A radionuclide identification and positioning method and device based on a pixel detector

Abstract

The present application relates to radionuclide identification positioning method and device, specifically relates to a kind of radionuclide identification positioning method and device based on pixel detector, solve the problem that traditional radiation detection means cannot consider nuclide type identification and spatial accurate positioning.This application synchronously acquires multiple gamma-ray energy spectrum by multiple independent detection units, and the nuclide type of radioactive source can be accurately identified by using the joint comparison of each channel characteristic peak information.On this basis, the normalized count result of each detection unit is combined with the pre-constructed fitting curve function, an overdetermined equation set is constructed and solved, so that the direction of radioactive source relative to the detector is accurately back calculated;This method breaks the limitation of mutual fragmentation of identification and positioning function in traditional technology, completes the two core tasks at the same time under the same detection architecture, significantly improves the comprehensive detection capability, especially suitable for the rapid judgment of complex unknown source term.

Description

Technical Field

[0001] This invention relates to a method and apparatus for identifying and locating radionuclides, specifically to a method and apparatus for identifying and locating radionuclides based on a pixel detector. Background Technology

[0002] With the widespread application of nuclear technology in fields such as medical diagnosis, industrial non-destructive testing, scientific research, and energy development, the frequency and scale of the use of radioactive materials continue to grow. From radiopharmaceuticals used for targeted therapy in nuclear medicine to sealed radioactive sources used in industrial flaw detection, and to the tracking of trace radionuclides in environmental monitoring, the application of radioactivity has been deeply integrated into many key aspects of modern society.

[0003] However, the expansion of applications has also brought new challenges. On the one hand, the types of radioactive materials are becoming increasingly complex, with significant differences in half-life, radiation energy characteristics, and potential hazards among different nuclides. On the other hand, the risks of accidental loss, illegal transfer, or environmental leakage of radioactive sources during transportation, use, and disposal have increased. Against this backdrop, how to quickly, accurately, and remotely identify and locate unknown radioactive sources has become a crucial technical challenge for ensuring public safety and the ecological environment.

[0004] The core objective of radionuclide identification and localization technology is to determine the type of nuclide and accurately locate its spatial position. Traditional radiation detection methods, such as Geiger counters or scintillator detectors, often only detect the presence of radiation but cannot distinguish the type of nuclide, or provide only a rough estimate for location, making precise positioning difficult. These limitations may lead to misjudgments or delays in emergency response. Therefore, there is an urgent need to develop technologies that can simultaneously identify the type of nuclide and precisely locate it spatially. This has become a pressing requirement for improving nuclear safety, enhancing emergency response efficiency, optimizing radioactive waste management, and promoting the sustainable development of nuclear technology. Summary of the Invention

[0005] This invention aims to solve the technical problem that traditional radiation detection methods in the prior art cannot simultaneously identify nuclide types and accurately locate them in space, making it difficult to conduct rapid, accurate, and long-distance comprehensive analysis of unknown radioactive sources in complex application scenarios. Therefore, this invention proposes a radioactive nuclide identification and location method and device based on a pixel detector.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A method for identifying and locating radioactive nuclides based on pixel detectors, used for identifying and locating radioactive point sources on a two-dimensional plane, is characterized by including the following steps:

[0008] Step 1: Place a calibrated detector within the radiation area of ​​the radioactive source to be identified and located. The detector comprises N detection units, where N ≥ 3. The calibration results include fitting curve functions f for the relative azimuth angles x of various radioactive sources with different nuclides to the detector. i (x), where i is the detector unit number, i∈[1,N];

[0009] Step 2: Measure the gamma-ray energy spectrum of the radioactive source under test independently using N detection units to obtain N gamma-ray energy spectra, and combine the N gamma-ray energy spectra into a total energy spectrum;

[0010] Step 3: Based on the characteristic peak energy of the total energy spectrum, find the corresponding nuclide type in the radionuclide characteristic peak lookup table to identify the nuclide type of the radioactive source;

[0011] Step 4: Based on the identified nuclide types, count the net count of the corresponding nuclide characteristic peaks on each γ-ray energy spectrum to obtain the net count of N nuclide characteristic peaks;

[0012] Step 5: Normalize the net count of each nuclide characteristic peak relative to the total count to obtain N normalized count values ​​c. i The total count is the sum of the net counts of the characteristic peaks of N nuclides.

[0013] Step 6: Find the fitting curve function f corresponding to the identified nuclide species. i (x), representing N normalized count values ​​c i The function f used to find the fitted curve i The function values ​​of (x) are used to construct an overdetermined system of equations;

[0014] Step 7: Solve the overdetermined system of equations to obtain the optimal common solution, which is the direction of the radioactive source relative to the detector, thus completing the identification and positioning of radionuclides based on the pixel detector.

[0015] Further, in step 6, the overdetermined system of equations is: .

[0016] Further, in step 1, the calibration step includes:

[0017] Step A: Place a calibrated radioactive source of known nuclide type around the detector;

[0018] Step B: Obtain the azimuth angle x of the calibration radiation source relative to the detector, and obtain N normalized count values ​​c corresponding to the azimuth angle x using the methods in steps 2, 4, and 5. i ;

[0019] Step C: Change the position of the calibration radiation source around the detector M times. After each position change, repeat step B to obtain M sets of calibration data. Each set of calibration data includes a known azimuth angle x and N corresponding normalized count values ​​c. i M≥300;

[0020] Step D: Obtain the fitting curve function f of the azimuth angle x of the calibration radiation source relative to the detector using M sets of calibration data. i (x);

[0021] Step E: Replace the calibration radioactive source with a different type of nuclide, and repeat steps B to D to obtain the fitting curve function f of the radioactive source with respect to the detector azimuth angle x of various different types of nuclides. i (x).

[0022] Furthermore, in step 1, each detection unit is fan-shaped, and N detection units are arranged around the same central axis to form a cylindrical detector; the central axis is perpendicular to the two-dimensional plane where the radiation source to be tested is located.

[0023] Furthermore, in step 1, the detector has a diameter of 10mm to 30mm and a height of 10mm to 20mm; the detector is encapsulated by an aluminum shell, carbon fiber shell, or beryllium shell with a thickness of 0.5mm to 1.5mm.

[0024] Furthermore, in step 1, the material of the detection unit is cadmium zinc telluride or germanium.

[0025] Furthermore, in step 1, N=3.

[0026] A pixel detector-based radionuclide identification and positioning device is used to implement the above-mentioned pixel detector-based radionuclide identification and positioning method, which is characterized by:

[0027] It includes a detector, a data recording and analysis module, and a power supply; the data recording and analysis module contains a pre-stored lookup table of characteristic peaks of radionuclides;

[0028] The detector comprises N detection units, where N ≥ 3;

[0029] The data recording and analysis module is connected to N detection units through N signal acquisition circuits respectively;

[0030] The power supply is connected to the detector, the data recording and analysis module, and the signal acquisition circuit, respectively.

[0031] Furthermore, each of the aforementioned detection units is fan-shaped, and N detection units are arranged around the same central axis to form a cylindrical detector; the central axis is perpendicular to the two-dimensional plane where the radiation source to be tested is located;

[0032] The detector has a diameter of 20mm and a height of 15mm.

[0033] Furthermore, the material of the detection unit is cadmium zinc telluride or germanium.

[0034] The beneficial effects of this invention are:

[0035] 1. It has achieved integrated collaborative detection of nuclide species identification and spatial positioning.

[0036] This invention provides a method for identifying and locating radionuclides based on pixel detectors. By simultaneously acquiring multiple gamma-ray energy spectra using multiple independent detection units and jointly comparing the characteristic peak information of each channel, the type of radionuclide from the radioactive source can be accurately identified. Furthermore, this invention innovatively combines the normalized counting results of each detection unit with a pre-constructed fitted curve function to build and solve an overdetermined system of equations, thereby accurately deducing the direction of the radioactive source relative to the detector. This method overcomes the limitation of traditional techniques where identification and location functions are separated, simultaneously completing two core tasks within the same detection architecture, significantly improving overall detection capabilities, and is particularly suitable for the rapid assessment of complex and unknown source terms.

[0037] 2. It has high identification and positioning efficiency, fully meeting the timeliness requirements of emergency response.

[0038] This invention provides a method for identifying and locating radionuclides based on pixel detectors. By acquiring energy spectrum data from each detection unit in real time and combining it with a pre-stored characteristic peak lookup table in the system for rapid comparison, it avoids the complex offline energy spectrum analysis process and significantly shortens the nuclide interpretation time. Simultaneously, the location step employs a numerical solution strategy for overdetermined equations, resulting in low computational load and fast convergence speed, allowing for immediate output of orientation estimation results after obtaining valid counts. The entire identification and location process requires no manual intervention or repeated measurements, exhibiting excellent real-time performance and automation, and providing timely and reliable technical support for time-sensitive tasks such as emergency response and the search for lost radioactive sources.

[0039] 3. The device has a simple structure, controllable cost, and good engineering practicality and deployability.

[0040] This invention provides a radionuclide identification and positioning device based on a pixel detector, which mainly consists of basic components such as a detector, a signal acquisition circuit, a data recording and analysis module, and a power supply. The overall architecture is clear and the components are highly versatile. It does not require a complex mechanical scanning mechanism or a precision displacement platform, thereby effectively reducing the system hardware cost and manufacturing difficulty. At the same time, due to its compact structure and light weight, the device is easy to set up, carry and transfer quickly on site. It can be flexibly deployed in various application scenarios such as nuclear facility entrances and exits, border ports, important urban locations or field environments, and has outstanding engineering practical value and broad application prospects. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of an embodiment of a radionuclide identification and positioning device based on a pixel detector according to the present invention.

[0042] Figure 2 This is an embodiment of the present invention. 137 Total energy spectrum of Cs point source;

[0043] Figure 3 This is a graph showing the relationship between the normalized count of radioactive sources corresponding to each detection unit and its position in this embodiment of the invention.

[0044] The attached figures are labeled as follows:

[0045] 1. Detector; 2. Signal acquisition circuit; 3. Data recording and analysis module; 4. Power supply. Detailed Implementation

[0046] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This invention provides a method for identifying and locating radioactive nuclides based on pixel detectors, used for radioactive point sources on a two-dimensional plane. The method includes the following steps:

[0048] Step 1: Place a calibrated detector 1 within the radiation area of ​​the radioactive source to be identified and located. Detector 1 consists of N detection units, where N ≥ 3. The calibration results include fitting curve functions f for the relative azimuth angles x of radioactive sources of various nuclides to the detector. i (x), where i is the detector unit number, i∈[1,N]; the fitting curve function f i (x) is a polynomial fitting function. The higher the degree of fitting, the more accurate the functional relationship.

[0049] like Figure 1As shown, in this embodiment, detector 1 includes three detection units: detection unit 11, detection unit 12, and detection unit 13. All three detection units are fan-shaped and arranged around the same central axis to form a cylindrical detector 1. The diameter of this cylinder ranges from 10 mm to 30 mm, and the height ranges from 10 mm to 20 mm. In this embodiment, the diameter of the cylinder is 20 mm, and its height is 15 mm. The entire detector 1 is encapsulated in an aluminum shell of 0.5 mm to 1.5 mm thickness; in other embodiments, it can also be encapsulated in a carbon fiber shell or a beryllium shell. In this embodiment, the aluminum shell thickness is 1 mm. The material of the detection units is cadmium zinc telluride; in other embodiments, it is also made of high-purity germanium or other materials. The central axis of detector 1 is perpendicular to the two-dimensional plane where the radiation source is located. Each detection unit is connected to a data recording and analysis module 3 via an independently configured signal acquisition circuit 2. The signal acquisition circuit 2 is used to acquire the gamma-ray energy spectrum output by each detection unit, and the data recording and analysis module 3 is used to execute steps 3 to 7. The data recording and analysis module 3 pre-stores a lookup table of characteristic peaks of radionuclides. Detector 1, signal acquisition circuit 2 and data recording and analysis module 3 are all powered by power supply 4.

[0050] Step 2: Measure the gamma-ray energy spectrum of the radioactive source under test independently using N detection units to obtain N gamma-ray energy spectra, and combine the N gamma-ray energy spectra into a total energy spectrum.

[0051] Step 3: Based on the characteristic peak energy of the total energy spectrum, find the corresponding nuclide type in the radionuclide characteristic peak lookup table to identify the nuclide type of the radioactive source.

[0052] In this embodiment, the synthesized total energy spectrum is as follows: Figure 2 As shown in the figure, the characteristic peak energy is 662 keV, as can be seen from the total energy spectrum. By searching the corresponding nuclide type in the radionuclide characteristic peak lookup table pre-stored in the data recording and analysis module 3, the characteristic peak is identified as belonging to... 137 Cs, therefore, the types of nuclides in this radioactive source are 137 Cs.

[0053] Step 4: Based on the identified nuclide types, count the net count of the corresponding nuclide characteristic peaks on each γ-ray energy spectrum to obtain the net count of N nuclide characteristic peaks.

[0054] Step 5: Normalize the net count of each nuclide characteristic peak relative to the total count to obtain N normalized count values ​​c. i , where i is the detector unit number, i∈[1,N]; the total count mentioned above is the sum of the net counts of the characteristic peaks of N nuclides. Count normalization can eliminate errors caused by inconsistencies in source intensity.

[0055] Step 6: Find the fitting curve function f corresponding to the identified nuclide species. i(x), representing N normalized count values ​​c i The function f used to find the fitted curve i The function values ​​of (x) are used to construct an overdetermined system of equations:

[0056] .

[0057] In this embodiment, the curves of the normalized counts of the radiation source measured by detection units 11, 12, and 13 as a function of azimuth angle x are shown below. Figure 3 As shown, a 9th-order polynomial fitting was used to obtain the fitting curve function of the detection unit. , and :

[0058]

[0059]

[0060] Step 7: Solve the above overdetermined system of equations to obtain the optimal common solution, which is the direction of the radioactive source relative to detector 1, thus completing the radionuclide identification and localization method based on pixel detector.

[0061] The solution method is as follows:

[0062] Define the objective function To find the x that minimizes the objective function, F(x) is a non-negative polynomial. The minimum point is the optimal common solution, and the minimum value must occur at the point where its derivative is zero. This is equivalent to solving the equation... The optimal common solution to the system of equations is obtained, which gives the direction of the radiation source relative to detector 1. dF(x) is the differential of the objective function F(x), and dx is the differential of the independent variable x.

[0063] In step 1, the steps for calibrating the detector are as follows:

[0064] Step A: Place a calibrated radioactive source of known nuclide type around the detector;

[0065] Step B: Obtain the azimuth angle x of the calibration radiation source relative to the detector, and obtain N normalized count values ​​c corresponding to the azimuth angle x using the methods in steps 2, 4, and 5. i ;

[0066] Step C: Change the position of the calibration radiation source around the detector M times. After each position change, repeat step B to obtain M sets of calibration data. Each set of calibration data includes a known azimuth angle x and N corresponding normalized count values ​​c. i M≥300;

[0067] Step D: Obtain the fitting curve function f of the azimuth angle x of the calibration radiation source relative to the detector using M sets of calibration data. i (x);

[0068] Step E: Replace the calibration radioactive source with a different type of nuclide, and repeat steps B to D to obtain the fitting curve function f of the radioactive source with respect to the detector azimuth angle x of various different types of nuclides. i (x).

[0069] The aforementioned different nuclide species cover the radionuclides to be identified and located.

[0070] Using the above method, the radioactive source was successfully identified as... 137 Cs, and locate its specific position on the two-dimensional plane.

[0071] This invention provides a pixel detector-based radionuclide identification and positioning device for implementing the aforementioned radionuclide identification and positioning method, such as... Figure 1 As shown, the device includes a detector 1, a data recording and analysis module 3, and a power supply 4. The detector 1 includes three detection units; in other embodiments, it may include more detection units. The data recording and analysis module is connected to the three detection units via three signal acquisition circuits 2. The power supply 4 is connected to the detector 1, the data recording and analysis module 3, and the signal acquisition circuits 2. Each detection unit is fan-shaped, and the three detection units are arranged around the same central axis to form a cylindrical detector 1. The detector 2 has a diameter of 20 mm and a height of 15 mm. The detector 1 is encapsulated in a 1 mm thick aluminum shell, carbon fiber shell, or beryllium shell. The detection units are made of zinc cadmium telluride or germanium.

[0072] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for identifying and locating radioactive nuclides based on a pixel detector, used for identifying and locating radioactive point sources on a two-dimensional plane, characterized in that, Includes the following steps: Step 1: Place a calibrated detector within the radiation area of ​​the radioactive source to be identified and located. The detector comprises N detection units, where N ≥ 3. The calibration results include fitting curve functions f for the relative azimuth angles x of various radioactive sources with different nuclides to the detector. i (x), where i is the detector unit number, i∈[1,N]; Step 2: Measure the gamma-ray energy spectrum of the radioactive source under test independently using N detection units to obtain N gamma-ray energy spectra, and combine the N gamma-ray energy spectra into a total energy spectrum; Step 3: Based on the characteristic peak energy of the total energy spectrum, find the corresponding nuclide type in the radionuclide characteristic peak lookup table to identify the nuclide type of the radioactive source; Step 4: Based on the identified nuclide types, count the net count of the corresponding nuclide characteristic peaks on each γ-ray energy spectrum to obtain the net count of N nuclide characteristic peaks; Step 5: Normalize the net count of each nuclide characteristic peak relative to the total count to obtain N normalized count values ​​c. i The total count is the sum of the net counts of the characteristic peaks of N nuclides. Step 6: Find the fitting curve function f corresponding to the identified nuclide species. i (x), representing N normalized count values ​​c i The function f used to find the fitted curve i The function values ​​of (x) are obtained, thereby constructing an overdetermined system of equations; Step 7: Solve the overdetermined system of equations to obtain the optimal common solution, which is the direction of the radioactive source relative to the detector, thus completing the identification and positioning of radionuclides based on the pixel detector.

2. The method for identifying and locating radionuclides based on pixel detectors according to claim 1, characterized in that: In step 6, the overdetermined system of equations is: .

3. The method for identifying and locating radionuclides based on pixel detectors according to claim 1 or 2, characterized in that, In step 1, the calibration step includes: Step A: Place a calibrated radioactive source of known nuclide type around the detector; Step B: Obtain the azimuth angle x of the calibration radiation source relative to the detector, and obtain N normalized count values ​​c corresponding to the azimuth angle x using the methods in steps 2, 4, and 5. i ; Step C: Change the position of the calibration radiation source around the detector M times. After each position change, repeat step B to obtain M sets of calibration data. Each set of calibration data includes a known azimuth angle x and N corresponding normalized count values ​​c. i M≥300; Step D: Obtain the fitting curve function f of the azimuth angle x of the calibration radiation source relative to the detector using M sets of calibration data. i (x); Step E: Replace the calibration radioactive source with a different type of nuclide, and repeat steps B to D to obtain the fitting curve function f of the radioactive source with respect to the detector azimuth angle x of various different types of nuclides. i (x).

4. The method for identifying and locating radionuclides based on pixel detectors according to claim 3, characterized in that: In step 1, each detection unit is fan-shaped, and N detection units are arranged around the same central axis to form a cylindrical detector; the central axis is perpendicular to the two-dimensional plane where the radiation source to be tested is located.

5. The method for identifying and locating radionuclides based on pixel detectors according to claim 4, characterized in that: In step 1, the detector has a diameter of 10mm to 30mm and a height of 10mm to 20mm; the detector is encapsulated by an aluminum shell, carbon fiber shell, or beryllium shell with a thickness of 0.5mm to 1.5mm.

6. The method for identifying and locating radionuclides based on pixel detectors according to claim 5, characterized in that: In step 1, the material of the detection unit is cadmium zinc telluride or germanium.

7. The method for identifying and locating radionuclides based on pixel detectors according to claim 6, characterized in that: In step 1, N=3.

8. A pixel detector-based radionuclide identification and positioning device, used to implement the pixel detector-based radionuclide identification and positioning method according to any one of claims 1-7, characterized in that: It includes a detector, a data recording and analysis module, and a power supply; the data recording and analysis module contains a pre-stored lookup table of characteristic peaks of radionuclides; The detector comprises N detection units, where N ≥ 3; The data recording and analysis module is connected to N detection units through N signal acquisition circuits respectively; The power supply is connected to the detector, the data recording and analysis module, and the signal acquisition circuit, respectively.

9. The radionuclide identification and positioning device based on a pixel detector according to claim 8, characterized in that: Each of the aforementioned detection units is fan-shaped, and N detection units are arranged around the same central axis to form a cylindrical detector; the central axis is perpendicular to the two-dimensional plane where the radiation source to be tested is located; The detector has a diameter of 20mm and a height of 15mm.

10. The radionuclide identification and positioning device based on a pixel detector according to claim 9, characterized in that: The detection unit is made of zinc cadmium telluride or germanium.

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