JP6700882B2 - Radiation imaging apparatus, control method thereof, radiation imaging system and program - Google Patents

Description

  The present invention relates to a radiation imaging apparatus, a control method therefor, a radiation imaging system, and a program.

  The radiation image generated by the radiation imaging apparatus includes not only a component according to the incident radiation but also a component according to dark charge. A correction method is known in which an image (a so-called offset image) acquired in a state where the radiation imaging apparatus is not irradiated with radiation is subtracted from the radiation image in order to remove a component corresponding to the dark charge. Since the amount of dark charges generated depends on the internal temperature of the radiation imaging apparatus, if there is a difference in the temperature distribution inside the radiation imaging apparatus between when the offset image is acquired and when the radiation image is acquired, the offset component may not be removed correctly. . Patent Document 1 describes that an offset image is acquired with high accuracy by updating the offset image as needed while radiography is not performed. Further, Patent Document 2 describes that a decrease in temperature of the read IC is suppressed by periodically supplying power to the read IC even while the radiation imaging apparatus is in the sleep state.

US Pat. No. 5,452,338 JP, 2011-101693, A

  If the offset image is acquired at any time even when the radiation imaging apparatus is not used, as in Patent Document 1, the switch element of the radiation imaging apparatus easily deteriorates in characteristics. An example of such characteristic deterioration is a change in the threshold voltage of the switch element. If the threshold voltage of the switch element changes, the dark charge component leaking from the switch element may change, or on/off control of the switch element may not be possible. Further, as in Patent Document 2, when the offset image is not acquired by only supplying power to the reading IC periodically during the sleep state, it is necessary to acquire the offset image again after recovery from the sleep state. . Therefore, the operator of the radiation imaging apparatus needs to wait, for example, about 10 seconds to 1 minute until the acquisition of the offset image is completed, even when the operator wants to take an image in an emergency. An object of the present invention is to provide a technique for suppressing the deterioration of the switch element of the radiation imaging apparatus and reducing the waiting time until the image capturing is possible.

  In view of the above-mentioned problems, in some embodiments, a radiation imaging apparatus that constitutes a part of a radiation imaging system, including a conversion element that converts radiation into an electric charge and a sensor unit that has a switching element that transfers the electric charge. A read-out circuit that reads out electric charges from the sensor unit, and a control unit that controls the sensor unit and the read-out circuit so as to perform any one of a plurality of driving operations. The imaging operation for acquiring a radiation image according to the radiation incident on the image capturing apparatus, the offset acquisition operation for acquiring an offset image for correcting the radiation image, and the on/off switching of the switch element are repeated, thereby performing the imaging operation. An imaging standby operation that waits for switching to the operation, and a standby operation that supplies the electric power to the readout circuit and drives the sensor unit so as to suppress deterioration of the switch element more than the imaging standby operation. The radiation imaging apparatus is characterized in that the control unit temporarily suspends the execution of the standby operation and executes the offset acquisition operation at a frequency according to a usage condition of the radiation imaging system by an operator. To be done.

  By the above means, a technique is provided for suppressing the deterioration of the switch element of the radiation imaging apparatus and reducing the waiting time until the imaging becomes possible.

The figure explaining the structural example of the radiation imaging system of some embodiment. The figure explaining the structural example of the radiation detection part of some embodiment. The flowchart explaining the operation example of the radiation imaging device of some embodiment. The flowchart explaining the example of the imaging operation of some embodiment. The flowchart explaining the example of the estimation method of the usage condition of some embodiment. The flowchart explaining another example of the estimation method of the usage condition of some embodiment. The flowchart explaining another example of the estimation method of the usage condition of some embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Similar elements are denoted by the same reference numerals throughout the various embodiments, and overlapping description will be omitted. Further, the respective embodiments can be appropriately modified and combined.

  With reference to FIG. 1, a configuration example of a radiation imaging system 100 according to some embodiments will be described. The radiation imaging system 100 includes a radiation imaging device 200, a radiation generation device 300, and a control device 400. That is, the radiation imaging apparatus 200, the radiation generation apparatus 300, and the control apparatus 400 each constitute a part of the radiation imaging system 100. The radiation generation device 300 controls the radiation source 301 so as to irradiate the radiation imaging device 200 with radiation. The radiation from the radiation source 301 passes through the subject and then enters the radiation imaging apparatus 200. The radiation imaging apparatus 200 generates image data according to the incident radiation and transmits this image data to the control device 400. The control device 400 displays the received image data to the operator of the radiation imaging system 100. The operator of the radiation imaging system 100 is, for example, a doctor or a medical radiologist. The control device 400 is also used by an operator of the radiation imaging system 100 to control the radiation imaging device 200 and the radiation generation device 300 of the radiation imaging system 100.

  The control device 400 can communicate with each of the radiation imaging device 200 and the radiation generation device 300. This communication may be, for example, communication based on a communication standard such as RS232C, USB, Ethernet (registered trademark), or may be communication using a dedicated signal line. Further, this communication may be wired communication or wireless communication. Image data, imaging conditions, device states, and synchronization signals are communicated between the radiation imaging device 200 and the control device 400, for example. This synchronization signal is used, for example, to notify the timing at which imaging should be started or the timing at which radiation can be emitted. For example, radiation irradiation conditions, device states, actual irradiation information, and synchronization signals are communicated between the radiation generation device 300 and the control device 400. This synchronization signal is used, for example, to notify the timing at which radiation irradiation should be started.

  The control device 400 may be capable of communicating with an information system 501 that manages various types of information regarding examinations and patients via a hospital network 500 that is, for example, a LAN (Local Area Network). The information system 501 is, for example, a RIS (Radiology Information System) which is a radiation information system or a HIS (Hospital Information System) which is a hospital information system. The operator of the radiation imaging system 100 may use the control device 400 to acquire the imaging order of the radiation image or the imaging information including the patient information from the information system 501, or may be acquired by the radiation imaging device 200. The image data may be stored in the information system 501.

  The radiation imaging apparatus 200 includes a radiation detection unit 201, a control unit 202, and a power supply unit 203. The radiation detection unit 201 detects the radiation that has entered the radiation imaging apparatus 200 and generates image data corresponding to this radiation. The control unit 202 performs various operations by controlling the operation of the entire radiation imaging apparatus 200. A specific example of the operation of the control unit 202 will be described later. The power supply unit 203 supplies electric power to each component of the radiation imaging apparatus 200.

  The radiation imaging apparatus 200 includes a processing unit 204, a storage unit 205, a communication unit 206, and an internal clock 207. The processing unit 204 performs processing for the control unit 202 to control the radiation imaging apparatus 200. The processing unit 204 may be configured by a processor such as a microprocessor, a dedicated circuit such as an ASIC (application specific integrated circuit), or a combination thereof.

  The storage unit 205 stores various data regarding the radiation imaging apparatus 200. For example, the storage unit 205 stores image data obtained by the radiation detection unit 201, setting information on the operation of the radiation detection unit 201, and the like. When at least a part of the processing unit 204 is configured by a processor, the storage unit 205 may store a program that defines the processing of the radiation imaging apparatus 200. The processor reads the program from the storage unit 205 and executes the program to operate the radiation imaging apparatus 200. The storage unit 205 is composed of a memory such as a ROM or a RAM.

  The communication unit 206 is used for communication with the control device 400. The communication unit 206 is composed of communication hardware such as a network adapter. The internal clock 207 is used to acquire the current time.

  The control device 400 includes a processing unit 401, a storage unit 402, a communication unit 403, and a power supply unit 404. The processing unit 401 performs various processes regarding the control device 400. For example, the processing unit 401 controls the image acquisition timing and conditions of the radiation imaging apparatus 200, controls the irradiation timing and conditions of the radiation of the radiation generation apparatus 300, acquires radiation image data from the radiation imaging apparatus 200, and displays and captures it. Accept orders and register shooting information. The controller 400 may have application software for obtaining input from an operator through the input device 406, processing the input, and presenting the output to the operator through the display device 405. Hereinafter, such application software is referred to as a radiographic application. The radiation imaging application is stored as a program in the storage unit 402 and is executed by the processing unit 401.

  The processing unit 401 may be configured by a processor such as a microprocessor, a dedicated circuit such as an ASIC, or a combination thereof. The storage unit 402 stores various data regarding the control device 400. For example, the storage unit 402 stores image data received from the radiation imaging apparatus 200, setting information for controlling the radiation imaging apparatus 200 and the radiation generation apparatus 300, and the like. When at least a part of the processing unit 401 is configured by a processor, the storage unit 402 may store a program that defines the processing of the control device 400, and the processor reads the program from the storage unit 402 and executes the program. As a result, the processing of the control device 400 is performed. The storage unit 402 is composed of a memory such as a ROM or a RAM.

  The communication unit 403 is used for communication with the radiation imaging apparatus 200 and the radiation generation apparatus 300 and connection with the in-hospital network 500. The communication unit 403 is composed of communication hardware such as a network adapter. The communication unit 403 may be composed of separate communication hardware for each communication destination. The power supply unit 404 supplies electric power to each component of the control device 400.

  Next, with reference to FIG. 2, a configuration example of the radiation detection unit 201 will be described. The radiation detection unit 201 includes a sensor unit 210, a drive circuit 220, and a read circuit 230. The sensor unit 210 is composed of a plurality of pixels 211 arranged in a two-dimensional array so as to form a plurality of rows and a plurality of columns. Each pixel 211 includes a conversion element 212 and a switch element 213. The conversion element 212 converts incident radiation into electric charges and accumulates the electric charges. The conversion element 212 may include a scintillator that converts radiation into visible light and a photoelectric conversion element that converts visible light into electric charge. Alternatively, the conversion element 212 may directly convert the radiation into charges. The switch element 213 transfers the electric charge accumulated in the conversion element 212 to the signal line 214. The switch element 213 is composed of a transistor such as a TFT. The switch element 213 has a control terminal, and is turned on, that is, brought into a conductive state when an on-voltage is supplied to the control terminal, and turned off when the off-voltage is supplied to the control terminal, that is, non-conductive. It becomes a state.

  A bias voltage is supplied from the power supply unit 203 to one terminal of the conversion element 212 through the bias line 216. The other terminal of the conversion element 212 is connected to the signal line 214 via the switch element 213. The control terminal of the switch element 213 is connected to the drive line 215. In the sensor unit 210, a plurality of drive lines 215 each extending in the row direction (horizontal direction in FIG. 2) are arranged side by side in the column direction (vertical direction in FIG. 2). The control terminals of the switch elements 213 of the pixels 211 included in the same row are commonly connected to each drive line 215. Further, in the sensor unit 210, a plurality of signal lines 214 each extending in the column direction are arranged side by side in the row direction. One main terminal of the switch element 213 of the pixels 211 included in the same column is commonly connected to each signal line 214.

  The drive circuit 220 drives the sensor unit 210 according to the control signal supplied from the control unit 202. Specifically, the drive circuit 220 supplies a drive signal to the control terminal of each switch element 213 through the drive line 215. The drive circuit 220 turns on the switch element 213 by turning on the drive signal and turns off the switch element 213 by turning off the drive signal. When the switch element 213 is turned on, the charges accumulated in the conversion element 212 are transferred to the signal line 214.

  The reading circuit 230 reads the electric charge from the sensor unit 210 according to the control signal supplied from the control unit 202, generates a signal corresponding to the electric charge, and supplies the signal to the control unit 202. The read circuit 230 includes a sample hold circuit 231, a multiplexer 232, an amplifier 233, and an A/D converter 234. The sample hold circuit 231 holds the charges read from the conversion element 212 in pixel row units. The multiplexer 232 sequentially extracts the pixels for one row held by the sample hold circuit 231, and supplies the pixels to the amplifier 233. The amplifier 233 amplifies the supplied charge and supplies the amplified charge to the A/D converter 234. The A/D converter 234 converts the supplied analog signal into a digital signal and supplies the digital signal to the control unit 202.

  Subsequently, a plurality of operations performed by the control unit 202 of the radiation imaging apparatus 200 will be described. Such a plurality of operations include a plurality of driving operations, an image processing operation, and a situation estimation operation. The drive operation is an operation in which the control unit 202 drives the radiation detection unit 201. The control unit 202 controls the sensor unit 210 and the read circuit 230 so as to perform any of the plurality of driving operations. The control of the sensor unit 210 is performed through the control of the drive circuit 220. The plurality of driving operations include an imaging operation, an offset acquisition operation, an imaging standby operation, and a standby operation.

  The imaging operation is an operation of acquiring a radiation image corresponding to the radiation that has entered the conversion element 212. As an imaging operation, the control unit 202 performs the following processing. First, the control unit 202 controls the drive circuit 220 so as to supply the off voltage to all the drive lines 215 while the radiation imaging apparatus 200 is being irradiated with radiation. As a result, charges corresponding to the radiation are accumulated in each conversion element 212 of the sensor unit 210. The length of the period in which the off voltage is supplied to all the drive lines 215 is called the accumulation time. Subsequently, the control unit 202 controls the drive circuit 220 so as to temporarily switch the drive signals supplied to the plurality of drive lines 215 to the on-voltage in order. As a result, a digital signal representing the amount of charge accumulated in each conversion element 212 is supplied from the read circuit 230 to the control unit 202. The control unit 202 stores the digital signal in the storage unit 205 as radiation image data. One radiographic image is obtained by one imaging operation. The control unit 202 may generate moving image data by repeating the imaging operation.

  The offset acquisition operation is an operation of acquiring an offset image for correcting a radiation image. The control unit 202 can acquire the offset image by performing the same operation as the imaging operation in a state where the radiation imaging apparatus 200 is not irradiated with radiation. The offset image does not include radiation information but includes dark charge information generated in the conversion element 212 during the accumulation time. The control unit 202 stores the digital signal read by the offset acquisition operation in the storage unit 205 as offset image data. The control unit 202 may acquire a plurality of offset images and store one offset image obtained by averaging the offset images in the storage unit 205 as offset image data. The time required for the offset acquisition operation depends on how many offset images the offset image data is generated from, or if multiple shooting modes with different conditions such as frame rate can be set, how many types of offset image data are updated Depends on what you do. For example, in the 3 fps shooting mode, 10 seconds or more is required when 32 offset images are acquired and offset image data is generated. When updating the offset image data for each of the plurality of shooting modes, for example, an update time of about 1 minute is required.

  The image pickup standby operation is an operation of standing by for switching to the above-described image pickup operation by repeating ON/OFF switching of the switch element 213. Dark charges accumulate in the conversion element 212 as time passes. Therefore, as the imaging standby operation, the control unit 202 controls the drive circuit 220 so as to temporarily switch the drive signals supplied to the plurality of drive lines 215 to the ON voltage in order. As a result, the dark charge accumulated in the conversion element 212 is discarded. Since the discarded dark charges are not used for generating an image, the control unit 202 does not have to store the signal supplied from the read circuit 230 in the storage unit 205. In order to maintain the internal temperature of the radiation imaging apparatus 200, the control unit 202 supplies electric power to the reading circuit 230 even during the imaging standby operation. By repeating the imaging standby operation, the state in which the imaging operation can be immediately switched to is maintained.

  The standby operation is an operation of supplying electric power to the reading circuit 230 and driving the sensor unit 210 so as to suppress deterioration of the switch element 213 more than in the imaging standby operation described above. For example, the control unit 202 controls the drive circuit 220 so that the variation amount of the voltage of the drive signal supplied to the drive line 215 is smaller than the difference between the ON voltage and the OFF voltage. This fluctuation amount may be zero. That is, the drive signal supplied to the drive line 215 may have a constant voltage value. Instead of this, the control unit 202 controls the drive circuit 220 so that the difference between the length of the period in which the on-voltage is supplied as the drive signal and the length of the period in which the off-voltage is supplied is smaller than that in the imaging standby operation. In order to maintain the internal temperature of the radiation imaging apparatus 200, the control unit 202 supplies electric power to the reading circuit 230 even during the standby operation.

  The image processing operation is an operation of processing the radiation image obtained from the radiation detection unit 201. For example, the control unit 202 removes the offset component included in the radiation image by subtracting the offset image data from the radiation image data. The control unit 202 may further perform correction processing such as correction of defective pixels and gain correction for correcting gain variations of amplifiers in the radiation detection unit. In the present embodiment, the case where the control unit 202 of the radiation imaging apparatus 200 performs the image processing operation will be described, but instead of this, the control apparatus 400 may perform the image processing operation. In this case, the control unit 202 transmits both the radiation image data and the offset image data to the control device 400.

  The situation estimation operation is an operation of estimating the usage situation of the radiation imaging system 100 by the operator. In the present embodiment, the radiation imaging system 100 will be described as a case where three types of use statuses of “non-use”, “temporary interruption”, and “in use” can be taken. Instead of this, the radiation imaging system 100 may not have to take part of the situations of these three types, or may have other situations of use. The “non-use” is a situation where the operator is not using the radiation imaging system 100. For example, in the radiation imaging system 100, this situation occurs when the inspection device is off, such as at night, or when the control device 400 is powered off. “Temporarily suspended” refers to a situation in which the operator temporarily suspends the use of the radiation imaging system 100. For example, in the radiation imaging system 100, this situation occurs when the control device 400 is powered on, but the operator is temporarily away from the control device 400 between inspections. “In use” refers to a situation where the operator is using the radiation imaging system 100. For example, the radiation imaging system 100 is in this state during an examination or preparation for examination by the operator using the radiation imaging system 100. A method of estimating the usage status of the radiation imaging system 100 by the control unit 202 will be described later.

  Subsequently, the operation of the radiation imaging apparatus 200 will be described. The radiation imaging apparatus 200 sets the frequency of executing the offset acquisition operation according to the usage status of the radiation imaging system 100 described above. Then, during execution of the standby operation or the imaging standby operation, the control unit 202 temporarily interrupts the execution of the standby operation or the imaging standby operation and executes the offset acquisition operation at a frequency according to the estimated usage condition. Specifically, when the usage status is “not in use”, the control unit 202 suppresses deterioration of the switch element 213 by reducing the frequency of execution of the offset acquisition operation. The control unit 202 may set the execution frequency to zero when reducing the execution frequency of the offset acquisition operation. In this case, the control unit 202 does not execute the offset acquisition operation. In addition, when the usage status is “temporarily suspended” and “in use”, the control unit 202 increases the execution frequency of the offset acquisition operation, so that the offset value is corrected even when the emergency shooting instruction is received. Avoid getting images.

  The operation of the radiation imaging apparatus 200 will be described below with reference to the flowchart of FIG. The control part 202 estimates the use condition of the radiation imaging system 100 in step S001. The control unit 202 sets the execution frequency of the offset acquisition operation to low in step S002 when the usage status is “not used”, and sets the offset acquisition operation in step S003 when the usage status is “temporarily suspended”. Set the execution frequency to high.

  In step S004, the control unit 202 determines whether it is time to execute the offset acquisition operation. When it is time to execute the offset acquisition operation (“Yes” in step S004), the control unit 202 repeats the imaging standby operation for a predetermined time (for example, 2 to 3 seconds) in step S005, and then in step S006. Execute the offset acquisition operation. The reason why the image pickup standby operation is repeated in step S005 is to discard the dark charge accumulated in the conversion element 212 and stabilize the potential of the sensor unit 210. When it is not the time to execute the offset acquisition operation (“No” in step S004), the control unit 202 executes the standby operation in step S007. The control unit 202 also executes the standby operation in step S007 even after executing the offset acquisition operation in step S006.

  The control unit 202 determines in step S008 whether the process should be terminated. When the processing should be ended (“Yes” in step S008), the control unit 202 ends the processing. When the processing should not be ended (“No” in step S008), the control unit 202 returns the processing to step S001. Therefore, when the usage status of the radiation imaging system 100 is “not in use” or “temporarily suspended”, the control unit 202 continues to execute the standby operation. As a result, the internal temperature of the radiation imaging apparatus 200 is maintained while suppressing the deterioration of the switch element 213.

When the usage status estimated in step S001 is "in use", the control unit 202 acquires the elapsed time T from the last execution of the imaging operation in step S009. In step S010, the control unit 202 determines whether the elapsed time T is within the threshold time. If the threshold time is Tth1, the control unit 202 determines whether T<Tth1 is satisfied. Control unit 202, if the elapsed time is judged to be within the threshold time, when setting the execution frequency offset acquisition operation in the low, the elapsed time is determined to be not within the threshold time at Step S01 2, setting the execution frequency offset acquisition operation to high at step S01 1.

  Immediately after the image capturing operation is performed, there is a possibility that the charge may remain as an afterimage component for a certain period of time so that the charges generated during the previous image capturing may be burned in. If an offset image is acquired in this state, an afterimage component may be superimposed on the offset image itself, which may cause deterioration in image quality. Therefore, the control unit 202 suppresses the acquisition of an inappropriate offset image by reducing the execution frequency of the offset acquisition operation when the elapsed time T is within the threshold time.

  The control unit 202 executes an imaging standby operation in step S013. In this way, the control unit 202 allows the radiation imaging system 100 to immediately shift to the imaging operation by executing the imaging standby operation when the radiation imaging system 100 is “in use”.

  In step S014, the control unit 202 determines whether it is time to execute the offset acquisition operation. When it is time to execute the offset acquisition operation (“Yes” in step S014), the control unit 202 executes the offset acquisition operation in step S015. Since the control unit 202 has already performed the imaging standby operation in step S013, it is not necessary to perform the imaging standby operation again before step S015. When it is not the time to execute the offset acquisition operation (“No” in step S014), the control unit 202 advances the process to step S008.

  In the above-described embodiment, the control unit 202 sets the execution frequency of the offset acquisition operation to two levels. Instead of this, the control unit 202 may set the execution frequency of the offset acquisition operation to three or more stages. For example, the execution frequency set in step S012 may be lower than the execution frequency set in step S002. The execution frequency set in step S003 may be lower than the execution frequency set in step S011.

  Next, the operation when the radiation imaging apparatus 200 receives an imaging request from the control device 400 will be described along the flowchart of FIG. The imaging request is transmitted from the control device 400 to the radiation imaging apparatus 200 when the operator presses a switch that forms a part of the input device 406, for example. In step S101, the control unit 202 estimates the usage status of the radiation imaging system 100. When the usage status is "in use", the control unit 202 is executing the imaging standby operation as described with reference to FIG. Therefore, the control unit 202 immediately executes the imaging operation in step S102.

  When the usage status is “not in use”, the control unit 202 executes the offset acquisition operation at a low frequency as described with reference to FIG. Therefore, the offset image data stored in the storage unit 205 may be old and may not be suitable for offset correction. In that case, the control unit 202 executes the offset acquisition operation in step S107 after repeating the imaging standby operation in step S106 for a predetermined time (for example, 2 to 3 seconds). The reason for repeating the imaging standby operation in step S106 is as described above.

  When the usage status is “temporarily suspended”, as described with reference to FIG. 3, the control unit 202 frequently executes the offset acquisition operation. Therefore, in step S108, the control unit 202 stabilizes the sensor unit 210 by repeating the imaging standby operation for a predetermined time (for example, 2 to 3 seconds).

  After acquiring the radiation image in step S102, the control unit 202 corrects the radiation image data using the offset image data stored in the storage unit 205 in step S103. After that, the control unit 202 transfers the corrected image data to the control device 400 in step S104. The control unit 202 determines in step S105 whether or not the notification that the photographing request is turned off is received. For example, when the operator releases the switch, this notification is transmitted from the control device 400 to the radiation imaging device 200. If not notified (“No” in step S105), the control unit 202 returns the process to step S102, and acquires the radiation image of the next frame. When notified (“Yes” in step S105), the control unit 202 ends the process.

  Next, with reference to FIG. 5 to FIG. 7, step S001 of FIG. 3, that is, a specific example of the usage status estimation process will be described. In the example of FIGS. 5 and 6, the control unit 202 estimates the usage status of the radiation imaging system 100 based on the information from the control device 400.

  In the determination process of FIG. 5, the control device 400 periodically transmits a synchronization signal that determines the image acquisition timing to the radiation imaging device 200. The transmission cycle of the synchronization signal may be settable by setting an imaging condition using the radiation imaging application of the control device 400. For example, when the operator sets the moving image shooting condition of 15 fps, the synchronization signal is transmitted at a cycle of 15 Hz. This synchronization signal may be notified by, for example, a dedicated signal line, and is always periodically transmitted to the radiation imaging apparatus 200 while the control device 400 is powered on. The radiation imaging apparatus 200 executes an imaging operation according to this synchronization signal. Further, the control device 400 starts use by command communication with the radiation imaging device 200 when the operator performs an operation for preparing to start an examination by selecting an imaging technique after receiving the imaging order on the radiation imaging application. Notify the command. Further, the control device 400 notifies the radiation imaging device 200 of a use stop instruction command when the imaging of a series of inspection orders is completed. The control unit 202 of the radiation imaging apparatus 200 determines the usage status of the radiation imaging system 100 by the operator using the reception state of the synchronization signal and the notification of the use start instruction/stop instruction command.

  The control unit 202 determines whether a synchronization signal is received from the control device 400 in step S201. When the synchronization signal is not received (“No” in step S201), the control unit 202 estimates that the usage status of the radiation imaging system 100 is “non-use” in step S202. When the synchronization signal is input (“Yes” in step S202), the control unit 202 determines in step S203 whether the use start instruction command has been received. When the usage start instruction command has not been received (“No” in step S203), the control unit 202 estimates that the usage status of the radiation imaging system 100 is “temporarily suspended” in step S204. When the usage start instruction command has been received (“Yes” in step S203), the control unit 202 estimates that the usage status of the radiation imaging system 100 is “in use” in step S205.

  In the above example, the control device 400 communicates the use start instruction and the stop instruction as commands, but instead of this, a dedicated signal line may be used for notification. In addition, the control device 400 may notify the use stop instruction when the input device 406 has not been used for a predetermined time, and then notify the use start instruction when the input device 406 has been used. Further, the radiation imaging system 100 may include a sensor 407 (FIG. 2) for detecting the presence of a person (for example, a subject or an operator) near the radiation imaging system 100, for example, a camera or an infrared sensor. . The control unit 202 may estimate the usage status of the radiation imaging system 100 based on the detection result of the sensor 407. For example, when the control device 400 uses the sensor 407 to determine that a person exists near the radiation imaging system 100, the control device 400 notifies the radiation imaging device 200 of a use start instruction, and determines that there is no person in the vicinity. The radiation imaging apparatus 200 may be notified of the use stop instruction.

  In the determination process of FIG. 6, the control unit 202 estimates the usage status of the radiation imaging system 100 using only the command without using the above synchronization signal. In the example of FIG. 6, the control unit 202 determines the connection state between the control device 400 and the radiation imaging apparatus 200 depending on whether a command has been received from the radiation imaging application of the control device 400. The command used to determine the connection state may be a dedicated command, a command for setting imaging conditions, a command for acquiring the apparatus state, or the like, and may be transmitted from the radiation imaging apparatus 200. It may be a transmission response command (ACK command). The control unit 202 estimates the usage status of the radiation imaging system 100 based on the connection state between the control device 400 and the radiation imaging device 200. Also in the example of FIG. 6, the use start instruction command/use stop instruction command is the same as in the example of FIG.

  In step S301, the control unit 202 acquires the elapsed time Tcom since the command was last received. In step S302, the control unit 202 determines whether the elapsed time Tcom is equal to or longer than the threshold time. When the threshold time is Tthcom, the control unit 202 determines whether Tcom<Tthcom is satisfied. When it is determined that the elapsed time is equal to or longer than the threshold time (“Yes” in step S302), the control unit 202 determines that the radiation imaging application has not been started, and in step S303, the radiation imaging system 100 is used. Assume the situation is "not in use". When it is determined that the elapsed time is not equal to or longer than the threshold time (“No” in step S202), the control unit 202 advances the process to step S304. Since steps S304 to S306 are the same as steps S203 to S205, the description thereof will be omitted.

  In the example of FIG. 7, the control unit 202 estimates the usage status of the radiation imaging system 100 based on the elapsed time since the imaging operation was last executed and the current time. In step S401, the control unit 202 acquires the elapsed time T since the image pickup operation was last executed. In step S402, the control unit 202 determines whether the elapsed time T is within the threshold time. When the threshold time is Tth2, the control unit 202 determines whether T<Tth2 is satisfied. When it is determined that the elapsed time is within the threshold time, the control unit 202 estimates that the usage status of the radiation imaging system 100 is “in use” in step S403, and determines that the elapsed time is not within the threshold time. If so, the process proceeds to step S404.

  The control unit 202 acquires the current time using the internal clock 207 in step S404. In step S405, the control unit 202 determines whether the current time is included in the scheduled use time zone. The scheduled use time zone is set by the operator using, for example, a radiation imaging application, is notified from the control device 400 to the radiation imaging device 200 using a communication command, and is stored in the storage unit 205. When the current time is included in the scheduled use time zone (“Yes” in step S405), the control unit 202 estimates that the usage status of the radiation imaging system 100 is “temporarily suspended” in step S406. When the current time is not included in the scheduled use time zone (“No” in step S405), the control unit 202 estimates that the usage status of the radiation imaging system 100 is “non-use” in step S407. In the example of FIG. 7, the usage status can be estimated only by the radiation imaging apparatus 200, not by the control apparatus 400.

  In some embodiments, the control unit 202 may monitor the cumulative execution time of the imaging standby operation and notify the operator via the control device 400 that the cumulative execution time exceeds the threshold time. From this notification, the operator can understand the progress of deterioration of the switch element 213. Further, the control unit 202 may automatically reduce the value of the threshold time Tth2 used in step S402 in FIG. 7 when the cumulative execution time exceeds the threshold time. As a result, the time during which the radiation imaging system 100 is estimated to be “in use” is shortened, and the execution time of the imaging standby operation is also shortened.

  The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by the processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 radiation imaging system, 200 radiation imaging apparatus, 202 control section, 210 sensor section, 212 conversion element, 213 switch element, 230 readout circuit, 400 control apparatus

Claims (15)

A radiation imaging apparatus forming a part of a radiation imaging system,
A sensor unit having a conversion element for converting radiation into electric charge and a switch element for transferring the electric charge;
A readout circuit for reading out electric charges from the sensor unit,
A control unit that controls the sensor unit and the readout circuit to perform any one of a plurality of driving operations,
The plurality of driving operations are
An imaging operation for acquiring a radiation image according to the radiation incident on the conversion element,
An offset acquisition operation for acquiring an offset image for correcting the radiation image,
An imaging standby operation for waiting for switching to the imaging operation by repeating on/off switching of the switch element,
While supplying power to the readout circuit, a standby operation of driving the sensor unit so as to suppress deterioration of the switch element more than the imaging standby operation,
The radiation imaging apparatus, wherein the control unit temporarily suspends execution of the standby operation and executes the offset acquisition operation at a frequency according to a usage status of the radiation imaging system by an operator.   The execution frequency of the offset acquisition operation when the operator is not using the radiation imaging system is the execution frequency of the offset acquisition operation when the operator temporarily suspends use of the radiation imaging system. The radiation imaging apparatus according to claim 1, wherein the radiation imaging apparatus has a frequency lower than the frequency.   The radiation imaging apparatus according to claim 2, wherein the control unit does not execute the offset acquisition operation when the operator is not using the radiation imaging system. The control unit estimates the usage status of the radiation imaging system by the operator,
The radiation imaging apparatus according to any one of claims 1 to 3, wherein the frequency is a frequency according to the estimated use situation. The radiation imaging system includes a control device for the operator to control the radiation imaging device,
The radiation imaging apparatus according to claim 4, wherein the control unit estimates the usage status of the radiation imaging system based on information from the control apparatus. The control device periodically transmits a synchronization signal to the radiation imaging device,
The radiation imaging apparatus according to claim 5, wherein the control unit estimates the usage status of the radiation imaging system based on whether the synchronization signal is received.   7. The radiation imaging apparatus according to claim 5, wherein the control unit estimates the usage status of the radiation imaging system based on a connection state between the radiation imaging apparatus and the control apparatus. The control unit is
Obtaining the elapsed time since the image pickup operation was last executed,
The radiation imaging apparatus according to claim 4, wherein the usage status of the radiation imaging system is estimated based on the elapsed time. The radiation imaging system includes a sensor for detecting the presence of a person in the vicinity,
The radiation imaging apparatus according to claim 4, wherein the control unit estimates the usage status of the radiation imaging system based on a detection result of the sensor.   The radiation imaging apparatus according to claim 4, wherein the control unit estimates the usage status of the radiation imaging system based on the current time. The control unit determines whether the elapsed time from the last execution of the imaging operation is within a threshold time,
When the operator is using the radiation imaging system, the execution frequency of the offset acquisition operation when the elapsed time is determined to be within the threshold time is determined to be not the elapsed time within the threshold time. The radiation imaging apparatus according to any one of claims 1 to 10, wherein the frequency is lower than a frequency of performing the offset acquisition operation in the case of being performed.   The radiation imaging apparatus according to any one of claims 1 to 11, wherein the control unit notifies the operator that the cumulative execution time of the imaging standby operation has exceeded a threshold time. A radiation imaging system comprising a radiation imaging device,
The radiation imaging apparatus,
A sensor unit having a conversion element for converting radiation into electric charge and a switch element for transferring the electric charge;
A readout circuit for reading out charges from the sensor section,
A control unit that controls the sensor unit and the readout circuit to perform any one of a plurality of driving operations,
The plurality of driving operations are
An imaging operation for acquiring a radiation image according to the radiation incident on the conversion element,
An offset acquisition operation for acquiring an offset image for correcting the radiation image,
An imaging standby operation for waiting for switching to the imaging operation by repeating on/off switching of the switch element,
While supplying power to the readout circuit, a standby operation of driving the sensor unit so as to suppress deterioration of the switch element more than the imaging standby operation, including:
The radiation imaging system, wherein the control unit temporarily suspends the execution of the standby operation and executes the offset acquisition operation at a frequency according to a usage status of the radiation imaging system by an operator. A method for controlling a radiation imaging apparatus forming part of a radiation imaging system, comprising:
The radiation imaging apparatus,
A sensor unit having a conversion element for converting radiation into electric charge and a switch element for transferring the electric charge;
A readout circuit for reading out electric charges from the sensor section,
The control method is
A step of controlling the sensor unit and the readout circuit to perform any of a plurality of driving operations, wherein the plurality of driving operations include:
An imaging operation for acquiring a radiation image according to the radiation incident on the conversion element,
An offset acquisition operation for acquiring an offset image for correcting the radiation image,
An imaging standby operation for waiting for switching to the imaging operation by repeating on/off switching of the switch element,
While supplying power to the readout circuit, a standby operation of driving the sensor unit so as to suppress deterioration of the switch element rather than the imaging standby operation,
And a step of temporarily interrupting the execution of the standby operation and executing the offset acquisition operation at a frequency according to the usage status of the radiation imaging system by the operator.   A program for causing a computer to execute each step of the control method according to claim 14.

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