Radiography apparatus and radiography system

Abstract

To provide a technique advantageous for acquiring signals from a plurality of regions of interest at high speed in AEC.SOLUTION: A radiography apparatus includes: a plurality of pixels; a plurality of drive circuits to which a plurality of row signal lines are connected to drive the plurality of pixels line by line; and a control unit. The control unit supplies a selection signal to a drive circuit group composed of two or more drive circuits, among a plurality of drive circuits, that drive detection pixels, in order to set, prior to irradiation, two or more detection pixels for measuring the dose of radiation incident from a plurality of pixels during irradiation. The control unit causes each of the drive circuits included in the drive circuit group to select a row signal line to which the detection pixel is connected from a plurality of row signal lines, and supplies a drive signal for driving a pixel connected to the row signal line selected from a plurality of row signal lines to each drive circuit included in the drive circuit group during irradiation, thereby acquiring a signal for measuring the dose of radiation incident from each of the detection pixels.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a radiation imaging apparatus and a radiation imaging system. [Background technology]

[0002] In medical image diagnosis and non-destructive testing, radiation imaging devices using flat panel detectors (FPDs) made of semiconductor materials are widely used. It is known that such radiation imaging devices measure radiation incident on the radiation imaging device in real time. 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). When performing AEC, high time resolution may be required. Patent Document 1 shows that a high-level signal is continuously supplied from the start of exposure to a gate line to which a detection element set for AEC is connected, and the detection element is continuously turned on. The operation shown in Patent Document 1 can always obtain a signal from the detection element, so that high time resolution can be realized. Patent Document 2 also shows that during radiation irradiation, a sensor whose output-dependent value exceeds a threshold is excluded from an effective sensor group from a plurality of sensors set for AEC. By reducing the number of sensors constituting an effective sensor group, it is possible to increase the sampling frequency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-75556 A [Patent Document 2] JP 2016-15721 A Summary of the Invention [Problem to be solved by the invention]

[0004] When performing AEC, multiple regions of interest may be set. In the operation shown in Patent Document 1, a high-level signal is always supplied to a gate line to which a detection element used for AEC is connected, so that signals cannot be acquired independently from detection elements connected to gate lines other than the gate line to which the detection element is connected. In other words, in the operation shown in Patent Document 1, when multiple regions of interest are set, it is necessary to use detection elements connected to the same gate line, and the degree of freedom in setting the regions of interest is low. In the operation shown in Patent Document 2, the degree of freedom in setting multiple regions of interest is high, but a complex circuit configuration may be required to acquire signals from an effective sensor group.

[0005] An object of the present invention is to provide a technique that is advantageous for quickly acquiring signals from multiple regions of interest in AEC. [Means for solving the problem]

[0006] In view of the above problems, a radiation imaging device according to an embodiment of the present invention is a radiation imaging device including a plurality of pixels arranged in a matrix to acquire a radiation image, a plurality of driving circuits each connected to a plurality of row signal lines for driving the plurality of pixels on a row-by-row basis, and a control unit for controlling the plurality of driving circuits, wherein before radiation is irradiated, the control unit supplies a selection signal to a driving circuit group constituted by two or more driving circuits among the plurality of driving circuits that drive detection pixels in order to set two or more detection pixels for measuring a dose of radiation incident from the plurality of pixels during radiation irradiation, and causes each of the driving circuits included in the driving circuit group to select a row signal line among the plurality of row signal lines to which a detection pixel is connected, and during radiation irradiation, the control unit supplies a driving signal to each driving circuit included in the driving circuit group for driving a pixel connected to the selected row signal line among the plurality of row signal lines, thereby causing the radiation imaging device to acquire a signal for measuring the dose of radiation incident from each of the detection pixels. Effect of the Invention

[0007] The above means provides an advantageous technique for quickly acquiring signals from multiple regions of interest in AEC. [Brief description of the drawings]

[0008] [Figure 1] 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 2] FIG. 2 is an equivalent circuit diagram showing an example of the configuration of the radiation imaging apparatus shown in FIG. [Diagram 3] FIG. 11 is an equivalent circuit diagram showing an example of connection between a control unit and a driving circuit of a radiation imaging apparatus according to a comparative example. [Figure 4] 4 is a timing chart showing an example of the operation of the control unit and the drive circuit in FIG. 3. [Diagram 5] 2 is a flow diagram showing an example of the operation of the radiation imaging apparatus of FIG. 1; [Figure 6] 2 is an equivalent circuit diagram showing an example of connection between a control unit and a driving circuit of the radiation imaging apparatus in FIG. 1. [Figure 7] 7 is a timing chart showing an example of the operation of the control unit and the drive circuit in FIG. 6. [Figure 8] FIG. 7 is a diagram showing a modification of the arrangement of the regions of interest in FIG. 6. [Figure 9] 2 is an equivalent circuit diagram showing an example of connection between a control unit and a driving circuit of the radiation imaging apparatus in FIG. 1. [Figure 10] 10 is a timing chart showing an example of the operation of the control unit and the drive circuit in FIG. 9. [Figure 11] 2 is an equivalent circuit diagram showing an example of connection between a control unit and a driving circuit of the radiation imaging apparatus in FIG. 1. [Figure 12] 12 is a timing chart showing an example of the operation of the control unit and the drive circuit in FIG. 11. [Figure 13] FIG. 2 is a schematic diagram showing an example of the arrangement of the radiation imaging apparatus shown in FIG. 1; [Figure 14] FIG. 14 is a timing diagram of an example of operation of the arrangement of FIG. 13. [Figure 15] FIG. 14 is a timing diagram of an example of operation of the arrangement of FIG. 13. [Figure 16] FIG. 14 is a timing diagram of an example of operation of the arrangement of FIG. 13. [Figure 17]12 is a timing chart showing an example of the operation of the control unit and the drive circuit in FIG. 11. 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] First embodiment A radiation imaging device according to some embodiments of the present invention will be described with reference to Figs. 1 to 12. Fig. 1 shows a block diagram of a configuration example of a radiation imaging system SYS using a radiation imaging device 100 according to this embodiment. The radiation imaging system SYS includes the radiation imaging device 100, a control computer 200, a radiation control device 300, and a radiation generation device 400.

[0012] The radiation imaging device 100 includes a detection unit 112 that detects radiation, a calculation unit 117 that calculates charge information from the detection unit 112 and outputs exposure information, and a control unit 116 that controls driving of the detection unit 112 and irradiation of radiation based on the exposure information. In the detection unit 112, a plurality of pixels including sensors that detect radiation are arranged in a matrix in order to obtain a radiation image, and outputs a signal according to the incident radiation. The calculation unit 117 measures the dose of the incident radiation based on the signal output from the detection unit 112 during irradiation of radiation. A digital signal processing circuit such as an FPGA, a DSP, or a processor may be used as the calculation unit 117. The calculation unit 117 may be configured using an analog circuit such as a sample-and-hold circuit or an operational amplifier. In the configuration shown in FIG. 1, the calculation unit 117 is included in the radiation imaging device 100, but the function of the calculation unit 117 may be provided in the control computer 200. The control unit 116 controls the detection unit 112 based on a signal input from the control computer 200. Furthermore, the control unit 116 can change the driving method of the detection unit 112 using the exposure information output by the calculation unit 117 .

[0013] The control computer 200 performs overall control of the radiation imaging system SYS. The control computer 200 can also function as a user interface when a user (such as a radiologist) captures a radiation image using the radiation imaging system SYS. For example, the user inputs conditions for capturing a radiation image to the control computer 200, and the control computer 200 controls the radiation imaging apparatus 100 and the radiation generating apparatus 400 according to the input imaging conditions. The control computer 200 may further include a signal processing unit that processes signals for generating a radiation image output from the radiation imaging apparatus 100. The control computer 200 processes signals for generating a radiation image output from the radiation imaging apparatus 100, and displays the radiation image captured by the radiation imaging apparatus 100 on a display unit included in the control computer 200 or an external display.

[0014] The radiation control device 300 controls the radiation generation device 400 in response to a signal output from the control computer 200. The radiation generation device 400 irradiates radiation in response to a signal output from the radiation control device 300.

[0015] Fig. 2 is an equivalent circuit diagram showing an example of the configuration of the radiation imaging device 100. For ease of explanation, Fig. 2 shows a detection unit 112 having 3 rows x 3 columns of pixels. However, an actual radiation imaging device has more pixels, and for example, a 17-inch radiation imaging device has approximately 3500 rows x approximately 3500 columns of pixels.

[0016] The detection unit 112 is a two-dimensional detector including a plurality of pixels PIX arranged in a matrix. Each pixel PIX includes a conversion element 102 that converts radiation or light into an electric charge, and a switch element 101 that outputs an electric signal according to the electric charge. In this embodiment, as a photoelectric conversion element that converts light irradiated on the conversion element 102 into an electric charge, an MIS type photodiode arranged on an insulating substrate such as a glass substrate and mainly made of a semiconductor material such as amorphous silicon is used, but a PIN type photodiode may also be used. In addition, the conversion element 102 includes a wavelength converter such as a scintillator that converts radiation into light in a wavelength band that can be sensed by the photoelectric conversion element on the radiation incident side of the photoelectric conversion element. The wavelength converter may be arranged for each pixel PIX, or may be an integrated structure shared by a plurality of pixels PIX. In addition, the conversion element 102 is not limited to the indirect type conversion element as described above, and a direct type conversion element that directly converts radiation into an electric charge may be used. A transistor having a control terminal and two main terminals may be used as the switch element 101. In this embodiment, a thin film transistor (TFT) is used for the switch element 101. One electrode of the conversion element 102 is electrically connected to one of two main terminals of the switch element 101, and the other electrode is electrically connected to the bias power supply 103 via a common bias wiring Bs. A plurality of switch elements 101 (e.g., T11, T12, T13) arranged in the row direction have their control terminals electrically connected in common to the row signal line Vg1 of the first row, and a drive signal for controlling the conductive state of the switch elements 101 is provided row by row from the drive circuit 114 via the row signal line Vg1. A plurality of switch elements 101 (e.g., T11, T21, T31) arranged in the column direction have their other main terminals electrically connected to the column signal line Sig1 of the first column, and while the switch element 101 is in a conductive state, a signal according to the charge of the conversion element is output to the readout circuit 113 via the column signal line Sig1. The column signal lines Sig1 to Sig3 arranged in the column direction transmit signals output from a plurality of pixels PIX to the readout circuit 113 in parallel.

[0017] In the readout circuit 113, an amplifier circuit 106 that amplifies the signals output in parallel from the detection unit 112 is provided for each column signal line Sig. The amplifier circuit 106 also includes an integral amplifier 105 that amplifies the output electric signal, a variable amplifier 104 that amplifies the signal input from the integral amplifier 105, and a sample-and-hold circuit 107 that samples and holds the amplified signal. The integral amplifier 105 includes an operational amplifier that amplifies and outputs the signal read from the pixel PIX, an integral capacitance, and a reset switch. The integral amplifier 105 can change the amplification factor by changing the value of the integral capacitance. The electric signal output from the pixel PIX is input to the inverting input terminal of the integral amplifier 105, a reference voltage Vref is input from a reference power supply 111 to the non-inverting input terminal, and an amplified signal is output from the output terminal. An integral capacitance is also disposed between the inverting input terminal and the output terminal of the operational amplifier. The sample-and-hold circuit 107 includes a sampling switch and a sampling capacitance. The readout circuit 113 also includes a multiplexer 108 that sequentially outputs signals read out in parallel from the respective amplifier circuits 106 as a serial image signal, and a buffer amplifier 109 that performs impedance conversion on the image signal and outputs it. The image signal Vout, which is an analog electrical signal output from the buffer amplifier 109, is converted into digital data by an A / D converter 110. For example, the digital data during irradiation of radiation is output to a calculation unit 117 and can be used for exposure control or the like. For example, the digital data after irradiation of radiation is output to a control computer 200, and the control computer 200 can process the acquired signal to generate a radiation image.

[0018] The radiation imaging apparatus 100 also includes a power supply unit including a reference power supply 111 for the amplifier circuit and a bias power supply 103. The reference power supply 111 supplies a reference voltage Vref to the non-inverting input terminals of the operational amplifiers. The bias power supply 103 supplies a bias voltage Vs commonly to the conversion elements 102 via a bias line Bs.

[0019] The drive circuit 114 outputs drive signals including a conductive voltage Vcom for turning the switch element 101 into a conductive state and a non-conductive voltage Vss for turning the switch element 101 into a non-conductive state to the row signal line Vg in response to control signals CPV, OE, and DIO input from the control unit 116. In this way, the drive circuit 114 controls the conductive state and non-conductive state of the switch element 101, and drives the multiple pixels PIX arranged in the detection unit 112 on a row-by-row basis. The configuration of the drive circuit 114 and the connection between the control unit 116 and the drive circuit 114 will be described later.

[0020] The control signal CPV is a shift clock for the shift register used in the drive circuit. The control signal DIO is a signal for making the shift register start shifting in response to the shift clock. The control signal OE is a signal for controlling the output terminal of the shift register. Using the above control signals CPV, DIO, and OE, the control unit 116 sets the time required for the drive circuit 114 to drive the detection unit 112 and the scanning direction. The control unit 116 also supplies a control signal RC, a control signal SH, and a control signal CLK to the readout circuit 113 to control the operation of each component of the readout circuit 113. Here, the control signal RC controls the operation of the reset switch of the integral amplifier, the control signal SH controls the operation of the sample-and-hold circuit 107, and the control signal CLK controls the operation of the multiplexer 108.

[0021] Next, a connection between the control unit 116 and the drive circuit 114 of the radiation imaging apparatus 100 and a drive method using automatic exposure control (AEC) will be described. Before describing the connection between the control unit 116 and the drive circuit 114 and the drive method of the present embodiment, a comparative example will be described first. Fig. 3 is an equivalent circuit showing the connection between the control unit 116 and the drive circuit 114 in the comparative example.

[0022] 3, the radiation imaging device 100 includes a plurality (seven) of readout circuits 113a-113g and a plurality (seven) of drive circuits 114a-114g for one detection section 112. A plurality of row signal lines Vg for driving a plurality of pixels PIX on a row-by-row basis are connected to each of the drive circuits 114a-114g. Signal lines for supplying control signals CPV and OE from the control section 116 are connected in parallel to the drive circuits 114a-114g, respectively, and a signal line for supplying a control signal DIO is connected in series to the drive circuits 114a-114g. In other words, the control section 116 and the drive circuit 114 are connected by three signal lines.

[0023] In the detection unit 112, regions of interest 1 to 5 are arranged at coordinates corresponding to the region of interest of the external AEC chamber. In each of the regions of interest 1 to 5, a pixel for use in exposure control (hereinafter, sometimes referred to as a detection pixel) is arranged. Here, for the sake of simplicity, it is described that there are five regions of interest, but the number of regions of interest is not limited to this, and may be four or less, or six or more. In addition, the positions of the regions of interest are not limited to the positions shown in FIG. 3, and may be set to any positions. In this embodiment, the detection pixel for exposure control is appropriately selected from the pixels PIX for acquiring a radiation image. However, it is not limited to this, and a plurality of pixels dedicated to AEC may be arranged in the detection unit 112, and any pixel may be selected from among them.

[0024] The detection pixels arranged in the regions of interest 1 to 5 are connected to row signal lines Vgb (R1) to Vgf (R5), which respectively control the switch elements 101. The driving circuit 114b drives the detection pixels in the region of interest 1 via the row signal line Vgb (R1). Similarly, the driving circuit 114c drives the detection pixels in the region of interest 2 via the row signal line Vgc (R2), the driving circuit 114d drives the detection pixels in the region of interest 3 via the row signal line Vgd (R3), the driving circuit 114e drives the detection pixels in the region of interest 4 via the row signal line Vge (R4), and the driving circuit 114f drives the pixels in the region of interest 5 via the row signal line Vgf (R5).

[0025] Fig. 4 is a timing chart showing the operation of the drive circuit 114 in the comparative example. Fig. 5 is a flow chart showing the operation of the radiation imaging apparatus 100 in this embodiment and the comparative example. The driving of the AEC in the comparative example will be described with reference to Figs. 3 to 5.

[0026] First, when the user completes preparations for imaging, such as setting conditions for imaging a radiation image, in S501, the radiation imaging apparatus 100 transitions to S502. In S502, the radiation imaging apparatus 100 starts pre-reading. Pre-reading is a reset operation in which the switch element 101 of each pixel PIX of the detection unit 112 is repeatedly turned on / off to reset the dark current of the pixel PIX. The control unit 116 supplies a control signal DIO to the driving circuit 114a in units of frames, and supplies control signals CPV and OE to each of the driving circuits 114a to 114g to sequentially scan them. Here, "Vga(0)" shown in FIG. 4 corresponds to one of the row signal lines connected to the driving circuit 114a shown in FIG. 3. For example, if the driving circuit 114a is a 512-channel driving circuit, the driving circuit 114a is connected to 512 row signal lines Vga(0) to Vga(511), and sequentially scans the 512 channels. The other driving circuits 114b to 114g are basically the same. The detection pixels are also sequentially scanned via the row signal lines Vgb (R1) to Vgf (R5), respectively, and the dark current is reset. The radiation imaging device 100 performs a pre-read until a signal indicating the start of radiation irradiation is input (S503), such as when the user presses an exposure switch.

[0027] Next, in S503, when the user instructs to start irradiating radiation by pressing an exposure switch, etc., the radiation imaging apparatus 100 transitions to S504. In S504, the radiation imaging apparatus 100 acquires a radiation image using AEC. As shown in FIG. 4, the control unit 116 first performs a preparatory operation and then performs an accumulation operation. The preparatory operation is an operation in which the control unit 116 supplies a control signal DIO and a control signal CPV multiple times to the driving circuit 114 up to the row signal line Vgb(R1) to which the detection pixel set in the region of interest 1 is connected, and advances the shift register. When the control unit 116 advances the shift register up to the row signal line Vgb(R1) to which the first detection pixel is connected, the control unit 116 transmits an exposure permission signal to the control computer 200 notifying that preparation is complete. In response to this exposure permission signal, the control computer 200 causes the radiation generating device 400 to start irradiating radiation via the radiation control device 300. In this embodiment, the radiation imaging apparatus 100 transmits an exposure permission signal to the control computer 200, but may also transmit the exposure permission signal directly to the radiation control apparatus 300, and in response thereto, the radiation generation apparatus 400 starts irradiating radiation.

[0028] When irradiation of radiation is started, the control unit 116 performs an operation for sequentially reading out signals from the detection pixels arranged in the regions of interest 1 to 5. At the same time, the pixels connected to row signal lines other than the row signal line to which the pixel set as the detection pixel is connected start an accumulation operation for acquiring a radiographic image. Specifically, the control unit 116 outputs a control signal CPV to advance the shift register, and when the driving circuit 114 selects the row signal lines Vgb (R1) to f (R5), it outputs a control signal OE to send a signal that turns on the gate of the switch element 101 of the detection pixel and drives the detection pixel. Then, the control unit 116 supplies a control signal DIO to the driving circuit 114a on a frame basis, and repeats acquisition of a signal for AEC. At this time, the readout circuit 113 reads out a signal (charge) corresponding to the incident radiation from the detection pixel, and the calculation unit 117 measures the dose of the incident radiation based on the signal acquired from the detection pixel. For example, the calculation unit 117 adds up the signals for each detection pixel. When the radiation dose measured by the calculation unit 117 reaches a preset dose, the control unit 116 of the radiation imaging apparatus 100 transmits a signal to the radiation generating apparatus 400 for irradiating the radiation imaging apparatus 100 with radiation to stop the irradiation of radiation. Specifically, when the signal added by the calculation unit 117 reaches a preset threshold, the control unit 116 transmits an exposure stop signal to the control computer 200 (S505). In response to this exposure stop signal, the control computer 200 stops the irradiation of radiation from the radiation generating apparatus 400 via the radiation control device 300 (S506). In this embodiment, the radiation imaging apparatus 100 transmits the exposure stop signal to the control computer 200, but may also transmit the exposure stop signal directly to the radiation control device 300, and in response to this, the radiation generating apparatus 400 stops the irradiation of radiation. Furthermore, when it is predicted that the radiation dose measured by the calculation unit 117 will reach a preset dose, the control unit 116 may send an exposure stop signal to the control computer 200.

[0029] When the irradiation of radiation is completed, the control unit 116 performs a main read operation. In this main read operation, the driving circuit 114 sequentially applies a conductive voltage Vcom to the row signal lines Vg, which turns on the switch elements 101, and reads out signals (charges) accumulated during the irradiation of radiation from the conversion elements 102 of the pixels connected to each row signal line to the readout circuit 113. The signals read out by the readout circuit 113 are converted into digital data and transferred to the control computer 200 as image information. The control computer 200 generates a radiation image from the acquired image information and displays it on a display or the like.

[0030] Next, in comparison with a comparative example, the connection between the control unit 116 and the drive circuit 114 of the radiation imaging apparatus 100 of this embodiment and a drive method using AEC will be described with reference to Figs. 6, 9 and 11 are equivalent circuits showing the connection between the control unit 116 and the drive circuit 114 in this embodiment. Figs. 7, 10 and 12 are timing charts showing the operation of the drive circuit 114 corresponding to the connections in Figs. 6, 9 and 11, respectively.

[0031] First, the connection between the control unit 116 and the drive circuit 114 in this embodiment and the drive method using AEC will be described with reference to Figs. 6 and 7. In the comparative example shown in Fig. 3, the control unit 116 supplies the control signals CPV, DIO, and OE to the drive circuits 114a to 114g through three signal lines corresponding to the control signals CPV, DIO, and OE, respectively. On the other hand, in this embodiment shown in Fig. 6, the control units 116 supply the control signals CPVa to CPVg, DIOa to DIOg, and OEa to OEg to the seven drive circuits 114a to 114g through three signal lines each, totaling 21 signal lines. That is, the control unit 116 and the drive circuit 114 are connected through 21 signal lines.

[0032] The radiographic image is captured according to the flow chart shown in Fig. 5, similar to the comparative example. When preparation for capturing an image is completed (S501), the control unit 116 causes the driving circuits 114a to 114g to start blank reading (S502). At this time, unlike the comparative example, the control unit 116 supplies a control signal DIO to each of the driving circuits 114a to 114g. The control unit 116 also inputs control signals CPV and OE to each of the driving circuits 114a to 114g to cause sequential scanning.

[0033] Next, in S503, when the user instructs the start of irradiation of radiation by pressing an exposure switch, for example, the radiation imaging apparatus 100 transitions to S504. In S504, the radiation imaging apparatus 100 acquires a radiation image using AEC. As shown in Fig. 7, the control unit 116 first performs a preparation operation, and then performs an accumulation operation.

[0034] The preparation operation in this embodiment will be described in detail. When the process proceeds to S504, before the irradiation of radiation, the control unit 116 measures the dose of radiation incident from the plurality of pixels PIX during the irradiation of radiation, and supplies a selection signal to a drive circuit group consisting of two or more drive circuits that drive the detection pixels among the plurality of drive circuits 114a to 114g in order to set two or more detection pixels for performing exposure control. Specifically, the control unit 116 outputs control signals DIOb to DIOf and CPVb to CPVf that function as selection signals to each of the drive circuits 114b to 114f of the drive circuit group to which the detection pixels arranged in the regions of interest 1 to 5 among the drive circuits 114a to 114g are connected. This advances the shift registers of the drive circuits 114b to 114f, and causes each of the drive circuits 114b to 114f included in the drive circuit group to select the row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected among the plurality of row signal lines Vg. At this time, as shown in Fig. 7, the control unit 116 may supply selection signals (control signals DIO, CPV) in parallel to the drive circuits 114b to 114f included in the drive circuit group. Because of the connection relationship that allows the control units 116 to supply the control signals DIO, CPV individually to each of the drive circuits 114a to 114g, the selection signals (control signals DIO, CPV) can be supplied in parallel to the drive circuits 114b to 114f included in the drive circuit group. This makes it possible to shorten the time for the preparation operation. In addition, a signal line that supplies the selection signals (control signals DIO, CPV) is independent for each of the drive circuits 114a to 114g. Therefore, the control unit 116 does not need to supply selection signals (control signals DIO, CPV) to the drive circuits 114a and 114g that are not included in the drive circuit group while causing each of the drive circuits 114b to 114f included in the drive circuit group to select one of the row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected among the multiple row signal lines Vg. When the selection of the row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected is completed, the control unit 116 transmits an exposure permission signal to the control computer 200 notifying the completion of preparation. In response to this exposure permission signal, the control computer 200 causes the radiation generation device 400 to start irradiating radiation via the radiation control device 300.As described above, the exposure permission signal may be sent directly from the radiation imaging apparatus 100 to the radiation control apparatus 300.

[0035] When the irradiation of radiation is started, the control unit 116 performs an operation for sequentially reading out signals from the detection pixels arranged in the regions of interest 1 to 5. At the same time, the pixels connected to row signal lines other than the row signal line to which the pixel set as the detection pixel is connected start an accumulation operation for acquiring a radiation image. Specifically, during the irradiation of radiation, the control unit 116 individually supplies control signals OEb to OEf that function as drive signals for driving pixels connected to row signal lines Vgb (R1) to Vgf (R5) selected from among the multiple row signal lines Vg to each of the drive circuits 114b to 114f included in the drive circuit group. In this way, the radiation imaging device 100 obtains signals for performing exposure control from each of the detection pixels. During the irradiation of radiation, the control unit 116 does not supply a drive signal (control signal OE) to the drive circuits 114a, 114g that are not included in the drive circuit group (drive circuits 114b to 114f). During radiation irradiation, the drive circuits 114b-114f select the row signal lines Vgb(R1)-Vgf(R5) to which the detection pixels are connected, and therefore the control unit 116 does not supply selection signals (control signals DIO, CPV) to the drive circuits 114b-114f included in the drive circuit group. In other words, during radiation irradiation, the control unit 116 does not need to supply selection signals (control signals DIO, CPV) to all of the drive circuits 114a-114g.

[0036] As shown in FIG. 7, the control unit 116 repeats the operation of reading out signals for AEC from the detection pixels, with the forward scanning of the control signals OEb to OEg being one frame. That is, each of the detection pixels can be connected to a different driving circuit 114 among the multiple driving circuits 114a to 114g. At the same time, the readout circuit 113 reads out a signal (charge) corresponding to the incident radiation from the detection pixel, and the calculation unit 117 adds up the signals acquired for each detection pixel. When the signal added up by the calculation unit 117 reaches a predetermined threshold value, the control unit 116 transmits an exposure stop signal to the control computer 200 (S505). In response to this exposure stop signal, the control computer 200 stops the irradiation of radiation from the radiation generation device 400 via the radiation control device 300 (S506). As described above, the exposure stop signal may be directly transmitted from the radiation imaging device 100 to the radiation control device 300. Furthermore, the threshold for transmitting the exposure stop signal may be common to the regions of interest 1 to 5, or may be different for each region of interest, and may be set appropriately depending on the conditions for capturing the radiation image, etc.

[0037] When the irradiation of radiation is completed, the control unit 116 performs a main read operation. In this main read operation, the driving circuit 114 sequentially applies a conductive voltage Vcom to the row signal lines Vg, which turns on the switch elements 101, and reads out signals (charges) accumulated during the irradiation of radiation from the conversion elements 102 of the pixels connected to each row signal line to the readout circuit 113. The signals read out by the readout circuit 113 are converted into digital data and transferred to the control computer 200 as image information. The control computer 200 generates a radiation image from the acquired image information and displays it on a display or the like.

[0038] Here, the effect of this embodiment will be described. When reading out signals from detection pixels for AEC, in the above-mentioned comparative example, the shift register is advanced in series to all row signal lines Vg of the detection unit 112. On the other hand, as shown in Figs. 6 and 7, in this embodiment, in a preparation operation, the shift register is advanced to the row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected in advance, and the driving circuits 114b to 114f select the row signal lines Vgb(R1) to Vgf(R5). This eliminates the need to advance the shift register, and during radiation irradiation, it becomes possible to read out signals for AEC by simply supplying the control signal OE to each of the driving circuits 114b to 114f (driving circuit group).

[0039] For example, consider a case where 3584 columns of detectors 112 are used with seven 512-channel drive circuits 114 to scan five regions of interest 1 to 5 when performing AEC. If the supply of a control signal CPV for advancing the shift register and the supply of a control signal OE for causing the drive circuit 114 to output a conduction voltage Vcom for driving the pixel PIX are considered as one step, 3584 steps are required to scan one frame in the comparative example. On the other hand, in this embodiment, one frame can be scanned in five steps. That is, during irradiation of radiation, signals can be read out from detection pixels in multiple regions of interest at high speed. This allows the number of readouts to be increased for a given dose and irradiation time, enabling more accurate AEC. In addition, since the scanning time for one frame can be shortened, AEC can be performed even when the irradiation time is short.

[0040] In this manner, in the present embodiment, it is possible to obtain signals from multiple regions of interest at high speed without requiring a complex circuit configuration while increasing the degree of freedom in setting the region of interest when performing AEC, thereby realizing a radiation imaging apparatus 100 that can perform AEC with high accuracy and ease of use.

[0041] In this embodiment, when irradiation of radiation is started, the control unit 116 performs an operation for sequentially reading out signals from the detection pixels arranged in the regions of interest 1 to 5, and the calculation unit 117 adds up the signals acquired for each detection pixel. That is, for each region of interest, the control unit 116 may determine whether or not the signal added up by the calculation unit 117 reaches a predetermined threshold value. However, the setting of the regions of interest is not limited to this. For example, the calculation unit 117 may add up (average) the signals output from the detection pixels of the regions of interest 1 to 5, and the control unit 116 may perform exposure control by comparing the cumulative value of the added up (averaged) signals with a threshold value. That is, as shown in FIG. 8, the control unit 116 may determine whether or not the signal added up by the calculation unit 117 reaches a predetermined threshold value using one region of interest 6 including the regions of interest 1 to 5. The regions of interest 1 to 5 and the region of interest 6 may be used appropriately depending on the conditions of radiographic imaging. The regions of interest 1 to 5 and the region of interest 6 may be selectively used, for example, by the user operating the control computer 200 in S501. Also, the control unit 116 may select the regions of interest 1 to 5 or the region of interest 6 according to the imaging conditions input in S501. For example, depending on the positioning of the patient, exposure control may be performed using the regions of interest 1 to 5 if the patient is in an upright position, and exposure control may be performed using the region of interest 6 if the patient is in a supine position.

[0042] When the region of interest 6 is used, the control unit 116 may perform the same operation as that shown in FIG. 7. The calculation unit 117 adds up signals obtained by adding up or averaging signals acquired from each detection pixel. When the signal added up by the calculation unit 117 reaches a predetermined threshold, the control unit 116 may transmit an exposure stop signal to the control computer 200. When the region of interest 6 is used, the signals output from each detection pixel may be added up as described above. Therefore, even if the detection pixels are connected to the same column signal line Sig, the signals can be read out simultaneously. Therefore, the control unit 116 may simultaneously input the control signals OEb-OEf to the drive circuits 114b-114f and obtain signals for exposure control from each of the detection pixels in one step. That is, during irradiation of radiation, the control unit 116 simultaneously supplies drive signals (control signals OE) for driving pixels connected to a row signal line selected from among the plurality of row signal lines Vg to each drive circuit 114 included in the drive circuit group. This allows signals for measuring the dose of radiation incident on each detection pixel to be acquired from five detection pixels in one step.As a result, one frame in which a signal is read out from each detection pixel once is one step, achieving more accurate AEC.

[0043] Next, the connection between the control unit 116 and the driving circuit 114 shown in Figs. 6 and 7, and a modified example of the driving method using AEC will be described with reference to Figs. 9 and 10. In Fig. 6, it has been described that the control unit 116 supplies the control signals DIO, CPV, and OE to each of the driving circuits 114a to 114g individually using three signal lines. That is, the control unit 116 has a configuration capable of supplying a driving signal (control signal OE) and a selection signal (control signals DIO, CPV) to each of the driving circuits 114a to 114g individually. On the other hand, in the configuration shown in Fig. 9, a total of 15 signal lines are connected from the control unit 116 to five driving circuits 114b to f connected to pixels PIX in areas set as regions of interest 1 to 5, three for each. In addition, signal lines supplying control signals CPVa and OEa are connected in parallel to the driving circuits 114a and 114g connected to pixels PIX in areas not set as regions of interest, and a signal line supplying a control signal DIOa is connected in series. In other words, the pixels PIX include pixels that can be set as detection pixels and pixels that cannot be set as detection pixels. In response to this, the control unit 116 has a configuration capable of supplying a drive signal (control signal OE) and a selection signal (control signals DIO, CPV) to each of the drive circuits 114b-114g that drive the pixels that can be set as detection pixels among the drive circuits 114a-114g.

[0044] In this way, the number of signal lines for supplying control signals to the connection between the control unit 116 and the drive circuits 114 shown in Fig. 6 can be reduced, making it possible to downsize the circuit and reduce costs. This effect is particularly significant when there are many drive circuits 114 connected to pixels in an area where a region of interest is not set.

[0045] As shown in Fig. 10, in obtaining a radiographic image using AEC in S504, signals can be read out at high speed from detection pixels arranged in a plurality of regions of interest 1 to 5, similar to the connection configuration shown in Fig. 6. Also, as shown in Fig. 10, the control unit 116 may supply selection signals (control signals DIO, CPV) in parallel to the drive circuits 114b to 114f included in the drive circuit group, thereby shortening the time for the preparation operation.

[0046] This allows the number of readouts to be increased for a given dose and exposure time, enabling more accurate AEC. Also, since the scanning time for one frame can be shortened, AEC can be performed even when the exposure time is short. Also, in the configuration shown in FIG. 9, the regions of interest 1 to 5 can be used as one region of interest 6, as described above. In this case, the control unit 116 may perform the same operation as that shown in FIG. 10, or may simultaneously input control signals OEb to OEf to the driving circuits 114b to 114f and obtain signals for exposure control from each of the detection pixels in one step.

[0047] Next, a further modified example of the connection between the control unit 116 and the driving circuit 114 shown in Figs. 6 and 7 and the driving method using AEC will be described with reference to Figs. 11 and 12. In the configuration shown in Fig. 11, compared to the configuration shown in Fig. 6, there is one signal line that supplies the control signal CPV from the control unit 116 to the driving circuits 114a to 114g. There is also one signal line that supplies the control signal DIO. Meanwhile, the signal lines that supply the control signals OEb to OEf from the control unit 116 to the five driving circuits 114b to f connected to the pixels PIX in the areas set as the regions of interest 1 to 5 are arranged separately. In addition, a signal line that supplies the control signal OEa is connected in parallel to the driving circuits 114a and 114g connected to the pixels PIX in the areas not set as the regions of interest. That is, the multiple pixels PIX include pixels that can be set as detection pixels and pixels that cannot be set as detection pixels. In response to this, the control unit 116 has a configuration capable of supplying a drive signal (control signal OE) individually to each of the drive circuits 114b to 114g that drive pixels that can be set as detection pixels among the plurality of drive circuits 114a to 114g.

[0048] By doing so, the number of steps for causing the driving circuits 114b to 114f to select the signal lines Vgb (R1) to Vgf (R5) to which the detection pixels are connected increases in the preparation operation. However, compared to the configurations shown in Figures 6 and 8, the number of signal lines for supplying control signals can be further reduced, and the circuit can be further downsized and costs can be further reduced.

[0049] As shown in FIG. 12, in acquiring a radiation image using AEC in S504, signals can be read out at high speed from detection pixels arranged in a plurality of regions of interest 1 to 5, similar to the connection configuration shown in FIG. 6. This allows the number of readouts to be increased for a given dose and exposure time, enabling more accurate AEC. Furthermore, since the scanning time for one frame can be shortened, AEC can be performed even when the exposure time is short. Furthermore, in the configuration shown in FIG. 11, the regions of interest 1 to 5 can be used as one region of interest 6, similar to the above. In this case, the control unit 116 may perform the same operation as that shown in FIG. 12, or may simultaneously input control signals OEb to OEf to the driving circuits 114b to 114f and acquire signals for exposure control from each of the detection pixels in one step.

[0050] Second embodiment 13(a) to 16, radiation imaging devices according to some embodiments of the present invention will be described. In the present embodiments, the configuration of the radiation imaging device 100 may be the same as that of the first embodiment described above, and therefore description thereof will be omitted here.

[0051] 13(a) to 13(d) are schematic diagrams showing the positional relationship between the subject and the radiation imaging device 100. In contrast to FIG. 13(a), FIGS. 13(b) to 13(d) show the radiation imaging device 100 rotated by 90° with respect to the subject. FIGS. 14 to 16 are timing charts showing the operation of the driving circuit 114 in this embodiment. The pre-reading operation, preparatory operation, and main reading operation may be the same as those in the first embodiment described above, and therefore will not be described here. The timing charts shown in FIGS. 14 to 16 show the operation in the connection between the control unit 116 and the driving circuits 114a to 114g shown in FIG. 11.

[0052] In the arrangement shown in FIG. 13(a), the operation shown in the timing diagram of FIG. 12 is performed. In contrast, when the subject and the radiation imaging device 100 are arranged as shown in FIG. 13(b) to FIG. 13(d), the driving shown in the timing diagram of FIG. 14 to FIG. 16 may be performed. Specifically, in the arrangement shown in FIG. 13(a), a case is considered in which reading is performed from the detection pixels in the order of the regions of interest 1→2→3→4→5. In this case, in the arrangement shown in FIG. 13(b), the driving shown in FIG. 14 may be performed so that reading is performed from the detection pixels in the order of the regions of interest 4→1→3→5→2. Similarly, in the arrangement shown in FIG. 13(c), the driving shown in FIG. 15 may be performed so that reading is performed from the detection pixels in the order of the regions of interest 5→4→3→2→1. Similarly, in the arrangement shown in FIG. 13(d), the driving shown in FIG. 16 may be performed so that reading is performed from the detection pixels in the order of the regions of interest 2→5→3→1→4. By driving the radiation imaging apparatus 100 in this manner, signals can be always read out from the regions of interest in a fixed order for the part of the subject, and AEC can be performed with high accuracy.

[0053] The order of reading out signals from the region of interest according to the positional relationship between the subject and the radiation imaging device 100 may be set arbitrarily by the user. Also, for example, as shown in Figs. 13(a) to 13(d), the radiation imaging device 100 may further include a rotation detection unit 120 for detecting the in-plane direction of the detection unit 112 in which a plurality of pixels PIX are arranged. In this case, the control unit 116 may change the order of acquiring signals from the detection pixels according to the direction detected by the rotation detection unit 120. Also, the rotation detection unit 120 may detect the in-plane direction independently, or may recognize the rotation direction according to the connection status with the imaging stand or the like. Also, the connection between the control unit 116 and the drive circuit 114 may be any of the configurations shown in Figs. 6, 9, and 11.

[0054] The order in which signals are read out from detection pixels when AEC is performed is changed depending on the relative positions of the subject and the radiation imaging device 100. This allows for high-speed acquisition of signals from multiple regions of interest without requiring a complex circuit configuration while increasing the degree of freedom in setting the region of interest when AEC is performed. This realizes a radiation imaging device 100 that can perform AEC with high accuracy and ease of use.

[0055] Third embodiment With reference to Figs. 13(a) and 17, radiation imaging devices according to some embodiments of the present invention will be described. In this embodiment, the configuration of the radiation imaging device 100 may be the same as that of the first embodiment described above, and therefore the description will be omitted here. Fig. 17 is a timing chart showing the operation of the driving circuit 114 in this embodiment. The pre-reading operation, preparatory operation, and main reading operation may be the same as those of the first embodiment described above, and therefore the description will be omitted here. The timing chart shown in Fig. 17 shows the operation in the connection between the control unit 116 and the driving circuits 114a to 114g shown in Fig. 11.

[0056] When the radiation imaging device 100 is disposed with respect to the subject as shown in FIG. 13(a), AEC is performed by radiation that has passed through the region of interest 1 (the upper left lung), the region of interest 2 (the upper right lung), the region of interest 3 (the spine), the region of interest 4 (the left abdomen), and the region of interest 5 (the right abdomen). Here, radiation is incident on the radiation imaging device 100 according to the transmittance of each part of the subject. In general, the transmittance of each part of the subject is roughly as follows: upper left lung=upper right lung>left abdomen=right abdomen>spine. Therefore, the signal value per time when signals are read from the detection pixels by the drive shown in FIG. 12 may be region of interest 1=2>4=5>3. When the signal value sampled per time is large, the signal (electric charge information) may be saturated and may not be correctly determined. Also, when the signal value sampled per time is small, the signal may be buried in noise and the end of radiation irradiation may not be correctly determined.

[0057] 17, the control unit 116 changes the intervals at which the control signals OEb to OEf are supplied to the regions of interest 1 and 2, the region of interest 3, and the regions of interest 4 and 5. That is, the detection pixels include, for example, detection pixels arranged in the region of interest 1 and detection pixels arranged in the region of interest 3, and during irradiation of radiation, the control unit 116 may make the sampling period for acquiring signals different between the detection pixels arranged in the region of interest 1 and the detection pixels arranged in the region of interest 3. If the transmittance of the subject is upper lung: upper right lung: spine: left abdomen: right abdomen = 3:3:1:2:2, the control unit 116 sets the intervals at which the control signals OEb to OEf are supplied as OEb:OEc:OEd:OEf:OEg = 3:3:1:2:2. This makes it possible to read out appropriate signals from the detection pixels arranged in the regions of interest 1 to 5 while suppressing the influence of the transmittance of radiation through the subject.

[0058] The radiation transmittance for each region of interest may be set arbitrarily by the user. Also, the control unit 116 may automatically recognize it from the signal value of the signal read out during imaging using AEC. Also, the connection between the control unit 116 and the drive circuit 114 may be any of the configurations shown in Figs. 6, 9, and 11.

[0059] In the present embodiment, it is also possible to obtain signals from multiple regions of interest at high speed without requiring a complex circuit configuration while increasing the degree of freedom in setting the region of interest when performing AEC, thereby realizing a radiation imaging apparatus 100 that can perform AEC with high accuracy and ease of use.

[0060] 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]

[0061] 100: Radiography device, 114: Drive circuit, 116: Control unit

Claims

1. A drive device for driving a plurality of pixels arranged in a plurality of rows on a row-by-row basis, comprising: a plurality of drive circuits arranged to drive different rows among the plurality of rows; the plurality of drive circuits include two or more drive circuits receiving different drive signals to drive rows, and two or more drive circuits receiving the same drive signal to drive rows; A drive device characterized by:

2. In the plurality of drive circuits, a row to be selected in an AEC operation is set in a preparation operation, The two or more drive circuits that receive the different drive signals to drive rows drive the rows set in the preparation operation by receiving the different drive signals in the AEC operation.

2. The drive device according to claim 1 .

3. The plurality of drive circuits drive the plurality of rows in response to drive signals respectively applied thereto during a main reading operation.

3. The drive device according to claim 2.

4. One of the plurality of drive circuits receives a first selection signal from a drive circuit other than the plurality of drive circuits, and the other of the plurality of drive circuits receives a second selection signal output from a drive circuit other than itself among the plurality of drive circuits.

4. The drive device according to claim 2 or 3.

5. Each of the plurality of drive circuits includes a shift register that operates in response to a shift clock, the first selection signal includes a pulse signal to be shifted in response to the shift clock; the second selection signal is output from each of the plurality of driving circuits in response to the shift clock; the plurality of drive circuits are connected in series such that the second selection signal is passed from an upstream drive circuit to a downstream drive circuit; 5. The drive device according to claim 4.

6. The one drive circuit is supplied with the pulse signal multiple times during the preparatory operation.

6. The drive device according to claim 5.

7. In the preparatory operation, the shift clock is supplied to the plurality of drive circuits and the pulse signal is supplied to the one drive circuit multiple times, thereby setting a row to be selected in the AEC operation.

7. The drive device according to claim 6.

8. A radiation imaging device comprising: a plurality of pixels; a driving device described in any one of claims 1 to 7 configured to drive the plurality of pixels on a row-by-row basis; and a control unit that controls the driving device.

9. A radiation imaging system comprising: a radiation imaging device as described in claim 8; and a control device that receives a signal from the control unit of the radiation imaging device and controls the operation of a radiation generating device for irradiating the radiation imaging device with radiation.

Images