Radiation imaging apparatus and radiation imaging system

Abstract

To provide a radiation imaging apparatus capable of achieving acquisition of offset correction information accurately and in a short time, and quickly starting imaging using latest offset information.SOLUTION: A radiation imaging apparatus includes: an acquisition unit for acquiring electric charge accumulated by the irradiation of a radioactive ray as image data, and acquiring accumulated electric charge without the irradiation of the radioactive ray as correction data; a control unit for controlling an operation of the acquisition unit; and an image processing unit for generating radiation image data using the image data and the correction data acquired by the acquisition unit. The control unit controls the acquisition unit so that the accumulation time of part of the elements and that of the other elements differs from each other while causing the accumulation periods of the part of the elements and the other elements different from the part of the elements of a plurality of elements to overlap with each other in the acquisition of the correction data.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radiation imaging apparatus and a radiation imaging system that acquire an image of the intensity distribution of radiation that has passed through a subject. [Background technology]

[0002] Conventionally, radiation imaging devices and radiation imaging systems have been commercially available that irradiate a subject with radiation from a radiation generating device, digitize the intensity distribution of the radiation that has passed through the subject, and perform image processing on the digitized radiation image to obtain a clear radiation image.

[0003] Here, a radiation image generated by a radiation imaging device includes not only a component corresponding to the incident radiation but also a component corresponding to dark charge. To remove the component corresponding to dark charge, a correction technique is known in which an image acquired when the radiation imaging device is not irradiated with radiation (a so-called offset image) is subtracted from the radiation image. The amount of dark charge generated depends on, for example, the internal temperature of the radiation imaging device. Therefore, if there is a difference in the temperature distribution within the radiation imaging device between when the offset image and the radiation image are acquired, the offset component may not be properly removed. Furthermore, depending on the radiation imaging device, dark charge may be generated not only by temperature but also by residual image components due to the influence of the previous imaging. Therefore, it is desirable to acquire the offset image as close to the time of radiation imaging as possible.

[0004] Patent Document 1 describes a method in which, when a new offset image is acquired in one of a plurality of radiation imaging modes, offset information for other modes is calculated and updated based on the fluctuation components of the acquired offset image. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 04203710 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology disclosed in Patent Document 1 has room for improvement in terms of accuracy of offset correction data in multiple imaging modes and speed of acquisition. In view of the above-mentioned problems, an object of the present invention is to provide a technology for accurately and quickly acquiring offset correction data for each of multiple radiation imaging modes. [Means for solving the problem]

[0007] The present invention, which solves the above-mentioned problems, comprises: a detection unit including a plurality of elements capable of generating electric charges when irradiated with at least radiation; The apparatus includes an acquisition unit that accumulates charges generated when the element is irradiated with radiation and acquires them as image data, and accumulates charges generated when the element is not irradiated with radiation and acquires them as correction data, a control unit that controls the operation of the acquisition unit, and an image processing unit that generates radiation image data using the image data and the correction data acquired by the acquisition unit, wherein the control unit controls the acquisition unit in acquiring the correction data so that the accumulation periods of some of the multiple elements overlap with those of other elements other than the some of the elements, while the accumulation times of the some of the elements and the other elements are different from each other. [Effects of the Invention]

[0008] According to the present invention, offset correction information for multiple modes can be acquired simultaneously in a radiation imaging device, so that the offset correction information can be acquired in a short time, and imaging can be performed immediately using accurate offset information in each imaging mode. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a radiation imaging system. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a radiation detection unit in a radiation imaging apparatus. [Figure 3]3A to 3C are diagrams illustrating an example of an imaging mode of the radiation imaging apparatus of the present invention. [Figure 4] 10 is a flowchart showing an offset correction data update process of the radiation imaging apparatus of the present invention. [Figure 5] FIG. 4 is a timing chart showing an example of offset data acquisition control in the radiation imaging apparatus according to the first embodiment of the present invention. [Figure 6] 10A and 10B are diagrams illustrating an example of offset correction data generation in the radiation imaging apparatus of the present invention. [Figure 7] FIG. 10 is a timing chart showing an example of offset data acquisition control in the radiation imaging apparatus according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] [Embodiment 1] FIG. 1 illustrates an exemplary configuration of a radiation imaging system. The radiation imaging system 1 of this embodiment includes a radiation imaging device 100 including a radiation detection unit 200, and a control device that acquires radiation image data acquired by the radiation imaging device 100 and generates a radiation image. The present embodiment shown in FIG. 1 also includes a radiation source 301 that irradiates radiation, a radiation generating device 300 that controls the radiation source 301, and an image control device 500 that can acquire radiation image data output from the radiation imaging device 100 and output the image data to the control device 400. The control device 400 controls the radiation imaging device 100 and the radiation generating device 300, and includes a radiation imaging application 404 that can collect and display captured images from the radiation imaging devices, accept imaging orders, and register imaging information. The control device 400 is also connected to a hospital network 600, which is, for example, a local area network (LAN). A radiology information system (RIS) 601 or a hospital information system (HIS) is also connected to the hospital network 600. The control device 400 and the RIS 601 can communicate with each other, enabling the exchange of radiographic image capture orders, imaging information including, for example, patient information, and captured image data itself.

[0012] The radiation imaging apparatus 100 includes a radiation detection unit 200 that detects radiation and generates image data, a control unit 101 that controls imaging and communication operations, and a power supply unit 115. The control unit 101 includes a drive control unit 102 that controls driving of the radiation detection unit 200 and acquisition of image data and offset data. The control unit 101 also includes an offset correction data generation unit 108 that generates offset correction data from the acquired offset data. The control unit 101 also includes an image processing unit 106 that performs image processing on image data acquired from the radiation detection unit 200 using the offset correction data, etc., to generate radiation image data. The control unit 101 also includes a storage unit 109 that stores the acquired image data, offset data, offset correction data, radiation image data, etc. The image data and radiation image data are stored as radiation data 110, and the offset data and offset correction data are stored as correction data 111. The control unit 101 also includes a communication control unit 112 that controls communication with the control device 400 and communication with the radiation generation device 300. The control unit 101 also includes an internal clock 113 that acquires imaging time, elapsed time, etc., and a radiation generation device control unit 114 that controls irradiation timing based on a radiation irradiation signal from the radiation generation device 300. The control unit 101 reads out a program stored in a storage unit, for example, and controls the entire radiation imaging apparatus based on the program. Alternatively, the apparatus may be controlled by a control signal generating circuit such as an ASIC, or the entire apparatus may be controlled by both a program and a control circuit.

[0013] The radiation generating device 300 has an operation UI 302 for operating the radiation generating device. The operation UI 302 is used to set radiation irradiation conditions and irradiate radiation. A dedicated signal line enables information exchange between the radiation generating device 300 and the radiation imaging device 100. Synchronization signals, such as notifications of the start and end of radiation irradiation and notifications of timing when radiation irradiation is possible, are exchanged between the radiation generating device 300 and the radiation imaging device 100.

[0014] The control device 400 includes a radiation imaging device control unit 402 that controls the timing and conditions for image acquisition by the radiation imaging device 100, and a radiation generation device control unit 403 that controls the radiation irradiation conditions of the radiation generation device 300. The control device 400 also includes a communication control unit 401 that controls communication between radiation imaging devices, between radiation generation devices, and with an in-hospital LAN, the radiation imaging application 404, a display unit 406 for displaying captured images and imaging information, and a power supply 405 that supplies power to these components. For example, the control device 400 can acquire radiation image data from the radiation imaging device, perform image processing in the radiation imaging application 404, and display the radiation image on the display unit 406. The control device 400 also includes an operation UI (keyboard, mouse, etc.) 407 for operating the radiation imaging application. Information can be exchanged between the control device 400 and the radiation imaging device 100, and between the control device 400 and the radiation generation device 300, via cable connection communication using standards such as RS232C, USB, or Ethernet, or via dedicated signal lines. Information can be exchanged not only via wired communication but also via wireless communication or multiple other means. Control communication such as radiation image data, image acquisition condition setting, and device status acquisition is performed between the control device 400 and the radiation imaging device 100. Control communication such as radiation irradiation condition setting, device status acquisition, and actual irradiation information is performed between the control device 400 and the radiation generation device 300.

[0015] The image control device 500 performs image processing on the radiation image data transferred from the radiation imaging device 100 and transfers the image to the control device 400. In this embodiment, the image control device 500 performs image processing, but the radiation image data may be transferred to the control device 400 without image processing, and the radiation image may be processed in the control device 400 to generate a radiation image. The image control device 500 also has a display unit 501, and if the control device 400 goes down, the display unit 501 displays the radiation image.

[0016] FIG. 2 shows an example of the configuration of the radiation detection unit 200. The radiation detection unit 200 has a sensor array 204 consisting of a plurality of elements (pixels) arranged in a two-dimensional array to form a plurality of rows and a plurality of columns. Each of the plurality of elements (pixels) is capable of generating an electric charge when irradiated with at least radiation. Specifically, each pixel 207 on the sensor array is composed of a switching element 208, such as a TFT, and a photoelectric conversion element 209, and each pixel 207 is provided with, for example, a phosphor. In this case, radiation incident on the radiation detection unit 200 is converted into visible light by the phosphor, and the converted visible light enters the photoelectric conversion element 209 of each pixel, where an electric charge corresponding to the visible light is generated in each photoelectric conversion element 209. Note that this embodiment will be described assuming that a conversion element is configured that converts incident radiation into an electric charge using the above-mentioned phosphor and photoelectric conversion element. However, for example, a so-called direct conversion type conversion element may be configured that directly converts incident radiation into an electric charge without providing a phosphor. By switching the TFT 208 ON and OFF, electric charges are accumulated and read out, and a radiation image can be obtained.

[0017] When the drive circuit 201 applies a TFT ON voltage to the drive line 211 of the pixels on a certain row of the two-dimensional sensor array of the radiation detection unit, the TFTs of each pixel on the row are turned ON, and charge is held in the sample-and-hold circuit 202 via the respective signal lines 210. The held pixel output charges are then sequentially read out via the multiplexer 203, amplified by the amplifier 205, and converted into digital image data by the A / D converter 206. After charge readout has been completed for a row, the drive circuit 201 applies a TFT OFF voltage to the drive line 211, causing each pixel on the row to return to charge accumulation. In this way, the drive circuit 201 sequentially drives and scans each row on the sensor array, and ultimately converts the charge of all pixel outputs into digital values. This allows image data to be read out. The drive and readout operations of these detection units are controlled by the drive control unit 102. The image data converted into digital values ​​is stored in the memory unit 109 shown in FIG. 1.

[0018] The drive control unit 102 is configured to switch between and control a standby drive control unit 105 that prepares for radiation imaging, an image data acquisition control unit 103 that acquires image data of a radiation image, and an offset data acquisition control unit 104 that acquires offset data. The standby drive control unit 105 applies the same voltage as during imaging to the radiation detection unit 200, while periodically reading out charges and resetting the dark charge accumulated in each pixel. The charges read out at this time are not treated as image data and do not need to be stored in the storage unit 109. The image data acquisition control unit 103 performs the same drive as the standby drive control unit, irradiating each pixel with radiation while accumulating. The image data is read out and stored in the storage unit 109. Continuous operation of the image data acquisition control unit 103 enables video imaging. The offset data acquisition control unit 104 also performs the same drive as the standby drive control unit, while storing data read out without irradiating radiation as offset data. In this way, the drive control unit 102 acquires image data using the image data acquisition control unit 103, and acquires offset data using the offset data acquisition control unit 104. Therefore, the drive control unit 102, the image data acquisition control unit 103, and the offset data acquisition control unit 104 may be simply referred to as acquisition units in the following description.

[0019] Here, the offset data acquisition control unit 104 of the present invention simultaneously acquires offset data with multiple different accumulation times by reading out offset data for only specific lines with an accumulation time different from that of other lines. As described above, when the drive circuit 201 sequentially drives and scans each line on the sensor array for a fixed accumulation time, offset data for all pixels can be acquired for that accumulation time. However, in the present invention, while accumulating a certain line (some lines), the TFTs are repeatedly turned on and off while only other lines (specific lines) are driven, so that offset data with a shorter accumulation time is read out only for specific lines. In other words, by overlapping the accumulation periods of some lines with those of other lines and controlling the accumulation times of some lines to be different from those of other lines, offset data with different accumulation times is simultaneously acquired. Note that the offset data acquisition is not limited to the form in which the accumulation periods are overlapped on a line-by-line basis and offset data is acquired with different accumulation times. It is also possible to acquire offset data with different accumulation times by overlapping the accumulation periods of some elements (pixels) with those of other elements (pixels). Then, using the offset data thus acquired by the offset data acquisition control unit 104 with different accumulation times for each line, the offset correction data generation unit 108 generates correction data (offset correction data) 111 for multiple modes and stores it in the storage unit 109. Because the offset data acquisition control unit 104 and the offset correction data generation unit 108 make it possible to acquire correction data (offset correction data), the offset correction data generation unit 108 may also be referred to simply as an acquisition unit (correction data acquisition unit) below.

[0020] Next, the effects obtained by this operation of this embodiment will be described. For example, in a case where there are multiple shooting modes as shown in FIG. 3, in the conventional method, offset data is acquired with an accumulation time of 33 msec for shooting mode number 1, and offset correction data for shooting mode number 1 is generated. Then, similarly, offset correction data for shooting modes 2 to 4 must be acquired in sequence and generated, which means it takes time to update the offset correction data for all modes. On the other hand, in this embodiment, while accumulation is taking place with an accumulation time of 200 msec for shooting mode number 4, which has a long accumulation time, offset data is acquired for only specific lines with an accumulation time of 100 msec for shooting mode number 3, 50 msec for shooting mode number 2, and 33 msec for shooting mode number 1. This allows offset data for shooting mode numbers 1 to 3 to be acquired for only specific lines, while offset data for shooting mode number 4 is acquired for other lines, thereby simultaneously obtaining offset data for different shooting modes. By generating offset correction data for shooting modes 1 to 4 based on the offset data acquired in this manner, offset correction data for multiple modes can be generated in a short time.

[0021] Image data acquired from the radiation detection unit 200 during imaging undergoes offset correction processing by the offset correction unit 107 of the image processing unit 106 using offset correction data corresponding to the imaging mode. The radiation image data acquired in this manner is transferred to the image control device 500 via the communication control unit 112. Note that while only the offset correction processing has been described here, other correction processing such as correction of defective pixels and gain correction for correcting gain variations of amplifiers within the radiation detection unit may also be performed. Furthermore, these correction processing processes are not limited to being performed in the radiation imaging device 100. For example, the acquired image data and offset correction data may be transferred to the image control device 500 without correction, and the correction processing may be performed within the image control device. Furthermore, the offset correction data used in the offset correction processing may be generated, for example, by using offset data acquired multiple times with the same accumulation time and performing processing such as averaging to reduce noise components.

[0022] FIG. 4 is a flowchart of the offset correction data update in this embodiment.

[0023] In this embodiment, the offset correction data is updated in the following steps.

[0024] In step S101, the time elapsed since the previous update of the offset correction data is obtained using the internal clock 113. If the offset correction data has never been updated, the elapsed time is set to the maximum value.

[0025] In step S102, if the elapsed time is greater than T, the process proceeds to step S103, and if the stop period is less than or equal to T, the process returns to step S101. For example, T=5 minutes.

[0026] In step S103, it is confirmed whether fluoroscopy or radiography is in progress. If fluoroscopy or radiography is not in progress, the process proceeds to step S104, and if fluoroscopy or radiography is in progress, the process returns to step S101. If fluoroscopy or radiography is not in progress, standby drive control is performed.

[0027] In step S104, the standby drive control is switched to offset data acquisition control, and offset data is acquired and offset correction data is generated. In this embodiment, offset data with different accumulation times for each line is acquired at once, and offset correction data for multiple modes is generated at once. This makes it possible to reduce the time required to update the offset correction data compared to generating offset correction data for all modes in sequence. This makes it possible to immediately perform imaging using the latest offset information.

[0028] Although not included in the above steps, if offset data is acquired immediately after shooting, there is a possibility that an afterimage may be included in the offset image. For this reason, the time elapsed since shooting was completed may be measured, and if both the elapsed time since shooting was completed and the elapsed time since the offset correction data was updated are met, offset data acquisition and offset correction data generation may be performed.

[0029] Next, an example of offset data acquisition control in this embodiment will be described in detail using FIG. 5. This example has multiple lines, and offset data is acquired for specific lines among the multiple lines using a different accumulation time than the other lines. The specific lines are arranged periodically by placing other lines between them. Here, offset data is acquired for three shooting modes with accumulation times t1, t2, and t3. Note that the accumulation times have a relationship of t1>t2>t3. Furthermore, for each line L1 to Ln on the sensor array, lines L4, L8, ..., which are multiples of 4, are read out while changing the accumulation time to t2 and t3, and the other lines are read out using the longer accumulation time t1. Furthermore, each offset data is read out at least m times using the same accumulation time.

[0030] First, at T101, offset data acquisition begins. Lines L1 to Ln are scanned in order, the entire image is read, and the dark charge of all pixels is reset. The readout line is immediately switched to an accumulation state (T102). This results in the accumulation periods of each line overlapping. After that, while lines L1 to L3 continue accumulating, line L4 is read out for accumulation time t2 (T103), and offset data D1_L4(t2) for accumulation time t2 is acquired. Similarly, L8 and the other lines that are multiples of four are read out for accumulation time t2, and offset data D1_L8(t2) for accumulation time t2 and the offset data of the other lines that are multiples of four are acquired.

[0031] Next, while accumulation continues on lines other than those that are multiples of 4, L4, L8, and other lines that are multiples of 4 are read out at accumulation time t3 (T104). Then, offset data D1_L4(t3), D1_L8(t3), and the offset data of the other lines that are multiples of 4 for accumulation time t3 are obtained.

[0032] Thereafter, L1 to L3 and lines other than a multiple of 4 are read out at the timing of accumulation time t1 (T105). Then, offset data D1_L1(t1), D1_L2(t1), D1_L3(t1) for accumulation time t1 and offset data for other lines other than a multiple of 4 are obtained. In this way, offset data with different accumulation times is obtained while overlapping the accumulation periods.

[0033] Thereafter, in a similar manner, at timing T106, lines that are multiples of four are read out with an accumulation time of t2, and then at timing T107, lines that are multiples of four are read out with an accumulation time of t3. Then, at timing T108, lines that are not multiples of four are read out with an accumulation time of t1. This is repeated m times, and at timing T109, offset data for accumulation time t1 can be obtained m times for lines that are not multiples of four. Furthermore, offset data for accumulation times t2 and t3 can be obtained m times for L4, L8, and other lines that are multiples of four. From each offset data obtained in this manner, offset correction data for the shooting mode corresponding to accumulation times t1, t2, and t3 is generated.

[0034] Next, an example of offset correction data generation in this embodiment will be described in detail with reference to FIG. 6. The offset data acquisition control of FIG. 5 allows m offset data for lines that are not multiples of four to be acquired during accumulation time t1. Furthermore, m offset data for lines that are not multiples of four to be acquired during accumulation times t2 and t3. First, average offset data is generated by averaging m offset data for each line. For example, for line L1 with accumulation time t1, m data items D1_L1(t1), D2_L1(t1), ..., Dm_L1(t1) are averaged to calculate average offset data Dave_L1(t1) for line L1. This process is repeated for the other lines to generate average offset data Dave_L1(t1), Dave_L2(t1), Dave_L3(t1), and other lines that are not multiples of four.

[0035] Similarly, at accumulation time t2, Dave_L4(t2), Dave_L8(t2), and average offset data for each line are generated, as well as for other lines that are multiples of 4. At accumulation time t3, Dave_L4(t3), Dave_L8(t3), and average offset data for other lines that are multiples of 4 are generated.

[0036] Next, because offset data for lines that are multiples of four does not exist, average offset data for integration time t1 is generated using average offset data for different integration times. While offset data for integration time t3 could also be used, offset data for t2, which has an integration time closer to t1, is preferable because its characteristics are closer. Therefore, average offset data for t2, which has a closer integration time, is used to generate offset data for integration time t1 for lines that are multiples of four. Here, the average value of all pixels for the average offset data for integration time t1 is defined as Dave(t1), and the average value of all pixels for the average offset data for integration time t2 is defined as Dave(t2). For example, offset data for line L4 for integration time t1 is generated by multiplying the average offset data for line L4 for integration time t2, Dave_L4(t2), by the ratio of the average values ​​of all pixels for integration times t1 and t2. In other words, it is calculated as Dave_L4(t2) × Dave(t1) / Dave(t2).

[0037] Similarly, the offset data for line L8 for accumulation time t1 is calculated by Dave_L8(t2)×Dave(t1) / Dave(t2). The offset data for other lines that are multiples of 4 is calculated in a similar manner. The offset data for accumulation time t1 prepared in this manner is stored in the storage unit 109 as correction data (offset correction data) 111 for the shooting mode corresponding to accumulation time t1.

[0038] Next, since there is no offset data for lines that are not multiples of four, the average offset data for accumulation time t2 is generated using the average offset data for accumulation time t1. For example, the offset data for line L1 for accumulation time t2 is generated by multiplying the average offset data Dave_L1(t1) for line L1 for accumulation time t1 by the ratio of the average values ​​of all pixels for accumulation times t2 and t1. In other words, it is calculated as Dave_L1(t1) × Dave(t2) / Dave(t1). The offset data for other lines that are not multiples of four is calculated in the same way. The offset data for accumulation time t2 prepared in this way is stored in the storage unit 109 as correction data (offset correction data) 111 for the shooting mode corresponding to accumulation time t2.

[0039] Similarly, offset correction data for the imaging mode corresponding to the accumulation time t3 can be generated by using the average offset data for the accumulation time t1.

[0040] Using the offset correction data for each imaging mode generated in this manner, it becomes possible to correct the image data stored in the storage unit 109 as radiation data 110 and obtain radiation image data.

[0041] [Embodiment 2] Next, another embodiment of offset data acquisition control will be described using FIG. 7. In this embodiment, offset data for three imaging modes with accumulation times t1, t2, and t3 is acquired, and the accumulation times have the same relationship of t1>t2>t3. Also, in each of the lines L1 to Ln on the sensor array, lines L4, L8, ..., which are multiples of 4, are read out while varying the accumulation time, including the short accumulation times t2 and t3, and the other lines are read out with the long accumulation time t1. Also, each offset data is read out m times with the same accumulation time.

[0042] In the first embodiment, during the t1 accumulation of the lines other than a multiple of four, the lines that are multiples of four are sequentially read out for accumulation times t2 and t3, which are shorter than t1, to acquire offset data. In the present embodiment, similarly, while the lines that are not a multiple of four are accumulated and read out for accumulation time t1, the lines that are multiples of four are repeatedly accumulated and read out for accumulation time t2, which is shorter than t1, to acquire offset data for m accumulation times t2 (T203 to T206). After that, the lines that are multiples of four are switched to accumulation time t3, and similarly, m offset data are acquired (T207 to T209). In parallel with this, the lines that are not a multiple of four are repeatedly accumulated and read out for accumulation time t1, to acquire m offset data (T210).

[0043] Once offset data for all lines for accumulation times t1 to t3 has been acquired in this way, offset correction data is generated in the same manner as in the first embodiment.

[0044] In the case of a radiation detector that has characteristics such that stable charges cannot be read out immediately after switching the accumulation time, this embodiment repeatedly acquires offset data using the same accumulation time, and is therefore more suitable than embodiment 1. In the case of such a radiation detector, the offset data acquired multiple times immediately after switching the accumulation time may be discarded, and control may be exercised so that m sets of offset data are acquired starting from the offset data after the charges have stabilized.

[0045] In the offset data acquisition control in the first and second embodiments, only lines that are multiples of four are selected from the offset data for the base accumulation time t1, and the data is acquired at different accumulation times t2 and t3. However, this is not limited to this. For example, even or odd lines may be selected, or lines of other multiples may be periodically selected. Furthermore, it is not necessary to periodically select lines for which the accumulation time is changed; any non-periodic lines, such as L3, L8, and L15, may be selected. However, when generating offset correction data for accumulation times t2 and t3, it is preferable to have a certain number of offset data to improve correction accuracy. Furthermore, to eliminate bias in the offset data, it is desirable to sample the entire image at regular intervals (i.e., periodically).

[0046] However, this does not apply to radiation imaging devices with little in-plane data variation across the entire image. For example, consider a radiation imaging device or imaging mode in which, among lines L1 to Ln on the sensor array, only the range L11 to L(n-10) is used as the effective area (radiation image generation area) and image data is transferred to the control device. In this case, lines L1 to L10, L(n-9) to Ln, or a portion thereof, which are invalid areas (radiation image non-generation areas), may be selected to acquire offset data with different accumulation times. That is, multiple offset data with different accumulation times may be acquired using elements arranged in the non-generation areas not used to generate a radiation image, and image data acquired from image forming elements arranged in the generation area where a radiation image is generated may be acquired. Radiation image data may then be generated by correcting the image data acquired from the image forming elements arranged in the generation area with offset correction data obtained using the offset data acquired from the elements in the non-generation areas.

[0047] Furthermore, although it has been explained up to this point that the specific selected lines are all controlled in the same way, for example, by reading them out at accumulation times t2 and t3, this is not limitative. For example, if lines that are multiples of 4 are selected, it is also possible to acquire offset data at different accumulation times for each line, such as acquiring offset data for line L4 at accumulation time t2 and for line L8 at accumulation time t3.

[0048] Furthermore, when generating the offset correction data, the average offset data for accumulation time t1 is generated using the average offset data for accumulation time t2, which is close to the accumulation time t1, because offset data for lines that are multiples of four does not exist. In this case, the average offset data for t2 is generated by multiplying the ratio of the all-pixel average values ​​for accumulation times t1 and t2, but this is not limited to this. For example, offset data for a line that does not have accumulation time t1 may be generated by interpolation using offset data for accumulation time t1 for lines above and below it or neighboring lines above and below it. The interpolation method may simply be interpolation using the average pixel values ​​of the lines above and below, or linear interpolation using offset data for multiple neighboring lines above and below, or interpolation using a separate spatial filter, etc.

[0049] However, in this case, it is desirable that at least the lines above and below the line to be generated have offset data with the same accumulation time. For example, when offset data is acquired for lines that are multiples of four using different accumulation times t2 and t3, multiple consecutive lines of the offset data to be generated exist when generating offset correction data for accumulation times t2 and t3. In such a case, generating offset correction data for accumulation times t2 and t3 using interpolation processing is not suitable. Therefore, it is desirable to generate offset correction data using offset data for other accumulation times. On the other hand, consider a control case in which offset data for even-numbered lines are acquired with different accumulation times t2 and t3. In this case, since the lines above and below the offset data for the line that does not exist in accumulation times t2 and t3 have offset data for accumulation times t2 and t3, interpolation processing is also possible.

[0050] As described above, compared to updating the offset correction data for all modes in sequence, the present invention obtains offset data for multiple modes at once to generate offset correction data, thereby shortening the update time. Furthermore, in the present invention, offset data for all imaging modes, even if only for a portion of the lines, is actually obtained and used to generate offset correction data. This allows imaging to be performed using more up-to-date offset information.

[0051] The disclosure of the present specification includes the following radiation imaging apparatus and radiation imaging system.

[0052] (Item 1) a detection unit including a plurality of elements capable of generating electric charges when irradiated with at least radiation; an acquisition unit that accumulates charges generated by irradiating the element with radiation and acquires the charges as image data, and accumulates charges generated without irradiating the element with radiation and acquires the charges as correction data; a control unit that controls the operation of the acquisition unit; an image processing unit that generates radiation image data using the image data and the correction data acquired by the acquisition unit, The control unit controls the acquisition unit in acquiring the correction data so that the accumulation periods of some of the plurality of elements overlap with other elements other than the some of the elements, while the accumulation times of the some of the elements and the other elements are different from each other.

[0053] (Item 2) 2. The radiation imaging device according to item 1, wherein the detection unit has a plurality of the partial elements, and the partial elements are periodically arranged with other elements disposed therebetween.

[0054] (Item 3) 3. The radiation imaging device according to item 1 or 2, wherein the plurality of elements further comprises an image-forming element separate from the some of the elements and the other elements, the detection unit has an effective area where the radiation image is generated and an ineffective area where the radiation image is not generated, the some of the elements and the other elements being disposed in the ineffective area, and the image-forming element being disposed in the effective area.

[0055] (Item 4) 4. The radiation imaging apparatus according to any one of items 1 to 3, wherein the acquisition unit corrects the correction data acquired from the part of the elements based on the accumulation times of the other elements.

[0056] (Item 5) 5. The radiation imaging device according to item 4, wherein the acquisition unit accumulates the charges generated by the some of the elements for a plurality of accumulation times different from each other to acquire a plurality of correction data, and corrects the correction data among the plurality of correction data acquired for an accumulation time closest to the accumulation time of the other elements based on the accumulation time of the other elements.

[0057] (Item 6) 6. The radiation imaging device according to any one of items 1 to 5, wherein the acquisition unit corrects the correction data acquired from the partial elements based on a ratio between the correction data acquired from the partial elements and the correction data acquired from the other elements.

[0058] (Item 7) 3. The radiation imaging device according to item 2, wherein the acquisition unit replaces correction data acquired from another element disposed between the plurality of elements with correction data interpolated using correction data acquired from the plurality of elements disposed between the other elements.

[0059] (Item 8) 8. A radiation imaging system comprising: the radiation imaging device according to any one of items 1 to 7; and a control device that acquires the radiation image data from the radiation imaging device and generates a radiation image. [Explanation of symbols]

[0060] 100 Radiation imaging device 101 Control section 102 Drive control unit 103 Radiation image acquisition control unit 104 Offset data acquisition control section 106 Image processing section 107 Offset correction unit 200 Radiation detection unit 400 control device 500 Image control device

Claims

1. a detection unit including a plurality of elements capable of generating electric charges when irradiated with at least radiation; an acquisition unit that accumulates charges generated by irradiating the element with radiation and acquires the charges as image data, and accumulates charges generated when the element is not irradiated with radiation and acquires the charges as correction data; a control unit that controls the operation of the acquisition unit; an image processing unit that generates radiation image data using the image data and the correction data acquired by the acquisition unit, The control unit controls the acquisition unit in acquiring the correction data so that the accumulation periods of some of the plurality of elements overlap with other elements other than the some of the elements, while the accumulation times of the some of the elements and the other elements are different from each other.

2. 2. The radiation imaging apparatus according to claim 1, wherein the detection unit includes a plurality of the partial elements, the partial elements being periodically arranged with other elements disposed therebetween.

3. 2. The radiation imaging device according to claim 1, wherein the plurality of elements further include an image-forming element separate from the some of the elements and the other elements, the detection unit has an effective area where the radiation image is generated and an ineffective area where the radiation image is not generated, the some of the elements and the other elements being arranged in the ineffective area, and the image-forming element being arranged in the effective area.

4. The radiation imaging apparatus according to claim 1 , wherein the acquisition unit corrects the correction data acquired from the part of the elements based on accumulation times of the other elements.

5. 5. The radiation imaging device according to claim 4, wherein the acquisition unit accumulates the charges generated by the some of the elements for a plurality of accumulation times different from each other to acquire a plurality of correction data, and corrects the correction data among the plurality of correction data acquired for an accumulation time closest to the accumulation time of the other elements based on the accumulation time of the other elements.

6. 2. The radiation imaging device according to claim 1, wherein the acquisition unit corrects the correction data acquired from the partial element based on a ratio of the correction data acquired from the partial element to the correction data acquired from the other element.

7. The radiation imaging device according to claim 2, wherein the acquisition unit replaces correction data acquired from another element arranged between the plurality of elements with correction data interpolated using correction data acquired from the plurality of elements arranged between the other elements.

8. A radiation imaging system comprising: the radiation imaging device according to claim 1; and a control device that acquires the radiation image data from the radiation imaging device and generates a radiation image.

Images