Radiation imaging apparatus and radiation imaging system

Abstract

To reduce an exposure dose to a subject in radiation imaging.SOLUTION: The radiation imaging apparatus includes a radiation detector configured to obtain a radiation image by causing radiation to be incident on the radiation detector, a unit configured to obtain dose information of the radiation incident on the radiation detector, a unit configured to obtain imaging condition information of radiation imaging for obtaining the radiation image by causing the radiation to be incident on the radiation detector up to a target dose, and a unit configured to issue a notification to stop radiation irradiation by a radiation generating apparatus so as to stop the radiation irradiation by the radiation generating apparatus before the radiation is incident up to the target dose after the start of the radiation imaging based on the imaging condition information.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a radiation imaging apparatus and a radiation imaging system. The radiation imaging apparatus is used as a medical diagnostic device and a non-destructive testing device, for example, an X-ray flat panel detector. [Background technology]

[0002] Conventionally, in a radiation imaging device that acquires a radiation image based on radiation, a technology is known in which the amount of radiation incident on the radiation imaging device is measured and used for imaging control. One example of such a technology is an automatic exposure control (AEC) function. Patent Document 1 discloses a radiation imaging device equipped with an AEC function. By using the AEC function, it is possible to reduce the amount of radiation exposure to a subject when completing radiation imaging. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-90869 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 leaves room for improvement in terms of the radiation dose to the subject when radiation imaging cannot be completed normally. When performing radiation imaging, various factors can cause situations in which radiation imaging cannot be completed normally. For example, in an X-ray imaging system having multiple radiation imaging devices and AEC sensors, it is conceivable that the radiation imaging device is not irradiated with X-rays at the desired dose due to an incorrect selection of the radiation imaging device or AEC sensor to be used, or an incorrect orientation or irradiation field of the X-ray tube. In such a situation, the subject is irradiated even though imaging cannot be completed normally. Therefore, when imaging cannot be completed normally, it is desirable to detect this early and stop the irradiation of radiation.

[0005] An object of the present invention is to reduce the amount of radiation to be exposed to a subject in radiographic imaging. [Means for solving the problem]

[0006] The radiation imaging apparatus of the present invention is characterized by comprising: a radiation detector for irradiating radiation to obtain a radiation image; means for acquiring dose information of radiation incident on the radiation detector; means for acquiring imaging condition information for radiation imaging in which radiation is incident on the radiation detector up to a target dose to obtain a radiation image; and means for issuing a notification to stop radiation irradiation by the radiation generating device after radiation imaging based on the imaging condition information has started, so that radiation irradiation by the radiation generating device is stopped before radiation reaches the target dose. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the amount of radiation to be exposed to a subject in radiographic imaging. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a radiation imaging system. [Figure 2] FIG. 1 is a diagram illustrating a configuration of a radiation imaging apparatus. [Figure 3]Fig. 3(A) is a diagram illustrating the measurement field, and Fig. 3(B) is a diagram illustrating the arrangement of pixels in the measurement field. [Figure 4] FIG. 2 is a diagram illustrating a configuration of a control device. [Figure 5] FIG. 10 is a diagram illustrating early stopping. [Figure 6] FIG. 2 is a diagram showing a control flow of the radiation imaging apparatus. [Figure 7] FIG. 10 is a diagram illustrating early stopping in consideration of delay time. [Figure 8] FIG. 10 is a diagram showing a control flow of a radiation imaging apparatus and an irradiation control unit in another embodiment. [Figure 9] FIG. 10 is a diagram illustrating early stopping in consideration of a delay time of irradiation. [Figure 10] FIG. 11 is a diagram showing the control flow of S602 in the third embodiment. [Figure 11] FIG. 10 is a diagram showing the increasing trend of cumulative dose in each measurement field. [Figure 12] Fig. 12(A) is a diagram for explaining an error in setting the measurement field, and Fig. 12(B) is a diagram showing the increasing trend of the cumulative dose in each measurement field. [Figure 13] Fig. 13(A) is a diagram explaining the subdivided measurement fields, Fig. 13(B) is a diagram showing the cumulative dose in each measurement field, and Fig. 13(C) is a diagram showing the cumulative dose in each measurement field. [Figure 14] FIG. 10 is a diagram illustrating the relationship between the radiation field and the implant. [Figure 15] FIG. 2 is a diagram showing a control flow of the radiation imaging apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present invention will be described in detail with reference to specific examples and drawings. Note that the following examples do not limit the scope of the claimed invention. Although the examples describe multiple features, not all of these features are necessarily essential to the invention, and multiple features may be combined in any manner.

[0010] Example 1 <System> 1 is a diagram showing a schematic configuration of a radiation imaging system. The radiation imaging system 1 includes a radiation imaging device 10, a control device 400, a radiation generation unit 300, a RIS 510, a PACS 520, and an HIS 530. RIS is an abbreviation for Radiology Information Systems. PACS is an abbreviation for Picture Archiving and Communication Systems (image server). HIS is an abbreviation for Hospital Information Systems.

[0011] The radiation generating unit (radiation generating device) 300 includes a radiation tube that generates radiation, and irradiates a subject 600 such as a patient with the radiation.

[0012] The radiation imaging device 10 generates an image based on radiation that is emitted from a radiation generating unit 300 and transmitted (passes through) a subject such as a patient. The radiation imaging device 10 is, for example, a flat panel detector. The radiation imaging device 10 has a function of performing automatic exposure control (hereinafter referred to as AEC). Details of the radiation imaging device 10 will be described later.

[0013] The control device 400 is a device that relays the radiation imaging device 10, the radiation generation unit 300, and each device that can be connected via the network 500. The control device 400 has an imaging control unit 410, an irradiation control unit 420, and a UI control unit 430.

[0014] The imaging control unit 410 performs various controls for radiation imaging (radiography) by communicating with the radiation imaging apparatus 10. For example, the imaging control unit 410 executes various communication processes associated with radiation imaging with the radiation imaging apparatus 10. In this communication process, setting information for imaging conditions, setting information for operation control, image information, information on radiation dose, etc. are exchanged.

[0015] The irradiation control unit 420 communicates with the radiation generation unit 300 and controls the irradiation conditions of the radiation.

[0016] The irradiation control unit 420 outputs information such as an irradiation control signal to the radiation generation unit 300 based on the acquired dose information.

[0017] The irradiation control signal transmitted from the irradiation control unit 420 to the radiation generation unit 300 may include two signals: a stop signal (irradiation stop signal) for stopping irradiation of radiation, and an irradiation signal (non-irradiation stop signal) for irradiating radiation. The irradiation control unit 420 can control the start and stop of irradiation of radiation from the radiation generation unit 300 by controlling the output of both or one of the stop signal and irradiation signal.

[0018] The UI control unit 430 controls the input of information via the operation unit 431 and the output of information via the display unit 432. For example, imaging conditions for radiation imaging are input via the operation unit 431, and the results of radiation imaging are output via the display unit 432. The operation unit 431 includes input devices such as a keyboard, a pointing device (e.g., a mouse), and a touch panel. The display unit 432 includes a monitor such as a liquid crystal display.

[0019] A technician inputs various information required for radiographic imaging into the UI control unit 430. The input information includes the dose, irradiation time (ms), tube current (mA), tube voltage (kV), and an irradiation field, which is an area where radiation is detected. This information is transmitted to the radiographic imaging device 10 via the imaging control unit 410.

[0020] The imaging control unit 410, the illumination control unit 420, and the UI control unit 430 can cooperate by communicating with each other. In Fig. 1, for the sake of simplicity, the control device 400 is illustrated as a single device, but the control device 400 may be composed of multiple devices.

[0021] For example, the imaging control unit 410, the illumination control unit 420, and the UI control unit 430 may be independent devices.

[0022] The control device 400 is connected to the radiation generation unit 300 via a wired connection and to the radiation imaging device 10 via wired or wireless communication, and communicates with each device to control its operation. Wired communication can be performed via a LAN (Local Area Network) such as Ethernet (registered trademark), but communication can also be performed using other wired communication methods. The wireless communication configuration includes, for example, an antenna and a communication IC. A circuit board equipped with the communication IC performs communication processing using a protocol based on the wireless LAN via the antenna. Note that there are no particular limitations on the frequency band, standard, or method for wireless communication, and methods such as near field communication (NFC), Bluetooth, or UWB can be used. Alternatively, multiple wireless communication methods can be provided and an appropriate method can be selected for communication.

[0023] The control device 400 is also connected to the RIS 510, PACS 520, and HIS 530 via a network 500, and can exchange radiographic images, patient information, etc. Although the radiation imaging system 1 is shown in Fig. 1 as including the RIS 510, PACS 520, and HIS 530, the system may not include at least some of these.

[0024] <Control device> 4 is a diagram showing the configuration of the control device. The control device 400 has a CPU 401, a RAM 402, a ROM 403, an external memory 404, a communication I / F unit 405, and a bus 406. The CPU 401, RAM 402, ROM 403, external memory 404, and communication I / F unit 405 are connected via the bus 406 so as to be able to communicate with each other.

[0025] A CPU (Central Processing Unit) 401 controls the overall operation of the control device 400, and controls each component shown in FIG.

[0026] A RAM (writable memory) 402 functions as a main memory, work area, etc. for the CPU 401. When executing processing, the CPU 401 loads necessary computer programs 407, data, etc. from the ROM 403 into the RAM 402, and executes the computer programs 407, etc. to realize various functional operations.

[0027] A ROM (read only memory) 403 stores a computer program 407, data, etc. required for the CPU 401 to execute processing. The computer program 407, data, etc. may be stored in an external memory 404.

[0028] The external memory 404 is a large-capacity storage device, and is realized by, for example, a hard disk drive, an IC memory, or the like. The external memory 404 stores, for example, various data and various information required when the CPU 401 executes the computer program 407 and performs processing. The external memory 404 also stores, for example, various data and various information obtained when the CPU 401 executes the computer program 407 and performs processing. The communication I / F (interface) unit 405 controls communication between the control device 400 and the outside. The bus 406 connects the CPU 401, the RAM 402, the ROM 403, the external memory 404, and the communication I / F unit 405 so that they can communicate with each other.

[0029] The control device 400 is provided as, for example, a dedicated embedded device, but is not limited to this and may be realized by a general-purpose information processing device such as a PC (personal computer), a tablet terminal, etc. Also, as described above, the control device 400 may be configured by multiple devices, and in that case, each of the multiple devices has the above-mentioned configuration.

[0030] <Radiation imaging device> 2 is a diagram showing the configuration of a radiation imaging device. The radiation imaging device 10 has a plurality of pixels arranged in an imaging region of a radiation detector 100 (sensor panel) to form a plurality of rows and a plurality of columns. The plurality of pixels includes a plurality of imaging pixels 101 for acquiring a radiation image based on detected radiation, and detection pixels 121 for detecting dose (dose detection pixels) for monitoring the dose of radiation irradiated from a radiation source 1003.

[0031] The imaging pixel 101 includes a conversion element 102 that converts radiation into an electrical signal, and a switch element 103 that is arranged between the column signal line 106 and the conversion element 102. Similar to the imaging pixel 101, the detection pixel 121 for dose detection also includes a conversion element 122 that converts radiation into an electrical signal, and a switch element 123 that is arranged between the detection signal line 125 and the conversion element 122.

[0032] The conversion elements 102 and 122 include a scintillator that converts radiation into light and a photoelectric conversion element that converts light into an electrical signal. The scintillator is formed, for example, in a sheet shape so as to cover the imaging region of the radiation detector 100 that includes a plurality of imaging pixels 101, 121. The conversion elements 102 and 122 may also be replaced with conversion elements that directly convert radiation into an electrical signal.

[0033] The switch element 103 and the switch element 123 are thin film transistors (TFTs) whose active regions are made of semiconductors such as amorphous silicon or polycrystalline silicon. In this embodiment, TFTs using polycrystalline silicon are used as the switch elements 103 and 123.

[0034] The radiation imaging device 10 includes a plurality of column signal lines 106 and a plurality of drive lines 104. Each column signal line 106 corresponds to one of a plurality of columns in the imaging region of the radiation detector 100. Each drive line 104 corresponds to one of a plurality of rows in the imaging region of the radiation detector 100. Here, "column" indicates the vertical direction in FIG. 4, and "row" indicates the horizontal direction in FIG. 4. A drive signal is supplied to each drive line 104 by a drive unit 221.

[0035] Here, the pixels are arranged to form a plurality of measurement fields in the imaging region of the radiation detector 100. Fig. 3(A) is a diagram illustrating the measurement fields. Fig. 3(B) is a diagram illustrating the arrangement of pixels in the measurement fields.

[0036] The radiation measurement field 150 is an area for detecting the radiation dose during imaging, and the radiation dose is detected by multiple detection pixels 121 arranged within the radiation measurement field 150. There are various ways to arrange the multiple radiation measurement fields 150, but by arranging them symmetrically about the center of the radiation imaging device 10, the radiation imaging device 10 can be used in the same way regardless of its orientation. The shape of the radiation measurement field 150 may be a quadrilateral such as a square or rectangle, or a circle or ellipse. It may also be a shape that follows the shape of the subject. AEC detects the radiation dose irradiated into the radiation measurement field by reading out the outputs of multiple radiation detection pixels arranged within the radiation measurement field during radiation irradiation. The imaging pixel output within the radiation measurement field corresponds to the irradiated dose.

[0037] In addition, it is possible to arbitrarily select which measurement field to use to detect the dose depending on conditions such as the imaging region, and in this embodiment, an example is shown in which three measurement fields 1501, 1502, and 1503 are selected as a group of measurement fields from the multiple measurement fields shown in Fig. 3(A). The selection of the measurement field is determined by the UI control unit 430 based on the user's instruction via the operation unit 431.

[0038] The drive unit 221 is configured to supply drive signals to the pixels to be driven via the multiple drive lines 104 in accordance with control signals from the control unit 225. In this embodiment, the drive signals are signals for turning on switch elements included in the pixels to be driven. The switch elements of each pixel are turned on by a high-level signal and turned off by a low-level signal. Therefore, this high-level signal is called a drive signal. When a drive signal is supplied to a pixel, the signal accumulated in the conversion element of that pixel becomes available for reading by the readout unit 222.

[0039] One of the main electrodes of the conversion element 102 is connected to one of the main electrodes of the switch element 103, and the other electrode of the conversion element 102 is connected to a bias line 108. Here, the bias line 108 extends in the column direction and is commonly connected to the other electrodes of the multiple conversion elements 102 arranged in the column direction. A bias voltage Vs is supplied to the bias line 108 from a power supply unit 226. The other of the main electrodes of the switch elements 103 of the multiple imaging pixels 101 that make up one column is connected to a corresponding column signal line 106. The control electrodes of the switch elements 103 of the multiple imaging pixels 101 that make up one row are connected to a corresponding drive line 104.

[0040] The column signal lines 106 are connected to a readout unit 222. The readout unit 222 includes a plurality of detectors 132, a multiplexer 134, and an analog-to-digital (AD) converter 136. Each of the column signal lines 106 is connected to a corresponding one of the detectors 132 in the readout unit 222. Each column signal line 106 corresponds to a corresponding detector 132. The detector 132 includes, for example, a differential amplifier. The multiplexer 134 selects the detectors 132 in a predetermined order and supplies a signal output from the selected detector 132 to the AD converter 136. The AD converter 136 converts the supplied analog signal into a digital signal and outputs it.

[0041] One of the main electrodes of the conversion element 122 is connected to one of the main electrodes of the switch element 123, and the other electrode of the conversion element 122 is connected to the bias line 108. The other of the main electrodes of the switch element 123 is electrically connected to a detection signal line 125. A control electrode of the switch element 123 is electrically connected to a drive line 124. The radiation imaging device 10 has a plurality of detection signal lines 125. One or more detection pixels 121 for dose detection are connected to one detection signal line 125. The drive line 124 is driven by a drive unit 241. One or more detection pixels 121 for dose detection are connected to one drive line 124.

[0042] The driving unit 241 is configured to supply driving signals to the pixels to be driven through the plurality of driving lines 104 in accordance with control signals from the control unit 225. When the driving signals are supplied to the pixels, the signals stored in the conversion elements of the pixels become available for reading by the reading unit 242.

[0043] The detection signal lines 125 are connected to a readout unit 242 (AEC readout unit). The readout unit 242 includes a plurality of detection units 142, a multiplexer 144, and an AD converter 146. Each of the plurality of detection signal lines 125 is connected to a corresponding one of the plurality of detection units 142 of the readout unit 242. One detection signal line 125 corresponds to one detection unit 142. The detection unit 142 includes, for example, a differential amplifier. The multiplexer 144 selects the plurality of detection units 142 in a predetermined order and supplies a signal output from the selected detection unit 142 to the AD converter 146. The AD converter 146 converts the supplied signal into a digital signal and outputs it.

[0044] The output of the AD converter 146 of the readout unit 242 is supplied to the signal processing unit 224 and processed by the signal processing unit 224. The signal processing unit 224 outputs information about the radiation irradiated to the radiation imaging device 10 based on the output of the AD converter 146 of the readout unit 242.

[0045] The signal processing unit 224 acquires information about the dose of radiation incident on the detection pixel 121 based on an electrical signal generated by the detection pixel 121 in response to the radiation irradiated thereto. The signal processing unit 224 may generate a signal by performing digital signal processing on the detection result of the detection pixel 121. The signal processing unit 224 detects the start of irradiation of radiation to the radiation imaging device 10 based on the generated signal. Alternatively, the signal processing unit 224 calculates the irradiation dose or cumulative irradiation amount (reached dose) of radiation based on the generated signal.

[0046] The control unit 225 controls the operations of the drive unit 221, the drive unit 241, and the readout units 222 and 242. The control unit 225 has a CPU and memory (ROM, RAM), and can perform various processes by causing the CPU to execute programs stored in the memory.

[0047] The control unit 225 controls the drive unit 221 and the readout unit 222 based on information from the signal processing unit 224. The control unit 225 controls, for example, the start and end of exposure (accumulation of charge in the imaging pixels 101) based on information from the signal processing unit 224. The control unit 225 also acquires, for example, information on the dose of radiation incident on the detection pixels 121 via the signal processing unit 224 and determines whether or not it is necessary to stop the radiation irradiation. The control unit 225 can read out only the signals of the detection pixels 121 by controlling the drive unit 241 independently of the drive unit 221. Therefore, the control unit 225 can acquire dose information from the output of the detection pixels 121 even while charge is being accumulated in the imaging pixels 101.

[0048] The radiation imaging device 10 includes a communication unit 227 for communicating with the control device 400. The communication unit 227 has either a wired communication unit or a wireless communication unit, or both. The communication unit 227 transmits information output from the control unit 225 to the control device 400 using the wired communication unit or the wireless communication unit. For example, the communication unit 227 outputs information on the necessity of stopping radiation irradiation, which is determined by the control unit 225, to the control device 400.

[0049] <Early stopping process> Fig. 5 is a diagram illustrating early stopping, which shows the relationship between the dose (cumulative achieved dose) D shown on the vertical axis and the time (elapsed time) shown on the horizontal axis.

[0050] In radiological imaging, it is necessary to set the set irradiation time Bt appropriately according to the target dose and the intensity of the radiation to be irradiated (dose rate). When the set irradiation time (backup time) is fixed at the position shown in Figure 5, if the irradiation has a large cumulative dose increase per unit time, as shown in irradiation A, the target dose can be reached within the set irradiation time. On the other hand, if the irradiation has a small cumulative dose increase per unit time, as shown in irradiation B, the target dose cannot be reached within the set irradiation time.

[0051] AEC is a conventional technique for stopping irradiation at the target dose, as in irradiation A, where the target dose is reached before the set irradiation time. This technique can reduce the patient's exposure. By using AEC, the increase in dose shown by the dotted line in irradiation A in Figure 5 can be stopped at the target dose position, as shown by the solid line.

[0052] In this embodiment, as a different technique from the above, early termination processing is performed to terminate radiation irradiation early when the target dose is not reached within the set irradiation time, as in irradiation B.

[0053] By making a judgment based on the backup time and the target dose in this way, in cases where irradiation is insufficient and the target dose is not reached even after irradiation up to the backup time, and re-imaging is required, irradiation can be stopped early to prevent ineffective exposure to the subject. By using early stop processing, the increase in dose shown by the dotted line in irradiation B in Figure 5 can be stopped midway as shown by the solid line.

[0054] The early stop process is realized by a threshold condition using the early stop determination time information Etim (timing information) and the early stop determination threshold information Eth. Specifically, the early stop process is performed when the cumulative dose at the early stop determination time information Etim is less than the early stop determination threshold information Eth. The early stop determination time information Etim uses X% (0% to 100%, for example, 30%) of the backup time Bt. The early stop determination threshold information Eth uses Y% (0% to 100%, for example, 30%) of the target dose Dref. The starting point of the elapsed time is either the start of the dose detection operation, the permission of exposure, the start of the accumulation operation, or the start of irradiation. The elapsed time may be monitored by the read count number counted for each dose detection operation, or by a timer built into the radiation imaging device.

[0055] Here, an example has been shown in which the method of determining whether irradiation is insufficient is based on the backup time and the target dose, but a method of determining based on a unique determination value set in the radiation imaging device may also be used. In FIG. 5, the determination is made based on whether the dose detected at the determination timing after the set time has elapsed satisfies the determination criterion, but the determination may also be made based on the slope of the change in dose over time. The determination criterion for the dose slope may be set based on the target dose and the backup time, or may be a unique criterion set in the radiation imaging device. If backup time information is not available from the control device 400, the timing of determination may be determined based on the accumulation time setting of the radiation imaging device.

[0056] <Image capture control> 6 is a diagram showing the control flow of the radiation imaging apparatus. In step 501 (hereinafter referred to as S501, etc.), the control unit 225 of the radiation imaging apparatus 10 communicates with the control device 400 and sets various information. The set information includes, as imaging condition information (irradiation condition information), the tube voltage and tube current of the radiation tube, the target dose (cumulative achieved dose) Dref, the stop determination threshold Dth, etc. Other information includes the set irradiation time (backup time) Bt, time information Etim for early stop determination, threshold information Eth for early stop determination, and irradiation field information (ROI information).

[0057] In S502, the control unit 225, in response to the start request signal received from the control device 400, performs a process of switching the exposure permission signal from Lo level to Hi level. The control unit 225 also controls the drive unit 221 to start accumulating charges in the imaging pixels 101. Furthermore, the control unit 225 starts timing using an internal timer. In this manner, radiation imaging begins. The processing after the start of radiation imaging will be described below.

[0058] In S503, the control unit 225 drives the driving unit 241 to obtain the dose value of the detection pixel 121 corresponding to the irradiation field information.

[0059] In S504, the control unit 225 performs a process of accumulating the dose values ​​and updates the accumulated dose values.

[0060] In S505, the control unit 225 determines whether the timing indicated by the internal timer has reached the timing indicated by the time information Etim for early stop determination. If the timing for early stop determination has been reached (YES), the control unit 225 proceeds to S506. If the timing for early stop determination has not been reached (NO), the control unit 225 proceeds to S507.

[0061] In S506, the control unit 225 determines whether the accumulated dose value is equal to or greater than the early correction determination threshold Eth. It determines whether the timing (predetermined timing) indicated by the early stop determination time information Etim has been reached. If the accumulated dose value is equal to or greater than (exceeds) the early stop determination threshold Eth as a predetermined condition (YES), the control unit 225 proceeds to S507. If the accumulated dose value is not equal to or greater than the early correction determination threshold Eth (NO), the control unit 225 proceeds to S511.

[0062] In S511, the control unit 225 transmits an early stop request to the control device 400. A flag or the like may be attached to this request (notification) so that it is processed with priority over other communications. Then, the control unit 225 controls the drive unit 221 to read signals from the imaging pixels 101 and terminate imaging. In S512, the signals read from the imaging pixels 101 are transferred to the control device 400 as a radiographic image. Note that information indicating early stop may be attached to this radiographic image.

[0063] In S507, the control unit 225 determines whether the timing has reached the set irradiation time Bt. If the timing has reached the set irradiation time Bt (YES), the control unit 225 proceeds to S510. If the timing has not reached the set irradiation time Bt (NO), the control unit 225 proceeds to S508.

[0064] In S510, the control unit 225 controls the drive unit 221 to read out signals from the imaging pixels 101, and ends imaging. In S512, the signals read out from the imaging pixels 101 are transferred as a radiographic image to the control device 400. Note that information indicating that irradiation has stopped at the set irradiation time may be added to this radiographic image.

[0065] In S508, the control unit 225 compares the accumulated dose value with the stop determination threshold Dth. If the accumulated dose value is equal to or greater than the stop determination threshold Dth (YES), the control unit 225 proceeds to S509. If the accumulated dose value is not equal to or greater than the stop determination threshold Dth (NO), the control unit 225 returns to the process of S503 and acquires additional dose values.

[0066] In S509, the control unit 225 transmits a normal stop request (AEC stop request) to the control device 400. Then, the control unit 225 controls the drive unit 221 to read signals from the imaging pixels 101 and terminates imaging. In S512, the signals read from the imaging pixels 101 are transferred to the control device 400 as a radiographic image. Note that information indicating normal stop may be added to this radiographic image.

[0067] The radiation image transferred to the control device 400 is used for display on the display unit 432 for diagnosis and for dose management.

[0068] Example 2 In the first embodiment, an example in which the determination process based on the dose is performed by the radiation imaging device 10 is described. In the second embodiment, an example in which the determination process based on the dose is performed by the control device 400 is described. Note that, except for the parts related to the above-mentioned features, the configuration of the second embodiment is the same as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0069] <Image capture control> 8 is a diagram showing the control flow of a radiation imaging apparatus and an irradiation control unit in another embodiment. In S801, the control unit 225 of the radiation imaging apparatus 10 communicates with the control device 400 including the irradiation control unit 420 and sets various information. Accordingly, the irradiation control unit 420 sets irradiation conditions.

[0070] In S802, the control unit 225, in response to the start request signal received from the control device 400, performs processing to switch the exposure permission signal from Lo level to Hi level.

[0071] In response to this, the irradiation control unit 420 starts irradiating radiation and also starts timing using an internal timer. In addition, the control unit 225 controls the drive unit 221 to start accumulating charges in the imaging pixels 101.

[0072] In S803 , the control unit 225 drives the drive unit 241 to obtain the dose value of the detection pixel 121 corresponding to the irradiation field information, and transmits the dose value to the irradiation control unit 420 .

[0073] In S804, the control unit 225 determines whether or not a stop notification has been received. The control unit 225 repeats the process of S803 until a stop notification is received (NO).

[0074] On the other hand, the irradiation control unit 420 performs processing to acquire the dose value sent from the radiation imaging apparatus 10 in S823.

[0075] In S824, the irradiation control unit 420 performs a process of accumulating the dose values ​​and updates the accumulated dose values.

[0076] In S825, the irradiation control unit 420 determines whether the timing indicated by the internal timer has reached the timing indicated by the time information Etim for early stop determination. If the timing for early stop determination has been reached (YES), the irradiation control unit 420 proceeds to S826. If the timing for early stop determination has not been reached (NO), the irradiation control unit 420 proceeds to S827.

[0077] In S826, the irradiation control unit 420 determines whether the accumulated dose value is equal to or greater than the early correction determination threshold Eth. It determines whether the timing indicated by the early stop determination time information Etim has been reached. If the accumulated dose value is equal to or greater than the early correction determination threshold Eth (YES), the irradiation control unit 420 proceeds to S827. If the accumulated dose value is not equal to or greater than the early correction determination threshold Eth (NO), the irradiation control unit 420 proceeds to S831.

[0078] In S831, the irradiation control unit 420 stops the radiation irradiation early, and the process proceeds to S832.

[0079] In S827, the irradiation control unit 420 determines whether the timing has reached the set irradiation time Bt. If the timing has reached the set irradiation time Bt (YES), the irradiation control unit 420 proceeds to S830. If the timing has not reached the set irradiation time Bt (NO), the control unit 225 proceeds to S828.

[0080] In S830, the irradiation control unit 420 stops the irradiation of radiation, and the process proceeds to S832.

[0081] In S828, the irradiation control unit 420 compares the accumulated dose value with the stop determination threshold Dth. If the accumulated dose value is equal to or greater than the stop determination threshold Dth (YES), the irradiation control unit 420 proceeds to S829. If the accumulated dose value is not equal to or greater than the stop determination threshold Dth (NO), the irradiation control unit 420 returns to S823 and acquires an additional dose value.

[0082] In S829, the irradiation control unit 420 normally stops the irradiation of radiation, and proceeds to S832.

[0083] In S832, the irradiation control unit 420 transmits a notification to the radiation imaging apparatus 10 indicating that the irradiation of radiation has stopped.

[0084] In S804, when the control unit 225 receives a stop notification (YES), the process proceeds to S805.

[0085] In S805, the control unit 225 controls the drive unit 221 to read out signals from the imaging pixels 101, and ends imaging.

[0086] In S806, the control unit 225 transmits a radiographic image based on the signals from the imaging pixels 101 to the control device 400.

[0087] Example 3 In the first embodiment, an example was described in which the delay time from exposure permission to radiation irradiation is not taken into consideration. In the third embodiment, an example will be described in which the delay time from exposure permission to radiation irradiation is taken into consideration. Note that, except for the parts related to the above-mentioned features, the configuration of the third embodiment is the same as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0088] <Early stop processing: delay time correction> FIG. 9 is a diagram illustrating early stopping in consideration of the delay time of irradiation.

[0089] Depending on the environment, the radiation imaging system 1 may experience a delay time Td between when the irradiation control unit receives the exposure permission signal transmitted from the radiation imaging device 10 and when radiation is generated from the radiation generation unit 300. The delay time Td is due to a response delay inherent to this radiation imaging system, and is a value that varies depending on imaging condition information (irradiation condition information) such as the tube voltage (kV) and tube current (mA) of the radiation tube.

[0090] The delay time Td is obtained by measuring the rise time of radiation from the rise of the exposure signal transmitted from the radiation imaging device 10, and is a value that includes a communication delay time that occurs through the communication unit 227, the imaging control unit 410, etc. This measured value can be obtained, for example, by measuring with an oscilloscope. Furthermore, since the delay time Td has different characteristics depending on the irradiation conditions, such as the tube voltage (kV), the tube current (mA), and the upper limit of irradiation time (ms), it is preferable that it can be set as a parameter corresponding to each irradiation condition. The delay time Td used for correction in this embodiment may be a value detected and calculated from past imaging. For example, the control unit 225 can obtain the cumulative dose value and the time information at that time at two or more points, starting from the rise time of the exposure permission signal, and calculate an approximate straight line.

[0091] Furthermore, the delay time Td used for the correction in the embodiment may be obtained by measuring the rise time of radiation from the rise of the exposure permission signal input to the radiation generation unit 300. However, this method assumes that each device in the radiation imaging system is time-synchronized. Furthermore, adjustment must be made taking into account a communication delay time that occurs via the imaging control unit 410. For example, the control unit 225 obtains timing information T1 at which the radiation imaging device 10 permits the radiation generation unit 300 to irradiate radiation, and timing information T2 at which the radiation generation unit 300 permits radiation irradiation via the communication unit 227, the imaging control unit 410, etc. Then, it calculates the communication delay time ΔT (T2-T1) from each of the information. The control unit 225 adjusts the delay due to communication by adding the calculated communication delay time ΔT to the delay time Td.

[0092] If such a delay occurs, there is a risk that the radiation irradiation will be determined to be insufficient even though it is actually sufficient, resulting in an erroneous determination. As shown in Figure 9, radiation irradiation starts after a delay time Td after the exposure permission signal is switched from Lo to Hi.

[0093] In this environment, if a determination is made based on the early stop dose Eth at the early stop position similar to that shown in Figure 5 (early stop position before correction), a cumulative dose lower than the early stop dose Eth will be measured for both irradiation A, which has a high dose rate, and irradiation B, which has a low dose rate. As a result, early stop will be performed for both imaging by irradiation A and imaging by irradiation B. In this environment, we want to take the delay time Td into consideration and make corrections so that imaging by irradiation A is not stopped early, but imaging by irradiation B is stopped early. Specifically, the early stop position before correction is delayed by the correction time Ta (= delay time Td) to determine the early stop position after correction. By performing such a correction, the irradiation A exceeds the early stop dose Eth at the corrected early stop position, and the irradiation B falls below the early stop dose Eth at the corrected early stop position.

[0094] <Adjustment and control of irradiation delay time> FIG. 10 is a diagram showing the control flow of S602 in the second embodiment.

[0095] In S1001, the control unit 225 acquires information on the delay time Td in the environment of the radiation imaging system 1.

[0096] In S1002, the control unit 225 acquires information about the delay time Td in the environment of the radiation imaging system 1. The control unit 225 switches the exposure permission signal from Lo to Hi to permit irradiation.

[0097] In S1003, the control unit 225 compares the measurement value of the internal timer with the delay time Td. If the measurement value of the internal timer is smaller than the delay time Td (measurement value<delay time Td), the control unit 225 continues measurement by the internal timer. If the measurement value of the internal timer is equal to or greater than the delay time Td (measurement value≧delay time Td), the control unit 225 proceeds to S1004.

[0098] In S1004, the control unit 225 resets the internal timer to 0. Then, the internal timer restarts counting time.

[0099] By the above process, the early stop position before correction can be delayed by the correction time Ta (=delay time Td) to become the early stop position after correction.

[0100] Example 4 In this embodiment, three measurement fields, 1501, 1502, and 1503, are selected to detect the dose. FIG. 11 illustrates the increasing trend of the cumulative dose in each measurement field. As shown in FIG. 11, early stop processing is performed when the cumulative dose at Etim is less than Eth in all three selected measurement fields. For example, if the cumulative dose at Etim in one of the selected measurement fields is less than Eth due to the influence of an implant or the like, while the cumulative dose at Etim in the other selected measurement fields is equal to or greater than Eth, the image may have been captured normally. If early stop processing is performed in such a case, re-imaging will be required, resulting in increased ineffective exposure to the subject. To avoid this, in this embodiment, early stop processing is performed when it is determined that early stop processing is necessary in multiple selected measurement fields. This prevents ineffective exposure to the subject.

[0101] Furthermore, in this embodiment, an example was shown in which early stop processing was performed when the cumulative dose at Etim was less than Eth in all three selected measurement fields 1501, 1502, and 1503, but this is not limited to this. That is, early stop processing may be performed when the cumulative dose is less than Eth in some of the selected measurement fields. For example, of the three selected measurement fields, attention is focused on two measurement fields 1501 and 1502. If the cumulative doses in these two measurement fields are less than Eth at Etim, early stop processing may be performed even if the cumulative dose in measurement field 1503 at Etim is equal to or greater than Eth.

[0102] As described above, according to this embodiment, the early stop process is determined based on the combination of the cumulative doses in the multiple measurement fields, so that an appropriate early stop process can be executed in accordance with the imaging conditions.

[0103] Example 5 In the fourth embodiment, an example was described in which a determination as to whether early stopping processing is necessary is made based on a measurement field selected by a user. In the fifth embodiment, an example is described in which measurement fields other than the selected measurement field are also used to determine whether early stopping processing is necessary. Note that, except for the parts related to the above-mentioned features, the configuration of the fifth embodiment is the same as that of the fourth embodiment. Therefore, the same components are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0104] <Early stopping process> In this embodiment, an example is described in which a user mistakenly selects measurement fields 1503, 1504, and 1505 when imaging should involve selecting measurement fields 1501, 1502, and 1503 from the measurement field 150 in FIG. 12A . FIG. 12A illustrates an example of incorrectly setting the measurement fields. Such an error can occur, for example, when the orientation of the radiation imaging device 10 is incorrectly recognized. This embodiment provides a function that enables appropriate early stop processing even when such an error occurs. Specifically, a secondary determination is made as to whether early stop processing is required for a combination of measurement fields that is highly related to the selected combination of measurement fields. For example, as shown in FIG. 12B , even if the cumulative doses of the actually selected measurement fields 1503, 1504, and 1505 are less than Eth at Etim, the cumulative doses of the measurement fields 1501 and 1502 are equal to or greater than Eth at Etim. In this case, the imaging intended by the user may have been performed appropriately. Figure 12(B) shows the increasing trend of the cumulative dose in each measurement field. In such a case, it is desirable not to perform early shutdown judgment. It is also desirable to perform early shutdown processing not only for the selected measurement fields 1503, 1504, and 1505, but also for the unselected measurement fields 1501 and 1502 when the cumulative dose is less than Eth at the time of Etim. In the above explanation, a combination of selected measurement fields rotated 180 degrees was given as an example of a combination of measurement fields that is highly relevant to the combination of selected measurement fields. However, examples of combinations of selected measurement fields that are highly relevant to the combination of selected measurement fields are not limited to this. For example, the selected measurement fields may be rotated 90 degrees, 270 degrees, or mirrored. Furthermore, while the cumulative dose values ​​of all measurement fields may be referenced to determine whether early stopping processing is necessary, it is more preferable to reference the cumulative dose values ​​of only highly relevant measurement fields. Narrowing the measurement fields for which cumulative dose values ​​are referenced to only some of the measurement fields can reduce processing time and contribute to improved response performance.

[0105] As described above, according to this embodiment, even if the user makes a mistake in selecting the measurement field, it is possible to prevent unnecessary early stopping processing from occurring and to prevent an increase in the number of re-imaging operations.

[0106] The user may be able to set whether to additionally determine whether early stopping processing is required for combinations of measurement fields that are highly related to the selected combination of measurement fields. The user can input an instruction to the UI control unit 430 via the operation unit 431 to set this function to ON / OFF.

[0107] Example 6 In the first embodiment, an example was described in which a determination as to whether early stop processing is necessary is made based on the measurement field selected by the user. In the sixth embodiment, an example is described in which a determination as to whether early stop processing is necessary is made based on the results of a comparison condition that compares cumulative dose information estimated from information on the imaging protocol with cumulative dose information in the measurement field for which early stop processing has actually been made. Note that, except for the parts related to the above-mentioned features, the configuration of the sixth embodiment is the same as that of the fourth embodiment. Therefore, similar configurations are denoted by similar reference numerals, and detailed descriptions thereof will be omitted.

[0108] <Early stopping process> Fig. 13(A) is a diagram explaining the subdivided measurement fields, Fig. 13(B) is a diagram showing the cumulative dose in each measurement field, and Fig. 13(C) is a diagram showing the cumulative dose in each measurement field.

[0109] In this embodiment, a radiation imaging device 10 having an 8×8 matrix of 64 measurement fields as shown in Fig. 13A is used, and protocol information is used as imaging condition information. Note that the number of divisions of the measurement field may be other numbers such as 16×16 or 32×32.

[0110] This protocol information identifies the imaging region, such as the head, chest, abdomen, etc. Since there is a tendency for the cumulative dose for each imaging field to be high or low depending on the imaging region, this can be used to determine whether to stop the imaging process early.

[0111] For example, when imaging the lungs as shown in Fig. 13(A), the cumulative dose distribution is as shown in Fig. 13(B). Specifically, the cumulative dose tends to be higher in measurement fields 1551 and 1558, which include non-radioactive areas, and in measurement fields 1553 and 1556, which overlap the lung fields. The cumulative dose tends to be lower in measurement fields 1554 and 1555, which overlap the mediastinum.

[0112] The above-described cumulative dose distribution trend applies when radiation is irradiated normally, but does not necessarily apply when radiation is not irradiated normally. For example, assume that radiation is irradiated only to the right half of the radiation imaging device 10 due to misalignment between the radiation generating unit 300 and the radiation imaging device 10, and radiation is not irradiated to the radiation measurement field indicated by the diagonal lines in FIG. 13(A). In this case, as shown in FIG. 13(C), the radiation measurement fields 1555-1558 on the right half have the cumulative dose values ​​that would be obtained if radiation were ideally irradiated, but the cumulative dose on the left half is lower, and the cumulative dose at Etim is equal to or less than Eth. When imaging lungs that are ideally irradiated, the horizontal profile of the cumulative dose should be symmetrical, as shown in FIG. 13(B). However, due to misalignment and other factors, the symmetry shown in FIG. 13(C) is not achieved.

[0113] In such a case, an appropriate radiographic image cannot be obtained even if radiation irradiation is continued. Therefore, in this embodiment, if it is determined that the dose distribution information differs from that expected from the protocol, early termination processing is executed.

[0114] When imaging the lungs, attention may be paid to convex portions of the lung field, such as the measurement fields 1553 and 1556. Because radiation easily passes through the lung field and the cumulative dose value is large, there should be two convex portions, such as the measurement fields 1553 and 1556. However, in Figure 13(C), there is only one convex portion, and therefore, abnormalities can be determined based on this.

[0115] In the above explanation, the comparison was made focusing on the difference in the profile shape of the cumulative dose, but a differential value may also be used to extract convex portions that represent the characteristics of the lung field. For example, the differential value is 0 near the center of the lung field and becomes higher at the borders of the lung field. When the measurement field 150 is arranged more finely, extracting convex portions using such a differential value is also effective.

[0116] <Exception handling> If a foreign object such as an implant is present in the body of a patient, the subject, the cumulative dose value will be locally reduced at the location corresponding to the foreign object. This may result in a difference between the cumulative dose value estimated from the protocol information and the actual cumulative dose value, which may cause the early termination process to be executed. Therefore, in this embodiment, exception processing is performed to prevent the early termination process from being executed due to such a foreign object.

[0117] As shown in Fig. 14, it is assumed that there are localized areas (shown with diagonal lines) in the measurement field 150 where the cumulative dose is less than Eth at the time of Etim due to the influence of an implant or the like. Fig. 14 is a diagram illustrating the relationship between the measurement fields and the implant.

[0118] In such a case, the cumulative dose is locally reduced only in the area containing the implant compared to the cumulative dose estimated from the protocol information, and the cumulative dose is considered to be normally distributed around it. Therefore, in this embodiment, a two-dimensional map of the measurement field as shown in FIG. 14 is referenced to check the status of the measurement fields around the measurement field where the cumulative dose is locally reduced (the measurement field where the cumulative dose at the time of Etim is less than Eth). If the cumulative dose is normally distributed around the four sides of the measurement field where the cumulative dose is locally reduced, it can be determined that this is due to the influence of an implant or the like. If this is due to the influence of an implant or the like, it can be determined that the imaging is normal, and early termination processing is not performed.

[0119] On the other hand, if a decrease in cumulative dose is observed in all four directions surrounding the irradiation field, where the cumulative dose is locally lower than the cumulative dose estimated from the protocol information, it can be determined that this is not due to the influence of an implant, etc. In this case, early termination processing is performed.

[0120] As mentioned above, if an imaging field with a cumulative dose less than Eth at the time of Etim is surrounded by an imaging field of Eth or more, early termination processing is not performed. Conversely, if an imaging field with a cumulative dose less than Eth at the time of Etim is not surrounded by an imaging field of Eth or more, the output expected from the protocol information is compared with the actual output, and if there is a difference, early termination processing is performed.

[0121] This reduces the risk of having to stop shooting unnecessarily and take the shot again.

[0122] <Image capture control> 15 is a diagram showing the control flow of the radiation imaging apparatus in this embodiment. Note that the description of the parts that overlap with FIG. 6 described in the first embodiment will be omitted.

[0123] In S706, the control unit 225 determines whether the accumulated dose value is equal to or greater than the early correction determination threshold Eth. It determines whether the timing (predetermined timing) indicated by the early stop determination time information Etim has been reached. If the accumulated dose value is equal to or greater than (exceeds) the early stop determination threshold Eth as a predetermined condition (YES), the control unit 225 proceeds to S707. If the accumulated dose value is not equal to or greater than the early correction determination threshold Eth (NO), the control unit 225 proceeds to S713.

[0124] In S713, the control unit 225 determines whether the measurement field with a cumulative dose value less than the early stop determination threshold Eth is surrounded by a measurement field with a cumulative dose value equal to or greater than Eth. If the measurement field with a cumulative dose value less than Eth is surrounded by a measurement field with a cumulative dose value equal to or greater than Eth (YES), the control unit 225 proceeds to S707. If the measurement field with a cumulative dose value less than Eth is not surrounded by a measurement field with a cumulative dose value equal to or greater than Eth (NO), the control unit 225 proceeds to S714.

[0125] In S714, the control unit 225 compares the cumulative dose value estimated from the protocol information with the actual cumulative dose value to ensure consistency. If consistency is established (YES), the control unit 225 proceeds to S707. If consistency is not established (NO), the control unit 225 proceeds to S711.

[0126] The subsequent control is the same as in the first embodiment, and therefore the explanation will be omitted.

[0127] As described above, the accumulated dose information estimated from the protocol information is compared with the actual accumulated dose information, and if there is a discrepancy, early shutdown processing is executed. Therefore, according to this embodiment, early shutdown processing can be executed appropriately based on the protocol information.

[0128] 13(B) and 13(C), the same Eth value is used for each measurement field, but this is not limited to this. For example, since measurement fields 1554 and 1555 overlapping the mediastinum tend to output a lower cumulative dose than measurement fields 1553 and 1556 overlapping the lung field, the Eth values ​​for measurement fields 1554 and 1555 may be set lower than those for measurement fields 1553 and 1556. In this case, Eth may be determined, for example, as a fixed percentage, such as 10%, of the cumulative dose for each measurement field estimated from protocol information.

[0129] In this embodiment, the imaging condition information includes protocol information, and an example is shown in which an output expected based on the protocol information is compared with an actual output. However, even if there is no protocol information, if a protocol can be expected from the actual output, the expected protocol information may be compared with the output to determine whether to perform early stopping processing.

[0130] (Other Examples) The present invention is not limited to the above-described embodiments, and various modifications (including organic combinations of the embodiments) are possible based on the spirit of the present invention, and are not excluded from the scope of the present invention. In other words, all configurations that combine the above-described embodiments and their modifications are included in the present invention.

[0131] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0132] The present invention may be applied to a system consisting of multiple devices, or to an apparatus consisting of a single device. For example, a part of the software module may be configured to be executed on an external server, and the function may be realized by obtaining the results processed by the external server.

[0133] In the first and second embodiments, the imaging pixels 101 for imaging and the detection pixels 121 for dose detection are formed on the same substrate. However, the imaging pixels 101 for imaging and the detection pixels 121 for dose detection may be formed on separate substrates and arranged in an overlapping manner. With this configuration, the detection pixels 121 in the above-described embodiments can be replaced by imaging pixels 101, thereby increasing the amount of information in the radiation image.

[0134] In addition, in the first and second embodiments, an example was described in which a single criterion was used to determine whether or not early shutdown was necessary. However, the process performed using the dose information acquired at the early shutdown determination time is not limited to sending an early shutdown notification. For example, multiple processes may be performed based on the dose information acquired at the early shutdown determination time, as follows: If the dose output of the radiation detection pixel does not satisfy the determination criterion based on the backup time and the target dose, a shutdown notification is sent (1). Alternatively, if the determination criterion is not satisfied and the dose output of the radiation detection pixel is increasing at a rate equal to or greater than the threshold, a notification that irradiation is insufficient is sent (2). Alternatively, if the determination criterion is not satisfied and the dose output of the radiation detection pixel is not increasing, a notification that irradiation is not occurring is sent (3). In this way, by changing the content of the notification sent to the radiation generator based on the dose information, it is possible to determine whether irradiation is insufficient or not occurring at all, and this information can be used as a reference for identifying the cause of the insufficient irradiation. These notifications may be displayed (announced) on the display unit 432 via the UI control unit 430. Alternatively, the user may be notified by a method such as audio, apart from the display. (1) and (2), or (1) and (3), may be transmitted simultaneously, or only (2) or (3) may be transmitted, with the radiation generating device making the decision to stop transmitting.

[0135] In the first embodiment, the timing of the stop notification and the timing of the radiation irradiation stop are described as being the same. However, depending on the usage environment of the radiation imaging system 1, communication delays may occur between the radiation imaging device 10 and the control device 400, and between the control device 400 and the radiation generation unit 300. If such communication delays occur, even if the timing of determining whether or not to stop is accurate, it may take time for radiation irradiation to actually stop, which may reduce the effectiveness of reducing the radiation exposure dose of the subject. Therefore, in an environment with such communication delays, it is preferable to make a determination at a timing earlier by the amount of this communication delay so that radiation irradiation can be stopped at the desired timing. Figure 7 is a diagram explaining early stopping taking delay times into account.

[0136] As shown in Figure 7, in an environment where delays due to communication delays occur, the early stop notification must be sent earlier than the actual early stop timing by the delay time. For example, if the desired early stop timing is X% (e.g., 30%) of the backup time Bt, the timing for sending the early stop notification is set to X'% (e.g., 20%) of Bt. Similarly, if the dose Eth at which early stop is desired is Y% (e.g., 30%) of the target dose Dref, the dose Eth' at the time of the early stop notification is set to Y'% (e.g., 20%) of the target dose Dref. Note that the length of the communication delay differs depending on the environment, so it is advisable to measure the communication status immediately before performing radiation imaging to determine the delay.

[0137] These parameters related to stopping radiation irradiation can be set to unique values ​​for each system. Alternatively, a single value may be set for each system. Alternatively, the irradiation conditions of the generator may be stored in a table (kV, mA, ms, focal spot size, etc.), and the appropriate time information may be set by comparing it with the irradiation conditions that have been set. Alternatively, the actual time that occurred in a previous scan under the same conditions may be taken and set for the next scan.

[0138] The disclosure of this embodiment includes the following configurations, methods, etc.

[0139] [Configuration 1] a radiation detector for receiving radiation and obtaining a radiation image; means for acquiring dose information of radiation incident on the radiation detector; a means for acquiring imaging condition information for radiographic imaging in which radiation is incident on the radiation detector up to a target dose to acquire a radiographic image; a means for issuing a notification to stop radiation irradiation by the radiation generating device so that radiation irradiation by the radiation generating device is stopped before radiation reaches the target dose after the start of radiation imaging based on the imaging condition information; A radiation imaging apparatus comprising:

[0140] [Configuration 2] the notification is made when dose information acquired up to a predetermined timing after the start of radiation imaging based on the imaging condition information does not satisfy a predetermined condition; The radiation imaging device according to configuration 1, characterized in that the notification is not made if the dose information acquired up to the predetermined timing after the start of radiation imaging based on the imaging condition information satisfies the predetermined condition.

[0141] [Configuration 3] 3. The radiation imaging apparatus according to configuration 2, wherein the predetermined timing is a timing that starts from any one of the start of a dose detection operation, permission of exposure, start of a storage operation, and start of irradiation.

[0142] [Configuration 4] 4. The radiation imaging apparatus according to configuration 2 or 3, wherein the predetermined condition is a condition in which the dose information acquired up to the predetermined time exceeds a predetermined threshold.

[0143] [Configuration 5] 5. The radiation imaging device according to any one of configurations 2 to 4, wherein the predetermined timing is determined based on a radiation irradiation time set in the radiation generation device.

[0144] [Configuration 6] The radiation imaging device according to any one of configurations 1 to 5, further comprising a means for issuing a further notification to stop the radiation irradiation by the radiation generating device in order to end the radiation imaging by injecting radiation up to the target dose.

[0145] [Configuration 7] 7. The radiation imaging apparatus according to claim 1, wherein the notification is processed with priority over other communications.

[0146] [Configuration 8] 8. The radiation imaging device according to any one of configurations 1 to 7, wherein the notification is a notification based on a communication delay between the radiation imaging device and the radiation generation device.

[0147] [Configuration 9] The radiation imaging device according to any one of configurations 1 to 8, characterized in that the imaging condition information includes one of the tube voltage and tube current of the radiation tube, the target dose, a threshold value for determining normal stop, a set irradiation time, timing information for determining early stop, threshold value information for determining early stop, and irradiation field information.

[0148] [Configuration 10] 10. The radiation imaging device according to any one of configurations 1 to 9, wherein the radiation detector has imaging pixels for acquiring the radiation image and detection pixels for acquiring the dose information arranged on the same substrate.

[0149] [Configuration 11] 10. The radiation imaging device according to any one of configurations 1 to 9, wherein the detection pixels for acquiring the dose information are arranged on a substrate different from the imaging pixels for acquiring the radiation image.

[0150] [Configuration 12] 12. A radiation imaging system comprising the radiation imaging apparatus according to any one of configurations 1 to 11 and the radiation generating apparatus.

[0151] [Configuration 13] A radiation imaging system including a radiation imaging device having a radiation detector for obtaining a radiation image by irradiating radiation, and a radiation generating device for irradiating radiation, The radiation generating device means for acquiring dose information of radiation incident on the radiation detector; a means for acquiring imaging condition information for radiographic imaging in which radiation is incident on the radiation detector up to a target dose to acquire a radiographic image; a means for stopping irradiation of radiation after starting radiation imaging based on the imaging condition information and before radiation reaches the target dose; A radiation imaging system comprising:

[0152] [Configuration 14] A radiation imaging system including a radiation imaging device having a radiation detector for obtaining a radiation image by irradiating radiation, and a notification device for notifying a user of information, The radiation imaging device means for acquiring dose information of radiation incident on the radiation detector; a means for acquiring imaging condition information for radiographic imaging in which radiation is incident on the radiation detector up to a target dose to acquire a radiographic image; a means for notifying the notification device based on dose information acquired after the start of radiation imaging based on the imaging condition information and up to a predetermined timing before the target dose is reached, and a means for notifying the user based on the notification by the notification device.

[0153] [Configuration 15] 15. The radiation imaging system according to configuration 14, wherein the notification notifies the user that the incidence of radiation is insufficient.

[0154] [Configuration 16] 15. The radiation imaging system according to configuration 14, wherein the notification notifies the user that radiation is not being incident.

[0155] [Configuration 201] a radiation detector for receiving radiation emitted by the radiation generating device and obtaining a radiation image; a means for permitting radiation irradiation by the radiation generating device; means for acquiring time information from when the permission is given until when the radiation generating device irradiates radiation; means for acquiring dose information of radiation incident on the radiation detector; a means for acquiring imaging condition information for radiographic imaging in which radiation is incident on the radiation detector up to a target dose to acquire a radiographic image; a means for issuing a notification to stop radiation irradiation by the radiation generating device in accordance with the fact that dose information acquired at least up to a predetermined timing based on the time information satisfies a predetermined condition after the start of radiation imaging based on the imaging condition information, so that radiation irradiation by the radiation generating device is stopped before radiation reaches the target dose; A radiation imaging apparatus comprising:

[0156] [Configuration 202] after the start of radiation imaging based on the imaging condition information, if the dose information acquired up to the predetermined timing does not satisfy the predetermined condition, the notification is made; The radiation imaging device according to configuration 201, characterized in that the notification is not made if the dose information acquired up to the specified timing after the start of radiation imaging based on the imaging condition information satisfies the specified condition.

[0157] [Configuration 203] 203. The radiation imaging apparatus according to configuration 202, wherein the predetermined timing is a timing that starts from any one of the start of a dose detection operation, permission of exposure, start of a storage operation, and start of irradiation.

[0158] [Configuration 204] The radiation imaging apparatus according to the configuration 202 or 203, wherein the predetermined condition is a condition in which the dose information acquired up to the predetermined timing exceeds a predetermined threshold.

[0159] [Configuration 205] The radiation imaging device according to any one of the configurations 202 to 204, wherein the predetermined timing is determined based on a radiation irradiation time set in the radiation generation device.

[0160] [Configuration 206] The radiation imaging device according to any one of configurations 201 to 205, further comprising a means for issuing a further notification to stop the radiation irradiation by the radiation generating device in order to end the radiation imaging by injecting radiation up to the target dose.

[0161] [Configuration 207] The radiation imaging device according to any one of the configurations 201 to 206, wherein the notification is processed with priority over other communications.

[0162] [Configuration 208] The radiation imaging device according to any one of configurations 201 to 207, wherein the notification is a notification based on a communication delay between the radiation imaging device and the radiation generation device.

[0163] [Configuration 209] A radiation imaging device described in any one of configurations 201 to 208, characterized in that the imaging condition information includes one of the tube voltage and tube current of the radiation tube, the target dose, a threshold value for determining normal shutdown, a set irradiation time, timing information for determining early shutdown, threshold value information for determining early shutdown, and irradiation field information.

[0164] [Configuration 210] A radiation imaging device described in any one of configurations 201 to 209, characterized in that the radiation detector has imaging pixels for acquiring the radiation image and detection pixels for acquiring the dose information arranged on the same substrate.

[0165] [Configuration 211] A radiation imaging device according to any one of configurations 201 to 209, characterized in that detection pixels for acquiring the dose information are arranged on a different substrate from imaging pixels for acquiring the radiation image.

[0166] [Configuration 212] A radiation imaging system comprising the radiation imaging device according to any one of configurations 201 to 211 and the radiation generating device.

[0167] [Configuration 301] a radiation detector for obtaining a radiological image by irradiating radiation that has passed through a subject, the radiation detector having a plurality of measurement fields for obtaining dose information of the incident radiation; a means for acquiring imaging condition information for radiographic imaging in which radiation is incident up to a target dose on a predetermined group of the plurality of radiation measurement fields to acquire a radiographic image; a means for issuing a notification to stop irradiation of radiation by the radiation generating device when the dose information of the predetermined group of irradiation fields does not satisfy a predetermined condition after the start of radiation imaging based on the imaging condition information, so that the irradiation of radiation by the radiation generating device is stopped before the radiation reaches the target dose in the predetermined irradiation fields; A radiation imaging apparatus comprising:

[0168] [Configuration 302] after the start of radiation imaging based on the imaging condition information, if the dose information acquired from the predetermined group of radiation measurement fields by a predetermined timing does not satisfy a predetermined condition, the notification is made; The radiation imaging device described in configuration 301 is characterized in that, after radiation imaging based on the imaging condition information is started, if the dose information acquired from the specified group of irradiation fields by the specified timing satisfies the specified conditions, the notification is not made.

[0169] [Configuration 303] The radiation imaging apparatus according to configuration 302, wherein the predetermined timing is a timing starting from any one of the start of a dose detection operation, permission of exposure, start of a storage operation, and start of irradiation.

[0170] [Configuration 304] The radiation imaging device according to configuration 302 or 303, wherein the predetermined condition is a condition in which dose information acquired from the predetermined group of irradiation areas by the predetermined timing exceeds a predetermined threshold.

[0171] [Configuration 305] The radiation imaging device according to any one of the configurations 302 to 304, wherein the predetermined timing is determined based on a radiation irradiation time set in the radiation generation device.

[0172] [Configuration 306] The radiation imaging device described in configuration 301, characterized in that the notification is made when, after the start of radiation imaging based on the imaging condition information, the dose information acquired from the specified group of radiation areas by a specified timing does not satisfy the specified condition, and when the dose information acquired from a further group of radiation areas related to the specified group of radiation areas does not satisfy the specified condition.

[0173] [Configuration 307] The radiation imaging device described in configuration 306, characterized in that after radiation imaging based on the imaging condition information begins, if the dose information acquired from the specified group of radiation areas by the specified timing does not satisfy the specified condition, and if the dose information acquired from the further group of radiation areas satisfies the specified condition, the notification is not made.

[0174] [Configuration 308] The radiation imaging apparatus according to any one of the configurations 301 to 307, wherein the predetermined condition is a threshold condition determined based on the target dose.

[0175] [Configuration 309] The radiation imaging apparatus according to any one of the configurations 301 to 307, wherein the predetermined condition is a comparison condition determined based on the imaging condition information.

[0176] [Configuration 310] The imaging condition information includes information for identifying an imaging region, and the dose information of the predetermined irradiation field group is dose distribution information, 309. The radiation imaging apparatus according to claim 309, further comprising a means for determining whether or not to issue the notification based on a difference between the information on the imaging region and the dose distribution information as the comparison condition.

[0177] [Configuration 311] The radiation imaging device according to any one of the configurations 301 to 310, wherein the predetermined group of measurement fields is a part of the plurality of measurement fields.

[0178] [Configuration 312] A radiation imaging device according to any one of configurations 301 to 311, characterized in that it has a means for issuing a further notification to stop the irradiation of radiation by the radiation generating device in order to end the radiation imaging by injecting radiation up to the target dose into the specified irradiation field.

[0179] [Configuration 313] The radiation imaging device according to any one of the configurations 301 to 312, wherein the notification is processed with priority over other communications.

[0180] [Configuration 314] The radiation imaging device according to any one of configurations 301 to 313, wherein the notification is a notification based on a communication delay between the radiation imaging device and the radiation generation device.

[0181] [Configuration 315] A radiation imaging device described in any one of configurations 301 to 314, characterized in that the imaging condition information includes any one of the tube voltage and tube current of the radiation tube, the target dose, a threshold value for determining normal stop, a set irradiation time, timing information for determining early stop, threshold value information for determining early stop, and irradiation field information.

[0182] [Configuration 316] A radiation imaging device described in any one of configurations 301 to 315, characterized in that the radiation detector has imaging pixels for acquiring the radiation image and detection pixels for acquiring the dose information arranged on the same substrate.

[0183] [Configuration 317] The radiation imaging device according to any one of configurations 301 to 316, wherein the detection pixels for acquiring the dose information are arranged on a substrate different from the imaging pixels for acquiring the radiation image.

[0184] [Configuration 318] A radiation imaging system including the radiation imaging device according to any one of configurations 301 to 317 and the radiation generating device. [Explanation of symbols]

[0185] 100 Radiation imaging device 101 imaging pixels 121 detection pixels 225 Control Unit 300 Radiation Generation Unit 400 control device 410 Imaging control unit 420 Irradiation control unit 430 UI control section

Claims

[Claim 1] a radiation detector for receiving radiation and obtaining a radiation image; means for acquiring dose information of radiation incident on the radiation detector; a means for acquiring imaging condition information for radiographic imaging in which radiation is incident on the radiation detector up to a target dose to acquire a radiographic image; a means for issuing a notification to stop radiation irradiation by the radiation generating device so that radiation irradiation by the radiation generating device is stopped before radiation reaches the target dose after the start of radiation imaging based on the imaging condition information; A radiation imaging apparatus comprising:

Images