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

Abstract

The invention provides a radiation source detection device capable of detecting the position of a radiation source even in an environment with many obstacles, such as a building. A radiation source detection device capable of estimating its own position and autonomously moving is provided with: a radiation sensor unit that detects incoming radiation from a specific direction; and a control unit that acquires a detection result from the radiation sensor unit and controls movement of the radiation source detection device, the control unit estimates a line source direction of the radiation on the basis of the detection result from the radiation sensor unit, and the control unit moves the radiation source detection device in the estimated line source direction. When the counting rate of radiation by the radiation sensor unit exceeds a threshold value, the control unit stops the movement and acquires the counting rate in the stopped state.

Description

TECHNICAL FIELD

[0001] The present application relates to a radioactive source probe device, a radioactive source probe system, a radioactive source probe method, and a program.

[0002] This application claims priority based on Japanese Application No. 2024-050873 filed on March 27, 2024, and the content thereof is incorporated herein. BACKGROUND

[0003] There is a radioactive source position detection method that uses a plurality of radioactive ray detectors to detect the position of a radioactive ray source. For example, in the radioactive source position detection method described in Patent Literature 1, three or more radioactive ray detectors are arranged at different positions. Each radioactive ray detector calculates a curved surface on which a radioactive ray source is located, based on the incident radioactive ray. Then, the position of the radioactive ray source is detected by simultaneously solving the equations of the curved surfaces.

[0004] PRIOR ART DOCUMENTS Patent Literature 1: Japanese Patent Application Publication No. 2003-337176 SUMMARY PROBLEMS TO BE SOLVED BY THE INVENTION However, in the radioactive source position detection method described in Patent Literature 1, in an environment in which there are many obstacles such as in a building, there is a problem that the position of the radioactive ray source cannot be detected at times.

[0005] The present application was made in view of such circumstances, and provides a radioactive source probe device, a radioactive source probe system, a radioactive source probe method, and a program that can detect the position of a radioactive ray source even in an environment in which there are many obstacles such as in a building.

[0006] SOLUTION TO THE PROBLEM The present application was made in view of such circumstances, and provides a radioactive source probe device, a radioactive source probe system, a radioactive source probe method, and a program that can detect the position of a radioactive ray source even in an environment in which there are many obstacles such as in a building.

[0007] Further, another aspect of the present application is the above-described radiation source search device, wherein the control section estimates the line source direction of the radiation while changing the specific direction in which the radiation sensor section detects the radiation.

[0008] Further, another aspect of the present application is the above-described radiation source search device, wherein the radiation sensor section includes a plurality of detection sections that detect the radiation from different directions, and the control section estimates the line source direction of the radiation using the two detection sections that detect the direction of the radiation when the difference between the count rates of the two detection sections is within a predetermined range and the count rate of the two detection sections is greater than the count rate of each of the remaining detection sections.

[0009] Further, another aspect of the present application is the above-described radiation source search device, wherein the radiation sensor section includes a plurality of detection sections that detect the radiation from different directions, and the control section estimates the line source direction of the radiation using the two detection sections that detect the direction of the radiation when the difference between the count rates of the two detection sections is within a predetermined range and the count rate of the two detection sections is greater than the count rate of each of the remaining detection sections.

[0010] Further, another aspect of the present application is the above-described radiation source search device, wherein the radiation source search device includes a communication section that communicates with another radiation source search device, and the control section notifies the position of the radiation source search device to the other radiation source search device using the communication section when the radiation sensor section detects the radiation.

[0011] Further, another aspect of the present application is a radiation source search system that includes: a plurality of the above-described radiation source search devices; and a line source estimation device that collects the count rates and the line source directions of the respective radiation source search devices to estimate the position of the line source of the radiation.

[0012] Further, another aspect of the present application is a radiation source search method based on a radiation source search device that can estimate its own position and autonomously move, the radiation source search method including: a step of estimating the line source direction of the radiation based on the detection result of a radiation sensor section that detects the radiation from a specific direction; a step of moving the radiation source search device to the estimated line source direction; and a step of stopping the movement and acquiring the count rate in the stopped state when the count rate of the radiation based on the radiation sensor section exceeds a threshold value.

[0013] Further, another aspect of the present application is a program for causing a computer of a radioactive source search device capable of estimating a self position and autonomously moving to execute the steps of: estimating a line source direction of a radioactive ray based on a detection result of a radioactive ray sensor section that detects a radioactive ray coming from a specific direction; moving the radioactive source search device to the estimated line source direction; and stopping the movement and acquiring a count rate in a stopped state when a count rate of the radioactive ray based on the radioactive ray sensor section exceeds a threshold value.

[0014] Effects of Invention According to the present application, a position of a radioactive ray source can be detected even in an environment where there are many obstacles. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic block diagram showing a structure of a radioactive source search system 10 of one embodiment of the present application.

[0016] Figure 2 is a schematic block diagram showing a structure of a radioactive source search device 100 in this embodiment.

[0017] Figure 3 is a perspective view showing an appearance of a radioactive ray detection section 110 in this embodiment.

[0018] Figure 4 is a flowchart showing an operation of the radioactive source search device 100 in this embodiment.

[0019] Figure 5 is a schematic view showing an example of measurement performed by a plurality of radioactive source search devices 100a to 100f in this embodiment.

[0020] Figure 6 is a schematic view showing an example of measurement performed by a plurality of radioactive source search devices 100g to 100k in this embodiment. DETAILED DESCRIPTION

[0021] Embodiments of the present application will be described below with reference to the drawings. Figure 1is a schematic block diagram showing the structure of a radiation source exploration system 10 according to an embodiment of the present application. The radiation source exploration system 10 includes a plurality of radiation source exploration devices 100, and a line source estimation device 300. The plurality of radiation source exploration devices 100 each include a radiation sensor that detects radiation, and are robots that can estimate their own positions and autonomously travel. Note that the radiation source exploration devices 100 can also move by flying, sailing, walking, or other methods of movement that include three-dimensional movement, rather than by traveling. Also, the ability to autonomously move here means that the radiation source exploration devices 100 can move without being instructed one by one, and can move on a path that is set in advance or a path that is determined by the radiation source exploration devices 100 themselves. The line source estimation device 300 collects the detection results (count rates) of radiation and the directions of line sources of the plurality of radiation source exploration devices 100, and estimates the positions of the line sources of the radiation. The line source estimation device 300 can also be realized by one or more computers reading in and executing a program. As a method of estimating the positions of the line sources of the radiation, for example, the positions of the line sources of the radiation in three-dimensional space can be estimated by performing inverse problem analysis based on the detection results of the radiation of the radiation source exploration devices 100, but are not limited thereto. When solving the inverse problem, for example, unfolding calculation or deep learning can also be used. Also, by performing analysis by synthesizing the detection results (count rates) of the radiation of the plurality of radiation source exploration devices 100, the estimation can be performed with higher accuracy than when the estimation is performed based on the detection results obtained from one radiation source exploration device 100.

[0022] The plurality of radiation source exploration devices 100 and the line source estimation device 300 are connected in a manner that enables them to communicate with each other via a network 200. Note that the network 200 can also include a multi-hop network based on the plurality of radiation source exploration devices 100.

[0023] Figure 2 is a schematic block diagram showing the structure of a radiation source exploration device 100 according to the present embodiment. The radiation source exploration device 100 includes a radiation detection section 110, a control section 120, a travel function section 130, a position detection sensor section 140, and a communication section 150. The radiation detection section 110 includes a first direction detection section 111, a second direction detection section 112, a third direction detection section 113, and an omnidirectional detection section 114.

[0024] The first direction detection section 111, the second direction detection section 112, and the third direction detection section 113 each (radiation sensor section) detect radiation more strongly coming from a different specific direction. The omnidirectional detection section 114 detects radiation coming from all directions. It can also be that the first direction detection section 111, the second direction detection section 112, the third direction detection section 113, and the omnidirectional detection section 114 each have a scintillator such as bismuth germanate and a photomultiplier tube, and detect radiation by amplifying the light emission of the scintillator caused by the incidence of radiation using the photomultiplier tube. The first direction detection section 111, the second direction detection section 112, and the third direction detection section 113 can also detect radiation more weakly coming from a specific direction by shielding radiation incident from other than the specific direction with a shield such as lead, that is, be more anisotropic in the detection direction. Furthermore, the radiation detection section can be any manner in which radiation can be detected anisotropically, and is not limited to the present embodiment.

[0025] The control section 120 acquires the detection results of the first direction detection section 111, the second direction detection section 112, the third direction detection section 113, and the omnidirectional detection section 114. In addition, the control section 120 controls the movement of the radiation source search device 100 based on the detection results. For example, the control section 120 estimates the line source direction of the radiation based on the detection results of the radiation detection section 110, and causes the radiation source search device to move in the estimated line source direction. Then, the control section 120 stops the movement in a case where the count rate of the radiation of the radiation detection section 110 exceeds a threshold value, and acquires the count rate in the stopped state. In addition, the control section 120 estimates the own position of the radiation source search device 100 using the detection results of the position detection sensor section 140. The method of estimating the own position can be any method, for example, if the position detection sensor section 140 is an inertial measurement unit, it can be a method of estimating the own position from acceleration, angular velocity, and the like, for example, if the position detection sensor section 140 is a LiDAR (Light Detection And Ranging or LIDAR (Laser Imaging Detection And Ranging)), it can also be a method of estimating the own position from a comparison of the situation around the radiation source search device 100 and a stored map. Furthermore, of course, it can also use a GPS (Global Positioning System) according to the place of use or the like.

[0026] The traveling function section 130 has a track or a wheel for traveling of the radioactive source exploration device 100, a motor or the like for driving the track or the wheel. The traveling function section 130 is not limited to this, and can be a device capable of flying like a drone, a device capable of sailing, or a device capable of walking like a robot. The traveling function section 130 changes the orientation of the radioactive source exploration device 100 or moves it in accordance with the control of the control section 120.

[0027] The position detection sensor section 140 is a sensor for detecting the position of the radioactive source exploration device 100. The position detection sensor section 140 can detect the rotation speed of each wheel of the traveling function section 130, for example, and can be an inertial measurement unit that detects acceleration, angular velocity, angular acceleration, or the like, and can be a sensor such as a LiDAR that detects the situation around the radioactive source exploration device 100. In addition, of course, a GPS can be used depending on the use site or the like.

[0028] The communication section 150 communicates with other radioactive source exploration devices 100 and the radioactive source estimation device 300. The communication of the communication section 150 can be any of wireless LAN (Local Area Network), Bluetooth (registered trademark), or the like.

[0029] Figure 3 is a perspective view showing the appearance of the radioactive detection section 110 in the present embodiment. The scintillators S1, S2, S3, S4 are scintillators of the first direction detection section 111, the second direction detection section 112, the third direction detection section 113, and the omnidirectional detection section 114, respectively. The scintillators S1, S2, S3, which are arranged at equal intervals on the disc-shaped substrate B1, are arranged with lead-made shielding walls W1, W2, W3 therebetween. Therefore, the scintillators S1, S2, S3 each mainly allow radioactive rays from a direction within 120° in which no shielding wall is arranged to come in. The scintillator S4 is arranged at a position higher than the shielding walls W1, W2, W3, and thus allows radioactive rays from all directions (360°) to come in.

[0030] Figure 4is a flowchart illustrating the operation of the radioactive source probe device 100 in the present embodiment. First, the radioactive source probe device 100 performs random walk of random travel (step Sa1). Further, the range of action based on the random walk can also be set in advance. For example, in the case where a multi-hop network is constituted by a plurality of radioactive source probe devices 100, the range of action of each radioactive source probe device 100 can also be set to be able to communicate with the adjacent radioactive source probe devices 100. In addition, the radioactive source probe device 100 can not perform random walk, but can travel on a planned path. The radioactive source probe device 100, in the case where the range of action is set, can detect the position of the radioactive source and the like within the range of action with higher accuracy, and thus it is preferable to travel throughout the range of action regardless of the set method of its movement.

[0031] The control section 120 of the radioactive source probe device 100 determines whether or not the radioactive ray is detected (step Sa2). In this determination, the detection results of all of the first direction detection section 111, the second direction detection section 112, the third direction detection section 113, and the omnidirectional detection section 114 can be used, or only the detection result of the omnidirectional detection section 114 can be used, and during the random walk of step Sa1, no power is supplied to the first direction detection section 111, the second direction detection section 112, and the third direction detection section 113. In addition, it can be determined whether or not the radioactive ray is detected depending on whether or not the count rate exceeds a threshold value set in advance.

[0032] In the case where it is determined that the radioactive ray is detected in step Sa2 (step Sa2-Yes), the control section 120 of the radioactive source probe device 100 notifies the other radioactive source probe devices 100 that the radioactive ray is detected via the communication section 150 (step Sa3). In this notification, information indicating the position of the radioactive source probe device 100 estimated by the radioactive source probe device 100, information indicating the count rate of the radioactive ray can also be included. In addition, the other radioactive source probe devices 100 that become the transmission destination of this notification can be a plurality of, but can be any one of the radioactive source probe devices 100 that only satisfies the radioactive source probe devices 100 within a predetermined distance from the radioactive source probe device 100, the radioactive source probe devices 100 that can directly receive the notification, the radioactive source probe devices 100 that do not detect the radioactive ray, and the like.

[0033] Next, the control section 120 of the radioactive ray source search device 100 estimates the direction of the line source of the radioactive ray (line source direction) (step Sa4). The estimation of the line source direction can be performed, for example, as follows. The radioactive ray source search device 100 changes the orientation of the device, or rotates the radioactive ray detection section 110, or the like, and performs measurement while causing each direction detection section to detect a specific direction change of the radioactive ray, and estimates the line source direction of the radioactive ray. For example, the control section 120, in a case where the difference between the count rates of two of the first direction detection section 111, the second direction detection section 112, and the third direction detection section 113 is within a predetermined range, and the count rates of the two are larger than the count rate of the remaining one, regards the direction of the center of the directions of the radioactive ray detected by the two, or the direction opposite to the direction of the radioactive ray detected by the remaining one, as the line source direction of the estimation result. In addition, the control section 120 can estimate the direction opposite to the direction of the radioactive ray detected by the direction detection section having the lowest count rate among the first direction detection section 111, the second direction detection section 112, and the third direction detection section 113, as the line source direction of the radioactive ray.

[0034] Further, the fact that the values of the two count rates are sufficiently close to each other means that the difference between the two count rates can be less than or equal to a predetermined threshold value, or the ratio of the two count rates can be within a predetermined range. In addition, the fact that the value of the remaining one count rate is sufficiently smaller than the values of the two count rates means that the result of subtracting the value of the remaining one count rate from the average of the values of the two count rates can be greater than or equal to a predetermined threshold value, or the result of dividing the average of the values of the two count rates by the value of the remaining one count rate can be greater than or equal to a predetermined threshold value. In addition, the radioactive ray source search device 100 can perform the estimation of the line source direction while moving, or can perform the estimation at a stop. Further, in the conditions in which the values of the two count rates are sufficiently close to each other, and the value of the remaining one count rate is sufficiently smaller than them, a condition in which the values of the two count rates are sufficiently smaller than the count rate of the all-direction detection section 114 can be added.

[0035] Next, the radiation source search device 100 moves toward the line source direction estimated in step Sa4 (step Sa5). The radiation source search device 100 also performs detection of radiation in the movement of step Sa5, and after a predetermined time has elapsed or a predetermined distance has been moved, the control section 120 determines whether the count rate is above a threshold value set in advance (step Sa6). The determination of this step Sa6 can also be a determination of whether the count rate exceeds a threshold value set in advance (for example, using the average value and the value of the standard deviation σ of the count rate measured from step Sa1 to step Sa6, it is possible to set "average value + 2 x σ" and "average value + 3 x σ" as the threshold value). In addition, the count rate can also be the count rate in the movement of the radiation source search device 100. In addition, the count rate can also be a count rate measured after a certain time has elapsed or a certain distance has been moved from the start of the movement of step Sa5. In addition, the count rate can be a count rate measured by the direction detection section among the first direction detection section 111, the second direction detection section 112, and the third direction detection section 113 that faces the estimated line source direction, or a count rate measured by the omnidirectional detection section 114.

[0036] In the case where it is determined in step Sa6 that the count rate is not above the threshold value (step Sa6-No), the radiation source search device 100 returns to step Sa4 and performs estimation of the line source direction. In the case where it is determined in step Sa6 that the count rate is above the threshold value (step Sa6-Yes), the radiation source search device 100 stops and performs measurement of the count rate (step Sa7). This measurement can be performed by the direction detection section among the first direction detection section 111, the second direction detection section 112, and the third direction detection section 113 that faces the line source direction, or by the omnidirectional detection section 114. In addition, when this measurement is performed, the radiation source search device 100 can also perform estimation of the line source direction and change the orientation so that any one of the first direction detection section 111, the second direction detection section 112, and the third direction detection section 113 faces the line source direction.

[0037] Next, the control section 120 of the radiation source search device 100 transmits the count rate measured in step Sa7, the estimated line source direction, and the own position to the line source estimation device 300 via the communication section 150 (step Sa8). By receiving this transmission from a plurality of radiation source search devices 100, the line source estimation device 300 can estimate the position, shape, and the like of the line source.

[0038] On the other hand, in a case where it is determined in step Sa2 that the radiation is not detected (step Sa2-No), the control section 120 of the radiation source search device 100 determines whether or not a notification is received from the other radiation source search device 100 via the communication section 150 (step Sa9). Here, the notification from the other radiation source search device 100 is a notification indicating the radiation detection of the other radiation source search device 100, and is the notification of the other radiation source search device 100 based on step Sa3. In a case where it is determined that there is no notification from the other radiation source search device 100 (step Sa9-No), the radiation source search device 100 returns to step Sa1 and performs random walk.

[0039] On the other hand, in a case where it is determined in step Sa9 that the notification is received from the other radiation source search device 100 (step Sa9-Yes), the radiation source search device 100 moves in the direction of the other radiation source search device 100 based on the position of the other radiation source search device 100 included in the notification (step Sa10). The radiation source search device 100 also performs the detection of the radiation in the movement in step Sa10, and after a predetermined time elapses or a predetermined distance is moved, the control section 120 determines whether or not the count rate is above a threshold value set in advance (step Sa11). The determination is the same as that in step Sa6. In step Sa11, in a case where it is determined that the count rate is not above the threshold value (step Sa11-No), the radiation source search device 100 returns to step Sa10 and moves in the direction of the other radiation source search device 100. In step Sa11, in a case where it is determined that the count rate is above the threshold value (step Sa11-Yes), the radiation source search device 100 proceeds to step Sa7 and stops to measure the count rate.

[0040] Thus, the radiation source search device 100 autonomously performs random walk and the like to perform measurement, and thus measurement can be performed even if there are obstacles such as walls and residues. In addition, since the radiation source search device 100 stops after the count rate becomes above the threshold value to measure the count rate for transmission, the accuracy of the count rate is improved. In addition, when the radiation detection section 110 (radiation sensor section) detects the radiation, the control section 120 of the radiation source search device 100 notifies the position (own position) of the radiation source search device 100 to the other radiation source search device 100 using the communication section 150, causes the other radiation source search device 100 to also move / assemble in the vicinity of the radiation source that becomes the object, and measures from a plurality of positions toward the radiation source that becomes the object. Thus, the radiation source can be found early, and measurement related to the same radiation source can be performed in parallel by a plurality of radiation source search devices 100, and the position of the radiation source and the like can be accurately estimated. After measurement related to the same radiation source is performed by a plurality of radiation source search devices 100 as described above, the process returns to step Sa1 again.Figure 4 The flowchart shown above, the radioactive source exploration device 100 starts random walk. In the case where the range of action of the radioactive source exploration device 100 is set, by repeating such Figure 4 The flowchart shown above, the radioactive source exploration device 100 starts random walk. In the case where the range of action of the radioactive source exploration device 100 is set, by repeating such Figure 4 In the flowchart shown above, it is not terminated. In such a case, for example, various changes can be made depending on the usage status or the like, for example, after traveling, measuring and ending on the planned path, after traveling and ending throughout the range of action, terminate; after traveling for a certain time, terminate, etc.

[0041] Figure 5 is a schematic diagram showing an example of measurement performed by a plurality of radioactive source exploration devices 100a to 100f in the present embodiment. The radioactive source exploration devices 100a to 100f are respectively Figure 1 , Figure 2 the radioactive source exploration device 100 shown above. Figure 5 The schematic diagram shown above is an example in which a plurality of radioactive source exploration devices 100a to 100f measure a large radioactive source R1 in comparison with them. In this way, in the case where the radioactive source R1 is large, the radioactive source exploration devices 100a to 100f concentrate around it to measure the count rate, and transmit it to the radioactive source estimation device 300. The radioactive source estimation device 300 can estimate at least the approximate shape of the radioactive source R1, the intensity distribution of the amount of radiation, and the like using the positions, the count rates of the radioactive source exploration devices 100a to 100f.

[0042] Figure 6 is a schematic diagram showing an example of measurement performed by a plurality of radioactive source exploration devices 100g to 100k in the present embodiment. The radioactive source exploration devices 100g to 100k are respectively Figure 1 , Figure 2 the radioactive source exploration device 100 shown above. Figure 6Fig. 10 is a schematic view of the case where the plurality of radioactive source search devices 100g to 100k measure the two line sources R2 and R3. In the case where the plurality of line sources R2 and R3 exist, the radioactive source search devices 100g to 100k concentrate around each of the plurality of line sources R2 and R3 to measure the count rates, and transmit them to the radioactive source estimation device 300. Thus, the radioactive source estimation device 300 can estimate the positions of the plurality of radioactive sources R2 and R3, and the like.

[0043] The present application can also be the following embodiment.

[0044] (1) One embodiment of the present application is a radioactive source search device capable of estimating its own position and autonomously moving, the radioactive source search device including: a radioactive sensor section that detects radioactive rays coming from a specific direction; and a control section that acquires a detection result of the radioactive sensor section, controls movement of the radioactive source search device, estimates a line source direction of the radioactive rays based on the detection result of the radioactive sensor section, and causes the radioactive source search device to move toward the estimated line source direction, wherein the control section stops the movement based on a count rate of the radioactive rays of the radioactive sensor section exceeding a threshold value, and acquires the count rate in a stopped state.

[0045] (2) In addition, the radioactive source search device according to (1), in another embodiment of the present application, the control section estimates the line source direction of the radioactive rays while causing the specific direction in which the radioactive sensor section detects the radioactive rays to change.

[0046] (3) In addition, the radioactive source search device according to (1) or (2), in another embodiment of the present application, the radioactive sensor section includes a plurality of detection sections that detect the radioactive rays coming from different directions, respectively, and the control section estimates the line source direction of the radioactive rays using the two detection sections that detect the direction of the radioactive rays based on a difference between count rates of the two detection sections being within a predetermined range and the count rates of the two detection sections being larger than count rates of the remaining detection sections.

[0047] (4) In addition, the radioactive source search device according to any one of (1) to (3), in another embodiment of the present application, the radioactive sensor section includes a plurality of detection sections that detect the radioactive rays coming from different directions, respectively, and the control section estimates a direction opposite to the direction of the radioactive rays detected by the detection section having the lowest count rate among the plurality of detection sections as the line source direction of the radioactive rays.

[0048] (5) In addition, according to any one of (1) to (3) the radiation source detection apparatus, another embodiment of the present invention includes a communication unit capable of communicating with other radiation source detection apparatuses. When the radiation sensor unit detects radiation, the control unit uses the communication unit to notify the other radiation source detection apparatus of the location of the radiation source detection apparatus.

[0049] (6) In addition, another embodiment of the present invention is a radiation source detection system, the radiation source detection system comprising: a plurality of radiation source detection devices as described in any one of (1) to (5); and a radiation source estimation device, which collects the count rate and radiation source direction of each of the plurality of radiation source detection devices to estimate the location of the radiation source.

[0050] (7) In addition, another embodiment of the present invention is a radiation source detection method, which is a radiation source detection method based on a radiation source detection device capable of estimating its own position and moving autonomously. The radiation source detection method includes: a step of estimating the radiation source direction based on the detection result of the radiation sensor unit that detects radiation from a specific direction; a step of moving the radiation source detection device toward the estimated radiation source direction; and a step of stopping the movement and obtaining the count rate in the stopped state when the count rate of the radiation from the radiation sensor unit exceeds a threshold.

[0051] (8) In addition, another embodiment of the present invention is a program for causing a computer of a radiation source detection device capable of estimating its own position and moving autonomously to perform the following steps: estimating the line source direction of the radiation based on the detection result of the radiation sensor unit that detects radiation from a specific direction; moving the radiation source detection device toward the estimated line source direction; and stopping the movement and obtaining the count rate in the stopped state if the count rate of the radiation based on the radiation sensor unit exceeds a threshold.

[0052] Alternatively, it can be used to implement Figure 1 The line source estimation device 300 in the middle Figure 2 The program for the functions of the control unit 120 is recorded on a computer-readable recording medium, which is then read and executed by the computer system, thereby realizing the line source estimation device 300 and the control unit 120. Furthermore, the term "computer system" as used here includes hardware such as the operating system and peripheral devices.

[0053] In addition, the "computer-readable recording medium" refers to a removable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, and the like, a storage device such as a hard disk built into a computer system. Further, the "computer-readable recording medium" includes a medium that dynamically retains a program for a short time, such as a communication line when a program is transmitted via a network such as the Internet, a communication line such as a telephone line, and the like, and a medium that retains a program for a certain period of time, such as a volatile memory inside a computer system that is a server or a client in this case. In addition, the above program can be a program for realizing a part of the above functions, or a program that can realize the above functions by being combined with a program already recorded in a computer system.

[0054] The above describes the embodiment of the present application in detail with reference to the drawings, but the specific structure is not limited to the embodiment, and design changes and the like within a range not departing from the gist of the present application are included.

[0055] Explanation of Reference Numerals 10, radioactive source survey system; 100, 100a to 100k, radioactive source survey device; 110, radioactive detection section; 111, first direction detection section; 112, second direction detection section; 113, third direction detection section; 114, omnidirectional detection section; 120, control section; 130, traveling function section; 140, position detection sensor section; 150, communication section.

Claims

1. A radioactive ray source search apparatus capable of estimating a self position and autonomously moving, wherein the radioactive ray source search apparatus comprises: a radioactive ray sensor section that detects a radioactive ray coming from a specific direction; and a control section that acquires a detection result of the radioactive ray sensor section and controls movement of the radioactive ray source search apparatus, the control section estimates a radioactive ray source direction of the radioactive ray based on the detection result of the radioactive ray sensor section, the control section moves the radioactive ray source search apparatus toward the estimated radioactive ray source direction, and in a case where a count rate of the radioactive ray based on the radioactive ray sensor section exceeds a threshold value, the control section stops the movement and acquires a count rate in a stopped state.

2. The radioactive ray source search apparatus according to claim 1, wherein the control section estimates the radioactive ray source direction while changing the specific direction in which the radioactive ray sensor section detects the radioactive ray.

3. The radioactive ray source search apparatus according to claim 1, wherein the radioactive ray sensor section comprises a plurality of detection sections that respectively detect a radioactive ray coming from different directions, in a case where a difference between count rates based on two detection sections among the plurality of detection sections is within a predetermined range and a count rate based on the two detection sections is larger than a count rate based on each of the remaining detection sections, the control section estimates the radioactive ray source direction using the two detection sections that detect a direction of the radioactive ray.

4. The radioactive ray source search apparatus according to claim 1, wherein the radioactive ray sensor section comprises a plurality of detection sections that respectively detect a radioactive ray coming from different directions, and the control section estimates a direction opposite to a direction of the radioactive ray detected by a detection section having the lowest count rate among the plurality of detection sections as the radioactive ray source direction.

5. The radioactive ray source search apparatus according to claim 1, wherein the radioactive ray source search apparatus comprises a communication section capable of communicating with another radioactive ray source search apparatus, and when the radioactive ray sensor section detects a radioactive ray, the control section notifies a position of the radioactive ray source search apparatus to the another radioactive ray source search apparatus using the communication section.

6. A radioactive ray source search system, wherein the radioactive ray source search system comprises: a plurality of radioactive ray source search apparatuses according to any one of claims 1 to 5; and a radioactive ray source estimation apparatus that collects a count rate and a radioactive ray source direction of each of the plurality of radioactive ray source search apparatuses and estimates a position of a radioactive ray source.

7. A radioactive ray source search method based on a radioactive ray source search apparatus capable of estimating a self position and autonomously moving, wherein the radioactive ray source search method comprises: a step of estimating a radioactive ray source direction of a radioactive ray based on a detection result of a radioactive ray sensor section that detects a radioactive ray coming from a specific direction; a step of moving the radioactive ray source search apparatus toward the estimated radioactive ray source direction; and a step of stopping the movement and acquiring a count rate in a stopped state in a case where a count rate of the radioactive ray based on the radioactive ray sensor section exceeds a threshold value.

8. A program, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The program for causing a radioactive ray source searching apparatus capable of estimating a self position and autonomously moving to execute the following steps: a step of estimating a line source direction of a radioactive ray based on a detection result of a radioactive ray sensor section which detects the radioactive ray coming from a specific direction; a step of moving the radioactive ray source searching apparatus to the estimated line source direction; and a step of stopping the movement and acquiring a count rate in a stopped state in a case where a count rate of the radioactive ray based on the radioactive ray sensor section exceeds a threshold value.

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