Radiation imaging system

Abstract

To synchronize radiation exposure control and image generation based on radiation.SOLUTION: An irradiation control device is a radiation imaging system having an irradiation control device that controls irradiation of radiation, and a radiation imaging device that is communicatively connected to the irradiation control device and generates an image based on radiation. The irradiation control device has a first communication unit that transmits irradiation start consent information to the radiation imaging device when a difference between a reception time of irradiation permission information received from the radiation imaging device after transmitting imaging request information to the radiation imaging device and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold. The irradiation imaging device has a second communication unit that retransmits the same irradiation permission information as the irradiation permission information to the irradiation control device when the irradiation start consent information is not received from the irradiation control device within a standby time after transmitting the irradiation permission information.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a radiation imaging system, an irradiation control device, a radiation imaging apparatus, a control method for a radiation imaging system, a control method for an irradiation control device, a control method for a radiation imaging apparatus, and a program. [Background technology]

[0002] Conventionally, radiographic imaging devices and radiographic imaging systems have been commercially available that irradiate a subject with radiation from a radiation generating device, digitize the intensity distribution of the radiation that has passed through the subject, and perform image processing on the digitized radiographic image to obtain a clear radiographic image.

[0003] Such a radiography device generally uses a two-dimensional solid-state imaging element as an image receptor (radiation detector). A solid-state imaging element generally operates by repeatedly storing charges in response to incident light, reading out the stored charges, and resetting. In a solid-state imaging element that does not have an electronic shutter, if light is incident on the solid-state imaging element during charge reading or resetting, the quality of the image obtained may be impaired, and particularly in a radiography device for medical use, this may cause the subject to suffer unnecessary exposure to radiation.

[0004] Therefore, the radiation imaging system operates while synchronizing the operation timing of the solid-state image pickup element on the image receptor (radiation detector) side with the radiation irradiation timing on the radiation generation device side.

[0005] Patent Documents 1 and 2 disclose a radiation source control device having a first clock means and a radiation imaging device having a second clock means synchronized with the first clock means, and the respective times are synchronized, and the radiation imaging device outputs a signal to the radiation source control device during radiation irradiation. If the radiation source control device cannot detect the signal, it stops the radiation irradiation signal. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6971611 [Patent Document 2] Patent No. 7071095 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in Patent Document 1, time synchronization is performed over a network line, and therefore message delays on the network line cause errors from true correction values ​​due to variations in the measurement values ​​of time synchronization, which causes misalignment between the charge accumulation period of the detector and the radiation irradiation period. This may result in ineffective radiation.

[0008] In addition, in Patent Document 2, time synchronization is also performed over a network line, and exposure timing is controlled taking communication delays into consideration, but no consideration is given to two-way communication delays between devices. Also, if communication delays occur intermittently, there is a possibility that exposure cannot be performed indefinitely.

[0009] An object of the present disclosure is to make it possible to synchronize radiation irradiation control and radiation-based image generation even when communication conditions are unstable. [Means for solving the problem]

[0010] The radiation imaging system includes an irradiation control device that controls irradiation of radiation, and a radiation imaging device that is communicatively connected to the irradiation control device and generates an image based on radiation, wherein the irradiation control device has a first communication unit that transmits irradiation start consent information to the radiation imaging device when a difference between a reception time of irradiation permission information received from the radiation imaging device after transmitting imaging request information to the radiation imaging device and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold, and the radiation imaging device has a second communication unit that transmits the same irradiation permission information as the irradiation permission information again to the irradiation control device when the irradiation start consent information is not received from the irradiation control device within a standby time after transmitting the irradiation permission information. Effect of the Invention

[0011] According to the present disclosure, even if the communication conditions are unstable, radiation irradiation control and radiation-based image generation can be synchronized. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a radiation imaging system. [Diagram 2] 4 is a timing chart showing synchronization of time information between devices. [Diagram 3] FIG. 11 is a diagram illustrating an example of a message communication procedure. [Figure 4] 4 is a flowchart showing a control method for the radiation imaging system. [Diagram 5] FIG. 11 is a diagram illustrating an example of a message communication procedure. [Figure 6] 4 is a flowchart showing a control method for the radiation imaging system. [Figure 7] FIG. 11 is a diagram illustrating an example of a message communication procedure. [Figure 8] 4 is a flowchart showing a control method for the radiation imaging system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Preferred embodiments will be described in detail below with reference to the drawings. However, the dimensions and details of the structure shown in each embodiment are not limited to those shown in the specification and drawings. Note that radiation includes X-rays, α-rays, β-rays, γ-rays, and various particle beams.

[0014] (First embodiment) 1 is a diagram showing an example of the configuration of a radiation imaging system 100 according to the first embodiment. The radiation imaging system 100 includes a radiation imaging apparatus (detection control apparatus) 101, a radiation generating apparatus (irradiation unit) 110, and an irradiation control apparatus 120 that controls the radiation generating apparatus 110. The radiation imaging system 100 further includes a radiation source 109, a wireless LAN access point (AP) 113, a wired communication hub (HUB) 114, and an exposure button 115.

[0015] The radiation imaging apparatus 101 includes a wired communication unit 104. The irradiation control device 120 includes a wired communication unit 121. The radiation imaging apparatus 101 and the irradiation control device 120 are connected to each other by the wired communication units 104 and 121 via a communication network.

[0016] The radiation imaging apparatus 101 may include a wireless communication unit 103. In this case, a wireless LAN access point (AP) 113 is included as part of the communication network infrastructure, and some sections of the communication network are connected by wireless communication using the wireless communication unit 103 and the wireless LAN access point (AP) 113. The wireless communication method is not limited to this.

[0017] The wired communication unit 121 communicates with the wired communication unit 104 via a wired communication hub (HUB) 114. The wired communication unit 121 is an example of a first communication unit. The wired communication unit 121 also communicates with the wireless communication unit 103 via the wired communication hub 114 and a wireless LAN access point (AP) 113. The wired communication unit 104 and the wireless communication unit 103 are an example of a second communication unit, and are connected to the shooting control unit 102.

[0018] Information is exchanged in the form of messages between the radiation imaging apparatus 101 and the irradiation control device 120, which are connected via a communication network.

[0019] In contrast, the radiation generating device 110 and the irradiation control device 120 are electrically connected directly without going through a communication network. Therefore, information between the radiation generating device 110 and the irradiation control device 120 is directly transmitted as an electrical signal without being converted into a message format.

[0020] The radiation imaging apparatus 101 is communicatively connected to an irradiation control device 120, and is an apparatus that generates radiation image data of a subject 112 based on radiation 111 that is emitted from a radiation source 109 and transmitted through the subject 112. For example, a radiation imaging apparatus using a flat panel detector (FPD) is preferably used as the radiation imaging apparatus 101.

[0021] The radiation imaging apparatus 101 has at least an image receptor (detection unit) 107 that generates radiation image data according to incident radiation, and an imaging control unit 102. The imaging control unit 102 controls the image receptor 107 that detects radiation. The imaging control unit 102 performs processes related to drive control of the image receptor 107, various image processing of captured radiation image data, storage of the radiation image data, determination of transfer timing of the radiation image data, transfer control of the radiation image data, etc. The radiation image data processed by the imaging control unit 102 is transferred to a control terminal (not shown) and used for examinations, etc.

[0022] The radiation imaging system 100 is capable of capturing moving images of radiation images, and the outline of its operation is as follows: First, prior to imaging, parameters for capturing moving images (e.g., frame rate and length of radiation pulse per frame) are set in advance in each component of the radiation imaging system 100.

[0023] An operator of the radiation imaging system 100 presses the exposure button 115 at the timing when he or she wishes to perform imaging. When the exposure button 115 is pressed, the radiation generation device 110 transmits the occurrence of the pressing of the exposure button 115 to the irradiation control device 120 as an electrical signal. Upon receiving this electrical signal, the irradiation control device 120 generates a message to the effect that imaging will start, and exchanges the message with the radiation imaging device 101 via the communication network. Note that the contents of the message exchange will be described later, and will not be described in detail here.

[0024] The irradiation control device 120 has a timing control unit 122 and an irradiation pulse generating unit 123, and controls irradiation of radiation. After the above message exchange, the irradiation pulse generating unit 123 in the irradiation control device 120 generates a timing pulse for irradiation of radiation. The timing control unit 122 in the irradiation control device 120 is an example of a first control unit, and holds time information. The irradiation pulse generating unit 123 generates a timing pulse based on the time information of the timing control unit 122. This timing pulse is transmitted to the radiation generating device 110, and the radiation generating device 110 irradiates radiation 111 from the radiation source 109 in accordance with the timing pulse.

[0025] On the other hand, in the radiation imaging apparatus 101, the imaging control unit 102 is an example of a second control unit, and includes a drive control unit 105 and a timing control unit 106. After exchanging messages, the drive control unit 105 in the imaging control unit 102 generates a drive control signal for the image receptor 107, and acquires radiation image data from the image receptor 107. The timing control unit 106 in the radiation imaging apparatus 101 holds time information. The drive control unit 105 generates a drive control signal based on the time information of the timing control unit 106.

[0026] Moreover, the drive control unit 105 acquires radiation image data at a time that does not overlap with the timing pulse of radiation irradiation. In other words, the acquisition of radiation image data is performed in a time period different from the time period of radiation irradiation.

[0027] When the operator of the radiation imaging system 100 stops pressing the exposure button 115 to end imaging, the irradiation control device 120 stops generating timing pulses, generates a message to the effect that imaging is to be stopped, and exchanges messages with the radiation imaging apparatus 101. Note that the contents of the message exchange will be described later, and will not be described in detail here.

[0028] 2 is a diagram showing a procedure by which the timing control unit 106 and the timing control unit 122 establish time synchronization through communication over a communication network. The mechanism and communication procedure for synchronizing the times of the timing control unit 106 and the timing control unit 122 will be described below.

[0029] In FIG. 2, the timing control unit 122 operates as a time server (ie, a reference clock), and the timing control unit 106 operates as a time client (ie, a clock that is corrected based on the time server).

[0030] First, in the radiation imaging apparatus 101, the imaging control unit 102 transmits a time request message 207 to the irradiation control device 120 via the wired communication unit 104 or the wireless communication unit 103, requesting the irradiation control device 120 to transmit the time (time information) of the timing control unit 122. At this time, the transmission time of the time request message 207 in the radiation imaging apparatus 101 (the time of the timing control unit 106) is included in the time request message 207. In the example of Fig. 2, a time value 10254 is recorded in the time request message 207. The time request message 207 is an example of time request information.

[0031] Upon receiving the time request message 207, the irradiation control device 120 returns a time message 208 to the radiation imaging device 101. At this time, the transmission time of the time message 208 in the irradiation control device 120 (the time of the timing control unit 122) is included in the time message 208. In Fig. 2, a time value 10254 is included in the time message 208. The time message 208 is response information to the time request message 207.

[0032] When the time message 208 arrives at the radiation imaging apparatus 101, the radiation imaging apparatus 101 acquires the reception time of the time message 208 as the time of the timing control unit 106. In FIG.

[0033] It is assumed that the propagation times of the time request message 207 and the time message 208 between the radiation imaging apparatus 101 and the irradiation control device 120 are approximately equal. In this case, the time at which the irradiation control device 120 returns the time message 208 can be estimated to be midway between the time value 10254 and the time value 10260 in the time of the timing control unit 106 (i.e., (10254+10260) / 2=10257).

[0034] The time value of the irradiation control device 120 included in the time message 208 is 10254. Therefore, by calculating the time difference from the estimated time, it is found that the time of the radiation imaging apparatus 101 is ahead by 10257-10254=3.

[0035] As a result, the time difference between the timing control unit 106 and the timing control unit 122 is calculated, and by correcting the time of the timing control unit 106, the times of the timing control unit 106 and the timing control unit 122 can be synchronized.

[0036] 2, the time synchronization correction value is determined based on a single inquiry of the time request message 207, but in reality, since fluctuations can occur in the propagation time in network communications, the correction value based on a single inquiry can deviate from the true amount. Therefore, multiple inquiries are executed to statistically calculate the correction value.

[0037] One example of calculating a correction value is to collect a certain number of time differences or correction values ​​from multiple query communications in order of shortest round trip time (communication time from sending a query to receiving a reply) and then take the average.

[0038] Furthermore, the radiation imaging apparatus 101 can measure a round-trip communication delay time between the irradiation control device 120 and the radiation imaging apparatus 101 by using this communication, and can calculate the communication delay time using the shortest value, average value, etc. based on the results of multiple measurements. The radiation imaging apparatus 101 has a means for storing the communication delay time.

[0039] Although the time message 208 has been described as including the transmission time of the time message 208, it may instead include the reception time of the time request message 207.

[0040] The radiographic imaging apparatus 101 includes an imaging control unit 102. The imaging control unit 102 is an example of a correction unit. The imaging control unit 102 corrects the current time of the timing control unit 106 based on information on the transmission time of the time request message 207 and information on the reception time of the time request message 207 or information on the transmission time of the time message 208 and information on the reception time of the time message 208. The current time of the timing control unit 106 is the current time of the radiographic imaging apparatus 101.

[0041] 2, an example in which the current time of the timing control unit 106 is corrected has been described, but the current time of the timing control unit 122 of the irradiation control device 120 may be corrected. In this case, the irradiation control device 120 transmits a time request message 207 to the radiation imaging apparatus 101 and receives a time message 208 from the radiation imaging apparatus 101. Upon receiving the time request message 207 from the irradiation control device 120, the radiation imaging apparatus 101 transmits the time message 208 to the irradiation control device 120. The irradiation control device 120 corrects the current time of the timing control unit 122 based on information on the transmission time of the time request message 207 and information on the reception time of the time request message 207 or information on the transmission time of the time message 208 and information on the reception time of the time message 208.

[0042] FIG. 3 is a diagram showing a communication procedure of messages for controlling the start and stop of shooting and occurrence of operation timing as shooting scheduling when the time synchronization is correctly performed according to the above-mentioned time synchronization.

[0043] The radiation imaging apparatus 101 and the irradiation control device 120 are provided with timing control units 106 and 122, respectively, and perform timing operations starting from the start-up of the radiation imaging system 100. As described above, the times of the radiation imaging apparatus 101 and the irradiation control device 120 are synchronized prior to imaging. In addition, the communication delay time between the radiation imaging apparatus 101 and the irradiation control device 120 is also calculated in advance as described above, and is stored as the communication delay time.

[0044] When the exposure button 115 is pressed, the irradiation control device 120 transmits to the radiation imaging apparatus 101 an imaging request message 300 requesting the start of imaging.

[0045] The image receptor 107 has a solid-state imaging element. The solid-state imaging element operates by repeatedly accumulating charge in response to radiation, reading out the accumulated charge, and resetting. The image receptor 107 performs a preparatory operation, accumulating charge, and reading out the charge. In the preparatory operation before radiation exposure, accumulation and resetting are repeated to reset the dark current before radiation exposure. Accumulation and resetting are repeated as a set. The data accumulated in the preparatory operation before radiation exposure is not used as image data. On the other hand, during radiation exposure, accumulation of charge in response to radiation and reading out of the accumulated charge are performed. The data accumulated during radiation exposure is used as image data.

[0046] When the radiation imaging apparatus 101 receives the imaging request message 300 from the irradiation control device 120, the radiation imaging apparatus 101 acquires the current time from the timing control unit 106 as the request reception time. The irradiation control device 120 calculates the time when a predetermined time has elapsed from the current time as the accumulation start notice time at which the charge accumulation of the image receptor 107 starts. Specifically, the radiation imaging apparatus 101 calculates the accumulation start scheduled time by adding a preset time to the current time. The added time is a time that is sufficient for the time for the radiation imaging apparatus 101 and the irradiation control device 120 to exchange messages and the time for the radiation imaging apparatus 101 to move to the imaging preparation operation for radiation detection. In addition, the added time is preferably a time that does not make the operator wait unnecessarily and deteriorate the operability. In addition, the added time may be calculated and set in advance when the radiation imaging system 100 is designed. The time to be added may be dynamically determined so as to use the above-mentioned communication delay time calculated by a prior negotiation through communication between the irradiation control device 120 and the radiation imaging apparatus 101 .

[0047] 3, a time value 150 is added to a current time (a time when the imaging request message 300 is received) 10150 to calculate a scheduled accumulation start time 10300. Since the scheduled accumulation start time is the scheduled exposure start time for the irradiation control device 120, it will be hereinafter referred to as the scheduled exposure start time.

[0048] When the scheduled exposure start time is calculated, the radiation imaging apparatus 101 transmits an irradiation permission message 301 to the irradiation control device 120. This irradiation permission message 301 includes the scheduled exposure start time as a parameter.

[0049] 3, the irradiation permission message 301 includes information corresponding to the radiation irradiation time length (such as the length of the radiation pulse and the irradiation window) and the irradiation cycle (such as the frame rate). However, it is not essential that this information is included in the irradiation permission message 301, and as described above, the information may be set or transmitted in advance by another means prior to imaging. In addition, other parameters not explicitly shown here may be included in the irradiation permission message 301 and transmitted.

[0050] Upon receiving the irradiation permission message 301, the irradiation control device 120 acquires the current time as the irradiation permission reception time from its own timing control unit 122. The irradiation control device 120 compares the current time with the scheduled exposure start time included in the irradiation permission message 301, and determines whether the irradiation preparation operation can be completed at the scheduled exposure start time.

[0051] If it is determined that the irradiation preparation operation can be completed at the scheduled exposure start time, the irradiation controller 120 transmits an irradiation start acknowledgement message 302 to acknowledge the start of irradiation to the radiation imaging apparatus 101 and executes the irradiation preparation operation.

[0052] When the radiation imaging apparatus 101 transmits the above-mentioned irradiation permission message 301 to the irradiation control device 120, the radiation imaging apparatus 101 waits to receive an irradiation start acknowledgement message 302 from the irradiation control device 120. Note that it is preferable that the waiting time for the irradiation start acknowledgement message 302 is not a fixed time but changes dynamically. As described above, it is preferable that the waiting time for the irradiation start acknowledgement message 302 is set to a communication delay time measured and calculated in the usage environment by a prior negotiation through communication between the irradiation control device 120 and the radiation imaging apparatus 101. It is also preferable that the waiting time for the irradiation start acknowledgement message 302 can be set to a different time depending on whether the communication is wired or wireless. As described above, the prior negotiation may measure a round-trip delay time in communication for time synchronization, or may be measured by a separate communication.

[0053] 3, the radiation imaging apparatus 101 completes receiving the irradiation start acknowledgement message 302 at time 10250, which is before the scheduled exposure start time 10300. Therefore, the irradiation control device 120 causes the irradiation pulse generating unit 123 to generate timing pulses for radiation irradiation from the scheduled exposure start time 10300 to 10350, as scheduled. Then, the radiation generating apparatus 110 causes the radiation source 109 to irradiate radiation 111 from the scheduled exposure start time 10300 to 10350.

[0054] In this way, when the radiation imaging apparatus 101 receives the imaging request message 300, it calculates the scheduled exposure start time and controls the image receptor 107 so that it is in a state where it can detect radiation at the scheduled exposure start time. Then, the radiation imaging apparatus 101 transmits an irradiation permission message 301 including the scheduled exposure start time to the irradiation control device 120.

[0055] When the irradiation control device 120 receives the irradiation permission message 301, it determines whether or not exposure is possible at the scheduled exposure start time based on the time of reception, and transmits an irradiation start acknowledgement message 302 to the radiation imaging apparatus 101. This allows the irradiation control device 120 and the radiation imaging apparatus 101 to perform exposure while sharing each other's preparation status.

[0056] If the irradiation control device 120 receives the irradiation permission message 301 before the time indicated by its own timing control unit 122 reaches the scheduled exposure start time, the irradiation control device 120 starts generating timing pulses for radiation irradiation from the scheduled exposure start time. The irradiation control device 120 then plans the radiation irradiation operation based on the time indicated by the timing control unit 122 so that the radiation pulse length and frame rate are determined in advance, and the irradiation pulse generating unit 123 executes the radiation irradiation operation.

[0057] On the other hand, when the time indicated by the timing control unit 106 of the radiation imaging apparatus 101 that has completed the imaging preparation operation reaches the scheduled exposure start time 10300, the radiation imaging apparatus 101 switches the operation of the image receptor 107 to a charge accumulation state in preparation for radiation irradiation. Then, after a time equivalent to the length of the radiation pulse has elapsed from the charge accumulation state (in FIG. 3, after the time indicated by the timing control unit 106 reaches time 10350), the image receptor 107 switches to a readout state in which the charge of the image receptor 107 is read out, and radiation image data is acquired. The charge accumulation period of the radiation imaging apparatus 101 is the same period as the radiation irradiation period. Note that the charge accumulation period may be longer than the radiation irradiation period.

[0058] Thereafter, similar to the irradiation control device 120, the radiation imaging device 101 plans the imaging operation (such as the charge accumulation operation and the charge readout operation) based on the time of the timing control unit 106 so as to achieve a predetermined frame rate, and the imaging control unit 102 executes the imaging operation.

[0059] As described above, the image receptor 107 in Fig. 1 operates by repeatedly accumulating charge in response to radiation, reading out the accumulated charge, and resetting the charge, as shown in Fig. 3. If the image receptor 107 is irradiated with radiation during charge reading or resetting, this may impair the quality of the obtained radiographic image, and cause the subject 112 the disadvantage of unnecessary exposure to radiation.

[0060] According to this embodiment, it is possible to synchronize the irradiation period of radiation 111 generated by the irradiation pulse generating unit 123 with the charge accumulation period of the image receptor 107. This prevents radiation from being irradiated to the image receptor 107 during charge readout and resetting, thereby preventing deterioration in the quality of the obtained radiographic image and preventing unnecessary exposure of the subject 112 to radiation.

[0061] Fig. 4 is a flowchart showing a control method for the radiation imaging system 100 according to the first embodiment. Note that this sequence is based on the assumption that the time synchronization and the calculation and storage of the communication delay time in Fig. 2 have been completed in advance.

[0062] In step S401, the operator presses the exposure button 115. Then, the radiation generation device 110 transmits a signal indicating that the exposure button 115 has been pressed to the irradiation control device 120.

[0063] In step S402, the irradiation control device 120 functions as a transmission unit and transmits an imaging request message 300 shown in Fig. 3 to the radiation imaging apparatus 101 via the communication network. The imaging request message 300 is an example of imaging request information.

[0064] The radiation imaging apparatus 101 functions as a receiving unit and receives an imaging request message 300 from the irradiation control apparatus 120 .

[0065] In step S403, the radiation imaging apparatus 101 receives the imaging request message 300. Then, the radiation imaging apparatus 101 calculates the scheduled exposure start time in consideration of the preparatory drive time until the start of charge accumulation drive of the image receptor 107, includes the scheduled exposure start time in the irradiation permission message 301 of Fig. 3, and transmits the irradiation permission message 301 to the irradiation control device 120. Specifically, the radiation imaging apparatus 101 obtains the current time of the timing control unit 106 of the radiation imaging apparatus 101 as the reception time of the imaging request message 300, and calculates the scheduled exposure start time by adding a preset time to the reception time of the imaging request message 300. The irradiation permission message 301 is an example of irradiation permission information, and includes information on the scheduled exposure start time. The scheduled exposure start time is the scheduled time to start irradiation of radiation.

[0066] The irradiation control device 120 functions as a receiving unit and receives an irradiation permission message 301 from the radiation imaging apparatus 101. The irradiation control device 120 then compares the received time with the scheduled exposure start time, and if it is a time when exposure is possible, transmits an irradiation start acknowledgement message 302 to the radiation imaging apparatus 101. Specifically, if a value obtained by subtracting the time at which the irradiation permission message 301 is received from the scheduled exposure start time is greater than the irradiation preparation operation time, the irradiation control device 120 transmits the irradiation start acknowledgement message 302 to the radiation imaging apparatus 101. The irradiation preparation operation time is an example of a first threshold value. The irradiation start acknowledgement message 302 is an example of irradiation start acknowledgement information. The subtracted value is the difference between the scheduled exposure start time and the time at which the irradiation permission message 301 is received. Furthermore, if the irradiation control device 120 does not receive the irradiation permission message 301 by the time (scheduled exposure start time-irradiation preparation operation time) due to a communication delay or the like, it does not transmit the irradiation start acknowledgement message 302 to the radiation imaging device 101. Here, the irradiation preparation time is a preparation time including the communication time of the irradiation start acknowledgement message 302, the time of the irradiation preparation operation of the irradiation control device 120, the time of the irradiation preparation operation of the radiation generation device 110, and the time of the irradiation preparation operation of the radiation source 109.

[0067] In step S404, the radiation imaging apparatus 101 determines whether or not the irradiation start acknowledgement message 302 is received within the waiting time for the irradiation start acknowledgement message 302 after the transmission of the irradiation permission message 301. The waiting time is dynamically determined based on the calculated communication delay time as described above, and is the communication time for the irradiation start acknowledgement message 302 plus a margin. If the irradiation start acknowledgement message 302 is received within the waiting time, the process proceeds to step S405. If the irradiation start acknowledgement message 302 is not received within the waiting time due to a communication delay or the like, the processes of steps S405 and S406 are not performed, and the radiation imaging apparatus 101 continues the preparation operation.

[0068] In step S405, when the current time of the timing control unit 122 reaches the scheduled exposure start time 10300, the irradiation controller 120 controls the irradiation pulse generating unit 123 to start generating a timing pulse for radiation irradiation, thereby starting radiation irradiation. Then, when the current time of the timing control unit 122 reaches time 10350 after the irradiation time length, the irradiation controller 120 stops generating the timing pulse for radiation irradiation by the irradiation pulse generating unit 123. The current time of the timing control unit 122 is the current time of the irradiation controller 120. Then, the radiation generating device 110 irradiates radiation 111 from the radiation source 109 from time 10300 to 10350.

[0069] The radiation imaging apparatus 101 controls the image receptor 107 to start accumulating charge based on radiation when the current time of the timing control unit 106 reaches the scheduled exposure start time (=scheduled accumulation start time) 10300. Then, the radiation imaging apparatus 101 controls the image receptor 107 to end accumulating charge based on radiation when the current time of the timing control unit 106 reaches time 10350 after the charge accumulation time. The current time of the timing control unit 106 is the current time of the radiation imaging apparatus 101. Thereafter, the radiation imaging apparatus 101 reads out charge from the image receptor 107 and acquires radiation image data.

[0070] In step S406, the irradiation controller 120 causes the irradiation pulse generator 123 to generate timing pulses for radiation irradiation at a specified number of times and frame rate set in advance or in the irradiation permission message 301, thereby irradiating radiation 111.

[0071] The radiation imaging apparatus 101 performs charge accumulation and charge readout on the image receptor 107 at the above-specified number of times and frame rate, and obtains radiation image data.

[0072] As described above, according to this embodiment, the radiation imaging system 100 can synchronize the radiation irradiation control of the irradiation control device 120 with the operation of the radiation imaging apparatus 101. The radiation imaging system 100 can realize imaging at appropriate radiation irradiation timing while performing time synchronization via a network line, and can increase the probability of successful exposure even in an unstable communication state.

[0073] Second embodiment In the first embodiment, an example in a stable communication state is shown, but in the second embodiment, a sequence assuming a situation in which the communication state is unstable and a delay occurs in communication is shown. The following describes the differences between the second embodiment and the first embodiment.

[0074] Fig. 5 is a diagram showing a message communication procedure and occurrence of operation timing according to the second embodiment. In Fig. 5, the flow from pressing the exposure button 115, transmitting an imaging request message 300, to transmitting an irradiation permission message 301 from the radiation imaging apparatus 101 to the irradiation control device 120 is the same as the sequence in Fig. 3.

[0075] After transmitting the above-mentioned irradiation permission message 301 to the irradiation control device 120, the radiation imaging apparatus 101 waits for reception of the irradiation start acknowledgement message 302 from the irradiation control device 120 during the waiting time for the irradiation start acknowledgement message 302. Note that, like the first embodiment, the waiting time for the irradiation start acknowledgement message 302 is dynamically determined.

[0076] If the radiation imaging apparatus 101 does not receive the irradiation start acknowledgement message 302 within the waiting time for the irradiation start acknowledgement message 302, the radiation imaging apparatus 101 transmits the same irradiation permission message 301 as the previously transmitted irradiation permission message 301 again to the irradiation control apparatus 120.

[0077] The irradiation controller 120 receives the irradiation permission message 301 at time 10260 , and transmits an irradiation start acknowledgement message 302 to the radiation imaging apparatus 101 because the irradiation permission reception time 10260 is a timing when exposure is possible at the scheduled exposure start time 10300 .

[0078] After transmitting the irradiation permission message 301 to the irradiation control device 120, the radiation imaging apparatus 101 waits for reception of the irradiation start acknowledgement message 302 from the irradiation control device 120 during a waiting time for the irradiation start acknowledgement message 302.

[0079] When the radiation imaging apparatus 101 receives the irradiation start acknowledgement message 302 within the waiting time for the irradiation start acknowledgement message 302, the same process as in the first embodiment is performed. That is, the irradiation control device 120 starts generating a timing pulse for radiation irradiation at the scheduled exposure start time 10300. The radiation imaging apparatus 101 starts charge accumulation at the scheduled exposure start time (=scheduled accumulation start time) 10300.

[0080] Fig. 6 is a flowchart showing a control method for the radiation imaging system 100 according to the second embodiment. Note that this sequence is based on the assumption that the time synchronization and the calculation and storage of the communication delay time in Fig. 2 have been completed in advance.

[0081] Figure 6 is obtained by adding step S601 to Figure 4. Below, the differences between Figure 6 and Figure 4 will be described.

[0082] In step S404, if the radiation imaging apparatus 101 does not receive the irradiation start acknowledgement message 302 within the standby time, the process proceeds to step S601.

[0083] In step S601, the radiation imaging apparatus 101 transmits the same irradiation permission message 301 as the irradiation permission message 301 transmitted in step S403 again to the irradiation control device 120. After that, the process returns to step S404.

[0084] When the irradiation control device 120 receives the irradiation permission message 301, it compares the received time with the scheduled exposure start time, and if it is a time when exposure is possible, it transmits an irradiation start acknowledgement message 302 to the radiation imaging apparatus 101.

[0085] In step S404, if the radiation imaging apparatus 101 receives the irradiation start acknowledgement message 302 within the waiting time, the process proceeds to step S405. The processes in steps S405 and S406 are the same as those in FIG.

[0086] If the irradiation control device 120 receives the irradiation permission message 301 after transmitting the irradiation start acknowledgement message 302 and before the scheduled exposure start time, the irradiation control device 120 recognizes that the radiation imaging apparatus 101 has made the determination of No in step S404. If the irradiation control device 120 does not receive the irradiation permission message 301 after transmitting the irradiation start acknowledgement message 302 and before the scheduled exposure start time, the irradiation control device 120 recognizes that the radiation imaging apparatus 101 has made the determination of Yes in step S404 and proceeds to step S405.

[0087] In step S405, if the irradiation controller 120 does not receive the irradiation permission message 301 after transmitting the irradiation start acknowledgement message 302 and before the scheduled exposure start time, the irradiation controller 120 controls to start radiation irradiation based on the information of the scheduled exposure start time. Also, if the irradiation controller 120 receives the irradiation permission message 301 after transmitting the irradiation start acknowledgement message 302 and before the scheduled exposure start time, the irradiation controller 120 controls not to start radiation irradiation based on the information of the scheduled exposure start time.

[0088] (Third embodiment) In the third embodiment, a sequence is shown assuming a situation in which the communication situation is even more unstable than in the second embodiment and a delay occurs in the communication.

[0089] FIG. 7 is a diagram showing a message communication procedure and occurrence of operation timing according to the third embodiment.

[0090] The flow from pressing the exposure button 115, transmitting an imaging request message 300, transmitting an irradiation permission message 301 from the radiation imaging apparatus 101 to the irradiation control device 120, and retransmission is the same as the sequence in FIG.

[0091] After transmitting the irradiation permission message 301, the radiation imaging apparatus 101 determines whether or not the irradiation start acknowledgement message 302 is received within the waiting time for the irradiation start acknowledgement message 302. The irradiation permission message 301 includes a scheduled exposure start time 10300.

[0092] When the radiation imaging apparatus 101 does not receive the irradiation start acknowledgement message 302 within the waiting time for the irradiation start acknowledgement message 302, the radiation imaging apparatus 101 determines whether or not the current time indicated by the timing control unit 106 is earlier than (scheduled exposure start time-time α).

[0093] The time α is a sufficient time for a message to be transmitted from the radiation imaging apparatus 101 to the irradiation control device 120. As an example, the time α is determined by sampling the delay time required for communication several times when the time synchronization shown in FIG. 2 is performed in advance, and using the average value of the samples.

[0094] When the current time indicated by the timing control unit 106 is earlier than (scheduled exposure start time 10300-time α), the radiation imaging apparatus 101 retransmits the same irradiation permission message 301 as the previously transmitted irradiation permission message 301, as in the first embodiment.

[0095] Upon receiving the irradiation permission message 301, the irradiation control device 120 acquires the current time 10300 as the irradiation permission reception time from the timing control unit 122. The irradiation control device 120 compares the current time 10300 with the scheduled exposure start time 10300 included in the irradiation permission message 301, and determines whether the irradiation preparation operation can be completed at the scheduled exposure start time 10300. If the irradiation control device 120 cannot complete the irradiation preparation operation at the scheduled exposure start time 10300, it does not transmit the irradiation start acknowledgement message 302 to the radiation imaging apparatus 101.

[0096] After retransmitting the irradiation permission message 301, the radiation imaging apparatus 101 determines whether or not it has received the irradiation start acknowledgement message 302 within the waiting time for the irradiation start acknowledgement message 302. If the radiation imaging apparatus 101 has not received the irradiation start acknowledgement message 302 within the waiting time for the irradiation start acknowledgement message 302, the radiation imaging apparatus 101 determines whether or not the current time indicated by the timing control unit 106 is earlier than (scheduled exposure start time-time α).

[0097] If the current time indicated by the timing control unit 106 is not earlier than (scheduled exposure start time 10300-time α), the radiation imaging apparatus 101 calculates a new scheduled exposure start time since radiation cannot be irradiated at the scheduled exposure start time 10300. As in the above, the radiation imaging apparatus 101 calculates a new scheduled exposure start time (=scheduled accumulation start time) 10450 by adding a preset time to the current time indicated by the timing control unit 106. Then, the radiation imaging apparatus 101 transmits an irradiation permission message 301' including the new scheduled exposure start time 10450 to the irradiation control device 120. The irradiation permission message 301' includes information corresponding to the scheduled exposure start time 10450, the radiation irradiation time length (length of radiation pulse, irradiation window, etc.), and the irradiation cycle (frame rate, etc.).

[0098] Upon receiving the irradiation permission message 301′, the irradiation controller 120 acquires the current time 10350 as the irradiation permission reception time from the timing control unit 122. The irradiation controller 120 compares the current time 10350 with the scheduled exposure start time 10450 included in the irradiation permission message 301′, and determines whether the irradiation preparation operation can be completed at the scheduled exposure start time 10450.

[0099] If the irradiation controller 120 can complete the irradiation preparation operation at the scheduled exposure start time 10450, it transmits an irradiation start acknowledgement message 302 for acknowledging the start of irradiation to the radiation imaging apparatus 101 and executes the irradiation preparation operation.

[0100] After transmitting the irradiation permission message 301', the radiation imaging apparatus 101 determines whether or not it has received the irradiation start acknowledgement message 302 within the standby time for the irradiation start acknowledgement message 302. At time 10400, the radiation imaging apparatus 101 receives the irradiation start acknowledgement message 302 within the standby time for the irradiation start acknowledgement message 302. Therefore, the irradiation control device 120 generates timing pulses for radiation irradiation from the scheduled exposure start time 10450 to 10500 by the irradiation pulse generating unit 123 as scheduled. Then, the radiation generating apparatus 110 irradiates radiation 111 from the radiation source 109 from the scheduled exposure start time 10450 to 10500.

[0101] Furthermore, the radiation imaging apparatus 101 sets the operation of the image receptor 107 to a charge accumulation state from scheduled exposure start time 10450 to 10500. Then, after a time equivalent to the length of the radiation pulse has elapsed from the charge accumulation state (in FIG. 7, after the time indicated by the timing control unit 106 reaches time 10450), the image receptor 107 enters a readout state in which the charge of the image receptor 107 is read out, and radiation image data is acquired.

[0102] Thereafter, the irradiation controller 120 generates a timing pulse for radiation irradiation based on the time of the timing control unit 122 so as to achieve a predetermined radiation pulse length and frame rate, and the irradiation pulse generating unit 123 irradiates radiation 111.

[0103] The radiation imaging apparatus 101 executes imaging operations (charge accumulation operations, charge readout operations, etc.) of the image receptor 107 based on the time of a timing control unit 106 so as to achieve a predetermined frame rate.

[0104] Fig. 8 is a flowchart showing a control method for the radiation imaging system 100 according to the third embodiment. Note that this sequence is based on the assumption that the time synchronization and the calculation and storage of the communication delay time in Fig. 2 have been completed in advance.

[0105] Figure 8 is obtained by adding steps S801 and S802 to Figure 6. Below, the differences between Figure 8 and Figure 6 will be described.

[0106] In step S404, if the radiation imaging apparatus 101 does not receive the irradiation start acknowledgement message 302 within the standby time, the process proceeds to step S801.

[0107] In step S801, the radiation imaging apparatus 101 determines whether or not the value obtained by subtracting the current time of the timing control unit 106 from the scheduled exposure start time is greater than time α. The time α is an example of a second threshold value. If the value obtained by subtracting the current time of the timing control unit 106 from the scheduled exposure start time is greater than time α, the process proceeds to step S601. If the value obtained by subtracting the current time of the timing control unit 106 from the scheduled exposure start time is not greater than time α, the process proceeds to step S802.

[0108] In step S802, since retransmitting the irradiation permission message 301 would be too late, the radiation imaging apparatus 101 calculates a new scheduled exposure start time (=scheduled accumulation start time) by adding a preset time to the current time indicated by the timing control unit 106. Then, the radiation imaging apparatus 101 transmits an irradiation permission message 301' including the new scheduled exposure start time to the irradiation control device 120. The new scheduled exposure start time included in the irradiation permission message 301' is a time later than the scheduled exposure start time included in the above-mentioned irradiation permission message 301. Then, the process returns to step S404.

[0109] In step S601, the radiation imaging apparatus 101 transmits the same irradiation permission message 301 (or 301') as the previously transmitted irradiation permission message 301 (or 301') again to the irradiation control device 120. After that, the process returns to step S404.

[0110] If it is determined in the prior negotiation that the communication delay between the radiation imaging apparatus 101 and the irradiation control device 120 is very large, the new scheduled exposure start time may be set by adding a large amount to the current scheduled exposure start time. This makes it possible to further increase the probability of exposure being possible at the new scheduled exposure start time.

[0111] By the processing of Figure 8 described above, even if a communication delay occurs between the radiation imaging device 101 and the irradiation control device 120, the radiation imaging system 100 can increase the probability that radiation imaging is possible without missing the timing of radiation imaging.

[0112] (Other embodiments) The present disclosure can also be realized by a process in which a program for implementing one or more functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) for implementing one or more functions.

[0113] It should be noted that the above-described embodiments are merely illustrative of specific examples of implementing the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by these embodiments. In other words, the present disclosure can be implemented in various forms without departing from its technical concept or main features.

[0114] The disclosure of this embodiment includes the following configuration, method, and program. (Configuration 1) 1. A radiation imaging system comprising: an irradiation control device that controls irradiation of radiation; and a radiation imaging device that is communicably connected to the irradiation control device and generates an image based on radiation, The irradiation control device includes: a first communication unit that transmits irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value; The radiation imaging apparatus includes: a second communication unit configured to retransmit the same irradiation permission information as the irradiation start consent information to the irradiation control device when the irradiation start consent information is not received from the irradiation control device within a waiting time after the transmission of the irradiation permission information. (Configuration 2) the irradiation control device has a first control unit that controls to start radiation irradiation based on information about the scheduled irradiation start time after transmitting the irradiation start acknowledgement information, The radiation imaging system according to configuration 1, characterized in that the radiation imaging device has a second control unit that controls the radiation imaging device to start accumulating charges based on radiation based on information about the scheduled irradiation start time after receiving the irradiation start acknowledgement information from the irradiation control device. (Configuration 3) the first control unit controls the irradiation control device to start radiation irradiation when a current time of the irradiation control device becomes the scheduled irradiation start time; The radiation imaging system of configuration 2, wherein the second control unit controls the radiation imaging device to start accumulating electric charges based on radiation when the current time of the radiation imaging device becomes the scheduled irradiation start time. (Configuration 4) 4. The radiation imaging system according to configuration 2 or 3, wherein when the radiation imaging device receives the irradiation start consent information from the irradiation control device within a waiting time after transmitting the irradiation permission information, the second control unit controls to start accumulation of charges based on radiation based on information about the scheduled irradiation start time. (Configuration 5) 5. The radiation imaging system according to any one of configurations 2 to 4, characterized in that when the radiation imaging device receives the irradiation start consent information from the irradiation control device within a waiting time after transmitting the irradiation permission information, the first control unit controls to start radiation irradiation based on information about the scheduled irradiation start time. (Configuration 6) The first control unit is when the irradiation control device does not receive the irradiation permission information after transmitting the irradiation start acknowledgement information and before the scheduled irradiation start time, control is performed so as to start radiation irradiation based on the information of the scheduled irradiation start time; 6. The radiation imaging system according to configuration 5, wherein when the irradiation control device receives the irradiation permission information after transmitting the irradiation start acknowledgement information and before the scheduled irradiation start time, the irradiation control device controls so as not to start radiation irradiation based on information about the scheduled irradiation start time. (Configuration 7) The second communication unit is if the radiation imaging apparatus does not receive the irradiation start acknowledgement information from the irradiation control device within a standby time after transmitting the irradiation permission information, and a value obtained by subtracting a current time of the radiation imaging apparatus from the scheduled irradiation start time is greater than a second threshold value, transmits the same irradiation permission information as the irradiation permission information to the irradiation control device again; 7. The radiation imaging system according to any one of configurations 1 to 6, characterized in that, when the radiation imaging apparatus does not receive the irradiation start consent information from the irradiation control apparatus within a standby time after transmission of the irradiation permission information, and a value obtained by subtracting a current time of the radiation imaging apparatus from the scheduled irradiation start time is not greater than a second threshold, the radiation imaging system transmits irradiation permission information including information on a scheduled irradiation start time that is later than the scheduled irradiation start time to the irradiation control apparatus. (Configuration 8) 3. The radiation imaging system according to configuration 2, wherein the irradiation control device or the radiation imaging device has a correction unit that corrects a current time of the irradiation control device or a current time of the radiation imaging device through communication between the irradiation control device and the radiation imaging device. (Configuration 9) 9. The radiation imaging system according to configuration 8, wherein the correction unit communicates time request information and response information to the time request information between the irradiation control device and the radiation imaging device, and corrects a current time of the irradiation control device or a current time of the radiation imaging device based on information of a transmission time of the time request information, information of a reception time of the time request information, information of a transmission time of the response information to the time request information, or information of a reception time of the response information to the time request information. (Configuration 10) 10. The radiation imaging system according to configuration 9, wherein the correction unit communicates time request information and response information to the time request information between the irradiation control device and the radiation imaging device, and corrects a current time of the irradiation control device or a current time of the radiation imaging device based on information of a transmission time of the time request information, information of a reception time of the time request information or information of a transmission time of the response information to the time request information, and information of a reception time of the response information to the time request information. (Configuration 11) the radiation imaging apparatus transmits the time request information to the irradiation control device, and receives response information to the time request information from the irradiation control device; when the irradiation control device receives the time request information from the radiation imaging device, the irradiation control device transmits response information to the time request information to the radiation imaging device; The radiation imaging system of configuration 10, characterized in that the correction unit corrects the current time of the radiation imaging device based on information on the transmission time of the time request information, information on the reception time of the time request information or information on the transmission time of the response information to the time request information, and information on the reception time of the response information to the time request information. (Configuration 12) the irradiation control device transmits the time request information to the radiation imaging apparatus and receives response information to the time request information from the radiation imaging apparatus; when the radiation imaging apparatus receives the time request information from the irradiation control device, the radiation imaging apparatus transmits a response to the time request information to the irradiation control device; 11. The radiation imaging system according to claim 10, wherein the correction unit corrects the current time of the irradiation control device based on information on a transmission time of the time request information, information on a reception time of the time request information or information on a transmission time of a response information to the time request information, and information on a reception time of the response information to the time request information. (Configuration 13) 13. The radiation imaging system according to any one of configurations 8 to 12, wherein the correction unit corrects a current time of the irradiation control device or a current time of the radiation imaging device based on a communication time of multiple communications between the irradiation control device and the radiation imaging device. (Configuration 14) a communication unit that transmits irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value; a control unit that controls to start radiation irradiation based on information on the scheduled irradiation start time after transmitting the irradiation start acknowledgement information; An irradiation control device comprising: (Configuration 15) a communication unit which, when an irradiation start acknowledgement information is not received from the irradiation control device within a waiting time after the transmission of the irradiation permission information, transmits the same irradiation permission information to the irradiation control device again; a control unit that, after receiving irradiation start consent information from the irradiation control device, controls to start accumulation of charges based on radiation based on information on a scheduled irradiation start time included in the irradiation permission information; A radiation imaging apparatus comprising: (Method 1) 1. A method for controlling a radiation imaging system having an irradiation control device that controls irradiation of radiation, and a radiation imaging device that is communicatively connected to the irradiation control device and generates an image based on radiation, comprising: a step of transmitting irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting the imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value, a step of transmitting, to the irradiation control device, irradiation permission information identical to the irradiation start consent information, again, when the irradiation control device does not receive the irradiation start consent information from the irradiation control device within a waiting time after transmission of the irradiation permission information. (Method 2) transmitting irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting the imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value; a step of controlling to start radiation irradiation based on information on a scheduled irradiation start time after transmitting the irradiation start acknowledgement information; 13. A method for controlling an irradiation control device comprising the steps of: (Method 3) when irradiation start acknowledgement information is not received from the irradiation control device within a waiting time after the transmission of the irradiation permission information, transmitting the same irradiation permission information as the irradiation control device again; a step of controlling to start accumulation of charges based on radiation, based on information on a scheduled irradiation start time included in the irradiation permission information after receiving irradiation start consent information from the irradiation control device; 13. A method for controlling a radiation imaging apparatus comprising: (Program 1) A program for causing a computer to execute the control method according to any one of Methods 1 to 3. [Explanation of symbols]

[0115] REFERENCE SIGNS LIST 100 Radiation imaging system, 101 Radiation imaging device, 102 Imaging control unit, 103 Wireless communication unit, 104 Wired communication unit, 105 Drive control unit, 106, 122 Timekeeping control unit, 107 Image receptor, 109 Radiation source, 110 Radiation generator, 115 Exposure button, 120 Irradiation control device, 121 Wired communication unit, 123 Irradiation pulse generation unit

Claims

1. A radiation imaging system including an irradiation control device that controls irradiation of radiation, and a radiation imaging device that is communicatively connected to the irradiation control device and generates an image based on radiation, The irradiation control device includes: a first communication unit that transmits irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value; The radiation imaging apparatus includes: a second communication unit configured to retransmit the same irradiation permission information as the irradiation start consent information to the irradiation control device when the irradiation start consent information is not received from the irradiation control device within a waiting time after the transmission of the irradiation permission information.

2. the irradiation control device has a first control unit that controls to start radiation irradiation based on information about the scheduled irradiation start time after transmitting the irradiation start acknowledgement information, 2. The radiation imaging system according to claim 1, further comprising a second control unit that controls the radiation imaging apparatus to start accumulating charges based on radiation based on information about the scheduled irradiation start time after receiving the irradiation start acknowledgement information from the irradiation control device.

3. the first control unit controls the irradiation control device to start radiation irradiation when a current time of the irradiation control device becomes the scheduled irradiation start time; The radiation imaging system according to claim 2 , wherein the second control unit performs control so as to start accumulation of charges based on radiation when a current time of the radiation imaging apparatus reaches the scheduled irradiation start time.

4. 3. The radiation imaging system according to claim 2, wherein when the radiation imaging device receives the irradiation start consent information from the irradiation control device within a waiting time after transmitting the irradiation permission information, the second control unit controls to start accumulation of charges based on radiation based on information about the scheduled irradiation start time.

5. 3. The radiation imaging system according to claim 2, wherein when the radiation imaging apparatus receives the irradiation start consent information from the irradiation control device within a waiting time after transmitting the irradiation permission information, the first control unit controls to start radiation irradiation based on information about the scheduled irradiation start time.

6. The first control unit is when the irradiation control device does not receive the irradiation permission information after transmitting the irradiation start acknowledgement information and before the scheduled irradiation start time, control is performed so as to start radiation irradiation based on the information of the scheduled irradiation start time; 6. The radiation imaging system according to claim 5, wherein when the irradiation control device receives the irradiation permission information after transmitting the irradiation start acknowledgement information and before the scheduled irradiation start time, the irradiation control device controls so as not to start radiation irradiation based on information about the scheduled irradiation start time.

7. The second communication unit is if the radiation imaging apparatus does not receive the irradiation start acknowledgement information from the irradiation control device within a standby time after transmitting the irradiation permission information, and a value obtained by subtracting a current time of the radiation imaging apparatus from the scheduled irradiation start time is greater than a second threshold value, transmitting the same irradiation permission information as the irradiation permission information to the irradiation control device again; 2. The radiation imaging system according to claim 1, wherein, when the radiation imaging apparatus does not receive the irradiation start consent information from the irradiation control apparatus within a waiting time after transmission of the irradiation permission information, and a value obtained by subtracting a current time of the radiation imaging apparatus from the scheduled irradiation start time is not greater than a second threshold, the radiation imaging system transmits irradiation permission information including information on a scheduled irradiation start time that is later than the scheduled irradiation start time to the irradiation control apparatus.

8. 3. The radiation imaging system according to claim 2, wherein the irradiation control device or the radiation imaging device comprises a correction unit that corrects a current time of the irradiation control device or a current time of the radiation imaging device through communication between the irradiation control device and the radiation imaging device.

9. 9. The radiation imaging system according to claim 8, wherein the correction unit performs communication of time request information and response information to the time request information between the irradiation control device and the radiation imaging device, and corrects a current time of the irradiation control device or a current time of the radiation imaging device based on information of a transmission time of the time request information, information of a reception time of the time request information, information of a transmission time of the response information to the time request information, or information of a reception time of the response information to the time request information.

10. 10. The radiation imaging system according to claim 9, wherein the correction unit performs communication of time request information and response information to the time request information between the irradiation control device and the radiation imaging device, and corrects a current time of the irradiation control device or a current time of the radiation imaging device based on information of a transmission time of the time request information, information of a reception time of the time request information or information of a transmission time of the response information to the time request information, and information of a reception time of the response information to the time request information.

11. the radiation imaging apparatus transmits the time request information to the irradiation control device, and receives response information to the time request information from the irradiation control device; when the irradiation control device receives the time request information from the radiation imaging device, the irradiation control device transmits response information to the time request information to the radiation imaging device; The radiation imaging system of claim 10, wherein the correction unit corrects the current time of the radiation imaging device based on information on the transmission time of the time request information, information on the reception time of the time request information or information on the transmission time of the response information to the time request information, and information on the reception time of the response information to the time request information.

12. the irradiation control device transmits the time request information to the radiation imaging apparatus and receives response information to the time request information from the radiation imaging apparatus; when the radiation imaging apparatus receives the time request information from the irradiation control device, the radiation imaging apparatus transmits a response to the time request information to the irradiation control device; 11. The radiation imaging system according to claim 10, wherein the correction unit corrects the current time of the irradiation control device based on information on a transmission time of the time request information, information on a reception time of the time request information or information on a transmission time of response information to the time request information, and information on a reception time of the response information to the time request information.

13. 9. The radiation imaging system according to claim 8, wherein the correction unit corrects the current time of the irradiation control device or the current time of the radiation imaging device based on a communication time of a plurality of communications between the irradiation control device and the radiation imaging device.

14. a communication unit that transmits irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value; a control unit that controls to start radiation irradiation based on information on the scheduled irradiation start time after transmitting the irradiation start acknowledgement information; An irradiation control device comprising:

15. a communication unit which, when an irradiation start acknowledgement information is not received from the irradiation control device within a waiting time after the transmission of the irradiation permission information, transmits the same irradiation permission information to the irradiation control device again; a control unit that, after receiving irradiation start consent information from the irradiation control device, controls to start accumulation of charges based on radiation based on information on a scheduled irradiation start time included in the irradiation permission information; A radiation imaging apparatus comprising:

16. 1. A method for controlling a radiation imaging system having an irradiation control device that controls irradiation of radiation, and a radiation imaging device that is communicatively connected to the irradiation control device and generates an image based on radiation, comprising: a step of transmitting irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting the imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value, a step of transmitting, to the irradiation control device, irradiation permission information identical to the irradiation start consent information, again, when the irradiation control device does not receive the irradiation start consent information from the irradiation control device within a waiting time after transmission of the irradiation permission information.

17. transmitting irradiation start acknowledgement information to the radiation imaging apparatus when a difference between a reception time of irradiation permission information received from the radiation imaging apparatus after transmitting the imaging request information to the radiation imaging apparatus and information on a scheduled irradiation start time included in the irradiation permission information is greater than a first threshold value; a step of controlling to start radiation irradiation based on information on a scheduled irradiation start time after transmitting the irradiation start acknowledgement information; 13. A method for controlling an irradiation control device comprising the steps of:

18. when irradiation start acknowledgement information is not received from the irradiation control device within a waiting time after the transmission of the irradiation permission information, transmitting the same irradiation permission information as the irradiation control device again; a step of controlling to start accumulation of charges based on radiation, based on information on a scheduled irradiation start time included in the irradiation permission information after receiving irradiation start consent information from the irradiation control device; 13. A method for controlling a radiation imaging apparatus comprising:

19. A program for causing a computer to execute the control method according to any one of claims 16 to 18.

Images