Radiation source surveying device, radiation source surveying system, radiation source surveying method, and program

Abstract

To provide a radiation source surveying device that can detect the position of a source of radiation even in an environment with a large number of obstacles, such as inside a building.SOLUTION: A radiation source surveying device estimates its self-position and is autonomously movable, and comprises: a radiation sensor unit that detects radiation arriving from a specific direction; and a control unit that acquires a result of detection performed by the radiation sensor unit and controls the movement of the radiation source surveying device. The control unit estimates the direction of a source of radiation on the basis of the result of detection performed by the radiation sensor unit, causes the radiation source surveying device to move in the estimated source direction, when the counting rate of radiation from the radiation sensor unit exceeds a threshold, causes the radiation source surveying device to stop the movement, and acquires the counting rate in the stopped state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radiation source detection device, a radiation source detection system, a radiation source detection method, and a program. [Background technology]

[0002] There are radiation source position detection methods that use multiple radiation detectors to detect the position of a radiation source. For example, in the radiation source position detection method described in Patent Document 1, three or more radiation detectors are arranged at different positions. A curved surface on which the radiation source exists is calculated based on the radiation incident on each radiation detector. Then, the position of the radiation source is detected by simultaneously solving equations for each curved surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-337176 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the radiation source position detection method described in Patent Document 1 has a problem in that it may not be possible to detect the position of the radiation source in an environment with many obstacles, such as inside a building.

[0005] The present invention has been made in consideration of the above circumstances, and provides a radiation source detection device, a radiation source detection system, a radiation source detection method, and a program that can detect the position of a radiation source even in an environment with many obstacles, such as inside a building. [Means for solving the problem]

[0006] The present invention has been made to solve the above-mentioned problems, and one aspect of the present invention is a radiation source tracking device that estimates its own position and is capable of moving autonomously, the radiation source tracking device comprising: a radiation sensor unit that detects radiation arriving from a specific direction; and a control unit that acquires the detection result of the radiation sensor unit and controls movement of the radiation source tracking device, the control unit estimating the direction of the radiation source based on the detection result of the radiation sensor unit, moving the radiation source tracking device in the estimated direction of the radiation source, and, when the count rate of the radiation detected by the radiation sensor unit exceeds a threshold, stopping the movement and acquiring the count rate in the stopped state.

[0007] Another aspect of the present invention is the above-mentioned radiation source detection device, wherein the control unit estimates the source direction of the radiation while changing the specific direction in which the radiation sensor unit detects the radiation.

[0008] Another aspect of the present invention is the above-mentioned radiation source detection device, wherein the radiation sensor unit includes a plurality of detection units that detect radiation arriving from different directions, and the control unit estimates the direction of the radiation source using the directions in which the two detection units detect the radiation when the difference in count rates between two of the plurality of detection units is within a predetermined range and the count rates of the two detection units are greater than the count rates of the remaining units.

[0009] Another aspect of the present invention is the radiation source detection device described above, wherein the radiation sensor unit includes a plurality of detection units that detect radiation arriving from different directions, and the control unit estimates, as the radiation source direction of the radiation, a direction opposite to a direction in which the detection unit with the lowest count rate among the plurality of detection units detects the radiation.

[0010] Another aspect of the present invention is the above-mentioned radiation source tracking device, which includes a communication unit capable of communicating with other radiation source tracking devices, and when the radiation sensor unit detects radiation, the control unit uses the communication unit to notify the other radiation source tracking device of the location of the radiation source tracking device.

[0011] Another aspect of the present invention is a radiation source tracking system including a plurality of radiation source tracking devices as described above, and a radiation source estimation device that collects count rates and radiation source directions from each of the plurality of radiation source tracking devices and estimates the position of the radiation source.

[0012] Another aspect of the present invention is a method for detecting a radiation source using a radiation source detection device that estimates its own position and is capable of moving autonomously, the method comprising the steps of: estimating the direction of the radiation source based on the detection result of a radiation sensor unit that detects radiation arriving from a specific direction; moving the radiation source detection device in the estimated direction of the radiation source; and, when the count rate of the radiation detected by the radiation sensor unit exceeds a threshold, stopping the movement and acquiring the count rate in the stopped state.

[0013] Another aspect of the present invention is a program for causing a computer of a radiation source tracking device that estimates its own position and is capable of moving autonomously to execute the following steps: estimating the direction of the radiation source based on the detection result of a radiation sensor unit that detects radiation arriving from a specific direction; moving the radiation source tracking device in the estimated direction of the radiation source; and, if the count rate of the radiation detected by the radiation sensor unit exceeds a threshold, stopping the movement and acquiring the count rate in the stopped state. [Effects of the Invention]

[0014] According to the present invention, the position of a radiation source can be detected even in an environment with many obstacles. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic block diagram showing the configuration of a radiation source exploration system 10 according to an embodiment of the present invention. [Figure 2] 2 is a schematic block diagram showing the configuration of a radiation source tracing device 100 according to the embodiment. FIG. [Figure 3] FIG. 2 is a perspective view showing the appearance of a radiation detection unit 110 in the same embodiment. [Figure 4] 10 is a flowchart illustrating the operation of the radiation source detection device 100 in the embodiment. [Figure 5] 1 is a schematic diagram showing an example of measurement by a plurality of radiation source exploration devices 100a to 100f in the embodiment. [Figure 6] 10 is a schematic diagram showing an example of measurement using a plurality of radiation source detection devices 100g to 100k in the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of a radiation source tracking system 10 according to an embodiment of the present invention. The radiation source tracking system 10 includes multiple radiation source tracking devices 100 and a radiation source estimation device 300. Each of the multiple radiation source tracking devices 100 is a robot equipped with a radiation sensor for detecting radiation, capable of estimating its own position, and capable of autonomous movement. Note that the radiation source tracking device 100 may move by other means, including three-dimensional movement, such as flying, navigating, or walking, rather than by running. Note that, here, being autonomously mobile means being able to move without receiving step-by-step instructions, and may move along a predetermined route or may determine its own route. The radiation source estimation device 300 collects radiation detection results (counting rates) and radiation source directions from the multiple radiation source tracking devices 100, and estimates the position of the radiation source. The radiation source estimation device 300 may be implemented by one or more computers reading and executing a program. A method for estimating the position of a radiation source may, for example, be to perform inverse problem analysis based on the radiation detection results obtained by the radiation source tracking device 100, thereby estimating the position of the radiation source in three-dimensional space, but is not limited to this. When solving the inverse problem, unfolding calculations or deep learning may be used, for example. Furthermore, by integrating and analyzing the radiation detection results (counting rates) obtained by multiple radiation source tracking devices 100, it is possible to achieve more accurate estimation than when estimating based on the detection results obtained from a single radiation source tracking device 100.

[0017] The plurality of radiation source tracking devices 100 and the radiation source estimation device 300 are communicably connected to each other via a network 200. The network 200 may include a multi-hop network formed by the plurality of radiation source tracking devices 100.

[0018] 2 is a schematic block diagram showing the configuration of the radiation source tracking device 100 in this embodiment. The radiation source tracking device 100 includes a radiation detection unit 110, a control unit 120, a navigation function unit 130, a position detection sensor unit 140, and a communication unit 150. The radiation detection unit 110 includes a first direction detection unit 111, a second direction detection unit 112, a third direction detection unit 113, and an omnidirectional detection unit 114.

[0019] Each of the first direction detection unit 111, the second direction detection unit 112, and the third direction detection unit 113 (radiation sensor unit) detects radiation arriving from a different specific direction more strongly. The omnidirectional detection unit 114 detects radiation arriving from all directions. Each of the first direction detection unit 111, the second direction detection unit 112, the third direction detection unit 113, and the omnidirectional detection unit 114 may include a scintillator such as bismuth germanate and a photomultiplier tube, and may detect radiation by amplifying the light emitted by the scintillator in response to incident radiation using the photomultiplier tube. The first direction detection unit 111, the second direction detection unit 112, and the third direction detection unit 113 may be configured to detect radiation arriving from a specific direction more weakly, i.e., to have more anisotropy in the detection direction, by shielding radiation incident from directions other than the specific direction with a shield such as lead. Note that the radiation detection unit is not limited to this embodiment as long as it can detect radiation anisotropically.

[0020] The control unit 120 acquires the detection results from the first direction detection unit 111, the second direction detection unit 112, the third direction detection unit 113, and the omnidirectional detection unit 114. The control unit 120 also controls the movement of the radiation source tracking device 100 based on the detection results. For example, the control unit 120 estimates the direction of the radiation source based on the detection result from the radiation detection unit 110, and moves the radiation source tracking device in the estimated direction of the radiation source. Then, when the count rate of radiation detected by the radiation detection unit 110 exceeds a threshold, the control unit 120 stops the movement and acquires the count rate in the stopped state. The control unit 120 also estimates the self-position of the radiation source tracking device 100 using the detection result from the position detection sensor unit 140. Any method for estimating the self-position may be used, but for example, if the position detection sensor unit 140 is an inertial measurement unit, a method for estimating the self-position may be used that estimates the self-position from acceleration, angular velocity, etc., or if the position detection sensor unit 140 is a LiDAR (Light Detection And Ranging or LIDAR (Laser Imaging Detection And Ranging)), a method for estimating the self-position may be used that compares the situation around the radiation source exploration device 100 with a stored map. In addition, it is of course possible to use a GPS (Global Positioning System) depending on the place of use, etc.

[0021] The traveling function unit 130 includes tracks or wheels for propelling the radiation source investigation device 100, a motor for driving the tracks or wheels, etc. The traveling function unit 130 is not limited to these, and may be a flying device such as a drone, a navigable device, or a walking device such as a robot. The traveling function unit 130 changes the orientation and moves the radiation source investigation device 100 under the control of the control unit 120. The position detection sensor unit 140 is a sensor for detecting the self-position of the radiation source tracking device 100. The position detection sensor unit 140 may, for example, detect the number of rotations of each wheel of the traveling function unit 130, or may be an inertial measurement unit that detects acceleration, angular velocity, angular acceleration, etc., or may be a sensor such as LiDAR that detects the situation around the radiation source tracking device 100. Of course, GPS can also be used depending on the location of use, etc.

[0022] The communication unit 150 communicates with other radiation source identification devices 100 and radiation source estimation devices 300. The communication by the communication unit 150 may be performed using any method such as a wireless local area network (LAN) or Bluetooth (registered trademark).

[0023] 3 is a perspective view showing the appearance of the radiation detection unit 110 in this embodiment. Scintillators S1, S2, S3, and S4 are the scintillators of the first direction detection unit 111, the second direction detection unit 112, the third direction detection unit 113, and the omnidirectional detection unit 114, respectively. Scintillators S1, S2, and S3 are arranged at equal intervals on a disk-shaped base plate B1, and lead shielding walls W1, W2, and W3 are disposed between the scintillators. Therefore, radiation mainly arrives at each of the scintillators S1, S2, and S3 from directions within 120° where no shielding walls are installed. Because scintillator S4 is installed above the shielding walls W1, W2, and W3, radiation arrives from all directions (360°).

[0024] FIG. 4 is a flowchart illustrating the operation of the radiation source tracking device 100 according to this embodiment. First, the radiation source tracking device 100 performs a random walk, which is a random movement (step Sa1). The movement range of the random walk may be set in advance. For example, when a multi-hop network is configured with multiple radiation source tracking devices 100, the movement range of each radiation source tracking device 100 may be set so that communication is possible with adjacent radiation source tracking devices 100. The radiation source tracking device 100 may also travel along a planned route instead of a random walk. When a movement range is set, it is preferable for the radiation source tracking device 100 to travel thoroughly within the movement range, regardless of the method for setting the movement, because this allows for more accurate detection of the position of a radiation source within the movement range.

[0025] The control unit 120 of the radiation source tracking device 100 determines whether radiation has been detected (step Sa2). This determination may use the detection results from all of the first direction detection unit 111, second direction detection unit 112, third direction detection unit 113, and omnidirectional detection unit 114, or may use only the detection result from the omnidirectional detection unit 114, and may prevent power from being supplied to the first direction detection unit 111, second direction detection unit 112, and third direction detection unit 113 during the random walk in step Sa1. Alternatively, whether radiation has been detected may be determined based on whether the counting rate exceeds a preset threshold.

[0026] If it is determined in step Sa2 that radiation has been detected (step Sa2-Yes), the control unit 120 of the radiation source tracking device 100 notifies the other radiation source tracking devices 100 that radiation has been detected via the communication unit 150 (step Sa3). This notification may include information indicating the self-position estimated by the radiation source tracking device 100 and information indicating the radiation counting rate. Furthermore, the other radiation source tracking devices 100 to which this notification is sent may be multiple, or may be limited to only those that satisfy any of the following conditions: those within a predetermined distance from the radiation source tracking device 100, those that can directly receive this notification, and those that have not detected radiation.

[0027] Next, the control unit 120 of the radiation source tracking device 100 estimates the direction of the radiation source (radiation source direction) (step Sa4). The radiation source direction may be estimated, for example, as follows. The radiation source tracking device 100 performs measurements while changing the specific direction in which each direction detection unit detects radiation, for example, by changing the orientation of the device itself or by rotating the radiation detection unit 110, and estimates the radiation source direction. For example, if the difference in count rates between two of the first direction detection unit 111, the second direction detection unit 112, and the third direction detection unit 113 is within a predetermined range and the count rate between the two is greater than the remaining count rate, the control unit 120 determines the estimated radiation source direction to be the center direction of the directions in which the two direction detection units detect radiation, or the opposite direction to the direction in which the remaining direction detection unit detects radiation. In addition, the control unit 120 may estimate the direction opposite to the direction in which the direction detection unit with the lowest count rate among the first direction detection unit 111, the second direction detection unit 112, and the third direction detection unit 113 detects the radiation as the direction of the radiation source.

[0028] Note that two count rate values ​​being sufficiently close may mean that the difference between the two count rates is less than or equal to a predetermined threshold, or that the ratio between the two count rates is within a predetermined range. Furthermore, a remaining count rate value being sufficiently smaller than two count rate values ​​may mean that the result of subtracting the remaining count rate value from the average of the two count rate values ​​is equal to or greater than a predetermined threshold, or that the result of dividing the average of the two count rate values ​​by the remaining count rate is equal to or greater than a predetermined threshold. The radiation source tracking device 100 may estimate the radiation source direction while moving or stationary. In addition to the conditions that the two count rate values ​​are sufficiently close and the remaining count rate value is sufficiently smaller than the two count rate values, a condition that the two count rate values ​​are sufficiently smaller than the count rate detected by the omnidirectional detection unit 114 may be added.

[0029] Next, the radiation source tracking device 100 moves in the direction of the radiation source estimated in step Sa4 (step Sa5). The radiation source tracking device 100 continues to detect radiation during the movement in step Sa5, and after a predetermined time has passed or after the device has moved a predetermined distance, the control unit 120 determines whether the count rate is equal to or greater than a preset threshold (step Sa6). This determination in step Sa6 may be based on whether the count rate exceeds a preset threshold (for example, the threshold may be set to "average value + 2 × σ" or "average value + 3 × σ" using the average value and standard deviation σ of the count rates measured from step Sa1 to step Sa6). This count rate may also be the count rate measured while the radiation source tracking device 100 is moving. This count rate may also be the count rate measured after the device has stopped moving in step Sa5 for a predetermined time or after moving a predetermined distance. Furthermore, this counting rate may be measured by one of the first direction detection unit 111, the second direction detection unit 112, and the third direction detection unit 113 that is facing the estimated radiation source direction, or it may be measured by the omnidirectional detection unit 114.

[0030] If it is determined in step Sa6 that the count rate is not equal to or greater than the threshold (step Sa6-No), the radiation source tracking device 100 returns to step Sa4 and estimates the radiation source direction. If it is determined in step Sa6 that the count rate is equal to or greater than the threshold (step Sa6-Yes), the radiation source tracking device 100 stops and measures the count rate (step Sa7). This measurement may be performed by one of the first direction detection unit 111, the second direction detection unit 112, and the third direction detection unit 113 that is facing the radiation source direction, or by the omnidirectional detection unit 114. Furthermore, when performing this measurement, the radiation source tracking device 100 may estimate the radiation source direction and change its orientation so that any one of the first direction detection unit 111, the second direction detection unit 112, and the third direction detection unit 113 faces the radiation source direction.

[0031] Next, the control unit 120 of the radiation source tracking device 100 transmits the count rate measured in step Sa7, the estimated radiation source direction, and its own position to the radiation source estimation device 300 via the communication unit 150 (step Sa8). By receiving this transmission from multiple radiation source tracking devices 100, the radiation source estimation device 300 becomes able to estimate the position, shape, etc. of the radiation source.

[0032] On the other hand, if it is determined in step Sa2 that radiation has not been detected (step Sa2-No), the control unit 120 of the radiation source tracking device 100 determines whether or not there has been a notification from another radiation source tracking device 100 via the communication unit 150 (step Sa9). Here, the notification from the other radiation source tracking device 100 is a notification indicating that the other radiation source tracking device 100 has detected radiation, and is the notification from step Sa3 of the other radiation source tracking device 100. If it is determined that there has been no notification from the other radiation source tracking device 100 (step Sa9-No), the radiation source tracking device 100 returns to step Sa1 and performs a random walk.

[0033] On the other hand, if it is determined in step Sa9 that a notification has been received from another radiation source tracking device 100 (step Sa9—Yes), the radiation source tracking device 100 moves in the direction of the other radiation source tracking device 100 based on the location of the other radiation source tracking device 100 included in the notification (step Sa10). The radiation source tracking device 100 continues to detect radiation while moving in step Sa10, and after a predetermined time has passed or after moving a predetermined distance, the control unit 120 determines whether the count rate is equal to or greater than a preset threshold (step Sa11). This determination is the same as in step Sa6. If it is determined in step Sa11 that the count rate is not equal to or greater than the threshold (step Sa11—No), the radiation source tracking device 100 returns to step Sa10 and moves in the direction of the other radiation source tracking device 100. If it is determined in step Sa11 that the count rate is equal to or greater than the threshold (step Sa11—Yes), the radiation source tracking device 100 proceeds to step Sa7, stops, and measures the count rate.

[0034] As described above, the radiation source tracking device 100 performs measurements autonomously by performing random walks, etc., and can therefore perform measurements even when there are obstacles such as walls or leftover objects. Furthermore, the radiation source tracking device 100 stops measuring the counting rate for transmission only after the counting rate reaches or exceeds a threshold, thereby improving the accuracy of the counting rate. Furthermore, when the radiation detection unit 110 (radiation sensor unit) detects radiation, the control unit 120 of the radiation source tracking device 100 notifies other radiation source tracking devices 100 of the location (self-location) of the radiation source tracking device 100 using the communication unit 150. The other radiation source tracking devices 100 then move and gather near the target radiation source and perform measurements from multiple locations toward the target radiation source. This allows for early detection of a radiation source and allows multiple radiation source tracking devices 100 to measure the same radiation source in parallel, thereby enabling highly accurate estimation of the radiation source's location, etc. After the multiple radiation source tracking devices 100 have performed measurements of the same radiation source, the flow returns to the start of FIG. 4 and the radiation source tracking device 100 starts random walking. When setting the movement range of the radiation source tracking device 100, the flow shown in FIG. 4 can be repeated to thoroughly travel through the movement range and measure the locations of radiation sources present within the movement range with higher accuracy. The radiation source tracking device 100 can also be configured to move to a pre-set location after thoroughly traveling and measuring the movement range. Alternatively, the radiation source tracking device 100 can also be configured to move to a pre-set location after traveling for a certain period of time. Even if the radiation source tracking device 100 has completed traveling and measuring the planned route or the movement range, if no radiation source with a certain intensity or higher is found, the count rate will not be greater than the threshold, and the flow chart of FIG. 4 will not end. In such cases, various changes can be made depending on the usage situation, such as ending the program after driving and measuring the planned route or after driving the entire area of ​​movement, or after driving for a certain period of time.

[0035] FIG. 5 is a schematic diagram showing an example of measurements performed by multiple radiation source tracking devices 100a-100f in this embodiment. Each of the radiation source tracking devices 100a-100f is the radiation source tracking device 100 shown in FIGS. 1 and 2. The schematic diagram in FIG. 5 shows an example in which multiple radiation source tracking devices 100a-100f are measuring a radiation source R1 that is larger than the other radiation source tracking devices. When the radiation source R1 is large, the radiation source tracking devices 100a-100f gather around it to measure the counting rate and transmit the counting rate to the radiation source estimation device 300. Using at least the positions and counting rates of the radiation source tracking devices 100a-100f, the radiation source estimation device 300 can estimate the outline of the radiation source R1, the intensity distribution of the radiation dose, and the like.

[0036] FIG. 6 is a schematic diagram showing an example of measurement by multiple radiation source tracking devices 100g to 100k in this embodiment. Each of the radiation source tracking devices 100g to 100k is the radiation source tracking device 100 shown in FIGS. 1 and 2. The schematic diagram in FIG. 6 shows an example in which the multiple radiation source tracking devices 100g to 100k measure two radiation sources R2 and R3. When multiple radiation sources R2 and R3 are present, the radiation source tracking devices 100g to 100k gather around each of the multiple radiation sources R2 and R3 to measure the count rate and transmit the measured count rate to the radiation source estimation device 300. This allows the radiation source estimation device 300 to estimate the position, etc., of each of the multiple radiation sources R2 and R3.

[0037] The present invention may be embodied as follows. (1) One embodiment of the present invention is a radiation source tracking device that estimates its own position and is capable of moving autonomously, and includes a radiation sensor unit that detects radiation arriving from a specific direction, and a control unit that acquires the detection results of the radiation sensor unit and controls movement of the radiation source tracking device, wherein the control unit estimates the source direction of the radiation based on the detection results of the radiation sensor unit, moves the radiation source tracking device in the estimated source direction, and stops movement when the radiation count rate of the radiation sensor unit exceeds a threshold, and acquires the count rate in the stopped state.

[0038] (2) Another embodiment of the present invention is a radiation source detection device as described in (1), wherein the control unit estimates the source direction of the radiation while changing the specific direction in which the radiation sensor unit detects the radiation.

[0039] (3) Another embodiment of the present invention is a radiation source detection device as described in (1) or (2), wherein the radiation sensor unit includes a plurality of detection units that detect radiation arriving from different directions, and the control unit estimates the direction of the radiation source using the directions in which the two detection units detect the radiation when the difference in count rates between two of the plurality of detection units is within a predetermined range and the count rates of the two detection units are greater than the count rates of the remaining units.

[0040] (4) Another embodiment of the present invention is a radiation source detection device according to any one of (1) to (3), wherein the radiation sensor unit includes a plurality of detection units that detect radiation arriving from different directions, and the control unit estimates, as the radiation source direction of the radiation, a direction opposite to the direction in which the detection unit with the lowest count rate among the plurality of detection units detects the radiation.

[0041] (5) Another embodiment of the present invention is a radiation source tracking device according to any one of (1) to (3), comprising a communication unit capable of communicating with other radiation source tracking devices, and when the radiation sensor unit detects radiation, the control unit uses the communication unit to notify the other radiation source tracking device of the location of the radiation source tracking device.

[0042] (6) Another embodiment of the present invention is a radiation source detection system including a plurality of radiation source detection devices according to any one of (1) to (5) above, and a radiation source estimation device that collects count rates and radiation source directions from each of the plurality of radiation source detection devices and estimates the position of the radiation source.

[0043] (7) Another embodiment of the present invention is a method for detecting a radiation source using a radiation source detection device that estimates its own position and is capable of moving autonomously, the method comprising the steps of: estimating the direction of the radiation source based on the detection result of a radiation sensor unit that detects radiation arriving from a specific direction; moving the radiation source detection device in the estimated direction of the radiation source; and, when the count rate of the radiation detected by the radiation sensor unit exceeds a threshold, stopping the movement and acquiring the count rate in the stopped state.

[0044] (8) Another embodiment of the present invention is a program for causing a computer of a radiation source tracking device that estimates its own position and is capable of moving autonomously to execute the following steps: estimating the direction of the radiation source based on the detection result of a radiation sensor unit that detects radiation arriving from a specific direction; moving the radiation source tracking device in the estimated direction of the radiation source; and, if the count rate of the radiation detected by the radiation sensor unit exceeds a threshold, stopping the movement and acquiring the count rate in the stopped state.

[0045] 1 and the control unit 120 in Fig. 2 may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to realize the radiation source estimation apparatus 300 and the control unit 120. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0046] "Computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" also includes devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or over communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within computer systems that serve as servers or clients. The programs may also be programs that implement some of the aforementioned functions, or may be programs that can realize the aforementioned functions in combination with programs already stored in the computer system.

[0047] The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0048] 10. Radiation Source Detection System 100, 100a~100k Radiation source detection device 110 Radiation detection unit 111 First direction detection unit 112 Second direction detection unit 113 Third direction detection unit 114 Omnidirectional detection unit 120 control section 130 Traveling function unit 140 Position detection sensor unit 150 Communications Department

Claims

1. A radiation source detection device that estimates its own position and is capable of moving autonomously, a radiation sensor unit that detects radiation arriving from a specific direction; a control unit that acquires the detection result of the radiation sensor unit and controls the movement of the radiation source tracking device; Equipped with The control unit estimating a radiation source direction of the radiation based on the detection result of the radiation sensor unit; moving the radiation source tracking device in the estimated direction of the radiation source; When the count rate of the radiation by the radiation sensor unit exceeds a threshold, the movement is stopped and the count rate in the stopped state is acquired. Radiation source detection equipment.

2. The radiation source tracking device according to claim 1 , wherein the control unit estimates the direction of the radiation source while changing the specific direction in which the radiation sensor unit detects the radiation.

3. the radiation sensor unit includes a plurality of detection units that detect radiation arriving from different directions, when a difference between count rates of two of the plurality of detection units is within a predetermined range and the count rates of the two detection units are greater than the count rates of the remaining detection units, the control unit estimates a radiation source direction of the radiation using directions in which the two detection units detect radiation; The radiation source detection device according to claim 1.

4. the radiation sensor unit includes a plurality of detection units that detect radiation arriving from different directions, the control unit estimates, as a radiation source direction of the radiation, a direction opposite to a direction in which a detection unit having the lowest count rate among the plurality of detection units detects radiation; The radiation source detection device according to claim 1.

5. a communication unit capable of communicating with other radiation source detection devices; When the radiation sensor unit detects radiation, the control unit notifies the other radiation source tracking device of the position of the radiation source tracking device using the communication unit. The radiation source detection device according to claim 1.

6. A plurality of radiation source detection devices according to any one of claims 1 to 5; a radiation source estimation device that collects count rates and radiation source directions from each of the plurality of radiation source tracking devices and estimates the position of a radiation source; A radiation source detection system comprising:

7. A radiation source exploration method using a radiation source exploration device that estimates its own position and is capable of moving autonomously, comprising: a step of estimating a radiation source direction of the radiation based on a detection result of a radiation sensor unit that detects radiation arriving from a specific direction; moving the radiation source tracking device in the estimated direction of the radiation source; a step of stopping movement when the count rate of the radiation by the radiation sensor unit exceeds a threshold value, and acquiring the count rate in a stopped state; A radiation source detection method comprising:

8. The computer of the radiation source detection device, which can estimate its own position and move autonomously, a step of estimating a radiation source direction of the radiation based on a detection result of a radiation sensor unit that detects radiation arriving from a specific direction; moving the radiation source tracking device in the estimated direction of the radiation source; a step of stopping movement when the count rate of the radiation by the radiation sensor unit exceeds a threshold value, and acquiring the count rate in a stopped state; A program to execute.

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