An obstacle-free array-type radioactive source rapid positioning system

Abstract

The invention discloses an obstacle-free array-type radioactive source rapid positioning system, which comprises a detector array: a frontal sodium iodide detector array of 7, a side sodium iodide detector array of 3, a sodium iodide nuclide identification probe, a 3 It consists of eight parts: He neutron detector, radiation signal processing circuit board, high-speed high-definition camera, equipment cover, and host computer software. The sodium iodide detector array plus a special lead shield is used to accurately locate the radiation source, the sodium iodide nuclide identification probe is used to identify the type of radioactive nuclides, and the neutron probe detects neutron radiation. The radiation signal processing circuit board converts the radiation signal collected by the probe into a digital signal and transmits it to the host computer software. The host computer software analyzes and processes the digital signal, gives the specific location and type of nuclides of the radiation source, and alarms. The camera takes pictures of the people in the monitoring area and catches suspicious people carrying excessive radioactive radiation according to the specific location.

Description

Technical Field

[0001] The invention relates to the field of positioning technology, in particular to an obstacle-free array-type radioactive source rapid positioning system. Background Art

[0002] The traditional method of detecting radioactive substances in pedestrian channels is to set up channels and detect pedestrians passing through. This detection method has a high detection rate because it is close to the detector, but the detection speed is slow due to the narrow channel, and the personnel passing efficiency is low due to the close proximity to the staff. Once radiation occurs, it will also have a certain impact on the staff. Summary of the invention

[0003] The object of the present invention is to provide a barrier-free array-type radiation source rapid positioning system to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An obstacle-free array-type radioactive source rapid positioning system, comprising:

[0006] The sodium iodide detector array with lead shielding surrounds the lead on the side of the sodium iodide crystal and extends forward. The Monte Carlo algorithm calculates the radiation response characteristics of a single crystal lead shield and then corrects the model through specific experiments. Based on the results of the experimental correction, the radiation of the positioning system under various conditions is simulated to obtain the actual radiation characteristic data;

[0007] The front and side detector array combination includes a front detector array and a side detector array. The front detector array is used to detect the radiation characteristics perpendicular to the pedestrian's path, and the side detector array is used to detect the radiation characteristics in the direction of pedestrian's advance. The cross combination determines the specific location of the person with excessive radiation;

[0008] The feature coding of the detection plane area is to encode the 4m×4m plane and divide it into 16 feature grids of 1m×1m. Then it is divided into 4 heights of 1.8m. The total detection area is divided into 64 feature grids to encode the radiation features.

[0009] The radiation positioning and camera linkage capture module detects the radiation characteristics, determines the radiation position according to the code, and transmits the position information to the camera to capture people with excessive radiation.

[0010] As a further solution of the present invention: the thickness of the lead shield is 2 cm, and the distance it extends forward is 5 cm.

[0011] As a further solution of the present invention: the front detector array is a 7-probe array, the center probe is parallel to the pedestrian direction, and the side detector array is a 3-probe array, the middle probe is perpendicular to the pedestrian direction.

[0012] As a further solution of the present invention: the special coding of the detection plane includes 64 grid codes of common radionuclides, the height direction is divided into 4 planes, and the same plane is divided into 16 grids. Monte Carlo simulation 137 The characteristic codes of Cs in different grids were modified through experiments, and after modification, the characteristic codes of 64 grids of common nuclides were calculated using Monte Carlo simulation.

[0013] As a further solution of the present invention: the radiation positioning and camera linkage capture module transmits the three-dimensional positioning information to the capture camera, and the capture camera locates the position of the person with excessive radiation in the two-dimensional plane through an algorithm and takes a photo to enlarge it.

[0014] As a further solution of the present invention: the front detector array is a 7-sodium iodide detector array, and the side detector array is a 3-sodium iodide detector array.

[0015] As a further solution of the present invention: the sodium iodide side detector includes a shell, a PMT and a front-end signal amplification circuit, a cylindrical lead shielding layer and a sodium iodide crystal probe installed in the shell, and the shell is made of a lightweight aluminum-plastic plate material with a thickness of 4 mm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The radiation detection area can reach a plane of 4m×4m, which is dozens of times larger than the channel-type pedestrian detection area; (2) If the radiation of the detected person is normal, he / she can pass directly without stopping; (3) If the radiation of the detected person exceeds the standard, not only an alarm message is given, but also the specific location of the person with excessive radiation is given, and the whole process is recorded by a high-speed high-definition camera and enlarged and displayed to the user. (4) The acquisition signal is 200ms, which is 5 times faster than the existing conventional pedestrian channel door of 1 second. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of barrier-free array radiation source rapid positioning system

[0018] Figure 2 Simulate the radiation characteristics of a bare crystal for Monte Carlo simulation.

[0019] Figure 3 Comparison of radiation characteristics after lead shielding

[0020] Figure 4 Schematic diagram of single crystal lead shielding

[0021] Figure 5 Installation position diagram

[0022] In the figure: 1-front detector array; 2. High-speed high-definition camera; 3. Side detector array; 4. Detection area; 5. PMT and front-end signal amplification circuit; 6. Cylindrical lead shielding layer, 7-sodium iodide crystal probe. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] See also Figure 1 Embodiment 1: In the embodiment of the present invention, an obstacle-free array-type radioactive source rapid positioning system includes: a front array of 7 sodium iodide front detectors 1, a side array of 3 sodium iodide side detectors 3, a sodium iodide nuclide identification probe, a 3He neutron detector, a radiation signal processing circuit board, a high-speed high-definition camera 2, a device cover, and a host computer software, a total of eight parts.

[0025] The sodium iodide detector is a 3-inch x 3-inch cylindrical crystal surrounded by a lead shielding layer. The lead shielding layer is a certain distance ahead of the detector, and the final distance of the lead shielding layer ahead of the detector is determined based on the detection height and distance. The size of the lead shielding is accurately calculated using the Monte Carlo method and corrected by experiments to ensure that the simulation effect is as close as possible to the actual scenario application. After correcting the single crystal simulation model through experiments, a sodium iodide detector model with a positive 7 and side 3 array is built according to the final application scenario of the product.

[0026] The final model of the detector array needs to be determined by Monte Carlo algorithm after multiple experiments. The detector height is 3m, the front detector is 50cm apart, and the side detector is 50cm apart.

[0027] The detector's downward and left and right tilt angles are obtained through Monte Carlo algorithm. By simulating hundreds of models, an optimal model is finally obtained.

[0028] The sodium iodide nuclide identification probe is different from the positioning array sodium iodide probe. In order to improve the efficiency of nuclide identification, it does not need to add lead shielding. It is placed below the center positioning probe of the front detector array, a certain distance in front. The nuclide identification algorithm adopts the characteristic peak nuclide identification method.

[0029] The neutron detector is a cylindrical 3He gas detector. To improve the detection efficiency of neutrons, a moderated layer of a certain thickness is wrapped around the detector. Neutron detection does not determine the specific location. Once a neutron alarm occurs, the alarm level is the highest level, and the entire detection area is displayed in red.

[0030] Radiation signal circuit processing board, this part includes signal conversion and collection of all detectors. The radiation collection signal is 200ms, which continuously collects radiation signals around the detector and transmits them to the host computer software for analysis and processing.

[0031] Since the neutron detector has less signal, a signal acquisition frequency of 1s is adopted to ensure data stability.

[0032] The high-speed HD camera records the detection area in real time. When the radiation position information is transmitted to it, it starts short-term HD recording and captures the license plate for storage. If there is no alarm, it only records the video in the usual way and saves it on a daily basis.

[0033] The outer cover of the equipment is made of lightweight aluminum-plastic plate with a thickness of 4mm. The light weight of the aluminum-plastic plate can minimize the shielding of radioactive rays by the shell. The aluminum-plastic plate has a smooth appearance and completely surrounds the detector and signal processing circuit board, which has a good aesthetic effect.

[0034] The host computer software is divided into the user operation interface and the background data processing system. The user operation interface is divided into the dose rate display interface, the detection plane grid diagram, and the camera recording interface. The background data processing system includes the detection grid area coding, the radiation positioning algorithm, and the dose rate algorithm.

[0035] The barrier-free array-type rapid positioning system for radioactive sources is tested by having the person being tested pass through the detection area 4 below the detector array at a normal speed. The positioning probe acquisition frequency is 200ms, and the specific location of the person with excessive radiation can be given in as fast as 1s, and video and photos can be taken. People with normal radiation do not need to stop and can pass at a normal speed.

[0036] The present invention is a positioning system integrating multiple radiation detectors, including 10 positioning 3-inch×3-inch cylindrical sodium iodide crystals, 1 nuclide identification sodium iodide crystal, and 1 neutron tube detector. Figure 1 This is a simplified schematic diagram of the detector array, in which the side auxiliary detector array can be installed on the left or right side of the main detector according to the actual site.

[0037] In the specific implementation of the present invention, the height of the detector array is 3m, and the detection plane is a 4m×4m barrier-free plane. The side detector array is centered on the detection side.

[0038] In one embodiment of the present invention, the detector is suspended from the ceiling at a height of 3 m above the ground. The specific height can be fine-tuned according to the actual environment. The scope of the embodiments of the present invention is not limited thereto. On the contrary, the embodiments of the present invention fall within the spirit and connotation of the appended claims. All changes, modifications and equivalents.

[0039] In this embodiment, after the initial single crystal model is built, the number of detectors, shielding method, detector angle and other parameters are modified to find an optimal detector array model. The simulation results are shown in Figure 2 and 3 .

[0040] Embodiment 2: Based on embodiment 1, Figure 4 FIG. 1 is a schematic diagram of the detector results in one embodiment of the present invention. Figure 5 As shown, the detector mainly includes five parts, a sodium iodide crystal probe 7, a cylindrical lead shielding layer 6, a PMT and a signal amplification circuit board 5, and a detector protective shell. The cylindrical lead shielding layer 6 in this embodiment is 2 cm thick and extends 5 cm from the front end of the detector. This lead shielding method has been verified by Monte Carlo simulation and experiments and is the optimal model.

[0041] The distance between the lead shield and the front end of the detector in the embodiment of the present invention is not necessarily 5 cm, and may vary according to the specific installation environment. The scope of the embodiment of the present invention is not limited thereto.

[0042] Figure 5 FIG. 1 is a schematic diagram of the installation position of a radiation source positioning system according to an embodiment of the present invention. The schematic diagram only includes a sodium iodide detector array for positioning. Figure 5 As shown, each detector in the detector array has a certain angle change, including up and down tilt angle and left and right tilt angle. The up and down tilt angle is unified as 45°, and the left and right tilt angle varies according to the installation position.

[0043] In one embodiment of the present invention, the nuclide identification detector is a 3-inch × 3-inch sodium iodide crystal. To improve the nuclide identification efficiency, no processing is done on the front end of the detector. The detector is located slightly below the center of the main array detector. The center position is slightly below, close to the detection plane and without any object blocking, so more radioactive rays can be detected.

[0044] In one embodiment of the present invention, the detector for detecting neutrons is a 3He gas detector of Φ 50mm×L600mm, which is surrounded by a layer of moderator of a certain thickness to improve the detection efficiency of neutrons.

[0045] In one embodiment of the present invention, a high-speed high-definition camera is located directly below the main detector, and its field of view covers the entire 4m×4m detection area. When there is a radiation alarm, video recording and snapshot actions are taken after receiving radiation positioning information.

[0046] In one embodiment of the present invention, the outer shell is made of an aluminum-plastic plate, which not only protects the main body of the detector, but also helps to reduce the shielding effect of the outer cover on radiation, thereby improving the detection efficiency of the device.

[0047] The thickness of the aluminum-plastic panel is 4mm.

[0048] The host computer software is divided into a user interface and a background data processing interface. The background data includes the position feature code of the array detector input when debugging with 137Cs. After debugging is completed, the code actually tested with the source is compared with the code calculated by Monte Carlo simulation, and the simulation results are corrected to obtain the model correction parameters.

[0049] The location feature coding includes common industrial nuclides and medical nuclides. Each nuclide includes 16 feature points in 4 different height planes. The heights are 0m, 0.6m, 1.2m, and 1.8m.

[0050] When a person with excessive radiation enters the detection area and triggers the alarm, the position of the person with excessive radiation is determined based on the position feature code and the position information is transmitted to the camera, which records and captures the person with excessive radiation. The recording stops when the radiation alarm is lifted. The radiation alarm can be lifted manually, and the system automatically releases it when the radiation value is lower than the alarm value.

[0051] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0052] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An obstacle-free array radiation source positioning system, characterized in that: include: The front and side detector array combination includes a front detector array and a side detector array. The front detector array is used to detect the radiation characteristics in the direction perpendicular to the pedestrians, and the side detector array is used to detect the radiation characteristics in the direction of the pedestrians. The cross combination determines the specific location of the person with excessive radiation. The front detector array and the side detector array are sodium iodide detector arrays with lead shielding. The sodium iodide detectors with lead shielding surround the lead on the side of the sodium iodide crystal and extend forward. The Monte Carlo algorithm calculates the radiation response characteristics of a single crystal lead shield and then corrects the model through specific experiments. Based on the results of the experimental correction, the radiation of the positioning system under various conditions is simulated to obtain the actual radiation characteristic data; The total detection area, where the 4m×4m detection plane area is divided into 16 feature grids of 1m×1m, and the 1.8m height is evenly divided into 4 heights, so that the total detection area is divided into 64 feature grids, and the radiation characteristics of the above 64 feature grids are encoded; The radiation positioning and camera linkage capture module is used to detect radiation characteristic data, determine the radiation position according to the code, and pass the position information to the camera to capture people with excessive radiation.

2. The barrier-free array radiation source positioning system according to claim 1, characterized in that: The lead shield has a thickness of 2 cm and extends forward by 5 cm.

3. The barrier-free array radiation source positioning system according to claim 2, characterized in that: The front detector array is a 7-probe array, with the center probe parallel to the pedestrian direction, and the side detector array is a 3-probe array, with the middle probe perpendicular to the pedestrian direction.

4. The barrier-free array radiation source positioning system according to claim 1, characterized in that: The special coding of the total detection area includes 64 grid codes of common radionuclides. The height direction is divided into 4 planes, and the same plane is divided into 16 grids. Monte Carlo simulation 137 The characteristic codes of Cs in different grids were modified through experiments, and after modification, the characteristic codes of 64 grids of common nuclides were calculated using Monte Carlo simulation.

5. The barrier-free array radiation source positioning system according to claim 4, characterized in that: The radiation positioning and camera linkage capture module transmits the three-dimensional positioning information to the capture camera, and the capture camera locates the position of the person with excessive radiation in the two-dimensional plane through an algorithm and takes a photo to enlarge it.

6. The barrier-free array radiation source positioning system according to claim 5, characterized in that: The sodium iodide side detector includes a shell, a PMT and a front-end signal amplifying circuit, a cylindrical lead shielding layer and a sodium iodide crystal probe installed in the shell. The shell is made of a lightweight aluminum-plastic plate material with a thickness of 4 mm.

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