Radiation imaging device and radiation imaging 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 device and a radiation imaging system.

Background Art

[0002] In medical image diagnosis and non-destructive inspection, radiation imaging devices using flat panel detectors (FPDs) composed of semiconductor materials are widely used. In such radiation imaging devices, it is known to measure in real time the radiation incident on the radiation imaging device. By detecting the radiation dose in real time, it becomes possible to grasp the integrated dose of the radiation incident during the 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 to a gate line to which a detection element set for AEC is connected from the start of exposure, and the detection element is continuously turned on. The operation shown in Patent Document 1 may be able to achieve high time resolution because a signal can always be acquired from the detection element. Further, Patent Document 2 shows that during the radiation irradiation, a sensor whose output exceeds a threshold value is excluded from an effective sensor group among a plurality of sensors set for AEC. By reducing the number of sensors constituting the effective sensor group, it becomes possible to increase the sampling frequency.

Prior Art Documents

Patent Documents

[0003] 1]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When performing AEC, it is sometimes necessary to set multiple regions of interest. In the operation shown in Patent Document 1, a high-level signal is always supplied to the gate line to which the detection element used in AEC is connected, so it is not possible to acquire signals independently from detection elements connected to gate lines other than the one to which the detection element is connected. In other words, in the operation shown in Patent Document 1, when setting multiple regions of interest, it is necessary to use detection elements connected to the same gate line, which reduces the degree of freedom in setting the regions of interest. 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 the effective sensor group.

[0005] The present invention aims to provide a technique that is advantageous for rapidly acquiring signals from multiple regions of interest in an AEC (Automated Economic Crossing). [Means for solving the problem]

[0006] One aspect of the present invention relates to a drive device for driving a plurality of pixels arranged to constitute a plurality of rows for detecting radiation, the drive device comprising a plurality of drive circuits arranged to drive pixels in different rows of the plurality of rows, each drive circuit controlling a switch element for outputting a signal from the pixel corresponding to a charge converted from radiation or light by a conversion element of the pixel driven by the drive circuit, the plurality of drive circuits including first and second drive circuits that operate in response to different first and second drive signals supplied via different signal lines, and third and fourth drive circuits that operate in response to the same third drive signal supplied via the same signal line. [Effects of the Invention]

[0007] The above means provides a technique that is advantageous for rapidly acquiring signals from multiple regions of interest in an AEC. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example configuration of a radiation imaging system using the radiation imaging device according to this embodiment. [Figure 2] Figure 1 shows an equivalent circuit diagram illustrating an example configuration of a radiation imaging device. [Figure 3] An equivalent circuit diagram showing an example of the connection between the control unit and the drive circuit of a comparative example radiation imaging device. [Figure 4] Figure 3 shows a timing diagram illustrating an example of the operation of the control unit and the drive circuit. [Figure 5] Figure 1 is a flowchart showing an example of the operation of a radiation imaging device. [Figure 6] Figure 1 shows an equivalent circuit diagram illustrating an example of the connection between the control unit and the drive circuit of the radiation imaging device. [Figure 7] A timing diagram showing an operation example of the control unit and the drive circuit in FIG. 6. [Figure 8] A diagram showing a modification example of the arrangement of the region of interest in FIG. 6. [Figure 9] An equivalent circuit diagram showing a connection example of the control unit and the drive circuit of the radiation imaging apparatus in FIG. 1. [Figure 10] A timing diagram showing an operation example of the control unit and the drive circuit in FIG. 9. [Figure 11] An equivalent circuit diagram showing a connection example of the control unit and the drive circuit of the radiation imaging apparatus in FIG. 1. [Figure 12] A timing diagram showing an operation example of the control unit and the drive circuit in FIG. 11. [Figure 13] A schematic diagram showing an arrangement example of the radiation imaging apparatus in FIG. 1. [Figure 14] A timing diagram of an operation example in the arrangement of FIG. 13. [Figure 15] A timing diagram of an operation example in the arrangement of FIG. 13. [Figure 16] A timing diagram of an operation example in the arrangement of FIG. 13. [Figure 17] A timing diagram showing an operation example of the control unit and the drive circuit in FIG. 11.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] In addition, the radiation in the present invention includes, in addition to α-rays, β-rays, γ-rays, etc., which are beams formed by particles (including photons) emitted by radioactive decay, beams having energy equal to or higher than the same level, for example, X-rays, particle beams, cosmic rays, etc. may also be included.

[0011] First Embodiment Referring to FIGS. 1 to 12, a radiation imaging apparatus according to some embodiments of the present invention will be described. FIG. 1 shows a block diagram of a configuration example of a radiation imaging system SYS using the radiation imaging apparatus 100 in the present embodiment. The radiation imaging system SYS includes a radiation imaging apparatus 100, a control computer 200, a radiation control apparatus 300, and a radiation generation apparatus 400.

[0012] The radiation imaging apparatus 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 for controlling the drive of the detection unit 112 and the irradiation of radiation based on the exposure information. In the detection unit 112, a plurality of pixels including sensors for detecting radiation are arranged in a matrix to acquire a radiation image and output a signal corresponding 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 the irradiation of radiation. As the calculation unit 117, a digital signal processing circuit such as an FPGA, a DSP, or a processor may be used. The calculation unit 117 may be configured using an analog circuit such as a sample and hold circuit or an operational amplifier. Also, in the configuration shown in FIG. 1, the calculation unit 117 is included in the radiation imaging apparatus 100, but the functions 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. Also, using the exposure information output by the calculation unit 117, the control unit 116 can change the driving method of the detection unit 112.

[0013] The control computer 200 controls the entire SYS radiation imaging system. The control computer 200 can also function as a user interface for users (such as radiologists) in acquiring radiation images using the SYS system. For example, a user inputs conditions for radiation image acquisition into the control computer 200, and the control computer 200 controls the radiation imaging device 100 and the radiation generator 400 according to the input conditions. Furthermore, the control computer 200 may include a signal processing unit that processes signals for generating radiation images output from the radiation imaging device 100. The control computer 200 processes the signals for generating radiation images output from the radiation imaging device 100 and displays the radiation images acquired by the radiation imaging device 100 on a display unit included in the control computer 200 or on an external display.

[0014] The radiation control device 300 controls the radiation generator 400 according to the signal output from the control computer 200. The radiation generator 400 emits radiation according to the signal output from the radiation control device 300.

[0015] Figure 2 is an equivalent circuit diagram showing an example configuration of the radiation imaging device 100. In Figure 2, for the sake of simplicity, a detection unit 112 with 3 rows and 3 columns of pixels is shown. However, actual radiation imaging devices have more pixels; for example, a 17-inch radiation imaging device has approximately 3500 rows and 3500 columns of pixels.

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

[0017] The readout circuit 113 includes an amplification circuit 106 for each column signal line Sig, which amplifies the signal output in parallel from the detection unit 112. The amplification circuit 106 also includes an integral amplifier 105 that amplifies the output electrical 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 out from the pixel PIX, an integral capacitor, and a reset switch. The amplification factor of the integral amplifier 105 can be changed by changing the value of the integral capacitor. The electrical signal output from the pixel PIX is input to the inverting input terminal of the integral amplifier 105, the reference voltage Vref from the reference power supply 111 is input to the forward input terminal, and the amplified signal is output from the output terminal. The integral capacitor is also placed 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 capacitor. The readout circuit 113 also includes a multiplexer 108 that sequentially outputs the signals read in parallel from each amplification circuit 106 and outputs them as a series image signal, and a buffer amplifier 109 that impedance-converts 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 the A / D converter 110. For example, the digital data during radiation irradiation is output to the calculation unit 117 and can be used for exposure control, etc. Also, for example, the digital data after radiation irradiation is output to the control computer 200, which can process the acquired signal and generate a radiation image.

[0018] Furthermore, the radiation imaging device 100 includes a reference power supply 111 and a bias power supply 103 for the amplification circuit as a power supply unit. The reference power supply 111 supplies a reference voltage Vref to the forward input terminal of each operational amplifier. The bias power supply 103 supplies a common bias voltage Vs to the conversion elements 102 via bias wiring Bs.

[0019] The drive circuit 114 outputs a drive signal to the row signal line Vg, which includes a conduction voltage Vcom to make the switch element 101 conduct and a non-conduction voltage Vss to make it non-conductive, in response to the control signals CPV, OE, and DIO input from the control unit 116. In this way, the drive circuit 114 controls the conduction and non-conduction states of the switch element 101 and drives the multiple pixels PIX arranged in the detection unit 112 row by row. 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 the shift clock for the shift register used in the drive circuit. The control signal DIO is a signal to cause the shift register to start shifting in accordance with the shift clock. The control signal OE is a signal to control the output terminal of the shift register. Based on the above control signals CPV, DIO, and OE, the control unit 116 sets the required time and scanning direction for driving the detection unit 112 by the drive circuit 114. The control unit 116 also supplies control signals RC, SH, and CLK to the readout circuit 113 to control the operation of each component of the readout circuit 113. Here, control signal RC controls the operation of the reset switch of the integrating amplifier, control signal SH controls the operation of the sample-and-hold circuit 107, and control signal CLK controls the operation of the multiplexer 108.

[0021] Next, the connection between the control unit 116 and the drive circuit 114 of the radiation imaging device 100, and the driving 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 driving method in this embodiment, a comparative example will be described first. Figure 3 is an equivalent circuit showing the connection between the control unit 116 and the drive circuit 114 in the comparative example.

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

[0023] The detection unit 112 has regions of interest 1 to 5 arranged at coordinates corresponding to the region of interest of the external AEC chamber. Each of the regions of interest 1 to 5 is equipped with a pixel (hereinafter sometimes referred to as a detection pixel) used for exposure control. Here, for the sake of simplicity, we will explain assuming there are five regions of interest, but the number of regions of interest is not limited to this, and may be four or fewer, or six or more. Also, the position of the regions of interest is not limited to the positions shown in Figure 3, but can be set to any position. In this embodiment, the detection pixels for exposure control are appropriately selected from the pixels PIX used to acquire the radiation image. However, this is not limited to this, and the detection unit 112 may be equipped with multiple pixels dedicated to AEC, from which any pixel may be selected.

[0024] Each detection pixel in regions of interest 1 to 5 is connected to a row signal line Vgb(R1) to Vgf(R5) that controls the switch element 101. Drive circuit 114b drives the detection pixel in region of interest 1 via row signal line Vgb(R1). Similarly, drive circuit 114c drives the detection pixel in region of interest 2 via row signal line Vgc(R2), drive circuit 114d drives the detection pixel in region of interest 3 via row signal line Vgd(R3), drive circuit 114e drives the detection pixel in region of interest 4 via row signal line Vge(R4), and drive circuit 114f drives the pixel in region of interest 5 via row signal line Vgf(R5).

[0025] Figure 4 shows a timing diagram illustrating the operation of the drive circuit 114 in the comparative example. Figure 5 is a flowchart illustrating the operation of the radiation imaging device 100 in this embodiment and the comparative example. The operation of the AEC in the comparative example will be explained using Figures 3 to 5.

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

[0027] Next, in S503, when the user instructs the start of radiation irradiation, such as by pressing the exposure switch, the radiation imaging device 100 transitions to S504. In S504, the radiation imaging device 100 acquires a radiation image using AEC. As shown in Figure 4, the control unit 116 first performs a preparation operation, and then performs an accumulation operation. The preparation operation is the operation in which the control unit 116 supplies the control signal DIO and multiple control signals CPV to the drive circuit 114 to advance the shift register up to the row signal line Vgb(R1) to which the detection pixel set in region of interest 1 is connected. 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, it sends an exposure permission signal to the control computer 200 to indicate that preparation is complete. In response to this exposure permission signal, the control computer 200 causes the radiation generator 400 to start irradiating with radiation via the radiation control device 300. In this embodiment, the radiation imaging device 100 transmits an exposure permission signal to the control computer 200, but it may also transmit the exposure permission signal directly to the radiation control device 300, in which case the radiation generator 400 will start irradiating with radiation.

[0028] When radiation irradiation begins, the control unit 116 sequentially reads signals from the detection pixels located in regions of interest 1 to 5. Simultaneously, pixels connected to row signal lines other than those to which the pixels set as detection pixels are connected begin accumulating data to acquire a radiation image. Specifically, the control unit 116 outputs a control signal CPV to advance the shift register, and when the drive circuit 114 selects row signal lines Vgb(R1) to f(R5), it outputs a control signal OE, sending 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 drive circuit 114a on a frame-by-frame basis, and repeats the acquisition of signals for AEC. At this time, the readout circuit 113 reads signals (charges) corresponding to the incident radiation from the detection pixels, and the calculation unit 117 measures the dose of incident radiation based on the signals acquired from the detection pixels. For example, the calculation unit 117 adds 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 device 100 transmits a signal to the radiation generator 400, which irradiates the radiation imaging device 100, to stop irradiating with radiation. Specifically, when the signal added by the calculation unit 117 reaches a predetermined 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 generator 400 via the radiation control device 300 (S506). In this embodiment, the radiation imaging device 100 transmits the exposure stop signal to the control computer 200, but it may also transmit the exposure stop signal directly to the radiation control device 300, and in response, the radiation generator 400 may stop irradiating with radiation. Furthermore, if the radiation dose measured by the calculation unit 117 is expected to reach a preset dose, the control unit 116 may transmit an exposure stop signal to the control computer 200.

[0029] Once radiation irradiation is complete, the control unit 116 performs a final read operation. This final read operation involves sequentially applying a conduction voltage Vcom from the drive circuit 114 to the row signal lines Vg, which turns on the switch element 101, and reading the signals (charges) accumulated during radiation irradiation from the pixel conversion elements 102 connected to each row signal line to the readout circuit 113. The signals read to the readout circuit 113 are converted into digital data and transferred as image information to the control computer 200. 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 device 100 of this embodiment, and the driving method using AEC will be explained using Figures 5 to 12. Figures 6, 9, and 11 are equivalent circuits showing the connection between the control unit 116 and the drive circuit 114 in this embodiment. Figures 7, 10, and 12 are timing charts showing the operation of the drive circuit 114 according to the respective connections in Figures 6, 9, and 11.

[0031] First, the connection between the control unit 116 and the drive circuit 114 in this embodiment, and the driving method using AEC, will be explained using Figures 6 and 7. In the comparative example shown in Figure 3, the control signals CPV, DIO, and OE were supplied from the control unit 116 to the respective drive circuits 114a to 114g by three signal lines corresponding to each of the control signals CPV, DIO, and OE. On the other hand, in this embodiment shown in Figure 6, the control unit 116 supplies the control signals CPVa to CPVg, DIOa to DIOg, and OEa to OEg to the seven drive circuits 114a to 114g by three signal lines each, for a total of 21 signal lines. In other words, the control unit 116 and the drive circuit 114 are connected by 21 signal lines.

[0032] The acquisition of the radiation image is performed according to the flowchart shown in Figure 5, similar to the comparative example. When the preparation for imaging is complete (S501), the control unit 116 starts reading blanks for the drive circuits 114a to 114g (S502). At this time, unlike the comparative example, the control unit 116 supplies a control signal DIO to each of the drive circuits 114a to 114g. The control unit 116 also inputs control signals CPV and OE to each of the drive circuits 114a to 114g and scans them sequentially.

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

[0034] The preparatory operations in this embodiment will now be described in detail. Upon transitioning to S504, before radiation irradiation, the control unit 116 measures the dose of radiation incident from multiple pixels PIX during radiation irradiation and supplies selection signals to a group of drive circuits consisting of two or more drive circuits from multiple drive circuits 114a to 114g that drive the detection pixels, in order to set two or more detection pixels for exposure control. Specifically, the control unit 116 outputs control signals DIOb to DIOf and CPVb to CPVf, which function as selection signals, to each of the drive circuits 114b to 114f in the group of drive circuits 114a to 114g to which the detection pixels located in regions of interest 1 to 5 are connected. This advances the shift registers of the drive circuits 114b to 114f, causing each of the drive circuits 114b to 114f included in the group of drive circuits to select row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected, from among multiple row signal lines Vg. In this case, as shown in Figure 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 the control unit 116 has a connection relationship that allows it to supply control signals DIO and CPV individually to each of the drive circuits 114a to 114g, it is possible to supply selection signals (control signals DIO, CPV) in parallel to the drive circuits 114b to 114f included in the drive circuit group. This makes it possible to shorten the preparation time. In addition, each of the drive circuits 114a to 114g has an independent signal line for supplying selection signals (control signals DIO, CPV). Therefore, while the control unit 116 causes each of the drive circuits 114b to 114f included in the drive circuit group to select row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected from among a plurality of row signal lines Vg, it 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. Once the selection of row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected is complete, it transmits an exposure permission signal to the control computer 200 to indicate that preparation is complete. In response to this exposure permission signal, the control computer 200 causes the radiation generator 400 to start irradiating with radiation via the radiation control device 300.As mentioned above, the exposure permission signal may be transmitted directly from the radiation imaging device 100 to the radiation control device 300.

[0035] When radiation irradiation begins, the control unit 116 sequentially reads signals from the detection pixels located in regions of interest 1 to 5. Simultaneously, pixels connected to row signal lines other than those to which the pixels set as detection pixels are connected begin accumulating data to acquire a radiation image. Specifically, during radiation irradiation, the control unit 116 individually supplies control signals OEb to OEf, which function as drive signals to drive pixels connected to selected row signal lines Vgb(R1) to Vgf(R5) from among multiple row signal lines Vg, to each of the drive circuits 114b to 114f included in the drive circuit group. As a result, the radiation imaging device 100 acquires signals for exposure control from each of the detection pixels. During radiation irradiation, the control unit 116 does not supply drive signals (control signals OE) to drive circuits 114a and 114g that are not included in the drive circuit group (drive circuits 114b to 114f). Furthermore, during radiation irradiation, the drive circuits 114b to 114f select the row signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected, so the control unit 116 does not supply selection signals (control signals DIO, CPV) to the drive circuits 114b to 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 drive circuits 114a to 114g.

[0036] As shown in Figure 7, the control unit 116 repeatedly reads signals for AEC from the detected pixels, with the sequential scanning of control signals OEb to OEg forming one frame. In other words, each detected pixel can be connected to a different drive circuit 114 from among the multiple drive circuits 114a to 114g. Simultaneously, the readout circuit 113 reads a signal (charge) corresponding to the incident radiation from the detected pixels, and the calculation unit 117 adds up the signals acquired for each detected pixel. When the signals added by the calculation unit 117 reach a predetermined 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 generator 400 via the radiation control device 300 (S506). As described above, the exposure stop signal may also be transmitted directly 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 all regions of interest 1-5, or it may differ for each region of interest. It should be set appropriately according to the conditions for acquiring the radiation image, etc.

[0037] Once radiation irradiation is complete, the control unit 116 performs a final read operation. This final read operation involves sequentially applying a conduction voltage Vcom from the drive circuit 114 to the row signal lines Vg, which turns on the switch element 101, and reading the signals (charges) accumulated during radiation irradiation from the pixel conversion elements 102 connected to each row signal line to the readout circuit 113. The signals read to the readout circuit 113 are converted into digital data and transferred as image information to the control computer 200. The control computer 200 generates a radiation image from the acquired image information and displays it on a display or the like.

[0038] The effects of this embodiment will now be explained. In the comparative example described above, when reading signals from the detected pixels for AEC, the shift register was advanced in series with respect to all row signal lines Vg of the detection unit 112. On the other hand, as shown in Figures 6 and 7, in this embodiment, the shift register is advanced in advance during the preparation operation to the row signal lines Vgb(R1) to Vgf(R5) to which the detected pixels are connected, and the drive circuits 114b to 114f are made to select the row signal lines Vgb(R1) to Vgf(R5). Therefore, it is not necessary to advance the shift register, and during radiation irradiation, it is possible to read out the AEC signal by simply supplying the control signal OE to each of the drive circuits 114b to 114f (drive circuit group).

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

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

[0041] In this embodiment, when radiation irradiation begins, the control unit 116 sequentially reads signals from the detection pixels arranged in regions of interest 1 to 5, and the calculation unit 117 adds up the signals acquired from each detection pixel. In other words, for each region of interest, the control unit 116 may determine whether the signals added by the calculation unit 117 reach a predetermined threshold. However, the setting of regions of interest is not limited to this. For example, the calculation unit 117 may sum (average) the signals output from each detection pixel in regions of interest 1 to 5, and the control unit 116 may perform exposure control by comparing the cumulative value of the sum (averaged) signals with a threshold. In other words, as shown in Figure 8, the control unit 116 may use one region of interest 6 that includes regions of interest 1 to 5 to determine whether the signals added by the calculation unit 117 reach a predetermined threshold. Depending on the conditions for imaging radiation images, regions of interest 1 to 5 and region of interest 6 can be used interchangeably as appropriate. The user may, for example, operate the control computer 200 in S501 to decide whether to use regions of interest 1-5 or region of interest 6. Alternatively, the control unit 116 may select regions of interest 1-5 or region of interest 6 according to the imaging conditions input in S501. For example, depending on the patient's positioning, exposure control may be performed using regions of interest 1-5 if the patient is standing, and using region of interest 6 if the patient is lying down.

[0042] When using region of interest 6, the control unit 116 may perform operations similar to those shown in Figure 7. The calculation unit 117 adds up the signals obtained from each detected pixel by summing or averaging them. When the signal added by the calculation unit 117 reaches a predetermined threshold, the control unit 116 should send an exposure stop signal to the control computer 200. Also, when using region of interest 6, the signals output from each detected pixel can be summed up as described above. Therefore, even if the detected pixels are connected to the same row signal line Sig, the signals can be read out simultaneously. Thus, the control unit 116 may simultaneously input control signals OEb to OEf to the drive circuits 114b to 114f and acquire signals for exposure control from each detected pixel in one step. In other words, during radiation irradiation, the control unit 116 simultaneously supplies drive signals (control signals OE) to each drive circuit 114 included in the drive circuit group to drive the pixels connected to the selected row signal line Vg from among the multiple row signal lines Vg. This allows signals for measuring the dose of incident radiation from each detection pixel to be acquired from the five detection pixels in a single step. As a result, one frame, in which the signal is read once from each detection pixel, corresponds to one step, enabling more accurate AEC (Autonomous Emergency Cycle).

[0043] Next, the connection between the control unit 116 and the drive circuit 114 shown in Figures 6 and 7, and a modified example of the driving method using AEC will be explained using Figures 9 and 10. In Figure 6 described above, the control unit 116 individually supplies control signals DIO, CPV, and OE to each of the drive circuits 114a to 114g using three signal lines each. In other words, the control unit 116 was configured to individually supply a drive signal (control signal OE) and selection signals (control signals DIO, CPV) to each of the multiple drive circuits 114a to 114g. On the other hand, in the configuration shown in Figure 9, a total of 15 signal lines, three each, are connected to the five drive circuits 114b to f connected to the pixels PIX in the regions set as regions of interest 1 to 5 from the control unit 116. In addition, for the drive circuits 114a and 114g connected to the pixels PIX in regions not set as regions of interest, signal lines supplying control signals CPVa and OEa are connected in parallel, and signal lines supplying control signal DIOa are connected in series. In other words, multiple pixels PIX include pixels that can be set as detection pixels and pixels that cannot be set as detection pixels. Accordingly, the control unit 116 is configured to supply a drive signal (control signal OE) and a selection signal (control signal DIO, CPV) individually to each of the drive circuits 114b to 114g that drive the pixels that can be set as detection pixels among the multiple drive circuits 114a to 114g.

[0044] By doing so, the number of signal lines supplying control signals to the connection between the control unit 116 and the drive circuit 114 shown in Figure 6 can be reduced, thereby reducing the size of the circuit and lowering costs. This effect is particularly significant when there are many drive circuits 114 connected to pixels in areas where no region of interest is set.

[0045] As shown in Figure 10, in acquiring radiation images using the AEC of S504, signals can be read out at high speed from detection pixels arranged in multiple regions of interest 1 to 5, similar to the connection configuration shown in Figure 6. Also, as shown in Figure 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 to shorten the preparation time.

[0046] This allows for an increased number of readouts for a given irradiation dose and duration, enabling more accurate AEC. Furthermore, it shortens the scanning time per frame, making AEC possible even with short irradiation times. In the configuration shown in Figure 9, regions of interest 1-5 can also be used as a single region of interest 6, similar to the configuration described above. In this case, the control unit 116 may perform operations similar to those shown in Figure 10, or it may simultaneously input control signals OEb-OEf to the drive circuits 114b-114f and acquire exposure control signals from each detected pixel in a single step.

[0047] Next, the connection between the control unit 116 and the drive circuit 114 shown in Figures 6 and 7, and further modifications of the driving method using AEC will be explained using Figures 11 and 12. In the configuration shown in Figure 11, compared to the configuration shown in Figure 6, there is only one signal line supplying the control signal CPV from the control unit 116 to the drive circuits 114a to 114g. There is also only one signal line supplying the control signal DIO. On the other hand, the signal lines supplying the control signals OEb to OEf to the five drive circuits 114b to 114f connected to the pixels PIX in the regions set as regions of interest 1 to 5 are individually arranged from the control unit 116. In addition, a signal line supplying the control signal OEa is connected in parallel to the drive circuits 114a and 114g connected to the pixels PIX in regions not set as regions of interest. In other words, 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 is configured to supply 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 multiple drive circuits 114a to 114g.

[0048] This approach increases the number of steps required in the preparation phase to select the signal lines Vgb(R1) to Vgf(R5) to which the detection pixels are connected in the drive circuits 114b to 114f. However, compared to the configurations shown in Figures 6 and 8, the number of signal lines for supplying control signals can be further reduced, allowing for circuit miniaturization and further cost reduction.

[0049] As shown in Figure 12, in acquiring radiation images using AEC of S504, signals can be read out at high speed from detection pixels arranged in multiple regions of interest 1 to 5, similar to the connection configuration shown in Figure 6. This allows for an increased number of readouts for a given irradiation dose and irradiation time, enabling more accurate AEC. Furthermore, the scanning time per frame can be shortened, making AEC possible even with short irradiation times. In addition, in the configuration shown in Figure 11, regions of interest 1 to 5 can be used as a single region of interest 6, similar to the above. In this case, the control unit 116 may perform the same operation as shown in Figure 12, or it may simultaneously input control signals OEb to OEf to the drive circuits 114b to 114f and acquire signals for exposure control from each detection pixel in one step.

[0050] Second Embodiment Referring to Figures 13(a) to 13(13), a radiation imaging apparatus in some embodiments of the present invention will be described. In this embodiment, the configuration of the radiation imaging apparatus 100 may be the same as in the first embodiment described above, so its description will be omitted here.

[0051] Figures 13(a) to 13(d) are schematic diagrams showing the arrangement of the subject and the radiation imaging device 100. Compared to Figure 13(a), Figures 13(b) to 13(d) depict the radiation imaging device 100 being rotated 90° relative to the subject, respectively. Figures 14 to 16 are timing charts showing the operation of the drive circuit 114 in this embodiment. The blank reading operation, preparation operation, and main reading operation may be the same as in the first embodiment described above, so their explanation is omitted here. The timing diagrams shown in Figures 14 to 16 show the operation in the connection between the control unit 116 shown in Figure 11 and the drive circuits 114a to 114g.

[0052] In the arrangement shown in Figure 13(a), the operation shown in the timing diagram of Figure 12 is performed. In contrast, when the arrangement of the subject and the radiation imaging device 100 is as shown in Figures 13(b) to 13(d), the drives shown in the timing diagrams of Figures 14 to 16 may be performed, respectively. Specifically, consider the case in the arrangement of Figure 13(a) where readout is performed from the detected pixels in the order of regions of interest 1→2→3→4→5. In this case, in the arrangement of Figure 13(b), the drives shown in Figure 14 may be performed so that readout is performed from the detected pixels in the order of regions of interest 4→1→3→5→2. Similarly, in the arrangement of Figure 13(c), the drives shown in Figure 15 may be performed so that readout is performed from the detected pixels in the order of regions of interest 5→4→3→2→1. Also, similarly, in the arrangement of Figure 13(d), the drives shown in Figure 16 may be performed so that readout is performed from the detected pixels in the order of regions of interest 2→5→3→1→4. By driving the radiation imaging device 100 in this manner, signals can always be read out from the region of interest in a fixed order for each part of the subject, enabling accurate AEC (Autonomous Electronic Compression).

[0053] The user may arbitrarily set the order in which signals are read from the region of interest, depending on the arrangement relationship between the subject and the radiation imaging device 100. Furthermore, as shown in Figures 13(a) to 13(d), the radiation imaging device 100 may further include a rotation detection unit 120 for detecting the in-plane orientation of a detection unit 112, which has multiple pixels PIX arranged within it. In this case, the control unit 116 may change the order in which signals are acquired from the detected pixels according to the orientation detected by the rotation detection unit 120. The rotation detection unit 120 may also independently detect the in-plane orientation or recognize the direction of rotation according to the connection status with the imaging table or the like. The connection between the control unit 116 and the drive circuit 114 may be any of the configurations shown in Figures 6, 9, and 11.

[0054] The order in which signals are read from the detected pixels during AEC is changed depending on the arrangement of the subject and the radiation imaging device 100. This allows for greater flexibility in setting the region of interest during AEC, while enabling high-speed signal acquisition from multiple regions of interest without requiring a complex circuit configuration. As a result, a radiation imaging device 100 that enables highly accurate and user-friendly AEC is realized.

[0055] Third Embodiment Referring to Figures 13(a) and 17, a radiation imaging device in 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 in the first embodiment described above, so its description will be omitted here. Figure 17 is a timing chart diagram showing the operation of the drive circuit 114 in this embodiment. The blank reading operation, preparation operation, and main reading operation may be the same as in the first embodiment described above, so its description will be omitted here. The timing diagram shown in Figure 17 shows the operation in the connection between the control unit 116 shown in Figure 11 and the drive circuits 114a to 114g.

[0056] When the radiation imaging device 100 is positioned relative to the subject as shown in Figure 13(a), AEC is performed by radiation that has passed through the upper left lung (region 1), the upper right lung (region 2), the spine (region 3), the left abdomen (region 4), and the right abdomen (region 5). Here, radiation enters the radiation imaging device 100 according to the transmittance of each part of the subject. Generally, the transmittance of each part of the subject is roughly upper left lung = upper right lung > left abdomen = right abdomen > spine. Therefore, when reading signals from the detection pixels with the drive shown in Figure 12, the signal value per sample may be 1 = 2 > 4 = 5 > 3. If the sampled signal value per sample is large, the signal (charge information) may saturate and it may not be possible to make a correct determination. Also, if the sampled signal value per sample is small, the signal may be buried in noise and it may not be possible to correctly determine the end of radiation irradiation.

[0057] Therefore, in the driving method shown in Figure 17, the control unit 116 changes the interval at which it supplies control signals OEb to OEf in regions of interest 1, 2, 3, 4, and 5. In other words, the detection pixels include, for example, detection pixels located in region of interest 1 and detection pixels located in region of interest 3, and during radiation irradiation, the control unit 116 may make the sampling period for acquiring signals different for the detection pixels located in region of interest 1 and the detection pixels located in 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 interval at which it supplies control signals OEb to OEf to OEb to OEb:OEb:OEc:OEd:OEf:OEg = 3:3:1:2:2. This makes it possible to read out appropriate signals from the detection pixels located in each of the regions of interest 1 to 5 while suppressing the influence of the radiation transmittance of the subject.

[0058] The user may set the radiation transmittance for each region of interest as they see fit. Alternatively, the control unit 116 may automatically recognize the transmittance from the signal value of the signal read out during imaging using AEC. Furthermore, the connection between the control unit 116 and the drive circuit 114 may be any of the configurations shown in Figures 6, 9, and 11.

[0059] In this embodiment as well, it is possible to acquire signals from multiple regions of interest at high speed without requiring a complex circuit configuration, while maintaining a high degree of freedom in setting the region of interest when performing AEC. This realizes a radiation imaging device 100 that can perform AEC with high accuracy and ease of use.

[0060] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

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

Claims

1. A drive device that drives multiple pixels in a row-by-row manner for detecting radiation arranged to constitute multiple rows, The system comprises multiple drive circuits arranged to drive pixels in rows that are different from each other among the aforementioned multiple rows, Each drive circuit controls a switch element for outputting a signal from the pixel corresponding to the charge converted from radiation or light by the conversion element of the pixel it drives, and the plurality of drive circuits include first and second drive circuits that operate by receiving different first and second drive signals supplied via different signal lines, respectively, and third and fourth drive circuits that operate by receiving the same third drive signal supplied via the same signal line. A drive device characterized by the following features.

2. In the aforementioned multiple drive circuits, the row to be selected in the AEC operation for acquiring a radiographic image is set in the preparation operation. The first and second drive circuits, which drive rows in response to the first and second drive signals which are different from each other, drive the rows set in the preparation operation in response to the first and second drive signals which are different from each other during the AEC operation. The drive device according to feature 1.

3. The aforementioned multiple drive circuits drive the multiple rows in accordance with the drive signals provided to each of them during the reading operation. The drive device according to feature 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 drive circuits receive a second selection signal output from a drive circuit other than itself among the plurality of drive circuits. The drive device according to claim 2 or 3.

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

6. The aforementioned drive circuit is supplied with the pulse signal multiple times during the preparation operation. The drive device according to feature 5.

7. In the preparation operation, the shift clock is supplied to the multiple drive circuits and the pulse signal is supplied to one of the drive circuits multiple times, thereby setting the row to be selected in the AEC operation. The drive device according to feature 6.

8. A radiation imaging apparatus comprising: a plurality of pixels; a drive device according to any one of claims 1 to 7 configured to drive the plurality of pixels in row units; and a control unit for controlling the drive device.

9. A radiation imaging system comprising: a radiation imaging device according to 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 generator for irradiating the radiation imaging device with radiation.

Images