging devices using a flat panel detector (FPD) made of semiconductor material are widely used. It is known that such radiation imaging devices monitor radiation incident on the radiation imaging device. By detecting the radiation amount in real time, it is possible to grasp the cumulative dose of radiation incident during radiation irradiation and perform automatic exposure control (AEC). Patent Document 1 shows that in order to detect the radiation amount more accurately, an offset amount of a detection pixel used to detect the radiation amount is acquired in advance, and a signal output from the detection pixel during radiation irradiation is corrected according to the previously acquired offset amount. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-089714 A Summary of the Invention [Problem to be solved by the invention]

[0004] The detection pixels that detect the radiation dose in real time may be arranged in multiple regions to accommodate multiple imaging techniques, and it is necessary to acquire an offset amount from the detection pixels arranged in each region. In addition, since the offset amount varies depending on environmental changes such as the temperature of the radiation imaging device, it is necessary to reacquire the offset amount of the detection pixels in each region as appropriate and update the offset amount data. The offset amount of the detection pixels is acquired while radiation is not being irradiated. In cases such as when imaging radiation images at short intervals, depending on the order in which the offset amount data of the detection pixels in each region is updated, radiation irradiation may start before updating the offset amount data of the detection pixels used for AEC.

[0005] An object of the present invention is to provide a technique that is advantageous for improving the accuracy of AEC in a radiation imaging apparatus. [Means for solving the problem]

[0006] In consideration of the above problem, a radiation imaging apparatus according to an embodiment of the present invention is a radiation imaging apparatus including: an imaging region in which a plurality of conversion elements are arranged for use in an imaging operation for acquiring a radiation image in response to incidence of radiation; a plurality of detection units in which detection elements for detecting an amount of radiation incident on the imaging region are respectively arranged; and a control unit, wherein the control unit is configured to perform an offset readout operation for reading out offset signals of the detection elements from the plurality of detection units in a state in which radiation is not being irradiated prior to the imaging operation, detect the amount of radiation incident on the imaging region using the offset signals and signals output from the detection elements during irradiation of radiation during the imaging operation, and change an order in which the offset signals are read out from the plurality of detection units during the offset readout operation in accordance with imaging conditions in the imaging operation. The control unit has a function of storing a frequency at which one of the plurality of detection units is designated as a detection unit for detecting a radiation dose in the imaging operation, and the control unit changes an order in which the offset signals are read out in accordance with the frequency. It is characterized by: Effect of the Invention

[0007] The above-mentioned means provides a technique that is advantageous for improving the accuracy of AEC in a radiation imaging apparatus. [Brief description of the drawings]

[0008] [Figure 1] FIG. 4 is a flowchart showing the flow of an imaging operation of the radiation imaging apparatus according to the present embodiment. [Diagram 2] 1 is a diagram showing an example of the arrangement of a radiation imaging system using a radiation imaging apparatus according to an embodiment of the present invention. [Diagram 3] 2 is a diagram showing the arrangement of an imaging area of ​​the radiation imaging apparatus according to the embodiment; [Figure 4] 5A and 5B are diagrams showing an example of an order in which offset signals are read out from the radiation imaging apparatus according to the embodiment. [Diagram 5] 5A and 5B are diagrams showing an example of an order in which offset signals are read out from the radiation imaging apparatus according to the embodiment. [Figure 6] 11A and 11B are diagrams showing a case where the orientation of an imaging area of ​​a radiation imaging apparatus according to the present embodiment is changed with respect to the up-down direction. [Figure 7] 5A and 5B are diagrams showing an example of an order in which offset signals are read out from the radiation imaging apparatus according to the embodiment. [Figure 8] 5A to 5C are diagrams showing an example of correction of an offset signal in the radiation imaging apparatus according to the embodiment. [Figure 9] 5A and 5B are diagrams showing an example of determining the order in which offset signals are read out from the radiation imaging apparatus according to the embodiment. [Figure 10] 5A and 5B are diagrams showing an example of determining the order in which offset signals are read out from the radiation imaging apparatus according to the embodiment. [Figure 11] 5A and 5B are diagrams showing an example of an order in which offset signals are read out from the radiation imaging apparatus according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] Furthermore, radiation in the present invention may include α-rays, β-rays, γ-rays, and other beams produced by particles (including photons) emitted by radioactive decay, as well as beams having the same or greater energy, such as X-rays, particle beams, and cosmic rays.

[0011] The configuration and operation of a radiation imaging apparatus according to this embodiment will be described with reference to Figs. 1 to 11. Fig. 1 is a flow diagram showing the flow of imaging operation of a radiation imaging apparatus 200 of this embodiment. Fig. 2 is a diagram showing an example of the configuration of a radiation imaging system SYS using the radiation imaging apparatus 200 according to this embodiment. Before describing the flow of imaging using the radiation imaging apparatus 200, the configuration of the radiation imaging apparatus 200 will be described. This radiation imaging apparatus 200 can be used, for example, for medical purposes.

[0012] 2, the radiation imaging system SYS includes a radiation imaging device 200 and a radiation generating device 201 that irradiates radiation to the radiation imaging device 200. The radiation generating device 201 irradiates a subject P with radiation. The radiation generating device 201 can be configured to include a radiation generating unit (bulb) that generates radiation, a collimator that defines the beam spread angle of the radiation generated in the radiation generating unit, and a radiation dosimeter attached to the collimator.

[0013] 2, the radiation imaging device 200 may include an imaging section 202, a setting section 203, a control section 204, a processing section 205, and a display section 206. The imaging section 202 includes an imaging region in which a plurality of conversion elements are arranged for use in an imaging operation for acquiring a radiation image in response to incidence of radiation, and a plurality of detection sections in which detection elements for detecting the amount of radiation incident on the imaging region are arranged. The imaging section 202 may be, for example, a flat panel detector (FPD) having a plurality of conversion elements distributed two-dimensionally, detecting the two-dimensional distribution of radiation that has reached the imaging section 202, and generating radiation image data. The imaging section 202 transmits radiation image data generated by the plurality of conversion elements during the imaging operation to the processing section 205. The imaging section 202 also transmits information on the amount of radiation detected by the detection section to the control section 204.

[0014] FIG. 3 is a diagram showing an example of the configuration of the imaging unit 202 of the radiation imaging device 200 of this embodiment. The imaging unit 202 has an imaging region 300 in which a plurality of conversion elements 301 for acquiring a radiation image are arranged. The conversion elements 301 may also be called pixels. The imaging unit 202 also has a plurality of detection units 302 in which detection elements 312 for detecting the amount of radiation incident on the imaging region are arranged. As shown in FIG. 2, the detection units 302 may be arranged in line with the conversion elements 301 in the imaging region 300, or may be arranged on the outer edge of the imaging region 300, or may be arranged outside the imaging region 300. In this embodiment, the detection units 302 are set in five regions, region A, region B, region C, region D, and region E. The detection elements 312 are arranged in three rows in each of the detection units 302 in regions A to E. The amount of radiation incident on the imaging region 300 is detected by one of the multiple detection units 302 or by a combination of two or more of them. In this embodiment, the detection units 302 are set in five regions A to E, and the detection elements 312 are arranged in three rows in each detection unit 302, but this is not limited to this. For example, the detection units 302 may be set in four or less regions, or six or more regions. Furthermore, the arrangement of the detection elements 312 in each detection unit 302 may be one or more. This may be set appropriately depending on the specifications required for the radiation imaging device 200.

[0015] The setting unit 203 has a configuration for an operator (e.g., a radiologist) to input imaging conditions such as an imaging site, a target dose, irradiation conditions set in the radiation generating device 201 for irradiating the radiation imaging device 200 with radiation, and information specifying an imaging technique. The irradiation conditions may be conditions such as a tube voltage kV, a tube current mA, a collimator, and a filter set in the radiation generating device 201. The setting unit 203 may include, for example, a keyboard or a touch panel for the operator to input the imaging conditions. In the configuration shown in FIG. 2, the radiation imaging device 200 includes the setting unit 203, but the present invention is not limited to this. The setting unit 203 may be disposed outside the radiation imaging device 200. When the imaging conditions are input to the setting unit 203, the setting unit 203 transmits information on the imaging conditions input by the operator to the control unit 204.

[0016] The control unit 204 controls each component of the radiation imaging device 200. Before an imaging operation is started by an operator pressing an exposure switch or the like requesting irradiation of radiation, an offset readout operation is performed to read out offset signals of the detection elements 312 from the multiple detection units 302 in a state where radiation is not being irradiated. At this time, the offset signals may be read out from the conversion elements 301 arranged in the imaging region 300. In addition, in the imaging operation, the control unit 204 detects the amount of radiation incident on the imaging region 300 using signals output from the detection elements 312 during irradiation of radiation and offset signals acquired before the imaging operation. That is, the control unit 204 performs a correction process on signals acquired from the detection elements 312 arranged in the detection unit 302 during irradiation of radiation, using offset signals acquired before the imaging operation. This improves the accuracy of detecting the amount of radiation.

[0017] The processing unit 205 performs processes such as gradation processing and noise reduction processing on data of a radiation image acquired by a plurality of conversion elements 301 arranged in an imaging region 300 of the imaging unit 202 in an imaging operation. For example, the processing unit 205 may perform correction processing of the radiation image data using an offset signal of the conversion elements 301 acquired before the imaging operation. The processing unit 205 transmits the processed radiation image data to the display unit 206. The display unit 206 displays the radiation image on a monitor or the like according to the data output from the processing unit 205. In the configuration shown in FIG. 2, the radiation imaging device 200 includes the processing unit 205 and the display unit 206, but is not limited to this. The processing unit 205 and the display unit 206 may be arranged outside the radiation imaging device 200.

[0018] Next, a flow of imaging operation of the radiation imaging device 200 of this embodiment will be shown with reference to FIG. 1. When the radiation imaging device 200 is powered on, in S101, the control unit 204 acquires offset signals of the detection elements 312 from all of the five detection units 302 arranged in the imaging unit 202. The control unit 204 acquires and stores offset signals of the detection elements 312 of the regions A to E of the detection unit 302. As shown in FIG. 2, the radiation imaging device 200 may be provided with a memory 207 for storing data of the acquired offset signals. The memory 207 may be provided inside the control unit 204. When the storage of the offset signals output from the detection elements 312 of all the detection units 302 is completed, the control unit 204 transitions from S101 to S102.

[0019] The period from S102 to S110 is a period of an offset readout operation in which offset signals of the detection elements 312 are read out from the multiple detection units 302 in a state where radiation is not irradiated before the imaging operation. In S102, the control unit 204 determines the order in which offset signals are read out from the multiple detection units 302 (regions A to E). The control unit 204 may control the imaging unit 202 to start reading out offset signals in a predetermined order in response to the start of the offset readout operation. For example, the control unit 204 may read out offset signals from the detection elements 312 of each detection unit 302 in an order according to the distance of the multiple detection units 302 from the center of the imaging region 300. For example, the control unit 204 may determine the order so that offset signals are read out from the region closest to the center of the imaging region 300 for the five detection units 302 (regions A to E) arranged in the imaging unit 202 as shown in FIG. 4. Also, for example, the control unit 204 may determine the order in which offset signals are read out from the region farthest from the imaging region 300.

[0020] When the order of acquiring offset signals is determined in S102, the control unit 204 transitions to S103 and controls the imaging unit 202 to acquire offset signals in the determined order. The imaging unit 202, under the control of the control unit 204, causes the detection elements 312 of each detection unit 302 to output offset signals in the order determined in S102. The control unit 204 stores the offset signal data read from the detection elements 312 of the detection unit 302 in the memory 207. At that time, if there is offset signal data acquired from the detection elements 312 of the same detection unit 302 previously acquired, the control unit 204 overwrites the new offset signal data.

[0021] When the reading of the offset signal in S103 starts, the process transitions to S104, and the control unit 204 checks whether the operator has set the imaging conditions using the setting unit 203. In this embodiment, the imaging conditions may be, as described above, the imaging site, the target dose of radiation irradiated to the subject P, irradiation conditions set in the radiation generating device 201 such as the tube voltage kV and the tube current mA, and information specifying the imaging procedure. When the imaging conditions are input and set by the operator, the setting unit 203 transmits information on the imaging conditions set by the operator to the control unit 204, and when the control unit 204 receives the information on the imaging conditions, the process transitions to S105. When the imaging conditions are not set, the process transitions to S103, and the control unit 204 performs a process of acquiring the offset signals in the order determined in S102. At this time, for example, when the control unit 204 makes a determination in S104 when reading out the offset signal from the detection element 312 of the detection unit 302 in the region B and transitions to S103, the control unit 204 may resume reading out the offset signal from the detection element 312 of the detection unit 302 in the region C. Furthermore, the control unit 204 may perform the reading of the offset signal in S103 and the determination in S104 in parallel.

[0022] When the imaging conditions are set in S104 and the process proceeds to S105, the control unit 204 performs control to change the order in which offset signals are read out in accordance with the set imaging conditions. First, in S105, the control unit 204 refers to the imaging conditions set in S104 and determines a new order in which offset signals are read out from the multiple detection units 302 arranged in the imaging unit 202.

[0023] For example, when information of "imaging of lungs" which is information specifying an imaging technique is set as an imaging condition, the control unit 204 determines the order to read out offset signals from the detection unit 302 located at the upper part of the imaging region 300. In this case, for example, as shown in Fig. 5, offset signals may be read out in the order of upper-center-lower part. Also, for example, when information of "imaging of stomach" is set, the control unit 204 determines the order to read out offset signals from the detection unit 302 located at the center of the imaging region 300 as shown in Fig. 4.

[0024] When the order of acquiring the offset signals is determined in S105, the control unit 204 transitions to S106 and controls the imaging unit 202 to acquire the offset signals in the determined order. The imaging unit 202, under the control of the control unit 204, causes the detection elements 312 of each detection unit 302 to output offset signals in the order determined in S105. The control unit 204 stores the offset signal data read from the detection elements 312 of the detection unit 302 in the memory 207. At that time, if there is offset signal data acquired from the detection elements 312 of the same detection unit 302 previously acquired, the control unit 204 overwrites the new offset signal data.

[0025] When the reading of the offset signal in S106 starts, the process transitions to S107, and the control unit 204 checks whether the operator has specified a detection unit 302 to detect the radiation amount in the imaging operation from among the multiple detection units 302 (areas A to E) using the setting unit 203. When the detection unit 302 to be used when detecting the radiation amount has been specified, the setting unit 203 transmits information of the detection unit 302 specified by the operator to the control unit 204, and when the control unit 204 receives the information of the detection unit 302 to be used for detecting the radiation amount, the process transitions to S108. When the detection unit 302 to be used has not been specified, the process returns to S106, and the control unit 204 continues the process of acquiring the offset signal in the order determined in S105. At this time, the control unit 204 may resume reading the offset signal from the detection unit 302 next in order to the detection unit 302 that read the signal before the determination in S107 was made, in the order determined in S105. Similar to the operations of S103 and S104 described above, the control unit 204 may execute S107 in parallel with S106.

[0026] When the detection unit 302 to be used in detecting the amount of radiation is designated in S107 and the process proceeds to S108, the control unit 204 determines the order in which to read out the offset signals from the designated detection unit 302 among the multiple detection units 302. At this time, the control unit 204 may determine the order so that the offset signals are acquired only from the detection unit 302 designated by the operator among the multiple detection units 302. For example, when one detection unit 302 is designated, the control unit 204 may determine to read out the offset signals continuously from the one designated detection unit 302. Also, for example, when two detection units are designated, the control unit 204 may determine to read out the offset signals alternately from the two designated detection units 302.

[0027] When the order of acquiring the offset signals is determined in S108, the control unit 204 transitions to S109 and controls the imaging unit 202 to acquire the offset signals in the determined order. The imaging unit 202, under the control of the control unit 204, causes the detection elements 312 of each detection unit 302 to output offset signals in the order determined in S108. The control unit 204 stores the offset signal data read from the detection elements 312 of the detection unit 302 in the memory 207. At that time, if there is offset signal data acquired from the detection elements 312 of the same detection unit 302 previously acquired, the control unit 204 overwrites the new offset signal data.

[0028] S110 is performed in parallel with S109. In S110, the control unit 204 determines whether or not the operator has requested irradiation of radiation. Specifically, when an irradiation request signal for requesting irradiation of radiation, which is generated by the operator pressing an exposure switch, etc., has been input to the control unit 204, the process proceeds to S111. When an irradiation request signal has not been input, the control unit 204 continues the process of acquiring an offset signal in S109.

[0029] When an irradiation request signal is input to the control unit 204 in S110 and the process transitions to S111, the control unit 204 transmits an irradiation command signal to the radiation generation device 201. Upon receiving the irradiation command signal, the radiation generation device 201 starts irradiating radiation in accordance with the irradiation command signal. Furthermore, the control unit 204 causes the conversion element 301 to start a storage operation for acquiring a radiation image, and starts reading out a signal for detecting the amount of incident radiation from the detection element 312 of the detection unit 302 specified in S107. This starts imaging of a radiation image by automatic exposure control (AEC) (hereinafter, may be referred to as AEC imaging). The operations from S111 to S116 correspond to a period of imaging operation for acquiring a radiation image in response to the incidence of radiation.

[0030] In the AEC imaging, the imaging unit 202, under the control of the control unit 204, causes a signal to be output from the detection element 312 of the detection unit 302 specified in S107. The control unit 204 performs offset correction on the signal read from the detection element 312, based on the offset signal data output from the detection element 312 of the same detection unit 302 stored in the memory 207. The control unit 204 sequentially adds the signals after the offset correction. When the added signal reaches the target dose set in S104, the control unit 204 transmits an irradiation end signal to the radiation generation device 201, and the process transitions to S112.

[0031] In S112, when the radiation generation device 201 receives the irradiation end signal, it stops irradiating radiation and ends the AEC imaging. Also, the control unit 204 ends the operation of reading out the signal from the detection element 312 of the detection unit 302. When the AEC imaging ends, the process proceeds to S113. In S113, the control unit 204 transmits the data of the radiation image acquired by each of the conversion elements 301 arranged in the imaging region 300 of the imaging unit 202 to the processing unit 205. Next, in S114, the processing unit 205 performs correction processing such as gradation processing and noise reduction processing on the data of the radiation image acquired by the conversion elements 301. The radiation image data corrected by the processing unit 205 is transmitted to the display unit 206. When the display unit 206 receives the data of the radiation image, in S115, the display unit 206 converts the received data of the radiation image into a two-dimensional image and displays it to the operator. Next, in S116, if the control unit 204 receives an imaging end signal indicating that there is no subsequent imaging, it ends the imaging flow shown in FIG. 1, and if the control unit 204 does not receive an imaging end signal, it returns to S102.

[0032] 1 shows an example in which the radiation imaging apparatus 200 performs correction processing and display of radiation image data, but the present invention is not limited to this. For example, in S113, the control unit 204 may output radiation image data to the outside of the radiation imaging apparatus 200. In this case, processing such as correction of the acquired radiation image data and display may be performed by a processing device or a display device disposed outside the radiation imaging apparatus 200. In this case, the processing of S114 and S115 may not be performed.

[0033] As described above, the radiation imaging device 200 of this embodiment is configured to be able to change the order in which offset signals are read out from the multiple detection units 302 according to the imaging conditions in the imaging operation during the offset readout operation performed before the imaging operation. This makes it possible, for example, to update the offset signal data of the detection elements 312 used when detecting the amount of radiation preferentially from the detection units 302 used for AEC. This makes it possible to reduce the possibility that radiation irradiation will start before updating the offset signal data of the detection elements 312 used for AEC. In other words, it becomes possible to correct the offset amount of the detection units 302 that may change due to changes in the environment of the radiation imaging device 200 with high accuracy, and it is possible to realize the radiation imaging device 200 that is capable of high-accuracy AEC imaging.

[0034] In this embodiment, the radiation imaging device 200 may further include a detection unit 601 that detects the orientation (rotation angle) of the imaging region 300 with respect to the up-down direction as shown in FIG. 6. The detection unit 601 may be disposed in the imaging unit 202 in which the imaging region 300 is disposed. The control unit 204 may change the order of reading out the offset signals according to the orientation detected by the detection unit. FIG. 6 shows a state in which the imaging region 300 shown in FIG. 3 is rotated 90 degrees clockwise. The control unit 204 uses the up-down direction of the imaging region 300 detected by the detection unit 601 to determine that the regions A and C of the detection unit 302 are the detection unit 302 located at the top. For example, when the orientation of the imaging region 300 is changed as shown in FIG. 6, the control unit 204 changes the order so that the offset signals are read out in the order shown in FIG. 7, with respect to the arrangement of the regions of the detection unit 302 shown in FIG. 3 and the readout order shown in FIG. 4.

[0035] Furthermore, in the case where the imaging unit 202 has a configuration capable of simultaneously acquiring offset signals from a plurality of detection units 302, in S103, S106, and S109, the control unit 204 may read out offset signals in parallel from two or more of the plurality of detection units 302. By reading out offset signals in parallel from a plurality of detection units 302, it becomes possible to shorten the interval for reading out the offset signals. This makes it possible to acquire newer offset signal data during the period until the imaging operation of the AEC imaging is started, and the offset amount of the detection unit 302 can be corrected with high accuracy, thereby realizing high-accuracy AEC imaging.

[0036] Furthermore, the detection elements 312 may detect the amount of incident radiation using a signal output from each element, or may detect the amount of incident radiation using signals output from multiple elements. Furthermore, the detection elements 312 may include a first element and a second element having different sensitivities, and the control unit 204 may detect the amount of radiation incident on the imaging region 300 using the signals output from the first element and the second element.

[0037] A case where radiation dose is detected using elements with different sensitivities will be described with reference to FIG. 8. First, the control unit 204 acquires offset signals O1 and O2 from a first element of the detection elements 312 and a second element having a lower sensitivity to radiation than the first element (S101, S106, S109). The offset signal O1 of the first element contains a dark component D1 that occurs regardless of the irradiation of radiation, as shown in FIG. 8. The offset signal O2 of the second element contains a dark component D2 that occurs regardless of the irradiation of radiation, as shown in FIG. 8. Here, the second element is, for example, completely shielded from light and has no sensitivity to radiation. The control unit 204 stores the data of the offset signals D1 and D2 in the memory 207.

[0038] Next, when irradiation of radiation is started in S111, the control unit 204 reads out the signals S1 and S2 from the first element and the second element at a predetermined interval. As shown in FIG. 8, the signal S1 of the first element that is read out includes a dark component D1 that occurs regardless of irradiation of radiation, a crosstalk component CT that occurs between the adjacent conversion element due to irradiation of radiation, and a signal component R of radiation. Similarly, as shown in FIG. 8, the signal S2 of the second element includes a dark component D2 that occurs regardless of irradiation of radiation, and a crosstalk component CT that occurs between the adjacent conversion element due to irradiation of radiation. The second element does not include the signal component R of radiation because it does not have sensitivity to radiation. The control unit 204 performs offset correction on the signals S1 and S2 of the first element and the second element that are irradiating radiation, respectively, using the data of the offset signals O1 and O2 of the first element and the second element. This makes it possible to remove the dark components D1 and D2 from the signals S1 and S2 of the first element and the second element.

[0039] As a result, the signal C1 of the first element after the offset correction includes a signal component R and a crosstalk component CT generated by the irradiation of radiation, and the signal C2 of the second element after the offset correction includes the crosstalk component CT. The control unit 204 subtracts the signal C2 of the second element after the offset correction from the signal C1 of the first element after the offset correction. As a result, a signal SS from which the crosstalk component CT generated in the signal S1 output by the first element has been removed is obtained. The control unit 204 sequentially adds the signals SS. When the added signal SS reaches the target dose set in S104, the control unit 204 transmits a radiation irradiation end signal to the radiation generation device 201. As a result, the influence of crosstalk generated between the conversion elements and detection elements when detecting the amount of incident radiation can be corrected, and the radiation imaging device 200 capable of AEC imaging with higher accuracy can be realized.

[0040] Furthermore, when a radiation irradiation request signal is input during acquisition of offset signals in S109 (YES in S110), the control unit 204 interrupts the process of S109. In this case, when determining the order of reading out offset signals again in S102, the control unit 204 may determine the order to start reading out offset signals from the detection unit 302 whose acquisition has been interrupted. For example, in an offset readout operation after an imaging operation of interest, the control unit 204 may start reading out offset signals in an order according to the set imaging conditions (set in S104) from the next detection unit in the order according to the set imaging conditions, from the detection unit that was last read out of the multiple detection units 302 in the offset readout operation performed before the imaging operation of interest.

[0041] Next, a modified example of this embodiment will be described. In the radiation imaging device 200, there may be a large bias in the usage frequency of the detection unit 302 used in AEC imaging or the like depending on conditions such as the location where the radiation imaging device 200 is installed. Therefore, the control unit 204 may have a function of storing the frequency specified in S107 for each detection unit 302 as the detection unit 302 for detecting the radiation dose among the multiple detection units 302 in the imaging operation. For example, the control unit 204 may have a counter function and store the counted value in the memory 207. The control unit 204 may change the order of reading out the offset signal, for example, in S102, according to the frequency specified when detecting the radiation dose. In addition, for example, the control unit 204 may have a function of storing the frequency specified in S107 for each detection unit 302 in association with the imaging condition set in S104. In this case, when the imaging condition is set in S104, the control unit 204 may change the order of reading out the offset signal in S105 according to the frequency associated with the set imaging condition. This makes it possible to realize a radiation imaging device 200 that can correct the effects of environmental changes with high accuracy in an installation location where the frequency of use varies greatly, and can perform AEC imaging with high accuracy.

[0042] The control unit 204 counts the information of the detection units 302 specified by the operator in S107 for each of the five areas A to E. Fig. 9 shows, for example, the operation in S102. In S901, the control unit 204 refers to information on the frequency of use of each of the five detection units 302 arranged in the imaging unit 202 for detecting a radiation dose in AEC imaging. Next, in S902, the control unit 204 determines the order in which to read out offset signals from the detection units 302 that are most frequently used for detecting a radiation dose among the multiple detection units 302. This control enables high-precision AEC imaging even when there is a large bias in the frequency of use of the detection units 302 used for detecting a radiation dose.

[0043] Furthermore, when the control unit 204 stores the frequency designated in S107 for each detection unit 302 in association with the imaging conditions set in S104, the processes of S901 and S902 may be performed in S105. In this case, when the imaging conditions are set in S104, the control unit 204 refers to information on the frequency of use of each of the five detection units 302 arranged in the imaging unit 202 to detect the amount of radiation under the imaging conditions set in S104 (S901). Next, the control unit 204 determines the order in which offset signals are read out in order from the detection unit 302 that is most frequently used to detect the amount of radiation associated with the set imaging conditions among the multiple detection units 302 (S902). This makes it possible to read out offset signals in an order suitable for each imaging condition, thereby realizing high-precision AEC imaging.

[0044] Furthermore, the imaging conditions in the imaging operation may include information on the state in which the radiation imaging device 200 (imaging section 202) is placed. For example, the information on the state in which the radiation imaging device 200 is placed may include information on whether the radiation imaging device 200 is placed on a fluoroscopy table. Furthermore, when the radiation imaging device 200 is placed on a fluoroscopy table, the imaging conditions may include information on the posture of the fluoroscopy table, such as lying down or standing up. A case in which the imaging conditions include information on the state in which the radiation imaging device 200 is placed will be described with reference to FIG. 10.

[0045] FIG. 10 illustrates the process in S105. In S104, the operator sets information on the state in which the radiation imaging device 200 is placed as an imaging condition. When the setting unit 203 transmits the input information on the state in which the radiation imaging device 200 is placed to the control unit 204, the process transitions to S105, and the process illustrated in FIG. 10 is started. In S1001, the control unit 204 refers to the received information on the state in which the radiation imaging device 200 is placed, and determines whether or not the radiation imaging device 200 is placed on the fluoroscopy table. If the radiation imaging device 200 is placed on the fluoroscopy table, the process transitions to S1002. If the radiation imaging device 200 is not placed on the fluoroscopy table, the process transitions to S1005. In S1002, the control unit 204 refers to the attitude of the fluoroscopy table from the information on the state in which the radiation imaging device 200 is placed. If the attitude of the fluoroscopy table is a supine position, the process transitions to S1003. Furthermore, if the position of the X-ray table is in the upright position (NO in S1002), the process proceeds to S1004.

[0046] In S1003, the control unit 204 may determine the order of reading out the offset signals according to the frequency specified in S107 as the detection unit 302 for detecting the amount of radiation described above. For example, when the imaging conditions are set in S104, the control unit 204 may read out the offset signals in order from the detection unit 302 that is most frequently associated with the set imaging conditions.

[0047] In S1004, the control unit 204 determines the order so as to read out offset signals from the upper detectors among the multiple detection units 302, as shown in Fig. 5. This is because it is assumed that imaging of the lung field is performed when the position of the fluoroscopy table is in the upright position.

[0048] When the radiation imaging device 200 is not placed on the fluoroscopy table, imaging may be performed in various states. For this reason, in S1005, the control unit 204 determines to read out the offset signals in the same order determined in S102 before the imaging conditions are set in S104. For example, as described above, the order is determined to read out the offset signals from the detection unit 302 closest to the center of the imaging region 300.

[0049] The processes shown in S1001 to S1005 enable the acquisition of offset signal data that is likely to be used for detecting a radiation amount from the detection unit 302 with priority, depending on the state in which the radiation imaging device 200 is placed. This makes it possible to realize the radiation imaging device 200 that can perform AEC imaging with high accuracy by correcting the influence of environmental changes with high accuracy even in various places where the radiation imaging device 200 is placed.

[0050] The information on the state in which the radiation imaging apparatus 200 is placed is not limited to being input by the operator using the setting unit 203. For example, the radiation imaging apparatus 200 may have a sensor for determining whether or not it is placed on a fluoroscopy table. For example, a sensor for determining that it is placed on the fluoroscopy table may be arranged on a portion of the radiation imaging apparatus 200 that contacts the fluoroscopy table. Also, for example, a connector that physically or electrically connects the radiation imaging apparatus 200 and the fluoroscopy table may be arranged, and it may be determined that it is placed on the fluoroscopy table according to the connection state of the connector. Furthermore, the radiation imaging apparatus 200 may detect the orientation of the fluoroscopy table by a detection unit 601 as shown in FIG. 6.

[0051] Furthermore, the control unit 204 may cyclically change the order when reading out offset signals from the detection elements 312 of the detection unit 302. This makes it easier to read out offset signals from the detection elements 312 of the detection unit 302 arranged in different regions during imaging operations, even when imaging operations are repeated in a short period of time. This makes it possible to realize a radiation imaging device 200 that can correct the effects of environmental changes and the like with high accuracy in all of the detection units 302 and perform AEC imaging with high accuracy.

[0052] Fig. 11 is a diagram showing an example of cyclically changing the order of reading out offset signals. In S103, the control unit 204 first performs an operation of reading out offset signals from the detection unit 302 in the order I shown in Fig. 11. Next, after reading out offset signals from each of the multiple detection units 302, the control unit 204 performs an operation of reading out offset signals from the detection unit 302 in the order I+1 shown in Fig. 11. Furthermore, after reading out offset signals from each of the multiple detection units 302 in the order I+1, the control unit 204 performs an operation of reading out offset signals from the detection unit 302 in the order I+2 shown in Fig. 11. Thereafter, the control unit 204 performs an operation of reading out offset signals from the detection unit 302 in the order I+3 and the order I+4, and also performs an operation of reading out offset signals from the detection unit 302 in the order I.

[0053] In this way, the order of reading out the offset signals determined in S102 is the same (area A-area B-area C-area D-area E), but the order is cyclically changed every time the offset signals are read out from each of the multiple detection units 302. In this case, as shown in FIG. 11, the priority of the detection unit 302 from which the offset signal was read out with the highest priority in order I may be changed to the lowest in order I+1. Specifically, consider a first operation of reading out the offset signals from each of the multiple detection units 302, and a second operation of reading out the offset signals from each of the multiple detection units 302 following the first operation. In this case, the order of reading out the offset signals is changed in the second operation so that the offset signal is read out last from the detection unit from which the offset signal was read out first in the first operation among the multiple detection units 302. This makes it easier to read out the offset signals from all the detection units 302 even in a short period of time.

[0054] The timing of transition from the order I to the order I+1 may be the timing when the offset signal is read once from each of the multiple detection units 302, or the timing when the offset signal is read two or more times from each of the multiple detection units 302. Moreover, not only in S103 but also in the processes of S106 and S109, the order of reading the offset signals may be cyclically switched in the same manner.

[0055] By cyclically changing the order in which the offset signals are read out, even when, for example, imaging is repeated in which a radiation irradiation request signal is input while offset signal data is being acquired, it becomes easier to read offset signals from all of the detection units 302. As a result, the influence of environmental changes and the like is suppressed, and a radiation imaging device 200 capable of AEC imaging with high accuracy can be realized.

[0056] Furthermore, the radiation imaging apparatus 200 may further include a method designation unit that allows the operator to designate the above-mentioned various methods for changing the order in which the control unit 204 reads out the offset signals. For example, the setting unit 203 may have a function of a method designation unit that allows the operator to select a method for changing the order in which the offset signals are read out. The control unit 204 changes the order in which the offset signals are read out, as described above, according to the method input to the method designation unit.

[0057] The present invention can also be realized by executing the following process: That is, software (programs) that realize the functions of the above-described embodiments are supplied to a system or device via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or device reads and executes the programs.

[0058] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0059] 200: radiation imaging device, 204: control unit, 300: imaging region, 301: conversion element, 302: detection unit, 312: detection element

Claims

1. an imaging region in which a plurality of conversion elements are arranged for use in an imaging operation for acquiring a radiographic image in response to incidence of radiation; a plurality of detection units each including a detection element for detecting an amount of radiation incident on the imaging region; A control unit; A radiation imaging apparatus comprising: The control unit is performing an offset readout operation of reading out offset signals of the detection elements from the plurality of detection units in a state in which radiation is not irradiated, before the imaging operation; In the imaging operation, a radiation amount incident on the imaging region is detected using a signal output from the detection element during irradiation of radiation and the offset signal; an order in which the offset signals are read out from the plurality of detection units can be changed according to an imaging condition in the imaging operation during the offset readout operation; the control unit has a function of storing a frequency at which the detection unit is designated as a detection unit for detecting a radiation amount among the plurality of detection units in the imaging operation, The radiation imaging apparatus according to claim 1, wherein the control unit changes an order in which the offset signals are read out in accordance with the frequency.

2. 2 . The radiation imaging apparatus according to claim 1 , wherein the control unit reads out the offset signals from the plurality of detection units in order of frequency.

3. 3. The radiation imaging device according to claim 1, wherein the control unit starts reading out the offset signals in a predetermined order in response to a start of the offset readout operation, and when the imaging condition is set, changes the order in which the offset signals are read out in response to the set imaging condition.

4. The radiation imaging device according to claim 3, characterized in that after the imaging conditions are set, when a detection unit that detects the amount of radiation in the imaging operation is designated among the plurality of detection units, the control unit reads out the offset signal from the designated detection unit among the plurality of detection units.

5. the imaging operation includes a first imaging operation and a second imaging operation performed following the first imaging operation, the offset readout operation includes a first offset readout operation performed before the first imaging operation and a second offset readout operation performed between the first imaging operation and the second imaging operation, 5. The radiation imaging device according to claim 3, wherein in the second offset readout operation, the control unit starts reading out the offset signal in an order according to the set imaging conditions from a detection unit that is next in order in the order according to the set imaging conditions to the detection unit that was last read out among the multiple detection units in the first offset readout operation.

6. 6. The radiation imaging apparatus according to claim 3, wherein the predetermined order corresponds to a distance from a center of the imaging region of the plurality of detecting sections.

7. Further comprising a detection unit that detects an orientation of the imaging area with respect to a vertical direction, 7. The radiation imaging apparatus according to claim 1, wherein the control unit changes an order in which the offset signals are read out depending on the orientation.

8. 8. The radiation imaging device according to claim 1, wherein the imaging conditions include at least one of an imaging area, a target dose, an irradiation condition set in a radiation generating device for irradiating the radiation imaging device with radiation, and information specifying an imaging technique.

9. 9. The radiation imaging apparatus according to claim 1, wherein the imaging conditions include information on whether or not the radiation imaging apparatus is placed on an observation table.

10. 10. The radiation imaging apparatus according to claim 9, wherein, when the radiation imaging apparatus is placed on the X-ray table, the imaging conditions further include information on the orientation of the X-ray table.

11. the imaging conditions include information on whether the radiation imaging apparatus is placed on a fluoroscopy table; The control unit is When the radiation imaging apparatus is not placed on a fluoroscopy table, the offset signals are read out in the same order as before the imaging conditions were set; when the radiation imaging apparatus is placed on a fluoroscopy table and the fluoroscopy table is in a supine position, the offset signal is read out in accordance with the frequency; 3. The radiation imaging apparatus according to claim 1, wherein when the radiation imaging apparatus is placed on a fluoroscopy table and the fluoroscopy table is in an upright position, the offset signals are read out in order from an upper detection unit among the plurality of detection units.

12. the offset read operation includes a first operation of reading out the offset signal from each of the plurality of detection units, and a second operation of reading out the offset signal from each of the plurality of detection units subsequent to the first operation, 12. The radiation imaging apparatus according to claim 1, wherein the control unit cyclically switches an order in which the offset signals are read out between the first operation and the second operation.

13. 13. The radiation imaging apparatus according to claim 12, wherein the control unit, in the second operation, changes the order in which the offset signals are read out so that the offset signal is read out last from the detection unit among the plurality of detection units that first read the offset signal in the first operation.

14. a method designation unit for designating a method for changing the order in which the control unit reads out the offset signals; 14. The radiation imaging apparatus according to claim 1, wherein the control unit changes the order in which the offset signals are read out in accordance with the method input to a method designation unit.

15. The detection element includes a first element and a second element having different sensitivities from each other, 15. The radiation imaging apparatus according to claim 1, wherein the control unit detects an amount of radiation incident on the imaging region by using signals output from the first element and the second element.

16. 16. The radiation imaging apparatus according to claim 1, wherein the control unit reads out the offset signals in parallel from two or more of the plurality of detection units.

17. An imaging region in which a plurality of conversion elements are arranged for use in an imaging operation for acquiring a radiographic image in response to incidence of radiation; a plurality of detection units each including a detection element for detecting an amount of radiation incident on the imaging region; A control unit; A radiation imaging apparatus comprising: The control unit is performing an offset readout operation of reading out offset signals of the detection elements from the plurality of detection units in a state in which radiation is not irradiated, before the imaging operation; In the imaging operation, a radiation amount incident on the imaging region is detected using a signal output from the detection element during irradiation of radiation and the offset signal; an order in which the offset signals are read out from the plurality of detection units can be changed according to an imaging condition in the imaging operation during the offset readout operation; the control unit starts reading out the offset signals in a predetermined order in response to a start of the offset readout operation, and when the imaging condition is set, changes an order in which the offset signals are read out in response to the set imaging condition; the imaging operation includes a first imaging operation and a second imaging operation performed following the first imaging operation, the offset readout operation includes a first offset readout operation performed before the first imaging operation and a second offset readout operation performed between the first imaging operation and the second imaging operation, a control unit that starts reading out the offset signal from the next detection unit in the order according to the set imaging conditions, from the detection unit that was last read out among the multiple detection units in the first offset readout operation, in an order according to the set imaging conditions.

18. An imaging region in which a plurality of conversion elements are arranged for use in an imaging operation for acquiring a radiographic image in response to incidence of radiation; a plurality of detection units each including a detection element for detecting an amount of radiation incident on the imaging region; A control unit; A radiation imaging apparatus comprising: The control unit is performing an offset readout operation of reading out offset signals of the detection elements from the plurality of detection units in a state in which radiation is not irradiated, before the imaging operation; In the imaging operation, a radiation amount incident on the imaging region is detected using a signal output from the detection element during irradiation of radiation and the offset signal; an order in which the offset signals are read out from the plurality of detection units can be changed according to an imaging condition in the imaging operation during the offset readout operation; the offset read operation includes a first operation of reading out the offset signal from each of the plurality of detection units, and a second operation of reading out the offset signal from each of the plurality of detection units subsequent to the first operation, the control unit cyclically switches an order in which the offset signals are read out between the first operation and the second operation; The control unit, in the second operation, changes the order in which the offset signals are read out so that the offset signal is read out last from the detection unit among the multiple detection units that first read the offset signal in the first operation.

19. A radiation imaging apparatus according to any one of claims 1 to 18, a radiation generating device that irradiates the radiation imaging device with radiation; A radiation imaging system comprising:

20. 1. A method for controlling a radiation imaging apparatus including: an imaging area in which a plurality of conversion elements are arranged for use in an imaging operation for acquiring a radiation image in response to incidence of radiation; a plurality of detection units in which detection elements for detecting an amount of radiation incident on the imaging area are respectively arranged; and a memory, comprising: a step of reading out offset signals of the detection elements from the plurality of detection units in a state in which no radiation is irradiated, before the imaging operation; detecting an amount of radiation incident on the imaging region using a signal output from the detection element and the offset signal during irradiation of radiation in the imaging operation; the memory stores a frequency at which one of the plurality of detection units is designated as a detection unit for detecting a radiation amount during the imaging operation; A control method comprising: changing an order in which the offset signals are read out from the plurality of detection units in accordance with the frequency in the step of reading out the offset signals.

21. A program for causing a computer to execute each step of the control method according to claim 20.

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