Radiographic apparatus, radiographic system, and control method and program of radiographic apparatus

Abstract

To suppress an increase in cost and enable transmission of image data from a radiographic apparatus capable of appropriately performing association with other information.SOLUTION: A radiographic apparatus includes: image generation means for generating a plurality of pieces of image data on radiation images on the basis of an emitted radioactive ray at a first frame rate; first timing means for measuring the time that the image data is generated; storage means for storing the plurality of pieces of image data to which first time information indicating the time that the image data is generated is imparted; and communication means for transmitting the plurality of pieces of image data to which the first time information, which is stored in the storage means, is imparted. When a data amount per unit time of the image data generated by the image generation means exceeds a data amount that can be transmitted per unit time, the communication means transmits the image data at a frame rate slower than the first frame rate.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] There is a radiation tomography system that uses a radiation imaging device to image a subject from multiple directions, performs reconstruction calculations using image data obtained by imaging, and visualizes the three-dimensional structure of the subject. In such a system, a mechanism is provided for moving the imaging system, which is made up of a radiation source and a radiation imaging device, relative to the subject in order to image the subject from multiple directions. In addition, when performing reconstruction calculations using image data obtained by imaging, it is useful to obtain geometric information indicating from which direction each piece of image data was imaged of the subject.

[0003] Patent Document 1 discloses a tomography device in which a radiation source and an imaging device supported by an arm are arranged to sandwich a subject from above and below, and the arm is driven to capture images from multiple directions. Patent Document 2 discloses a CT device in which a radiation source and an imaging device supported by a rotating ring are rotated around the subject to capture images from multiple directions. In both cases, geometric information and image information are collected in a device that performs reconstruction calculations, and a tomographic image is calculated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 63-230152 [Patent Document 2] JP 2013-226174 A Summary of the Invention [Problem to be solved by the invention]

[0005] One method for improving the performance of tomography is to increase the resolution and total number of pixels of the image obtained by the radiation imaging device, but as the resolution and number of pixels increase, the amount of data generated per unit time for the image obtained by imaging also increases. Since the image data obtained by the radiation imaging device is transmitted to and aggregated in a device that performs reconstruction calculation (reconstruction calculation device), it is necessary to increase the amount of information that can be communicated between the radiation imaging device and the reconstruction calculation device in response to the increase in the amount of data. However, providing a communication means with a large communication capacity has the problem of increasing costs. [Means for solving the problem]

[0006] The radiographic imaging apparatus of the present invention comprises an image generating means for generating image data of a plurality of radiographic images based on irradiated radiation at a first frame rate, a first timing means for measuring the time at which the image data was generated, a storage means for storing a plurality of the image data to which first time information indicating the time at which the image data was generated is attached, and a communication means for transmitting the plurality of image data to which the first time information is attached that is stored in the storage means, wherein the communication means transmits the image data at a frame rate slower than the first frame rate when the data amount per unit time of the image data generated by the image generating means exceeds the data amount that can be transmitted per unit time. Effect of the Invention

[0007] According to the present invention, it is possible to transmit image data from a radiation imaging apparatus while suppressing an increase in cost and enabling the image data to be appropriately linked with other information. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a radiation imaging system. [Diagram 2] FIG. 2 is a diagram illustrating an example of a functional configuration of a radiation imaging apparatus. [Diagram 3] FIG. 2 is a diagram illustrating an example of a hardware configuration of a radiation imaging apparatus. [Figure 4] FIG. 1 is a diagram illustrating an example of time synchronous communication. [Diagram 5] FIG. 2 is a diagram illustrating the association between image data and position information. [Figure 6] 11A and 11B are diagrams illustrating transmission of reduced images and RAW images. [Figure 7] 11 is a diagram for explaining control relating to time synchronous communication, and transmission of reduced images and RAW images. [Figure 8] 11A and 11B are diagrams illustrating an example of time synchronous communication, and transmission of reduced images and RAW images. [Figure 9] 1 is a diagram illustrating an example of an implementation of a configuration of a radiation imaging apparatus; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the following embodiments, radiation is not limited to X-rays, and may also include, for example, α-rays, β-rays, γ-rays, particle rays, cosmic rays, etc.

[0010] (First embodiment) 1 is a diagram showing an example of the configuration of a radiography system according to this embodiment. The radiography system 100 according to this embodiment is a system (radiation tomography system) capable of imaging a subject from multiple directions, performing reconstruction calculation using image data of a plurality of radiographic images obtained by imaging, and calculating a three-dimensional structure (tomogram) of the subject. The radiography system 100 includes a control device 101, a radiography device 102, driving mechanism units 103 and 105, a radiation source 106, position sensors 107 and 108, and a reconstruction calculation device 110.

[0011] The control device 101 controls the radiation imaging device 102, driving mechanisms 103 and 105, and the radiation source 106. The radiation source 106 is controlled by the control device 101 and irradiates the radiation imaging device 102 with radiation.

[0012] The radiation imaging apparatus 102 detects radiation irradiated from a radiation source 106 and generates a radiation image (image data) according to the dose distribution of the detected radiation. The radiation imaging apparatus 102 in this embodiment is capable of performing so-called multi-frame video imaging, in which radiation images are continuously captured at a predetermined frame rate. The radiation imaging apparatus 102 can also hold image data of a plurality of radiation images obtained by imaging, and can transmit the image data of the plurality of radiation images to the outside.

[0013] The driving mechanisms 103 and 105 are controlled by the control device 101 and the like, and are used to move the radiation imaging device 102 and the subject 104. The driving mechanisms 103 and 105 are an example of a driving means. In this embodiment, the first driving mechanism 103 can move the position of the radiation imaging device 102, and the second driving mechanism 105 can move the position of the subject 104. For example, the driving mechanisms 103 and 105 can move the radiation imaging device 102 and the subject 104 about two axes, the X direction and the Y direction, respectively.

[0014] In the radiation imaging system 100, the driving mechanism units 103 and 105 are linked to each other, thereby making it possible to displace the relative positional relationship between the radiation source 106, the radiation imaging device 102, and the subject 104. In the radiation imaging system 100, the driving mechanism units 103 and 105 are linked to each other, thereby making it possible to irradiate the subject 104 with radiation from the radiation source 106 at various angles (directions), and further make it possible to capture a transmitted image thereof by the radiation imaging device 102. In the example shown in Fig. 1, the driving mechanism units 103 and 105 are driven to cause each of the radiation imaging device 102 and the subject 104 to perform a circular orbital motion, and a video of this state is captured at a predetermined frame rate.

[0015] The position sensors 107 and 108 acquire position information of a target object. The position sensors 107 and 108 are an example of a position detection means. In this embodiment, the first position sensor 107 measures the position of the radiation imaging apparatus 102 and acquires position information related to the radiation imaging apparatus 102. The second position sensor 108 measures the position of the subject 104 and acquires position information related to the subject 104. The position information acquired by the position sensors 107 and 108 is transmitted to the reconstruction calculation device 110.

[0016] The reconstruction calculation device 110 performs reconstruction calculation based on the position information and image data of the radiation image to calculate the three-dimensional structure of the subject. Position information related to the radiation imaging device 102 and the subject 104 is transmitted to the reconstruction calculation device 110 from the position sensors 107 and 108. In addition, image data of the radiation image obtained by imaging from the radiation imaging device 102 is transmitted to the reconstruction calculation device 110 via a signal cable 109. The reconstruction calculation device 110 calculates volume data representing the three-dimensional structure of the subject 104 using the obtained position information and image data.

[0017] Here, the radiation imaging system 100 in this embodiment can display a display image based on a captured radiation image, an operation screen for performing various operations (which may include settings, etc.), and the like on the display device 111. An operator (user) 112 of the radiation imaging system 100 can view the display screen of the display device 111 and perform various operations, etc.

[0018] 2 is a diagram showing an example of the functional configuration of the radiation imaging apparatus 102. The radiation imaging apparatus 102 includes a sensor panel 201, an image storage unit 202, an image processing unit 203, a timer 204, a communication unit 205, and a control unit 206.

[0019] The sensor panel 201 converts the irradiated radiation into an electrical signal to generate image data of a radiation image corresponding to the intensity distribution (dose distribution) of the radiation. The sensor panel 201 can continuously convert the irradiated radiation into image data at a predetermined frame rate. The sensor panel 201 is an example of an image generating means.

[0020] The image storage unit 202 stores image data generated by the sensor panel 201. The image storage unit 202 can store image data of a plurality of frames of radiation images, and has a storage capacity capable of storing the number of image data necessary for calculating volume data by reconstruction calculation (back projection) in the reconstruction calculation device 110. The image data generated by the sensor panel 201 is stored in the image storage unit 202 together with a timestamp indicating the time when the image data was generated, measured by a timer 204. This timestamp indicating the time when the image data was generated is an example of first time information.

[0021] The image processing unit 203 performs image processing on the image data generated by the sensor panel 201. For example, the image processing unit 203 performs reduction processing on the image data generated by the sensor panel 201 to generate image data of a reduced image as used in the second and third embodiments described later. The timer 204 is a timer for measuring the time when each frame of image data is generated by the sensor panel 201. The timer 204 is an example of a first clocking means.

[0022] The communication unit 205 transmits image data stored in the image storage unit 202 and image data processed by the image processing unit 203 to the outside. For example, the communication unit 205 transmits image data stored in the image storage unit 202 and image data processed by the image processing unit 203 to the reconstruction calculation device 110 via the signal cable 109. The communication unit 205 also performs communication (time synchronization communication) related to time adjustment for synchronizing the time between the timer 204 of the radiation imaging apparatus 102 and the timer 211 of the reconstruction calculation device 110. The timer 211 of the reconstruction calculation device 110 is a timer for measuring the collection time when position information is collected from the position sensors 107 and 108. The timer 211 is an example of a second clocking means. The control unit 206 controls each functional unit of the radiation imaging apparatus 102.

[0023] 3 is a diagram showing an example of a hardware configuration of the radiation imaging apparatus 102. The radiation imaging apparatus 102 has a CPU 301, a ROM 302, a RAM 303, a storage device 304, a sensor panel 305, a communication unit 306, and a bus 307. The CPU 301, the ROM 302, the RAM 303, the storage device 304, the sensor panel 305, and the communication unit 306 are connected via the bus 307 so as to be able to communicate with each other.

[0024] A CPU (Central Processing Unit) 301 reads out a control program stored in a ROM (Read Only Memory) 302, executes various processes, and controls the entire radiation imaging apparatus 102. A RAM (Random Access Memory) 303 is used as a temporary storage area such as the main memory and work area of ​​the CPU 301. A storage device 304 is, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores various data, various programs, etc. A sensor panel 305 converts irradiated radiation into an electrical signal to generate image data of a radiation image. A communication unit 306 performs communication processing with an external device, for example, the reconstruction calculation device 110.

[0025] For example, the CPU 301 reads and executes a program stored in the ROM 302 or the storage device 304, thereby implementing various functions and processes of the radiation imaging apparatus 102.

[0026] The reconstruction calculation device 110 of the radiography system 100 calculates volume data (reconstruction calculation) for the subject 104 as follows. The reconstruction calculation device 110 prepares an array of unknown variables corresponding to the subject region by assigning variables to each of a plurality of voxels obtained by dividing the target region. The reconstruction calculation device 110 then performs an operation of adding image data obtained when the subject 104 is photographed by irradiating it with radiation in a specific irradiation direction to the unknown variable array in a fan-like (or cone-like) shape. By repeating the addition of image data to the unknown variable array for various irradiation directions, information on the three-dimensional structure of the subject can be obtained. This operation is called back projection, in which the state of projection within the subject when a transmission image is obtained is reproduced on a computer.

[0027] In the calculation of back projection, information on the irradiation direction at the time of imaging is required to reproduce the state of projection when a transmission image is obtained. The reconstruction calculation device 110 obtains information on the irradiation direction at the time of imaging using position information measured and acquired by the position sensors 107 and 108. From the position information of the radiation imaging device 102 and the subject 104 acquired by the position sensors 107 and 108, the positional relationship between the radiation source 106, the radiation imaging device 102, and the subject 104 can be known, and information on the irradiation direction at the time of imaging can be obtained. It is also possible to perform the calculation of back projection without using the position information acquired by the position sensors 107 and 108, assuming that the motion between the imaging system consisting of the radiation source 106 and the radiation imaging device 102 and the subject 104 is known in advance. However, since the motion of the imaging system and the subject is complicated with acceleration and deceleration, or a transmission image contains motion artifacts that differ depending on the position and are corrected in advance, it is preferable to use the actual position information acquired at the time of imaging.

[0028] In order to utilize the position information for backprojection, it is necessary to appropriately link the position information at the time when the image data was generated for each of the multiple image data. In order to simply link the image data and the position information, it is possible to build a system in which the image data and the position information arrive at the reconstruction calculation device 110 in real time without delay. In this way, the reconstruction calculation device 110 can link the image data and the position information that arrive at the same time. However, this method becomes difficult to transmit the image data in real time when the amount of data increases due to an improvement in the resolution of the image obtained by the radiation imaging device 102, etc.

[0029] In general, the upper limit of the amount of information that can be practically transmitted per unit time varies depending on the characteristics of the transmission path used for signal transmission. For example, when using copper wire as a transmission path, many ingenuity is required, such as using materials that can maintain high frequency characteristics and using multi-level signals to include a lot of information in a limited frequency. As multi-level signals and signal attenuation progress, it becomes necessary to provide enough time in the communication procedure to detect transmission errors and perform retransmission. The adoption of communication methods with such advanced mechanisms leads to increased system costs.

[0030] Therefore, in this embodiment, even if the image data obtained by imaging by the radiation imaging apparatus 102 is not transmitted in real time, the image data and the position information can be appropriately linked for each of the multiple image data. This suppresses an increase in system costs. Specifically, the radiation imaging apparatus 102 assigns a timestamp indicating the time (generation time) when the image data was generated by the sensor panel 201 to the image data. Furthermore, when the amount of data that can be transmitted per unit time on the transmission path is exceeded in real time transmission, the radiation imaging apparatus 102 transmits the image data at a frame rate slower than the frame rate of imaging. In this way, by transmitting the image data with the timestamp assigned thereto from the radiation imaging apparatus 102, the reconstruction calculation device 110 can appropriately associate the image data with the position information based on the timestamp.

[0031] The above-mentioned transmission of image data to which a time stamp has been added and the linking of image data with location information will be described with reference to FIG. When radiation is irradiated from the radiation source 106 and a moving image is captured of the subject 104, in the radiation imaging device 102, image data of a radiation image corresponding to the intensity distribution (dose distribution) of the irradiated radiation, which is generated by the sensor panel 201, is stored in the image storage unit 202. Image data of multiple frames captured from multiple directions is accumulated in the image storage unit 202, and the image data of each frame is stored together with a timestamp measured by a timer 204 indicating the generation time of that frame.

[0032] The communication unit 205 of the radiation imaging device 102 sequentially transmits the image data stored in the image storage unit 202 to the reconstruction calculation device 110 via the signal cable 109. The image data is transmitted so as to include a time stamp attached thereto. At this time, if the amount of data that can be transmitted per unit time on the transmission path in real time transmission is exceeded, the communication unit 205 transmits the image data stored in the image storage unit 202 at a frame rate slower than the frame rate of moving image capture (first frame rate). In other words, if the amount of image data per unit time generated by the sensor panel 201 according to the frame rate of moving image capture exceeds the amount of data that can be transmitted per unit time, the image data is transmitted at a frame rate slower than the frame rate of moving image capture.

[0033] The reconstruction calculation device 110 also collects position information of the radiation imaging device 102 and the subject 104 acquired by the position sensors 107 and 108. The reconstruction calculation device 110 saves the collected position information together with a timestamp indicating the collection time of the position information measured by the timer 211. The timestamp indicating the collection time of the position information is an example of second time information. When the transmission of image data and the collection of position information are advanced, the reconstruction calculation device 110 can obtain image data and position information each of which is assigned a timestamp. The image data and the position information are linked based on the correspondence between the image data and the position information based on the timestamps assigned to each of them.

[0034] In order to properly link image data and position information to which time stamps are respectively assigned, the timer 204 of the radiation imaging apparatus 102 and the timer 211 of the reconstruction calculation device 110 shown in Fig. 2 need to keep the same time without deviation. This can be realized by the timer 204 and the timer 211 performing time-synchronized communication with each other via the signal cable 109. This time-synchronized communication is performed periodically at predetermined timings (time intervals), for example.

[0035] 4 is a diagram for explaining an example of time synchronous communication for synchronizing the time of the timer 204 and the timer 211. In this example, the timer that is the reference time in the radiation imaging system 100 is the timer 211 included in the reconstruction calculation device 110, and this is called a time server. Also, a timer that corrects itself by tracking the reference timer is called a time client, and the timer 204 included in the radiation imaging apparatus 102 corresponds to this. Hereinafter, an operation for maintaining the synchronization of the time between the timer 204 and the timer 211 will be described.

[0036] First, the timer 204 of the radiation imaging apparatus 102 transmits a message (time inquiry message) inquiring about the time of the time server to the timer 211 of the reconstruction arithmetic device 110. When transmitting this time inquiry message, the timer 204 records its own time, i.e., the timer 204's time. In the example shown in FIG. 4, the timer 204 records a time value of 10254@client (@client indicates that the time is in the time client). The timer 211, which has received the time inquiry message transmitted from the timer 204, immediately replies to the timer 204 with a time reply message. At this time, the timer 204 includes its own time, i.e., the timer 211's time at the time of reply, in the time reply message. In the example shown in FIG. 4, the time reply message from the timer 211 includes a time value of 10254@server (@server indicates that the time is in the time server).

[0037] When the time reply message sent from timer 211 arrives at timer 204, timer 204 acquires its own time at the time of receiving the time reply message. In the example shown in Fig. 4, timer 204 acquires the time value 10260@client. If it is assumed that the propagation times of both the time inquiry message and the time reply message are equal, it can be estimated that the time when timer 211 returned the time reply message is midway between the sending time of the time inquiry message and the receiving time of the time reply message, in terms of the time of timer 204. In other words, it can be estimated that the time when timer 211 returned the time reply message was (10254+10260) / 2=10257@client, which is the midway between the sending time 10254@client and the receiving time 10260@client.

[0038] Incidentally, the time value of timer 211 included in the time reply message is 10254@server, and the time value (estimated value) at which timer 211 returned the time reply message at the time of timer 204 is 10257@client. If it is estimated that these times are simultaneous, then by taking the difference between the two time values, it is found that the time on timer 204 is ahead by 10257-10254=3. As the time difference between timer 204 and timer 211 has been calculated as described above, the time on timer 204 is corrected based on this time difference, thereby synchronizing the times on timer 204 and timer 211.

[0039] An example of data (image data and position information) obtained by the reconstruction calculation device 110 is shown in FIG. 5. In the example shown in FIG. 5, for simplicity, the position information respectively obtained by the position sensors 107 and 108 is shown collectively as one piece of position information. Since a timestamp is added to each of the image data and the position information, it is possible to link those having the same timestamp value and create a pair of image data and position information. In the example shown in FIG. 5, an image with a timestamp value of 1100 is <2> Image data and location <4> Image with a timestamp value of 1200 and a direct link to the location information of <4> Image data and location <9> The location information is directly linked to the

[0040] In addition, if there is no image with the same time stamp value, the position information corresponding to the time when the image data was generated can be calculated by interpolating the position information. In the example shown in FIG. 5, the image with the time stamp value of 1050 <1> The location information associated with the image data is the location with a timestamp value of 1040. <1> Location information and timestamp value is 1060 <2> The location information is calculated by interpolating the location information of the image with the timestamp value of 1150. <3> The location information associated with the image data is the location with a timestamp value of 1140. <6> Location information and timestamp value 1160 <7> The position information is calculated by interpolating the position information of

[0041] In the example shown in Fig. 5, for simplicity, both the image data and the location information are taken as being acquired at equal time intervals, but this may be the case in some cases where the intervals are not equal. Even in such cases, the image data and the location information can be linked using the timestamp as a key.

[0042] Since the image data and the position information are linked as described above, the reconstruction calculation device 110 can perform backprojection calculation based on the actual position information. Furthermore, since the image data and the position information are linked using the time stamp as a key, the speed of transmission of the image data through the signal cable 109 does not need to be real time and can be slower than the speed of generating the image data in the radiation imaging device 102.

[0043] According to this embodiment, by providing timers in both the radiation imaging apparatus 102 and the reconstruction calculation device 110, it is possible to provide a time stamp for each of the image data and the position information. This makes it possible to link the image data and the position information even if the image data is not transmitted in real time from the radiation imaging apparatus 102, and it is possible to appropriately link the image data and the position information while suppressing an increase in system costs. It is also possible to provide a radiation imaging system that accurately calculates volume data related to a subject while suppressing an increase in system costs.

[0044] In the above example, the reconstruction arithmetic device 110 has the timer 211 related to the position information, but the present invention is not limited to this. For example, the position sensors 107 and 108 may have a timer related to the position information. In addition, the server that synchronizes the time has been described as the timer 211, but the present invention is not limited to this. Both the timer 204 and the timer 211 may be made to follow a separate server (not shown). Furthermore, the protocol for time synchronization is not limited to the procedure described, and a separate protocol may be used. Regarding the correction of the time, an example in which a correction value of minus 3 is applied all at once has been described, but more preferably, the speed (rate) of the clock may be adjusted to gradually reduce the difference in time, and the rate may also be made to match eventually.

[0045] In the above example, the reconstruction calculation device 110 collects the position information acquired by the position sensors 107 and 108 together with the time stamp, but other information may be included. For example, with regard to the output of the radiation source 106, collecting the history of the X-ray tube current and the tube voltage is useful for more advanced reconstruction calculation.

[0046] Second Embodiment A second embodiment will be described below. In the following, in a radiation imaging system according to the second embodiment, the description of the same points as those in the first embodiment will be omitted, and only the points different from the first embodiment will be described.

[0047] In the first embodiment described above, it is possible to transmit image data obtained by imaging in a non-real-time manner, which is useful because the user does not observe the volume data calculated by the reconstruction calculation at the same time as imaging. On the other hand, there are also applications in which images are observed in real time at the same time as imaging. For example, if the alignment of the subject with respect to the imaging system is abnormal, it is desirable to interrupt imaging by irradiating radiation midway. In such applications, it is not necessary to observe the radiation image obtained by imaging at the same resolution as the resolution of the sensor panel, but it is desirable to transmit image data in real time.

[0048] In order to accommodate applications such as observing an image in real time while capturing an image, in the radiation imaging system 100 in the second embodiment, the image processor 203 of the radiation imaging device 102 generates a reduced image with a reduced amount of data, enabling real-time transmission. The image processor 203 reduces the amount of data by performing a reduction process on the image data generated by the sensor panel 201, and generates image data of a reduced image that enables transmission at the same frame rate as that of the image capture, even within the band of the signal cable 109. In general, there is no algorithm that can always compress all input information to a specific size or less in a reversible manner, so the reduced image data is data that cannot be restored. The generated reduced image is not suitable as source data for calculating precise volume data by reconstruction calculation, but has a sufficient resolution for applications such as alignment confirmation as described above. Hereinafter, image data before being reduced is referred to as a RAW image, and reduced image data is referred to as a reduced image.

[0049] As shown in an example in Fig. 6, the radiation imaging apparatus 102 in the second embodiment transmits image data by controlling so that the reduced images are transmitted at the same frame rate as the frame rate of imaging, and the RAW images are transmitted accurately even if it takes time. In Fig. 6, the horizontal axis represents time progression, and the progress of imaging and the progress of data transmission are shown side by side. 601, 602, 603, and 604 are RAW images obtained by imaging. In the image data to be transmitted, 611 is a reduced image of the RAW image 601, and 621 is a time-stamped RAW image of the RAW image 601. 612 is a reduced image of the RAW image 602, and 622 is a time-stamped RAW image of the RAW image 602. 613 is a reduced image of the RAW image 603, 623 is a time-stamped RAW image of the RAW image 603, and 614 is a reduced image of the RAW image 604.

[0050] The reduced image is reduced to a size that fits within the transmission band because it needs to have the same transmission frame rate as the frame rate of the imaging. When the reduced image and the RAW image to be transmitted are present simultaneously in the radiation imaging apparatus 102, the radiation imaging apparatus 102 transmits the reduced image with priority, and transmits the RAW image when the reduced image is not being transmitted. That is, when the transmission of the reduced image and the transmission of the RAW image conflict with each other, the radiation imaging apparatus 102 processes the transmission of the reduced image with priority over the transmission of the RAW image. In order to transmit such image data, as shown in the example of FIG. 6, the transmission of the reduced image is always delayed by a certain time with respect to the imaging operation, whereas the delay in the transmission of the RAW image gradually increases. Although not shown in FIG. 6, the present embodiment also performs time synchronous communication to synchronize the times of the timer 204 and the timer 211. When the time synchronous communication and the transmission of the RAW image conflict with each other, the radiation imaging apparatus 102 performs the time synchronous communication with priority. In addition, there is no particular provision for what to do when there is a conflict between time-synchronized communication and transmission of reduced images, and the radiation imaging device 102 may perform the time-synchronized communication and transmission of reduced images, for example, according to a predetermined priority order, or according to a round-robin method.

[0051] In FIG. 6, the reduced image and the RAW image (RAW image with time stamp) are shown as always being transmitted one image at a constant time, but in reality, the transmission time per image may be extended due to retransmission caused by a transmission error. In this case, the radiation imaging apparatus 102 controls the reduced image so that the upper limit of the transmission time is observed within the frame time by terminating the retransmission within a predetermined time limit even if the transmission of the reduced image cannot be completed, in order to prioritize the maintenance of the frame rate. On the other hand, the radiation imaging apparatus 102 controls the RAW image so that the transmission time is continued to be extended so that the transmission of the RAW image is completed, in order to prioritize the transmission of all information without omission. Due to such a difference in the transmission procedure, in this embodiment, the transmission of the reduced image is performed according to the UDP / IP (User Datagram Protocol / Internet Protocol) protocol. Also, the transmission of the RAW image is performed according to the TCP / IP (Transmission Control Protocol / Internet Protocol) protocol. Note that the retransmission of the reduced image due to the occurrence of a transmission error is performed, for example, based on an instruction from a higher-level application that processes the reduced image on the receiving side.

[0052] An example of the use of the reduced image transmitted from the radiation imaging apparatus 102 will be described with reference to Fig. 1. The reduced image transmitted in real time from the radiation imaging apparatus 102 is received by the reconstruction calculation device 110 and then displayed on the display device 111. An operator (user) 112 of the radiation imaging system 100 checks the reduced image displayed on the display device 111 and judges whether the imaging is progressing normally. If it is judged that there is an abnormality in the image of the subject shown in the reduced image, the operator (user) 112 operates the control device 101 to stop the irradiation of radiation from the radiation source 106 and discontinue imaging.

[0053] In this embodiment, the operator (user) 112 checks the displayed image and makes a decision to stop the radiation source 106, but the control device 101 may make a decision based on the reduced image to control the radiation source 106. In this case, the reduced image and the RAW image sent from the radiation imaging device 102 may be transmitted via the signal cable 109, and then distributed according to destinations by a demultiplexer, a network switch, or the like, and transmitted to the reconstruction calculation device 110 and the control device 101.

[0054] According to this embodiment, similarly to the first embodiment, image data and position information can be appropriately linked while suppressing an increase in system cost. Also, a radiation imaging system can be provided that accurately calculates volume data related to a subject while suppressing an increase in system cost. Also, while reliably transmitting RAW images that are the basis for reconstructing precise volume data related to a subject, real-time transmission of reduced images for monitoring the progress of imaging can be realized at the same time. For example, by displaying the reduced images transmitted in real time at any time, it becomes possible to stop irradiation of radiation when an abnormality occurs.

[0055] (Third embodiment) A third embodiment will be described below. In the following, in a radiation imaging system according to the third embodiment, the description of the same points as those in the first and second embodiments will be omitted, and only the points different from those in the first and second embodiments will be described.

[0056] In the third embodiment, priorities are set for three types of communication, namely, time synchronous communication, transmission of reduced images, and transmission of RAW images, performed by the radiation imaging apparatus 102, and in the event of contention, the communication is controlled according to the priorities. The control regarding communication in the third embodiment will be described with reference to Fig. 7.

[0057] Fig. 7 is a diagram showing an example of the configuration of the radiation imaging apparatus 102 in this embodiment. Fig. 7 shows only the configuration for controlling three types of communication: time synchronous communication, transmission of reduced images, and transmission of RAW images. The radiation imaging apparatus 102 has a time synchronous communication control unit 701, a reduced image transfer control unit 702, a RAW image transfer control unit 703, an arbiter 704, and an interface 705.

[0058] The time synchronous communication control unit 701 controls time synchronous communication. The reduced image transfer control unit 702 controls transfer of reduced images. The RAW image transfer control unit 703 controls transfer of RAW images (with time stamps). During shooting, the time synchronous communication control unit 701, reduced image transfer control unit 702, and RAW image transfer control unit 703 attempt to communicate simultaneously in parallel.

[0059] The arbiter 704 arbitrates transmission requests from the time synchronous communication control unit 701, the reduced image transfer control unit 702, and the RAW image transfer control unit 703. When the transmission requests from the time synchronous communication control unit 701, the reduced image transfer control unit 702, and the RAW image transfer control unit 703 overlap, the arbiter 704 grants permission to the transmission request with the highest priority among the overlapping transmission requests in accordance with the priority.

[0060] The time synchronous communication is given the highest priority because it is communication that governs timing, and therefore it is desirable to minimize delays, and the amount of communication per transaction is smaller than that of an image. As with the second embodiment, the transmission of reduced images and RAW images is given priority so that reduced images are transmitted in preference to RAW images. That is, in this embodiment, these three communications are processed in the order of highest priority: time synchronous communication, reduced image transmission, and RAW image transmission. The communication content for which transmission permission has been granted by the arbiter 704 is output to the interface 705 and transmitted from the radiation imaging apparatus 102.

[0061] An example of the operation of the radiation imaging apparatus 102 configured as described above with respect to time synchronous communication and transmission of reduced images and RAW images will be described with reference to Fig. 8. Fig. 8 is a diagram showing an example of the occurrence status of each transmission request for time synchronous communication, transmission of reduced images, and transmission of RAW images, and the communication content actually output to the interface unit, with the vertical axis being the time axis. In the time synchronous communication, transmission of reduced images, and transmission of RAW images, the solid line rectangles indicate the occurrence status of communication, and the dotted line rectangles indicate that communication has been interrupted by another communication with a higher priority.

[0062] 8, time synchronous communications 801, 802 are executed, for example, at predetermined timing (time intervals) based on a transmission request from the time synchronous communication control unit 701. Also, reduced image transmissions 811-814 are executed at the same frame rate as the shooting frame rate based on a transmission request from the reduced image transfer control unit 702. Also, RAW image (with time stamp) transmissions 821-823 are executed based on a transmission request from the RAW image transfer control unit 703.

[0063] In the example shown in FIG. 8, the transmission 814 of the reduced image overlaps with the time synchronous communication 802, which is a communication having a higher priority than the transmission of the reduced image, and the time synchronous communication 802 is executed by interrupting the transmission 814 of the reduced image. That is, the transmission 814 of the reduced image is interrupted by the time synchronous communication 802 and resumed after the completion of the time synchronous communication 802. In addition, the transmission 821 of the RAW image overlaps with the time synchronous communication 801, which is a communication having a higher priority than the transmission of the RAW image. The transmission 821 of the RAW image is interrupted by the time synchronous communication 801 and resumed after the completion of the time synchronous communication 801. The transmission 822 of the RAW image of the next frame overlaps with the transmissions 811 and 812 of the reduced images, which are communications having a higher priority than the transmission of the RAW image. The transmission 822 of the RAW image is interrupted by the transmission 811 of the reduced image and resumed after the completion of the transmission 811 of the reduced image, and then is interrupted again by the transmission 812 of the reduced image and resumed after the completion of the transmission 812 of the reduced image. The transmission 823 of the RAW image of the next frame overlaps with the time synchronous communication 802 and the reduced image transmissions 813 and 814, which are communications with a higher priority than the transmission of the RAW image. Therefore, the transmission 823 of the RAW image is interrupted by the transmission 813 of the reduced image, resumed after the transmission 813 of the reduced image is completed, and then interrupted again by the transmission 814 of the reduced image and the time synchronous communication 802, and resumed after these communications are completed. In other words, the transmission of the RAW image is performed when the time synchronous communication and the transmission of the reduced image are not being executed.

[0064] In this way, high priority communication interrupts low priority communication, and low priority communication communicates in the gaps between high priority communications. As a result, time-synchronized communication, transmission of reduced images, and transmission of RAW images are switched and executed, as shown in the interface section of Figure 8.

[0065] According to the third embodiment, similarly to the first embodiment, it is possible to appropriately link image data with position information while suppressing an increase in system cost. Also, it is possible to provide a radiation imaging system that accurately calculates volume data related to a subject while suppressing an increase in system cost. Also, it is possible to appropriately perform time synchronous communication, transmission of reduced images, and transmission of RAW images (with time stamps) by the radiation imaging apparatus 102 according to their respective priorities.

[0066] In the radiation imaging apparatus 102 in each of the above-described embodiments, the configuration for executing time synchronous communication, transmission of image data, etc. can be implemented using, for example, an FPGA or an ASIC, etc. Fig. 9 is a block diagram showing an example of the configuration of an FPGA that processes image data from a sensor panel and outputs it to an interface.

[0067] The FPGA has a control processor 901, a DRAM 902, a time synchronous communication processor 903, a capture DMAC 905, an image reduction calculator 906, a reduced image transmission DMAC 907, a general-purpose transmission DMAC 908, and a memory bus 909. The FPGA also has an arbiter 910 and an interface 911. The control processor 901, the DRAM 902, the capture DMAC 905, the image reduction calculator 906, the reduced image transmission DMAC 907, and the general-purpose transmission DMAC 908 are connected via the memory bus 909 so as to be able to communicate with each other.

[0068] The control processor 901 performs various controls in the radiation imaging apparatus 102. The DRAM (Dynamic Random Access Memory) 902 is a memory for storing image data and the like. The DRAM 902 is provided with areas for storing RAW images and reduced images. For RAW images, an area sufficient to store image data for all frames (frames 1, 2, ..., N) required for reconstruction calculation is provided. For reduced images, an area for storing image data for only one or a small number of frames is provided, since it is sufficient to overwrite and reuse each frame.

[0069] The time synchronous communication processor 903 communicates with an external time server and holds a time stamp value synchronized with the time server. The time synchronous communication processor 903 does not access images on the DRAM 902 because it does not handle image data.

[0070] A capture DMAC (Direct Memory Access Controller) 905 acquires image data (RAW image) of a radiation image generated by the sensor panel 904 and stores it in the DRAM 902. The capture DMAC 905 writes the image data acquired from the sensor panel 904 to an area of ​​an appropriate frame number in the RAW image area of ​​the DRAM 902 according to the number of frames from the start of imaging. At this time, the capture DMAC 905 receives a timestamp value from the time synchronization communication processor 903, and also writes the time when the image data was acquired to the DRAM 902.

[0071] The image reduction calculator 906 reads a RAW image from an area of ​​an appropriate frame number in the RAW image area of ​​the DRAM 902, and performs a reduction calculation to generate a reduced image by reducing the amount of data. The image reduction calculator 906 writes the generated reduced image to the reduced image area of ​​the DRAM 902.

[0072] The reduced image transmission DMAC 907 reads image data (reduced image) from the reduced image area of ​​the DRAM 902, and performs MAC header processing, IP header processing, UDP header processing, and reduced image transfer protocol processing to generate and transmit packet data. In this way, a wide range of protocol processing from low layers to application layers can be performed without using the computing power of the control processor 901, and reduced images can be transferred at high speed. In the radiation imaging apparatus 102 according to the first embodiment, since reduced images are not used, the image reduction calculator 906 and the reduced image transmission DMAC 907 may not be provided.

[0073] The general-purpose transmit DMAC 908 transmits packet data related to various communications other than the transmission of reduced images described above. For communications other than the transmission of reduced images (including the transmission of RAW images), packet data is generated by the processing of the control processor 901, and communication procedures are executed. The general-purpose transmit DMAC 908 does not have a packet generation function of the application layer, and executes transmission according to instructions from the control processor 901.

[0074] The arbiter 910 arbitrates transmission requests from the time synchronous communication processor 903, the reduced image transmission DMAC 907, and the general-purpose transmission DMAC according to the set priority. Transmission data from the time synchronous communication processor 903, the reduced image transmission DMAC 907, and the general-purpose transmission DMAC 908 is processed in order of priority by arbitration processing by the arbiter 910. The packet selected by the arbiter 910 is transmitted to an external device such as the reconstruction arithmetic device 110 through the interface 911.

[0075] (Another embodiment of the present invention) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiment 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. The present invention can also be realized by a circuit (e.g., ASIC) for implementing one or more of the functions.

[0076] It should be noted that the above-mentioned embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features.

[0077] The disclosure of the present embodiment includes the following configurations, methods, etc. (Configuration 1) an image generating means for generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first clock means for measuring a time when the image data is generated; A storage means for storing a plurality of the image data to which first time information indicating the time when the image data was generated is added; a communication means for transmitting a plurality of image data to which the first time information is added and which are stored in the storage means, The communication means transmits the image data at a frame rate slower than the first frame rate when the amount of data per unit time of the image data generated by the image generation means exceeds the amount of data that can be transmitted per unit time. (Configuration 2) 2. The radiation imaging apparatus according to configuration 1, wherein the first clock means performs communication with another clock means regarding time adjustment for synchronizing the times. (Configuration 3) an image processing unit that generates image data of a reduced image by reducing the amount of data based on the image data generated by the image generating unit; 3. The radiation imaging apparatus according to claim 1, wherein the communication means further transmits image data of the reduced image at the first frame rate. (Configuration 4) The radiographic imaging device described in configuration 3, characterized in that when there is a conflict between the transmission of image data to which the first time information has been added and the transmission of image data of the reduced image, the communication means transmits the image data of the reduced image. (Configuration 5) When at least two of the transmission of the image data to which the first time information is added, the transmission of the image data of the reduced image, and the communication related to time setting between the first clock means and another clock means conflict, the communication means The communication related to the time adjustment is processed with a higher priority than the transmission of the image data to which the first time information is added and the transmission of the image data of the reduced image; 4. The radiation imaging apparatus according to configuration 3, wherein the transmission of the image data of the reduced image is processed with priority over the transmission of the image data to which the first time information has been added. (System 1) The radiation imaging apparatus according to any one of configurations 1 to 5, a radiation source for irradiating the radiation imaging device with radiation. (System 2) a driving unit that changes a relative positional relationship between the radiation source, the radiation imaging device, and a subject; The radiation imaging system according to System 1, further comprising a position detection unit for acquiring position information relating to the radiation imaging device and the position of the subject. (System 3) The radiation imaging system described in System 2 is characterized in that it has a reconstruction calculation means for calculating the three-dimensional structure of the subject based on multiple image data to which the first time information is attached and which is transmitted from the radiation imaging device and the position information acquired by the position detection means. (System 4) a second clock means for measuring a time when the location information is acquired; The radiation imaging system described in System 3, characterized in that the reconstruction calculation means collects the position information accompanied by second time information indicating the time at which the position information was acquired, performs reconstruction calculation based on the correspondence between the image data based on the first time information and the second time information and the position information, and calculates the three-dimensional structure of the subject. (System 5) The radiation imaging system described in System 4, characterized in that the reconstruction calculation means acquires position information regarding the positions of the radiation imaging device and the subject at the time the image data was generated based on the position information to which the second time information has been added. (Method 1) an image generating step of generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first time measurement step of measuring a time when the image data is generated; a storage step of storing a plurality of the image data in a storage means, the image data being provided with first time information indicating the time when the image data was generated; a communication step of transmitting a plurality of image data to which the first time information is added and which are stored in the storage means; A method for controlling a radiation imaging apparatus, characterized in that, in the communication process, if the amount of data per unit time of the image data generated in the image generation process exceeds the amount of data that can be transmitted per unit time, the image data is transmitted at a frame rate slower than the first frame rate. (Method 2) an image generating step of generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate by the radiation imaging apparatus; a first timing step of measuring a time when the image data is generated by the radiation imaging apparatus; a storage step of storing, in a storage unit, a plurality of pieces of image data to which first time information indicating a time when the image data was generated is added by the radiation imaging apparatus; a communication step in which the radiation imaging apparatus transmits a plurality of image data to which the first time information is added and which are stored in the storage means, to a reconstruction calculation device; a position detection step in which the reconstruction calculation device acquires position information relating to positions of the radiation imaging device and a subject; a reconstruction calculation step of calculating a three-dimensional structure of the subject based on a plurality of image data to which the first time information is added and which are transmitted from the radiation imaging device and the position information acquired in the position detection step, A method for controlling a radiation imaging system, characterized in that, in the communication process, if the amount of data per unit time of the image data generated in the image generation process exceeds the amount of data that can be transmitted per unit time, the image data is transmitted at a frame rate slower than the first frame rate. (Program 1) an image generating step of generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first time measurement step of measuring a time when the image data is generated; a storage step of storing a plurality of the image data, to which first time information indicating a time when the image data was generated is added, in a storage means; a communication step of transmitting a plurality of image data to which the first time information stored in the storage means is added; A program for transmitting image data at a frame rate slower than the first frame rate in the communication step if the amount of data per unit time of the image data generated in the image generation step exceeds the amount of data that can be transmitted per unit time. (Program 2) an image generating step in which the radiation imaging apparatus generates image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first time measurement step in which the radiation imaging apparatus measures a time when the image data is generated; a storage step in which the radiation imaging apparatus stores in a storage means a plurality of the image data to which first time information indicating a time when the image data was generated is added; a communication step in which the radiation imaging apparatus transmits a plurality of image data to which the first time information is added and which are stored in the storage means, to a reconstruction calculation device; a position detection step in which the reconstruction calculation device acquires position information relating to positions of the radiation imaging device and a subject; a reconstruction calculation step in which the reconstruction calculation device calculates a three-dimensional structure of the subject based on a plurality of image data to which the first time information is added and which are transmitted from the radiation imaging device and the position information acquired in the position detection step, A program for transmitting image data at a frame rate slower than the first frame rate in the communication step if the amount of data per unit time of the image data generated in the image generation step exceeds the amount of data that can be transmitted per unit time. [Explanation of symbols]

[0078] 100: Radiation imaging system 101: Control device 102: Radiation imaging device 103, 105: Driving mechanism 104: Subject 106: Radiation source 107, 108: Position sensor 110: Reconstruction calculation device 201: Sensor panel 202: Image storage unit 203: Image processing unit 204, 211: Timer 205: Communication unit 206: Control unit

Claims

1. an image generating means for generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first clock means for measuring a time when the image data is generated; a storage means for storing a plurality of the image data to which first time information indicating a time when the image data was generated is added; a communication means for transmitting a plurality of image data to which the first time information is added and which are stored in the storage means, The communication means transmits image data at a frame rate slower than the first frame rate when the amount of data per unit time of the image data generated by the image generation means exceeds the amount of data that can be transmitted per unit time.

2. 2. The radiation imaging apparatus according to claim 1, wherein the first clock means performs communication with another clock means for adjusting the time to synchronize the times.

3. an image processing unit that generates image data of a reduced image by reducing the amount of data based on the image data generated by the image generating unit; 2. The radiation imaging apparatus according to claim 1, wherein the communication means further transmits image data of the reduced image at the first frame rate.

4. The radiographic imaging device according to claim 3, characterized in that when there is a conflict between the transmission of image data to which the first time information has been added and the transmission of image data of the reduced image, the communication means transmits the image data of the reduced image.

5. When at least two of the transmission of the image data to which the first time information is added, the transmission of the image data of the reduced image, and the communication related to time setting between the first clock means and another clock means conflict, the communication means The communication related to the time setting is processed with a higher priority than the transmission of the image data to which the first time information is added and the transmission of the image data of the reduced image; 4. The radiation imaging apparatus according to claim 3, wherein transmission of the image data of the reduced image is processed with priority over transmission of the image data to which the first time information is added.

6. A radiographic imaging apparatus according to any one of claims 1 to 5, a radiation source for irradiating the radiation imaging device with radiation.

7. a driving unit that changes a relative positional relationship between the radiation source, the radiation imaging device, and a subject; 7. The radiation imaging system according to claim 6, further comprising a position detection unit for acquiring position information relating to the radiation imaging device and the position of the subject.

8. 8. The radiation imaging system according to claim 7, further comprising a reconstruction calculation means for calculating a three-dimensional structure of the subject based on a plurality of image data to which the first time information is added and which are transmitted from the radiation imaging device and the position information acquired by the position detection means.

9. a second clock means for measuring a time when the location information is acquired; 9. The radiation imaging system according to claim 8, wherein the reconstruction calculation means collects the position information to which second time information indicating a time at which the position information was acquired is added, performs reconstruction calculation based on a correspondence relationship between the image data and the position information based on the first time information and the second time information, and calculates a three-dimensional structure of the subject.

10. The radiation imaging system according to claim 9, wherein the reconstruction calculation means acquires position information regarding positions of the radiation imaging apparatus and the subject at the time when the image data was generated based on the position information to which the second time information has been added.

11. an image generating step of generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first time measurement step of measuring a time when the image data is generated; a storage step of storing a plurality of the image data in a storage means, the image data being provided with first time information indicating a time when the image data was generated; a communication step of transmitting a plurality of image data to which the first time information stored in the storage means is added, A method for controlling a radiation imaging apparatus, characterized in that, in the communication process, if the amount of data per unit time of the image data generated in the image generation process exceeds the amount of data that can be transmitted per unit time, the image data is transmitted at a frame rate slower than the first frame rate.

12. an image generating step of generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate by the radiation imaging apparatus; a first time measurement step of measuring a time when the image data is generated by the radiation imaging apparatus; a storage step of storing, in a storage unit, a plurality of pieces of image data to which first time information indicating a time when the image data was generated is added by the radiation imaging apparatus; a communication step in which the radiation imaging apparatus transmits a plurality of image data to which the first time information is added and which are stored in the storage means, to a reconstruction calculation device; a position detection step in which the reconstruction calculation device acquires position information relating to positions of the radiation imaging device and a subject; a reconstruction calculation step of calculating a three-dimensional structure of the subject based on a plurality of image data to which the first time information is added and which are transmitted from the radiation imaging device and the position information acquired in the position detection step, A control method for a radiation imaging system, characterized in that, in the communication step, if the amount of data per unit time of the image data generated in the image generation step exceeds the amount of data that can be transmitted per unit time, the image data is transmitted at a frame rate slower than the first frame rate.

13. an image generating step of generating image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first time measurement step of measuring a time when the image data is generated; a storage step of storing the plurality of image data in a storage means, the image data being provided with first time information indicating a time when the image data was generated; a communication step of transmitting a plurality of image data to which the first time information stored in the storage means is added; A program for transmitting image data at a frame rate slower than the first frame rate in the communication step if the amount of data per unit time of the image data generated in the image generation step exceeds the amount of data that can be transmitted per unit time.

14. an image generating step in which the radiation imaging apparatus generates image data of a plurality of radiation images based on the irradiated radiation at a first frame rate; a first time measurement step in which the radiation imaging apparatus measures a time when the image data is generated; a storage step in which the radiation imaging apparatus stores in a storage unit a plurality of the image data to which first time information indicating a time when the image data was generated is added; a communication step in which the radiation imaging apparatus transmits a plurality of image data to which the first time information is added and which are stored in the storage means, from the radiation imaging apparatus to a reconstruction calculation apparatus; a position detection step in which the reconstruction calculation device acquires position information relating to positions of the radiation imaging device and a subject; a reconstruction calculation step in which the reconstruction calculation device calculates a three-dimensional structure of the subject based on a plurality of image data to which the first time information is added and which are transmitted from the radiation imaging device and the position information acquired in the position detection step, A program for transmitting image data at a frame rate slower than the first frame rate in the communication step if the amount of data per unit time of the image data generated in the image generation step exceeds the amount of data that can be transmitted per unit time.

Images