Radiation imaging device and radiation imaging system

Abstract

To provide a technology advantageous for improving quality of an image displayed when a fluoroscopic imaging is interrupted in a radiation imaging system having a last image hold function.SOLUTION: A radiation imaging system includes a radiation imaging device, a radioactive ray source for continuously irradiating the radiation imaging device with a radioactive ray, a display unit, and a control unit for controlling an operation of the radiation imaging device. The control unit causes the radiation imaging device to repeat generation operations for generating one piece of image data by causing a plurality of pixels to execute an accumulation operation and a reading operation for at least every one line from a first line to a last line during radioactive ray irradiation, causes the radioactive ray source to stop the radioactive ray irradiation in response to the completion of the accumulation operation and the reading operation of the last line in the generation operation when an instruction is given to end the radioactive ray irradiation out of the generation operations when the instruction to end the radioactive ray irradiation is given, and causes the display unit to display an image based on the last image data generated by the generation operation when the instruction is given to end the radioactive ray irradiation out of the generation operations.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a radiation imaging system.

Background Art

[0002] In medical image diagnosis and non-destructive inspection, a radiation imaging apparatus using a flat panel detector (FPD) composed of a semiconductor material is widely used. The radiation imaging apparatus is used for fluoroscopic imaging to capture a moving image. Patent Document 1 shows an X-ray imaging apparatus having a last image hold function that displays the final image of fluoroscopic imaging on a monitor when the fluoroscopic imaging is interrupted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When performing fluoroscopic imaging by continuously irradiating radiation using an FPD with a line exposure sequential readout method that accumulates and reads out signals row by row, at the end of the radiation irradiation, the accumulation time from the start of signal accumulation to the end of irradiation may be different for each row. If the signal accumulation times are different, shading may occur in the final image obtained at the end of the radiation irradiation.

[0005] An object of the present invention is to provide a technique advantageous for improving the image quality of an image displayed when fluoroscopic imaging is interrupted in a radiation imaging system having a last image hold function.

Means for Solving the Problems

[0006] In view of the above problems, a radiation imaging system according to an embodiment of the present invention is a radiation imaging system comprising: a radiation imaging device in which a plurality of pixels are arranged in a matrix for acquiring a radiation image; a radiation source that continuously irradiates the radiation imaging device with radiation; a display unit; and a control unit that controls the operation of the radiation imaging device, wherein the control unit causes the radiation imaging device to repeatedly perform a generation operation during radiation irradiation, generating one image data by causing the plurality of pixels to perform an accumulation operation and a read operation at least one row at a time from the first row to the last row; when the end of radiation irradiation is instructed, the control unit causes the radiation source to stop irradiating with radiation in accordance with the completion of the accumulation operation and read operation of the last row in the generation operation when the end of radiation irradiation is instructed; and the control unit displays an image based on the final image data generated by the generation operation when the end of radiation irradiation is instructed. [Effects of the Invention]

[0007] The above means provides a technology that is advantageous for improving the image quality of the image displayed when fluoroscopy is interrupted in a radiographic imaging system having a last image hold function. [Brief explanation of the drawing]

[0008] [Figure 1] A block diagram showing an example configuration of the radiation imaging system according to this embodiment. [Figure 2] A block diagram showing an example configuration of the detection unit of the radiation imaging system in Figure 1. [Figure 3] A timing diagram illustrating the operation of the radiation imaging system shown in Figure 1. [Figure 4] A timing diagram illustrating the operation of the radiation imaging system shown in Figure 1. [Figure 5] Figure 1 is a flowchart illustrating the method for selecting the termination operation of continuous fluoroscopy in a radiographic imaging system. [Figure 6] Figure 1 shows an example of the image readout direction and region of interest in a radiation imaging system. [Figure 7]A timing diagram illustrating the operation of the radiation imaging system shown in Figure 1. [Figure 8] Figure 1 is a flowchart illustrating the method for selecting the termination operation of continuous fluoroscopy in a radiographic imaging system. [Modes for carrying out the invention]

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] Furthermore, the radiation in this invention may include not only alpha rays, beta rays, and gamma rays, which are beams created by particles (including photons) emitted by radioactive decay, but also beams with energy of equal or greater magnitude, such as X-rays, particle beams, and cosmic rays.

[0011] Referring to Figures 1-8, the configuration and operation of the radiation imaging system according to this embodiment will be described. Figure 1 is a block diagram showing an example configuration of the radiation imaging system SYS of this embodiment. The radiation imaging system SYS of this embodiment can be used, for example, for medical purposes.

[0012] The radiation imaging system SYS includes a radiation imaging device 100, a radiation source 301, and a control device 400 equipped with a display unit 406. The radiation imaging device 100 includes a detection unit 200 in which multiple pixels are arranged in a matrix for acquiring radiation images corresponding to the incidence of radiation. The radiation source 301 is controlled by the radiation source control device 300 and irradiates the radiation imaging device 100 with radiation. The control device 400 controls the radiation imaging device 100 and the radiation source control device 300. The control device 400 communicates control signals with the radiation imaging device 100 and collects radiation image data from the radiation imaging device 100 and displays radiation images based on the radiation image data. The control device 400 also includes a radiation imaging application 404 that can receive imaging orders and register imaging information for generating control signals, including the imaging mode when acquiring radiation images with the detection unit 200.

[0013] The control device 400 is connected to a hospital network 600, which is configured, for example, by a LAN (Local Area Network). The hospital network 600 is connected to a Hospital Information System (HIS) / Radiology Information System (RIS) 601. The control device 400 and the HIS / RIS 601 can communicate with each other, enabling, for example, the exchange of radiographic image acquisition orders, imaging information including patient information, and radiographic image data within the hospital.

[0014] The radiation imaging device 100 includes a detection unit 200, a control unit 101, and a power supply unit 115. The detection unit detects radiation incident on the detection unit 200 and generates image data corresponding to the detected radiation dose. The control unit 101 controls each component of the radiation imaging device 100. The control unit 101 includes a drive control unit 102, an image processing unit 106, an offset control unit 108, a storage unit 109, a communication unit 112, a timer 113, and an irradiation timing control unit 114. The drive control unit 102 controls the operation of the detection unit 200 so that radiation image data corresponding to radiation irradiation and offset image data for correcting the radiation image data are obtained. The image processing unit 106 performs image processing on the image data acquired from the detection unit 200. The offset control unit 108 controls the timing of updating the offset image. The storage unit 109 stores the acquired image data. The communication unit 112 controls communication with the control device 400 and the radiation source control device 300. The communication unit 112 receives control signals from the control device 400, including, for example, the imaging mode when the detection unit 200 acquires a radiation image. The timer 113 acquires the imaging time, elapsed time, etc. The irradiation timing control unit 114 controls the transition of the detection unit 200 to imaging operation, etc., in response to the radiation irradiation signal from the radiation source control device 300 to the radiation source 301. The power supply unit 115 supplies power to each component in the radiation imaging device 100.

[0015] The control unit 101 may, for example, read a program stored in the memory unit 109 and control the entire radiation imaging device 100 based on the read program. Alternatively, the control unit 101 may include a control signal generation circuit, such as an ASIC, to control the radiation imaging device 100. Furthermore, control of the entire radiation imaging device 100 may be achieved through both the program and the control signal generation circuit.

[0016] The drive control unit 102 controls the detection unit 200 by switching between multiple control modes, including imaging preparation drive control 103, radiation image acquisition control 104, and offset image acquisition control 105. Imaging preparation drive control 103 is a control that prepares the detection unit 200 to a state where radiation images can be captured. Radiation image acquisition control 104 is a control that drives the detection unit 200 so that radiation image data is acquired. Offset image acquisition control 105 is a control that drives the detection unit 200 so that offset image data is acquired. In imaging preparation drive control 103, the drive control unit 102 applies the same voltage to the detection unit 200 as during imaging, and periodically reads out the charge, thereby resetting the dark charge accumulated in each pixel of the detection unit 200. The signals read out from the pixels at this time are not treated as image data and do not need to be stored in the storage unit 109. In radiation image acquisition control 104, the drive control unit 102 drives the detection unit 200 in the same manner as in imaging preparation drive control 103, accumulating charge in the pixels of the detection unit 200 corresponding to radiation irradiation. Next, the charge accumulated in the pixels is stored in the readout storage unit 109 as radiation image data 110. By continuously performing this radiation image acquisition control 104, the drive control unit 102 makes it possible to capture moving images. In offset image acquisition control 105, the drive control unit 102 causes the detection unit 200 to perform the same drive as in imaging preparation drive control 103, and stores the image data read out without radiation irradiation as offset image data 111 in the storage unit 109.

[0017] The radiation image data 110 acquired from the detector 200 by the radiation image acquisition control 104 is offset-corrected using the offset image data 111 acquired in advance by the offset image acquisition control 105. The offset correction process may be performed by the offset correction unit 107 of the image processing unit 106. The offset-corrected radiation image data is transferred to the control device 400 via the communication unit 112. Although only the offset correction process is described here, the image processing unit 106 may perform other correction processes such as correction of missing pixels and gain correction for correcting the gain variation of the amplifiers arranged in the detector 200. Also, these correction processes may not be performed by the radiation imaging device 100. For example, the acquired radiation image data 110 and offset image data 111 may be transferred to the control device 400 without performing processes such as correction, and the control device 400 may perform these correction processes. Also, for the offset image data used for offset correction, for example, image data obtained by acquiring a plurality of offset image data and performing noise component reduction processing such as averaging may be used.

[0018] The radiation source control device 300 includes an operation UI 302 for operating the radiation source control device 300. The operation UI 302 may include a keyboard, a mouse, an exposure switch, and the like. Using the operation UI 302, the user may set the irradiation conditions of the radiation and perform the irradiation of the radiation. Information can be exchanged between the radiation source control device 300 and the radiation imaging device 100 via a dedicated signal line. Synchronization signals such as notification of the start and end of radiation irradiation and notification of the radiation irradiation enable timing may be exchanged between the radiation source control device 300 and the radiation imaging device 100. Thereby, the radiation imaging device 100 and the radiation source 301 controlled by the radiation source control device 300 are configured to be able to capture a radiation image without going through the control device 400.

[0019] The control device 400 includes an imaging control unit 402, an irradiation control unit 403, a communication unit 401, a radiation imaging application 404, a display unit 406, an operation UI 407, and a power supply unit 405, and controls each component of the radiation imaging system SYS. The imaging control unit 402 controls the radiation imaging device 100, such as controlling the timing of acquiring image data according to user settings via the radiation imaging application 404 and setting imaging conditions including the imaging mode when acquiring a radiation image by the detection unit 200. The irradiation control unit 403 controls the irradiation conditions of the radiation irradiated from the radiation source 301 by controlling the radiation source control device 300 according to user settings via the radiation imaging application 404. The communication unit 401 controls the communication between the radiation imaging device 100, the radiation source control device 300, and the in-hospital network 600. The radiation imaging application 404 receives imaging orders and registers imaging information. The display unit 406 displays radiation images based on the radiation image data obtained by the radiation imaging device 100 and information on imaging conditions such as the imaging mode when imaging. The operation UI 407 can be a keyboard, a mouse, etc. for operating the radiation imaging application 404. The power supply unit 405 supplies power to each component within the control device 400.

[0020] Here, the communication between the control device 400 and the radiation imaging device 100, and the communication between the control device 400 and the radiation source control device 300 may be cable connection communication using standards such as RS232C, USB, Ethernet, etc. Also, the communication between the control device 400 and the radiation imaging device 100, and the communication between the control device 400 and the radiation source control device 300 may be communication using a dedicated signal line, or may be wireless communication. Further, the communication between the control device 400 and the radiation imaging device 100, and the communication between the control device 400 and the radiation source control device 300 may be a combination of wired communication and wireless communication.

[0021] In communication between the control device 400 and the radiation imaging device 100, for example, the radiation imaging device 100 transmits signals indicating image data and the device status of the radiation imaging device 100 to the control device 400. Also, for example, the control device 400 transmits control signals to the radiation imaging device 100, including signals for setting conditions such as the imaging mode when acquiring image data. Furthermore, in communication between the control device 400 and the radiation source control device 300, for example, signals for setting radiation irradiation conditions are transmitted from the control device 400 to the radiation source control device 300. Also, for example, the radiation source control device 300 transmits signals to the control device 400, such as signals indicating the device status of the radiation source control device 300 and signals such as actual irradiation information when radiation is irradiated.

[0022] Figure 2 is a block diagram showing an example configuration of the detection unit 200 of the radiation imaging device 100. The detection unit 200 has a sensor array 204 including a plurality of pixels 207 arranged in a two-dimensional array to form a plurality of rows and a plurality of columns in order to acquire a radiation image corresponding to the incidence of radiation. The pixels 207 arranged in the sensor array 204 include a switch element 208 such as a thin-film transistor (TFT) and a photoelectric conversion element 209, and a scintillator (not shown) may be placed on the pixel 207 (photoelectric conversion element 209). The scintillator may be integrally formed in the sensor array 204, for example. When a pixel 207 includes a scintillator and a photoelectric conversion element 209, the radiation incident on the detection unit 200 is converted into visible light by the scintillator, the converted visible light is incident on the photoelectric conversion element 209 of the pixel 207, and a charge corresponding to the visible light is generated in the photoelectric conversion element 209. Thus, as the pixel 207, a so-called indirect conversion type conversion element may be used, which converts incident radiation into electric charge using a scintillator and a photoelectric conversion element 209. Alternatively, for example, a so-called direct conversion type conversion element that directly converts incident radiation into electric charge without a scintillator may be used for the pixel 207. By switching the ON (conducting) state and the OFF (non-conducting) state of the switch element 208, the accumulation and reading of charge generated by the photoelectric conversion element 209 are performed, and radiation image data can be acquired.

[0023] Pixels 207 arranged in the sensor array 204 of the detection unit 200 are turned ON by applying a voltage that turns ON the switch element 208 from the drive circuit 201 via a common drive line 211 for each row. When the switch element 208 is turned ON, a signal corresponding to the charge accumulated in the pixel 207 is transferred to the sample-and-hold circuit 202 via the signal line 210 to which each pixel 207 is connected. Subsequently, the signals output from the pixels 207 held in the sample-and-hold circuit 202 are sequentially read out via the multiplexer 203, amplified by the amplifier 205, and then converted into digital image data by the A / D converter 206. Next, the pixels 207 whose charge reading has finished are returned to the charge-accumulating state by applying a voltage that turns OFF the switch element 208 from the drive circuit 201 via the drive line 211. In this way, the drive circuit 201 sequentially scans the pixels 207 arranged on the sensor array 204 row by row, and finally the signals output from all pixels 207 are converted into digital values. This allows image data for generating a radiation image to be read out. The driving and reading operations of these detection units 200 are controlled by the drive control unit 102 of the control unit 101. The image data converted into digital values ​​may be temporarily stored, for example, in the storage unit 109 in Figure 1.

[0024] Next, the operation of the radiation imaging system SYS in this embodiment will be described. Figure 3 is a timing diagram showing an example of the operation of the radiation imaging system SYS in this embodiment. In this embodiment, radiation is continuously irradiated from the radiation source 301 to the radiation imaging device 100 according to the user's operation, and moving images are captured (continuous fluoroscopy). In addition, when fluoroscopy is interrupted or terminated, a last image hold operation is performed to display the last image of the fluoroscopy on the display unit 406. Figure 3 shows a series of operations between the radiation imaging device 100 and the radiation source 301 (radiation source control device 300) during this continuous fluoroscopy.

[0025] "Operation UI 302 Input" indicates a signal for the user to request the acquisition of a radiation image. In Figure 3, for example, when the user presses the exposure switch to start continuous fluoroscopy, "Operation UI 302 Input" changes to a high level. "Detection Unit 200 Operation" indicates the operating state of the sensor array 204 of the detection unit 200. "Readout Processing" indicates the operation of transferring image data from the detection unit 200 to the control unit 101 within the radiation imaging device 100. "Storage Unit 109 Storage Operation" indicates the operation of storing the image data transferred to the control unit 101 in the storage unit 109. "Irradiation Instruction" indicates a signal from the irradiation timing control unit 114 to the radiation source control device 300 instructing it to irradiate with radiation. "Radiation Source 301 Irradiation Instruction" indicates a signal in which the radiation source control device 300 instructs the radiation source 301 to irradiate with radiation in accordance with the "Irradiation Instruction". In Figure 3, while "Radiation Source 301 Irradiation Instruction" is at a high level, the radiation source 301 irradiates with radiation. "Radiation imaging device 100 output operation" indicates the operation of transferring image data from the radiation imaging device 100 to the control device 400.

[0026] Next, the operation of the radiation imaging device 100 and the radiation source 301 (radiation source control device 300) in continuous fluoroscopy will be described. Before the start of radiation irradiation is instructed by the user via the operation UI 302, the control device 400 causes the radiation imaging device 100 to start a generation operation to generate image data. The generation operation is an operation in which the detection unit 200 of the radiation imaging device 100 generates one image data by causing multiple pixels 207 to perform an accumulation operation 500 and a readout operation 510 at least one row at a time from the first row to the last row. By repeating this generation operation, it becomes possible to capture moving images.

[0027] Even before radiation irradiation begins, the storage operation 500 and the reading operation 510 are repeated, as shown in "Detection Unit 200 Operation" and "Readout Processing". This operation can also be called a reset drive to suppress the effects of dark charge generated in the pixel 207. The signal read out from the pixel 207 at this time is not treated as image data and does not need to be stored in the storage unit 109.

[0028] Next, when the user instructs the start of radiation irradiation, such as by pressing the exposure switch on the operation UI302, the radiation imaging system SYS starts continuous fluoroscopy. When the read operation 510 is completed up to the last row (indicated as row N in Figure 3) of the multiple pixels 207 arranged in the sensor array 204, the irradiation timing control unit 114 transmits a signal to the radiation source control device 300 instructing it to start radiation irradiation. Upon receiving the signal to start radiation irradiation, the radiation source control device 300 instructs the radiation source 301 to irradiate with radiation, and the radiation source 301 starts irradiating with radiation. In other words, when the start of radiation irradiation is instructed, the radiation source 301 is instructed to start irradiating with radiation in accordance with the completion of the read operation 510 of the last row in the generation operation when the start of radiation irradiation is instructed.

[0029] During radiation irradiation, the radiation imaging device 100 repeats the generation operation described above. The generation operation generates one image data per frame, and the image data read out by the reading operation 510 is transferred to the control unit 101 and stored in the storage unit 109 as radiation image data 110. The image data stored in the storage unit 109 as radiation image data 110 is subjected to offset correction processing by the offset correction unit 107 using offset image data 111 previously stored in the storage unit 109, and is transferred to the control device 400 via the communication unit 112. The image based on the image data transferred to the control device 400 is displayed in the display unit 406. Continuous fluoroscopy is performed by repeating these operations.

[0030] As shown in Figure 3, when generating the image data for the first frame, the radiation exposure time in the accumulation operation 500 differs from row to row. Therefore, shading may occur in the image generated from the image data for the first frame. On the other hand, from the second frame onward, the radiation exposure time in the accumulation operation 500 does not change from row to row, so shading can be suppressed.

[0031] Next, we will describe the case in the Nth frame where the user interrupts or terminates continuous fluoroscopy, for example, by returning the exposure switch on the operation UI 302. When the termination of radiation irradiation is instructed, in the Nth frame, where the accumulation operation 500 has already started, the irradiation timing control unit 114 maintains the "irradiation instruction" signal at a high level until the reading operation 510 of the last row (Nth row) of the multiple pixels 207 arranged in the sensor array 204 is completed. When the reading operation of all rows in the Nth frame is completed, the "irradiation instruction" signal changes to a low level. As the "irradiation instruction" changes to a low level, the radiation source control device 300 changes the "radiation source 301 irradiation instruction" output to the radiation source 301 to a low level. As a result, the radiation source 301 stops irradiating radiation in accordance with the completion of the accumulation operation 500 and reading operation 510 of the last row in the generation operation of the Nth frame when the termination of radiation irradiation was instructed.

[0032] By continuing radiation irradiation until the accumulation operation 500 and read operation 510 of the last row in the generation operation of the Nth frame are completed, the image data of the Nth frame when the end of radiation irradiation is instructed will be data where the radiation irradiation time during the accumulation operation 500 is the same for each row. Furthermore, the image data of the Nth frame may be data where the radiation irradiation time during the accumulation operation 500 is the same for each row. The control device 400 causes the display unit 406 to display an image based on the final image data generated by the generation operation of the Nth frame when the end of radiation irradiation is instructed. This provides a radiation imaging system SYS that can obtain a clear image in which each of the multiple pixels 207 arranged in the sensor array 204 is irradiated with radiation, even when continuous fluoroscopy is terminated or interrupted.

[0033] In the operation shown in Figure 3, the storage operation 500 and the reading operation 510 are performed for each row from the first row to the Nth row (the last row), but this is not limited to this. For example, the storage operation 500 and the reading operation 510 may be performed every two rows, every three rows, or every other row. Also, the radiation source 301 stopped irradiating with radiation in response to the completion of the storage operation 500 and the reading operation 510 for the last row in the generation operation of the Nth frame, but this is not limited to this. The radiation source 301 may stop irradiating with radiation in response to the completion of the storage operation 500 for the last row in the generation operation of the Nth frame. Even in this case, the radiation irradiation time during the storage operation 500 may be the same for each row.

[0034] After the radiation irradiation is instructed to end, the control device 400 stops the generation operations that perform the storage operation 500 and the reading operation 510 on the radiation imaging device 100. In this case, the control device 400 does not need to output image data generated by generation operations that occurred after the generation operation that produced the final image data from the radiation imaging device 100 to the control device 400. Also, in this case, image data generated by generation operations that occurred after the generation operation that produced the final image data does not need to be transferred from the detection unit 200 to the control unit 101. Furthermore, for example, image data generated by generation operations that occurred after the generation operation that produced the final image data does not need to be stored in the storage unit 109. Because image data generated by generation operations that occurred after the generation operation that produced the final image data is not transferred to the storage unit 109 or the communication unit 112, it is not output from the radiation imaging device 100.

[0035] Furthermore, for example, the image displayed on the display unit 406 after radiation irradiation has finished is not limited to an image based solely on the final image data. The control device 400 may cause the display unit 406 to display an image based on multiple image data, including the final image data generated in the Nth frame and the image data generated by the generation operation one frame prior to the generation operation that generated the final image data (the N-1th frame). A composite image based on data generated by adding or averaging multiple image data may be displayed on the display unit 406. Fluoroscopy often involves less incident radiation than still image capture. By generating an image based on multiple image data, noise components in the image displayed on the display unit 406 can be suppressed, potentially improving image quality.

[0036] Figure 4 is a timing diagram showing a modified example of the operation of the radiation imaging device 100 and the radiation source 301 (radiation source control device 300) in continuous fluoroscopy as shown in Figure 3. Similar to the operation shown in Figure 3, it shows a case where the end of radiation irradiation is instructed after the Nth frame following the start of continuous fluoroscopy.

[0037] In the operation shown in Figure 4, when an instruction to end radiation irradiation is received, the irradiation timing control unit 114 changes the "irradiation instruction" signal to a low level. As the "irradiation instruction" changes to a low level, the radiation source control device 300 changes the "radiation source 301 irradiation instruction" output to the radiation source 301 to a low level. As a result, the radiation source 301 stops irradiating radiation. Therefore, the image data of the Nth frame will have different radiation irradiation times for each row in the accumulation operation 500. Consequently, when the display unit 406 displays an image based on the image data of the Nth frame, shading may occur in the displayed image.

[0038] Therefore, the control device 400 causes the display unit 406 to display an image based on the image data (final image data) generated by the generation operation of the N-1 frame, which is one frame prior to the generation operation of the N frame when the end of radiation irradiation is instructed. In other words, the image displayed on the display unit 406 is an image based on image data from the accumulation operation 500 at the time when the radiation irradiation time is aligned for each row. As a result, in the operation shown in Figure 4, as in the operation shown in Figure 3, a radiation imaging system SYS can be provided that can obtain a clear image in which each of the multiple pixels 207 arranged in the sensor array 204 is irradiated with radiation.

[0039] In the operation shown in Figure 4, image data generated by generation operations after the generation operation that generated the final image data (from the Nth frame onward) does not need to be transferred from the radiation imaging device 100 to the control device 400. Also, image data generated by generation operations from the Nth frame onward does not need to be transferred from the detection unit 200 to the control unit 101, nor does it need to be stored in the storage unit 109. Furthermore, the image displayed on the display unit 406 may be generated using the final image data and one or more image data generated by generation operations for frames prior to the frame in which the final image data was generated. Alternatively, the image displayed on the display unit 406 may be generated using the final image data and image data generated by generation operations for frames two frames prior to the frame in which the final image data was generated. In other words, the image displayed on the display unit 406 may be generated using the final image data and image data generated by generation operations for at least one frame prior to the frame in which the final image data was generated.

[0040] Furthermore, when the exposure switch is released, the radiation imaging device 100 may determine whether to continue the "irradiation instruction" signal and extend the radiation irradiation until the reading operation 510 of the last row (row N) of the Nth frame is completed, as shown in Figure 3, or to immediately stop the radiation irradiation, as shown in Figure 4, and switch to an termination operation to end (interrupt) continuous fluoroscopy. An example of the determination flow for the termination operation in continuous fluoroscopy in this case will be explained using Figure 5.

[0041] First, in the Nth frame, if the user releases the exposure switch on the operation UI 302, the control unit 101 of the radiation imaging device 100 detects (recognizes) that the exposure switch is OFF (S101). At this time, the control unit 101 uses, for example, the timer 113 to obtain the time Toff from the completion of the read operation 510 of the last row (Nth row) of the previous N-1 frame until the exposure switch OFF is detected. Next, the control unit 101 obtains the time ΔT from the time the exposure switch OFF is released until the read operation 510 of the last row of the Nth frame is completed. For example, using the time Tcyc of one period of frames in the currently operating continuous fluoroscopy imaging mode, the time ΔT until the read operation 510 of the last row of the Nth frame is completed can be calculated as ΔT = Tcyc - Toff (S102).

[0042] Next, the control unit 101 determines whether ΔT is less than a predetermined threshold Tth (S103). If ΔT is less than the threshold Tth (YES in S103), the control unit operates to maintain the "irradiation instruction" signal at a high level (irradiation) until the reading operation 510 of the last row (Nth row) of the Nth frame is completed, as shown in Figure 3 (S104). The control device 400 also causes the display unit 406 to display an image based on the final image data generated by the generation operation of the Nth frame when the end of radiation irradiation is instructed (S105).

[0043] On the other hand, if ΔT is greater than or equal to the threshold Tth (NO in S103), and the "irradiation instruction" is maintained until the completion of the reading operation 510 of the last row (row N) of the Nth frame, radiation will be irradiated for a certain period of time or longer, even though the exposure switch has been released. In particular, if the frame rate of the imaging mode of the continuous fluoroscopy in operation is low, the time from when the exposure switch is turned OFF to when radiation is irradiated will be long. In such cases, as shown in Figure 4, the "irradiation instruction" signal is immediately changed to a low level in accordance with the user's instruction to end radiation irradiation, and radiation irradiation is stopped (S106). The control device 400 also displays an image on the display unit 406 based on the image data (final image data) generated by the generation operation of the N-1 frame, which is one frame prior to the generation operation of the Nth frame when the end of radiation irradiation is instructed (S107). In this way, after releasing the exposure switch to end radiation irradiation, it is possible to select an appropriate continuous fluoroscopy termination operation according to the timing of releasing the exposure switch, without continuing radiation irradiation excessively.

[0044] Furthermore, the method for selecting the termination operation of continuous fluoroscopy is not limited to those described above. For example, the termination operation may be uniquely determined according to the frame rate of the generation operation of the continuous fluoroscopy imaging mode used. For example, in the case of a frame rate faster than a certain level, the system may be controlled to continue the "irradiation instruction" until the read operation 510 of the last row of the Nth frame is completed, as shown in Figure 3. In the case of a frame rate slower than a certain level, since the period from the release of the exposure switch until the cessation of radiation irradiation may be long, the system may be controlled to stop the "irradiation instruction" immediately, as shown in Figure 4. In this way, after releasing the exposure switch, the system can select an appropriate termination operation for continuous fluoroscopy according to the frame rate of the continuous fluoroscopy imaging mode used, without continuing radiation irradiation excessively. Here, the frame rate is defined by the generation operation (accumulation operation 500 and read operation 510) performed in each row. For example, the frame rate can be the number of times the generation operation is performed in a given time in one row.

[0045] In the radiation imaging device 100, imaging may not be performed using all rows of the sensor array 204. Here, we will describe the termination operation of continuous fluoroscopy when a predetermined region of interest (ROI) 702 of the sensor array 204 is designated as the area to be used for imaging. In this embodiment, the period for which the "irradiation instruction" signal is maintained at a high level when terminating continuous fluoroscopy is changed according to the timing of the user's instruction to end radiation irradiation, such as when the exposure switch is released, and the designated ROI 702.

[0046] First, Figure 6 will be used to explain the reading direction of image data in the sensor array 204 and an example of ROI 702. As described above, the control unit 101 of the radiation imaging device 100 controls the reading operation of multiple pixels 207 arranged in the sensor array 204 in row units. Here, as shown in Figure 6, the image data is read in the direction indicated by arrow 703, from the top (1st row) to the bottom (Nth row) of the sensor array 204.

[0047] Here, ROI702 may, for example, indicate a predefined effective area of ​​the image for each imaging mode, or it may be individually defined as a region of interest, such as one set for each imaging procedure or protocol. Alternatively, ROI702 may be defined as the radiation irradiation range obtained from the aperture information of the collimator connected to the radiation source 301, acquired by the radiation imaging device 100. Here, we will explain using the example where ROI702 is set in the center of the sensor array 204, as shown in Figure 6.

[0048] The readout period Trd, which reads image data row by row from each pixel 207 of the sensor array 204, includes, as shown in Figure 6, the readout period Tout_u for image data outside the region of interest from row 1 to row (Roi1-1), the readout period Troi for image data of ROI702 (rows Roi1 to RoiM), and the readout period Tout_l for image data outside the region of interest from row (Roi1+1) to row N. An example of controlling the operation timing during continuous fluoroscopy when ROI702 is set as shown in Figure 6 will be explained using Figure 7. The operation when starting continuous fluoroscopy may be the same as in Figure 3, so the explanation is omitted here.

[0049] This section describes the case where, in the Nth frame, the user interrupts or terminates continuous fluoroscopy by returning the exposure switch on the operation UI302. If the termination of radiation irradiation is instructed, in the Nth frame, where the accumulation operation 500 has already started, the irradiation timing control unit 114 maintains the "irradiation instruction" signal at a high level until the reading operation 510 of the last row (RoiM row) in ROI702 is completed. Once the reading operation 510 of all rows in ROI702 in the Nth frame is completed, the irradiation timing control unit 114 changes the "irradiation instruction" signal to a low level and stops the radiation irradiation.

[0050] As a result, radiation is irradiated until the accumulation and reading operations of the last row in ROI 702 are completed during the generation operation of the Nth frame. Therefore, when the end of radiation irradiation is instructed, the image data of the Nth frame will contain data with consistent radiation irradiation times for at least each row in ROI 702. The control device 400 causes the display unit 406 to display an image based on the final image data generated by the generation operation of the Nth frame when the end of radiation irradiation is instructed. This provides a radiation imaging system SYS that can obtain clear images in which at least each pixel 207 in ROI 702 has been irradiated with radiation, even when continuous fluoroscopy is terminated or interrupted.

[0051] Furthermore, we will explain the case where the exposure switch is released during the readout operation of the (N-1) frame in Figure 7, between the (RoiM+1)th row and the Nth row (the period Tout_l in Figure 6). In this case, since the readout operation 510 of the last row (RoiM row) in the N-1 frame has already been completed, the irradiation timing control unit 114 maintains the "irradiation instruction" signal at a high level until the readout operation 510 of the last row (RoiM row) in the next N frame of the ROI 702 is completed. Once the readout operation 510 of all rows in the N frame of the ROI 702 is completed, the irradiation timing control unit 114 changes the "irradiation instruction" signal to a low level and stops the irradiation of radiation. In this way, the irradiation instruction may be continued from the time the exposure switch is released until the readout operation 510 of the last row (RoiM row) in the next ROI 702 is completed.

[0052] Furthermore, while Figure 7 shows that the storage operation 500 and the reading operation 510 are performed for each row from the first row to the Nth row (the last row), the operation is not limited to this. For example, the storage operation 500 and the reading operation 510 may be performed every two rows, every three rows, or every other row. Also, while the radiation source 301 stopped irradiating with radiation when the storage operation 500 and the reading operation 510 of the last row (RoiM row) in the ROI 702 during the generation operation of the Nth frame were completed, the operation is not limited to this. The radiation source 301 may also stop irradiating with radiation when the storage operation 500 of the last row (RoiM row) in the ROI 702 during the generation operation of the Nth frame was completed. Even in this case, the radiation irradiation time during the storage operation 500 may be the same for each row within the ROI 702.

[0053] For the region outside ROI702, from row (RoiM+1) to row N, the radiation exposure time in accumulation operation 500 differs for each row. Therefore, shading may occur in the region outside ROI702 in the image generated in the Nth frame. However, since this is not image data of the region used for observation or diagnosis, it is unlikely to cause problems in observation or diagnosis using the obtained image.

[0054] After the radiation irradiation is instructed to end, the control device 400 stops the generation operations that perform the storage operation 500 and the reading operation 510 on the radiation imaging device 100. In this case, the control device 400 does not need to output image data generated by generation operations that occurred after the generation operation that produced the final image data from the radiation imaging device 100 to the control device 400. Also, in this case, image data generated by generation operations that occurred after the generation operation that produced the final image data does not need to be transferred from the detection unit 200 to the control unit 101. Furthermore, for example, image data generated by generation operations that occurred after the generation operation that produced the final image data does not need to be stored in the storage unit 109. Because image data generated by generation operations that occurred after the generation operation that produced the final image data is not transferred to the storage unit 109 or the communication unit 112, it is not output from the radiation imaging device 100. These may be the same as the operations described using Figure 3 above.

[0055] Furthermore, for example, the image displayed on the display unit 406 after radiation irradiation is completed is not limited to an image based solely on the final image data. An image based on multiple image data may be displayed. These operations may be similar to those described using Figure 3 above.

[0056] Furthermore, in continuous fluoroscopy where a predetermined region of interest (ROI) 702 within the sensor array 204 is designated as the area to be used for imaging, the continuous fluoroscopy termination operation shown in Figure 4 above can also be performed. In this case, the operation is the same as that shown in Figure 4; when an instruction to end radiation irradiation is received, the irradiation timing control unit 114 changes the "irradiation instruction" signal to a low level and stops the radiation irradiation.

[0057] Furthermore, when the exposure switch is released, the radiation imaging device 100 may determine whether to maintain the "irradiation instruction" signal and extend the radiation irradiation until the completion of the reading operation 510 of the last row (RoiM row) in the Nth frame of ROI 702, as shown in Figure 7, or to immediately stop the radiation, as shown in Figure 4, and switch the termination operation accordingly. An example of the determination flow for the termination operation in continuous fluoroscopy in this case will be explained using Figure 8.

[0058] First, if the user releases the exposure switch on the operation UI302 during the period from the completion of the reading operation 510 for the last row (row M) in ROI702 of the (N-1) frame (start of the reading operation 510 for row M+1) to the reading operation 510 for the last row (row M) in ROI702 of the (N) frame, the control unit 101 of the radiation imaging device detects that the exposure switch has been turned OFF (S201). At this time, the control unit 101 uses, for example, the timer 113 to obtain the time Toff from the completion of the reading operation 510 for the last row (row M) in ROI702 of the (N-1) frame to the detection of the exposure switch being turned OFF. Next, the control unit 101 obtains the time ΔT from the time the exposure switch is turned OFF until the reading operation 510 for the last row (row M) in ROI702 of the (N) frame is completed. For example, using the time Tcyc of one frame cycle in the currently operating continuous fluoroscopy mode, the time ΔT from the exposure switch OFF until the reading operation 510 of the last row (RoiM row) in ROI702 of the Nth frame is completed can be calculated as ΔT = Tcyc - Toff (S202).

[0059] Next, the control unit 101 determines whether ΔT is less than a predetermined threshold Tth (S203). If ΔT is less than the threshold Tth (YES in S203), the control unit 400 operates to maintain the "irradiation instruction" signal at a high level (irradiation) until the reading operation 510 of the last row (RoiM row) in the Nth frame of ROI 702 is completed, as shown in Figure 7 (S204). The control device 400 also causes the display unit 406 to display an image based on the final image data generated by the generation operation of the Nth frame (S205).

[0060] On the other hand, if ΔT is greater than or equal to the threshold Tth (NO in S203), as shown in Figure 4, the irradiation timing control unit 114 immediately changes the "irradiation instruction" signal to a low level and stops the irradiation of radiation (S206). The control device 400 also displays on the display unit 406 an image based on the image data (final image data) generated by the generation operation of the N-1 frame that precedes the generation operation of the N frame when the end of radiation irradiation is instructed (S207). In this way, after releasing the exposure switch to end radiation irradiation, it is possible to select an appropriate continuous fluoroscopy termination operation according to the timing of releasing the exposure switch without continuing radiation irradiation excessively.

[0061] Furthermore, the method for selecting the termination operation during continuous fluoroscopy is not limited to those described above. For example, the termination operation may be uniquely determined according to the frame rate of the generation operation of the continuous fluoroscopy imaging mode used. For example, in the case of a frame rate faster than a certain level, the system may be controlled to continue the "irradiation instruction" until the reading operation 510 of the last row (RoiM row) in the Nth frame of ROI702 is completed, as shown in Figure 7. In the case of a frame rate slower than a certain level, since the period from releasing the exposure switch until radiation irradiation stops may be long, the system may be controlled to stop the "irradiation instruction" immediately, as shown in Figure 4. In this way, after releasing the exposure switch, it is possible to select a continuous fluoroscopy termination operation that suppresses shading on the image in ROI702, at least according to the frame rate of the continuous fluoroscopy imaging mode used, without continuing radiation irradiation excessively.

[0062] In this embodiment, the ROI 702 was described as being set in the center of the sensor array 204, as shown in Figure 6. However, it is not limited to this, and similar control can be applied to an ROI 702 set in any location.

[0063] Thus, in the SYS radiography system with a last image hold function, the image displayed on the display unit 406 when fluoroscopy is interrupted is generated from image data in which the radiation exposure times during the accumulation operation 500 are aligned row by row. This suppresses shading of the image displayed when fluoroscopy is interrupted, improving image quality and realizing a more user-friendly SYS radiography system.

[0064] 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. For example, the functions performed by each control unit of each device may be performed by the control units of other devices, and various modifications and variations are possible as long as each control unit of each device functions as a control unit for the system as a whole. Accordingly, claims are attached to make the scope of the invention public. [Explanation of Symbols]

[0065] 100: Radiation imaging device, 207: Pixel, 301: Radiation source, 406: Display unit, 500: Accumulation operation, 510: Readout operation, SYS: Radiation imaging system

Claims

1. A radiation imaging device for acquiring a radiation image based on radiation irradiated from a radiation irradiation device, A sensor panel in which a plurality of pixels are arranged in a matrix; a means for reading out image signals required for acquiring one radiation image from a plurality of pixels row by row in a radiation imaging process in which radiation is continuously irradiated from the radiation irradiation device, and sequentially acquiring a plurality of radiation images; a means for executing a communication process to stop irradiation of radiation by the radiation irradiation device so that irradiation of radiation is stopped after a timing at which readout of image signals from pixels in a predetermined row among the plurality of pixels is completed after a user instruction to end the radiation imaging is input; A radiation imaging apparatus comprising:

2. The radiation imaging device of claim 1, wherein the specified row is the last row of the matrix.

3. The radiation imaging device as described in claim 1, wherein the sensor panel has a plurality of regions of interest, and the specified row is the last row in a selected region of interest among the plurality of regions of interest.

4. A radiation imaging device as described in claim 1, characterized in that it has a means for executing a read process of image signals from a plurality of pixels row by row before an instruction to start radiation irradiation is input, and for executing a communication process to start radiation irradiation by the radiation irradiation device so that radiation irradiation is started at the timing when an instruction to start radiation irradiation is input and reading of image signals from pixels of a specified row of the plurality of pixels is completed in the read process.

5. A communication unit capable of communicating with an information processing device that displays information on a display unit; 2. The radiation imaging apparatus according to claim 1, further comprising: a unit for sequentially transmitting the plurality of radiation images to the information processing apparatus via the communication unit.

6. The radiation imaging device described in Claim 5, characterized in that the information processing device displays on the display unit an image based on multiple radiation images including the last radiation image acquired in the radiation imaging and the radiation image one before the last.

7. A radiation imaging device according to claim 5 or 6, A radiation imaging system comprising the information processing device.

8. A radiation imaging device capable of transmitting a radiation image to an information processing device that displays information on a display unit, A sensor panel in which a plurality of pixels are arranged in a matrix; a means for reading out image signals required for acquiring one radiation image from a plurality of pixels row by row in a radiation imaging process in which radiation is continuously irradiated from a radiation irradiation device, and sequentially acquiring a plurality of radiation images; a means for transmitting a first radiographic image of the plurality of radiographic images via a network to the information processing device in response to completion of readout of image signals necessary for acquiring the first radiographic image of the plurality of radiographic images, and for terminating the radiographic imaging without transmitting the second radiographic image to the information processing device in response to input of a user instruction to terminate the radiographic imaging during readout of image signals necessary for acquiring a second radiographic image subsequent to the first radiographic image; A radiation imaging apparatus comprising:

9. A radiation imaging device as described in claim 8, characterized in that it has a means for executing a read process of image signals from a plurality of pixels row by row before an instruction to start radiation irradiation is input, and for executing a communication process to start radiation irradiation by the radiation irradiation device so that radiation irradiation is started at the timing when an instruction to start radiation irradiation is input and reading of image signals from pixels of a specified row of the plurality of pixels is completed in the read process.

10. The radiation imaging device of claim 9, wherein the specified row is the last row of the matrix.

11. The radiation imaging device of claim 9, wherein the sensor panel has a plurality of regions of interest, and the specified row is the last row in a selected region of interest among the plurality of regions of interest.

12. A communication unit capable of communicating with an information processing device that displays information on a display unit; 9. The radiation imaging apparatus according to claim 8, further comprising: a unit for sequentially transmitting the plurality of radiation images to the information processing apparatus via the communication unit.

13. The radiation imaging device described in Claim 12, characterized in that the information processing device displays on the display unit an image based on multiple radiation images including the last radiation image acquired in the radiation imaging and the radiation image one before the last.

14. A radiation imaging device according to claim 12 or 13, A radiation imaging system comprising the information processing device.

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