Correction method of gamma-ray energy fluence spectrum, storage medium, correction device and correction system

Abstract

The embodiment of the present application provides a kind of gamma energy fluence spectrum correction method, storage medium, correction device and correction system, the gamma energy fluence spectrum correction method includes: based on the parameter model of detector, the parameter model of shielding structure and the neutron source parameter of irradiation beam are carried out Monte Carlo simulation, obtain the simulated pulse amplitude spectrum of secondary gamma ray induced by neutron;Total gamma ray pulse amplitude spectrum is obtained, and the total gamma ray pulse amplitude spectrum is obtained by detector to the irradiation beam of shielding structure measurement;According to the simulated pulse amplitude spectrum of secondary gamma ray, total gamma ray pulse amplitude spectrum is corrected, and primary gamma ray pulse amplitude spectrum is obtained;Primary gamma ray pulse amplitude spectrum is resolved to obtain gamma energy fluence spectrum.The gamma energy fluence spectrum correction method of the embodiment of the present application can improve the accuracy of detector measurement result.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radiation beam measurement, and in particular to a gamma energy fluence spectrum correction method, a storage medium, a correction device and a correction system. BACKGROUND

[0002] Boron neutron capture therapy (BNCT) is a binary targeted radiotherapy, which uses low-energy neutrons as an irradiation beam. In order to determine the primary gamma ray spectrum of the irradiation beam, a detector is used to measure the irradiation beam. In order to avoid radiation damage to the detector caused by high-intensity neutrons and gamma rays and the oversaturation effect of the measurement system, a shielding structure is arranged between the irradiation beam and the detector to reduce the radiation intensity.

[0003] Due to the presence of the shielding structure, the generation of secondary gamma rays induced by neutrons is inevitable. The intensity of neutrons is about two orders of magnitude higher than that of gamma rays, and the proportion of secondary gamma rays is very large, which will greatly affect the accuracy of the measurement results. SUMMARY

[0004] Therefore, the embodiments of the present application provide a gamma energy fluence spectrum correction method, a storage medium, a correction device and a correction system, which can improve the accuracy of the measurement results of the detector.

[0005] To achieve the above-mentioned purpose, the embodiments of the present application provide a gamma energy fluence spectrum correction method, which comprises:

[0006] Monte Carlo simulation is performed based on the parameter model of the detector, the parameter model of the shielding structure and the neutron source parameters of the irradiation beam to obtain a simulated pulse amplitude spectrum of secondary gamma rays induced by neutrons;

[0007] Obtain a total gamma ray pulse amplitude spectrum, which is obtained by measuring the irradiation beam through the shielding structure by the detector;

[0008] According to the simulated pulse amplitude spectrum of the secondary gamma rays, the total gamma ray pulse amplitude spectrum is corrected to obtain a primary gamma ray pulse amplitude spectrum;

[0009] The gamma energy fluence spectrum is obtained by deconvolution of the primary gamma ray pulse amplitude spectrum.

[0010] In some embodiments, the parameter model of the detector includes a size parameter model and a dead layer parameter model.

[0011] In some embodiments, the construction method of the dead layer parameter model comprises:

[0012] Obtain a pulse amplitude spectrum of a reference radiation field, which is obtained by measuring the reference radiation field by the detector;

[0013] obtaining a size parameter model of the detector and a preset dead layer parameter model of the detector;

[0014] performing Monte Carlo simulation based on the size parameter model of the detector, the preset dead layer parameter of the detector, and the radiation source parameter of the reference radiation field to obtain a simulated pulse amplitude spectrum of the reference radiation field;

[0015] correcting the preset dead layer parameter model of the detector according to the pulse amplitude spectrum of the reference radiation field and the simulated pulse amplitude spectrum of the reference radiation field, and taking the corrected preset dead layer parameter model as the dead layer parameter model.

[0016] In some embodiments, the step of correcting the preset dead layer parameter model of the detector according to the pulse amplitude spectrum of the reference radiation field and the simulated pulse amplitude spectrum of the reference radiation field, and taking the corrected preset dead layer parameter model as the dead layer parameter model comprises:

[0017] calculating a detector efficiency value according to the pulse amplitude spectrum of the reference radiation field;

[0018] calculating a simulated detector efficiency value according to the simulated pulse amplitude spectrum of the reference radiation field;

[0019] adjusting the preset dead layer parameter of the detector to change the simulated pulse amplitude spectrum of the reference radiation field, and the simulated detector efficiency value follows the change until the deviation between the simulated detector efficiency value and the detector efficiency value is less than a preset condition;

[0020] taking the adjusted dead layer parameter of the detector as the dead layer parameter model.

[0021] In some embodiments, the radiation source parameter of the reference radiation field comprises a γ source with an energy range of 0.1 MeV to 11 MeV.

[0022] In some embodiments, the step of deconvoluting the primary γ-ray pulse amplitude spectrum to obtain the γ energy fluence spectrum comprises:

[0023] establishing a response function of the detector by Monte Carlo simulation according to the size parameter model of the detector, the dead layer parameter model, the parameter model of the shielding structure, and the mono-energetic γ radiation source;

[0024] deconvoluting the primary γ-ray pulse amplitude spectrum to obtain the γ energy fluence spectrum according to the response function of the detector.

[0025] Embodiments of the present application also provide a storage medium storing computer executable instructions, which can be executed by a processor to implement the steps of the correction method.

[0026] This application embodiment also provides a correction device, the correction device comprising:

[0027] The first acquisition module is used to perform Monte Carlo simulation based on the parameter model of the detector, the parameter model of the shielding structure, and the neutron source parameters of the irradiation beam to obtain the simulated pulse amplitude spectrum of neutron-induced secondary gamma rays.

[0028] The second acquisition module is used to acquire the total gamma-ray pulse amplitude spectrum, which is obtained by the detector measuring the irradiation beam through the shielded structure.

[0029] The correction module is used to correct the total gamma-ray pulse amplitude spectrum based on the simulated pulse amplitude spectrum of the secondary gamma rays to obtain the primary gamma-ray pulse amplitude spectrum.

[0030] The spectrum decomposition module is used to decompose the amplitude spectrum of the primary gamma-ray pulse to obtain the gamma-ray energy fluence spectrum.

[0031] This application embodiment also provides a correction system, the correction system comprising:

[0032] A detector used to measure the illumination beam;

[0033] A shielding structure is disposed upstream of the detector along the emission direction of the irradiation beam. The shielding structure is used to slow down and absorb neutrons from the irradiation beam, shield gamma rays scattered from the detector, and collimate the gamma rays incident on the detector.

[0034] A memory that stores computer-executable instructions;

[0035] A processor for executing the computer-executable instructions to implement the steps of the correction method.

[0036] In some embodiments, the shielding structure includes: a gamma-ray shielding collimator having a shielding cavity and a collimation hole communicating with the shielding cavity, the shielding cavity being used to mount the detector probe and shield scattered gamma rays, and the collimation hole being used to collimate the gamma rays incident on the probe; and a neutron shielding member disposed in the outward direction of the collimation hole for slowing down and absorbing neutrons.

[0037] In some embodiments, a first preset interval is maintained between the neutron shield and the γ-shielded collimator in the extending direction of the collimation aperture.

[0038] In some embodiments, the γ-shielded collimator includes a lead cylinder and a tungsten alloy sealing block at one end of the cylinder, the cylinder and the sealing block forming a shielding cavity, and the collimation hole is formed on the sealing block.

[0039] In some embodiments, the neutron shield is made of high-density polyethylene.

[0040] The method, storage medium, correction device, and correction system for correcting the gamma-ray flux spectrum in this application utilize a detector to measure the irradiation beam, obtaining the total gamma-ray pulse amplitude spectrum. Monte Carlo simulations are performed based on the parameter models of the detector and the shielding structure, and the neutron source parameters of the irradiation beam, to obtain the simulated pulse amplitude spectrum of neutron-induced secondary gamma rays. The total gamma-ray pulse amplitude spectrum is corrected based on the simulated pulse amplitude spectrum of the secondary gamma rays to obtain the primary gamma-ray pulse amplitude spectrum, and the gamma-ray flux spectrum is obtained by spectral analysis. This eliminates the influence of the shielding structure on the measurement results. Attached Figure Description

[0041] Figure 1 This is a flowchart of a method for correcting the gamma flux spectrum according to an embodiment of this application;

[0042] Figure 2 This is a flowchart illustrating a method for constructing a dead-layer parameter model according to an embodiment of this application;

[0043] Figure 3 This is a schematic diagram of the shielding structure of a correction system according to an embodiment of this application.

[0044] Explanation of reference numerals in the attached figures

[0045] 10 gamma shielding collimator; 11 shielding cavity; 11a cylindrical body; 11b sealing block; 12 collimation hole; 20 neutron shielding component; 100 irradiation beam outlet. Detailed Implementation

[0046] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. It should be noted that, unless otherwise specified, the embodiments and technical features in the embodiments of this application can be combined with each other, and the detailed description in the specific embodiments should be understood as an explanation of the spirit of this application and should not be regarded as an undue limitation on this application.

[0047] Boron neutron capture therapy (BNCT) is a binary targeted radiotherapy that injects a boron-carrying drug, which is pro-tumor cell, into the patient's bloodstream. The boron-containing drug accumulates in tumor cells through metabolism and is then utilized to... 10 B captures low-energy neutrons with a large reaction cross-section (thermal or ultrathermal neutron-thermal neutron beams for treating superficial tumors, ultrathermal neutron beams for treating deep tumors) to irradiate the lesion area, producing alpha particles with high linear energy transfer density (LET). 7 The combined range of the Li nucleus and the other two in the tissue is about 12-13 μm, which is comparable to the size of a cell, thus selectively killing tumor cells and achieving the effect of precision treatment.

[0048] Determined by the method of beam generation and the needs of treatment, the BNCT irradiation beam has the following characteristics: 1) Wide energy range (neutrons: thermal energy ~ approximately 10 MeV, with thermal or ultrathermal neutrons as the main components; γ: approximately 100 keV ~ 10 MeV); 2) High radiation intensity (neutron flux rate: approximately 10... 9 cm -2 s -1 γ injection rate: approximately 10 7 cm -2 s -1 ;3) It is usually a cone-shaped collimated divergent beam, accompanied by a strong background of scattering in the room (caused by scattering from the walls and ceiling of the treatment room).

[0049] Due to the limitations of the BNCT irradiation beam, to avoid radiation damage to the detector caused by high-intensity neutrons and gamma rays, as well as the oversaturation effect of the measurement system, the relevant technical solutions employ an indirect measurement method. This involves using a suitable scatterer (primarily Compton scattering with photons, with a low interaction cross-section with neutrons) to scatter the beam, measuring the secondary gamma-ray energy spectrum at a certain scattering angle, and then reconstructing the spectrum to obtain the primary gamma-ray energy spectrum. Its disadvantages are: 1) Because BNCT irradiators typically use a conical collimator, the emitted beam is not parallel, so the measured secondary gamma-ray energy may not have a unique correspondence with the primary gamma-ray energy, leading to significant errors in spectrum reconstruction; 2) Because the secondary gamma-ray energy spectrum is severely compressed compared to the primary gamma-ray energy spectrum, the measurement uncertainty is relatively large (approximately 20%) in the important high-energy region.

[0050] Another related technical solution employs a direct measurement method, which involves placing a shielding structure between the irradiation beam and the detector to reduce radiation intensity and directly measure the primary gamma-ray energy spectrum of the irradiation beam. The problem with this method is that the presence of neutrons and the gamma-ray shielding collimation system inevitably leads to the generation of neutron-induced secondary gamma rays. Furthermore, since the neutron intensity is approximately two orders of magnitude higher than that of gamma rays, the proportion of secondary gamma rays is substantial, significantly affecting the accuracy of the measurement results.

[0051] In view of this, please refer to Figure 1 This application provides a method for correcting gamma energy fluence spectra, the method comprising:

[0052] S1: Monte Carlo simulations were performed based on the parameter models of the detector, the parameter models of the shielding structure, and the neutron source parameters of the irradiation beam to obtain the simulated pulse amplitude spectrum of neutron-induced secondary gamma rays.

[0053] Understandably, Monte Carlo simulations simulate the motion of a considerable number of particles, allowing the statistical laws governing particle motion to be reproduced. By constructing parameter models of the detector, shielding structure, and neutron source parameters of the irradiation beam, the environment for Monte Carlo simulation can be built, thus enabling the simulation of the pulse amplitude spectrum of neutron-induced secondary gamma rays.

[0054] It is understood that the detector's parameter model is established based on the detector's actual parameters. Specifically, the detector's parameter model can be obtained through X-ray imaging and precise measurements of the detector and shielding structure using high-precision measuring instruments. In some embodiments, the detector's parameter model includes a dimensional parameter model and a dead-layer parameter model. The detector's dimensional parameter model and dead-layer parameter model are established within Monte Carlo simulation software.

[0055] The size parameter model includes the size of the detector crystal and the size of the cavity surrounding the crystal.

[0056] In this context, the dead layer of the detector is the surface on which particles enter the detector crystal. The particles lose energy in the dead layer but generate almost no current signal; therefore, dead layer parameters need to be modeled in the simulation to eliminate their interference with the measurement results. Here, the dead layer parameter model includes the location parameters and thickness parameters of the dead layer.

[0057] It is understood that the parametric model of the shielding structure is based on the actual parameters of the shielding structure, which includes a gamma-ray shielding collimator 10 and a neutron shielding component 20. The gamma-ray shielding collimator 10 is used to shield and collimate the gamma rays incident on the detector probe, and the neutron shielding component 20 is placed between the detector probe and the radiation source to moderate and absorb neutrons. In the step of constructing the parametric model of the shielding structure, the parametric model includes the size model of the gamma-ray shielding collimator 10, the size model of the neutron shielding component 20, the relative positional dimensions of the gamma-ray shielding collimator 10 and the neutron shielding component 20 to the probe, and the material model, material density model, impurity composition model, and impurity content model of the neutron shielding component 20. It is understood that the above models can be obtained through a combination of methods such as X-ray imaging, high-precision measuring instruments, and mass spectrometry analysis.

[0058] S2: Obtain the total gamma-ray pulse amplitude spectrum, which is obtained by measuring the irradiation beam through the shielded structure using a detector.

[0059] Understandably, the neutrons in the irradiation beam are slowed down and absorbed by the shielding structure, and secondary gamma rays are induced to be generated. The secondary gamma rays and the primary gamma rays in the irradiation beam enter the detector to obtain the total gamma-ray pulse amplitude spectrum.

[0060] Its working principle is as follows: when secondary gamma rays and primary gamma rays irradiate the detector, they interact with the detector and cause photoelectric and Compton effects to occur and deposit. Electrons in the detector crystal undergo valence band to conduction band transitions, forming electron-hole pairs. The generated electrons and holes drift to the two poles under the action of the battery, thereby forming a pulse current signal in the output circuit and obtaining the total gamma ray pulse amplitude spectrum.

[0061] S3: Based on the simulated pulse amplitude spectrum of secondary gamma rays, the total gamma ray pulse amplitude spectrum is corrected to obtain the primary gamma ray pulse amplitude spectrum, thereby eliminating the influence of secondary gamma rays.

[0062] S4: Obtain the gamma flux spectrum by deconstructing the amplitude spectrum of the primary gamma-ray pulse.

[0063] It is understandable that the order of steps S1 and S2 is not important.

[0064] The method for correcting the gamma-ray flux spectrum in this application involves measuring the irradiated beam through a shielded structure using a detector to obtain the total gamma-ray pulse amplitude spectrum. Monte Carlo simulations are performed based on the parameter models of the detector and the shielding structure, as well as the neutron source parameters of the irradiated beam, to obtain the simulated pulse amplitude spectrum of neutron-induced secondary gamma rays. The total gamma-ray pulse amplitude spectrum is then corrected based on the simulated pulse amplitude spectrum of the secondary gamma rays to obtain the primary gamma-ray pulse amplitude spectrum, which is then analyzed to obtain the gamma-ray flux spectrum. This eliminates the influence of the shielding structure on the measurement results, yielding a highly accurate gamma-ray flux spectrum, which facilitates precise control of the irradiated beam parameters and improves treatment efficacy.

[0065] In some embodiments, an HPGe detector is selected as the detector, which can obtain a finer source term γ pulse amplitude spectrum of the illumination beam.

[0066] For example, please refer to Figure 2 The methods for constructing dead-layer parameter models include:

[0067] S11: Obtain the pulse amplitude spectrum of the reference radiation field, which is obtained by the detector measuring the pulse amplitude spectrum in the reference radiation field.

[0068] In some embodiments, the radiation source parameters of the reference radiation field include a γ source with an energy range of 0.1 MeV to 11 MeV.

[0069] In some embodiments, the reference radiation field includes a standard gamma source and a high-energy gamma reference radiation field. The specific parameters of the gamma source and the high-energy gamma reference radiation field are shown in Tables 1 and 2.

[0070] Table 1. Gamma source used for calibration

[0071]

[0072]

[0073] Table 2 High-energy γ-ray reference field used for calibration.

[0074]

[0075] When the detector's gamma-ray energy is less than 3.5 MeV, a source distance of 25 cm (the distance between the source and the surface between the detector) is selected for detector calibration.

[0076] S12: Obtain the detector's size parameter model and the detector's preset dead layer parameter model.

[0077] Understandably, the detector's preset dead-layer parameter model uses parameters inherent to the detector itself. Due to its insufficient accuracy, it needs to be modeled and corrected in subsequent steps to obtain relatively accurate dead-layer parameters.

[0078] S13: Based on the detector's size parameter model, the detector's preset dead layer parameters, and the radiation source parameters of the reference radiation field, a Monte Carlo simulation is performed to obtain the simulated pulse amplitude spectrum of the reference radiation field.

[0079] S14: Based on the pulse amplitude spectrum of the reference radiation field and the simulated pulse amplitude spectrum of the reference radiation field, the preset dead layer parameter model of the detector is corrected, and the corrected preset dead layer parameter model is used as the dead layer parameter model.

[0080] Understandably, the obtained dead layer parameter model is closer to the actual dead layer distribution of the detector than the preset dead layer parameter model, which improves the accuracy of the simulated pulse amplitude spectrum and gamma energy fluence spectrum of the secondary gamma rays subsequently obtained.

[0081] In some embodiments, step S14 includes:

[0082] S141: Calculate the detector efficiency value based on the pulse amplitude spectrum of the reference radiation field.

[0083] The formula for calculating the detection efficiency value in Table 1 is as follows: In the formula: n—count rate of the total energy peak, in seconds. -1 A—Activity of a radionuclide, measured in Bq; P γ —The branching ratio of the energy. The count rate of the full-energy peak is the full-energy peak count in the reference pulse amplitude spectrum divided by the measurement time.

[0084] To enable high-purity germanium (HPGe) detectors to perform measurements in the high-energy range (3.5 MeV to 11 MeV), the detectors need to be calibrated at the high-energy end. The high-energy end calibration uses high-energy gamma rays generated by accelerator target firing or radioactive nuclides that emit high-energy gamma rays.

[0085] The 6.13 MeV gamma rays are produced by 19 F(p,αγ) 16 The O resonance reaction produces gamma rays, which are measured at 55° to the proton beam using an HPGe detector, and at 125° using a gold-silicon surface barrier detector to measure alpha particles. The ratio of alpha to gamma is 1:1, and gamma rays are quantified using alpha particles.

[0086] N γ The unit for counting gamma rays emitted by the target per second is s. -1 Ω α The solid angle of the target-to-gold silicon surface barrier detector, in units of sr; n α The unit for counting alpha particles emitted per second from the target is s. -1 ;

[0087] n—Count rate of the total energy peak, in seconds. -1 N γ The unit for counting gamma rays emitted by the target per second is s. -1 .

[0088] 7ˉ11MeV high-energy gamma rays are produced by 27 Al(p,γ) 28 The reaction produces gamma rays, which are produced through a resonance reaction. Different energy protons produce gamma rays of varying energies, resulting in a cascade reaction where low-energy and high-energy gamma rays correspond one-to-one. Resonance energy points with similar emissivity and high yields were selected for the experiment.

[0089] Since the efficiency of the low-energy portion of the HPGe detector has been calibrated, the efficiency of the low-energy portion is known. The emission rate of high-energy gamma rays per second can be determined by the ratio of the emission rates of high-energy gamma rays to those of low-energy gamma rays.

[0090] ε1, n1, and P1 represent the detection efficiency, count rate, and emission rate of high-energy γ-rays, respectively, while ε2, n2, and P2 represent the detection efficiency, count rate, and emission rate of the corresponding low-energy γ-rays.

[0091] S142: Calculate the simulated efficiency value of the detector based on the simulated pulse amplitude spectrum of the reference radiation field.

[0092] Understandably, the calculation method for the detector's simulated efficiency value can refer to the calculation method for the detection efficiency value described above.

[0093] S143: Adjust the preset dead layer parameters of the detector so that the simulated pulse amplitude spectrum of the reference radiation field changes, and the simulated efficiency value of the detector changes accordingly, until the deviation between the simulated efficiency value and the actual efficiency value of the detector is less than the preset condition.

[0094] It is understood that a preset condition is met when the simulated detector efficiency value is close to the actual detector efficiency value. In this embodiment, the preset condition is that the ratio of the absolute value of the difference between the simulated detector efficiency value and the actual detector efficiency value to the actual detector efficiency value is 5%.

[0095] S144: Obtain the adjusted dead-layer parameters of the detector as the dead-layer parameter model.

[0096] For example, in step S3, the primary gamma-ray pulse amplitude spectrum is obtained by subtracting the simulated pulse amplitude spectrum of the secondary gamma rays from the total gamma-ray pulse amplitude spectrum. It should be understood that the neutron flux needs to be normalized before the calculation: the total gamma-ray pulse amplitude spectrum is divided by the measurement time, and the secondary gamma-ray pulse amplitude spectrum is multiplied by the neutron source intensity.

[0097] For example, step S4 includes:

[0098] S41: Based on the detector's size parameter model, dead layer parameter model, shielding structure parameter model, and monoenergetic gamma radiation source parameters, the detector's response function is established using Monte Carlo simulation.

[0099] S42: Based on the detector's response function, the gamma-ray pulse amplitude spectrum is despectrographed to obtain the gamma-ray flux spectrum.

[0100] It is important to understand that the response function records the response of monoenergetic photons at specific energy intervals. The selection of the energy interval has a significant impact on spectral interpretation; an interval that is too large will lead to excessive errors in spectral interpretation, while an interval that is too small will result in an excessively large matrix, increasing the difficulty of spectral interpretation. In some embodiments, the energy range of the monoenergetic gamma radiation source parameters is 0.1 MeV to 11 MeV, with an energy interval of 10 keV. It is understood that the response function in this embodiment records the response of monoenergetic gamma particles at specific energy intervals.

[0101] This application provides a storage medium storing computer-executable instructions that can be executed by a processor to implement the steps of the correction method.

[0102] In one embodiment, the storage medium may be a memory such as FRAM, ROM, PROM, EPROM, EEPROM, flash memory, magnetic surface memory, optical disk, or CD-ROM, or may include various devices that include one or any combination of the above-mentioned memories.

[0103] In one embodiment, the executable instructions may take the form of a program, software, software module, script, or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computer environment.

[0104] In one embodiment, the executable instructions may, but do not necessarily, correspond to a file in the file system. They may be stored as part of a file that holds other programs or data, for example, in one or more scripts in a Hyper Text Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple collaborative files.

[0105] In one embodiment, the executable instructions may be deployed to execute on a single computing device, or on multiple computing devices located at one location, or on multiple computing devices distributed across multiple locations and interconnected via a network.

[0106] This application provides a correction device, the correction device comprising:

[0107] The first acquisition module performs Monte Carlo simulations based on the detector's parameter model, the shielding structure's parameter model, and the neutron source parameters of the irradiation beam to obtain the simulated pulse amplitude spectrum of neutron-induced secondary gamma rays. The second acquisition module obtains the total gamma-ray pulse amplitude spectrum, which is acquired by measuring the irradiation beam through the shielding structure using the detector. The correction module corrects the total gamma-ray pulse amplitude spectrum based on the simulated pulse amplitude spectrum of the secondary gamma rays to obtain the primary gamma-ray pulse amplitude spectrum. The spectrum decomposition module decomposes the primary gamma-ray pulse amplitude spectrum to obtain the gamma-ray energy fluence spectrum.

[0108] This application provides a correction system, which includes a detector and a shielding structure.

[0109] The detector is used to measure the irradiation beam. A shielding structure is positioned upstream of the detector along the emission direction of the irradiation beam. The shielding structure is used to slow down and absorb neutrons from the irradiation beam, shield gamma rays scattered from the detector, and collimate the gamma rays incident on the detector.

[0110] The correction system further includes a memory and a processor, the memory storing computer-executable instructions. The processor is used to execute the computer-executable instructions to implement the steps of the correction method.

[0111] Please refer to Figure 3The shielding structure includes a γ-shielding collimator 10 and a neutron shield 20.

[0112] The gamma-ray shielding collimator 10 has a shielding cavity 11 and a collimation aperture 12 communicating with the shielding cavity 11. The shielding cavity 11 is used to mount the detector probe and shield scattered gamma rays. The collimation aperture 12 is used to collimate the gamma rays incident on the probe, thereby limiting the beam of rays passing through the collimation aperture 12 and entering the probe. In some embodiments, the collimation aperture 12 is a circular aperture with a diameter no greater than 0.5 cm. This allows for more efficient use of the detector's effective volume and minimizes the amount of scattered gamma rays entering the detector. In this embodiment, the collimation aperture 12 is a 0.5 cm circular aperture.

[0113] The neutron shield 20 is disposed in the outward extending direction of the collimation aperture 12 and is used to slow down and absorb neutrons. It can be understood that the irradiation beam outlet 100 is disposed on the side of the neutron shield 20 opposite to the shielding collimator 10, and the irradiation beam exits from the irradiation beam outlet 100, passes through the neutron shield 20, and enters the crystal of the detector probe through the collimation aperture 12.

[0114] It is understood that in some embodiments, the neutron shield 20 is spaced 0 from the irradiation beam outlet 100.

[0115] Understandably, in some embodiments, the neutron shield 20 is made of high-density polyethylene material, which slows down and absorbs neutrons, reduces the types of nuclides in the neutron shield, and simplifies the composition of secondary photons, thereby reducing interference with the total gamma-ray pulse amplitude spectrum.

[0116] It is understood that the structure of the neutron shield 20 is not limited. In some embodiments, the neutron shield 20 is a cylindrical structure with a diameter of 45cm and a length of 30cm.

[0117] For example, in the extending direction of the collimation aperture 12, the neutron shield 20 and the γ shield collimator 10 maintain a first preset interval, thereby further reducing the neutron flux rate in the detector.

[0118] In some embodiments, the first preset interval is greater than 100cm; specifically, in this embodiment, the first preset interval is 190cm.

[0119] For example, the γ-shielding collimator 10 includes a lead cylinder 11a and a tungsten alloy sealing block 11b that seals one end of the cylinder 11a. The cylinder 11a and the sealing block 11b form a shielding cavity 11, and the collimation hole 12 is formed on the sealing block 11b.

[0120] It is understandable that tungsten alloys have a larger attenuation coefficient for gamma rays than lead (tungsten is approximately 0.919 cm⁻¹). -1The lead content is approximately 0.564 cm³. -1 Therefore, tungsten has a better attenuation effect on gamma rays, and at the same attenuation level, it can be thinner and smaller in volume. At the same time, a thinner layer of lead can shield the scattered gamma background (at least an order of magnitude lower than direct gamma rays), while lead has a lower density than tungsten (lead is 11.35 g / cm³). 3 Tungsten is 19.3 g / cm³. -3 This allows for a lighter weight for the γ shield.

[0121] It is understood that the structure of the γ-shielding collimator 10 is not limited. In some embodiments, the cylinder 11a is made of high-purity lead, with a diameter of 24 cm and a length of 35 cm. The sealing block 11b is a tungsten alloy with a diameter of 16 cm and a length of 10 cm.

[0122] The various embodiments / implementations provided in this application can be combined with each other without creating contradictions.

[0123] The above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for correcting a gamma energy fluence spectrum, characterized in that, The correction method for the gamma flux spectrum includes: Monte Carlo simulations were performed based on the parameter models of the detector, the parameter models of the shielding structure, and the neutron source parameters of the irradiation beam to obtain the simulated pulse amplitude spectrum of neutron-induced secondary gamma rays. The total gamma-ray pulse amplitude spectrum is obtained by measuring the irradiation beam through the shielded structure using a detector. Based on the simulated pulse amplitude spectrum of secondary gamma rays, the total gamma ray pulse amplitude spectrum is corrected to obtain the primary gamma ray pulse amplitude spectrum. The gamma-ray flux spectrum was obtained by despectrographing the amplitude spectrum of the primary gamma-ray pulse. The detector's parameter model includes a size parameter model and a dead-layer parameter model, wherein the method for constructing the dead-layer parameter model includes: The pulse amplitude spectrum of the reference radiation field is obtained by the detector measuring the pulse amplitude spectrum in the reference radiation field. Obtain the detector's size parameter model and the detector's preset dead layer parameter model; Monte Carlo simulations were performed based on the detector's size parameter model, the detector's preset dead layer parameters, and the radiation source parameters of the reference radiation field to obtain the simulated pulse amplitude spectrum of the reference radiation field. Based on the pulse amplitude spectrum of the reference radiation field and the simulated pulse amplitude spectrum of the reference radiation field, the preset dead layer parameter model of the detector is corrected, and the corrected preset dead layer parameter model is used as the dead layer parameter model.

2. The method for correcting a γ-energy fluence spectrum as described in claim 1, characterized in that, The step of correcting the preset dead-layer parameter model of the detector based on the pulse amplitude spectrum of the reference radiation field and the simulated pulse amplitude spectrum of the reference radiation field, and using the corrected preset dead-layer parameter model as the dead-layer parameter model, includes: The detector efficiency value is calculated based on the pulse amplitude spectrum of the reference radiation field. The simulated efficiency value of the detector is calculated based on the simulated pulse amplitude spectrum of the reference radiation field. The preset dead-layer parameters of the detector are adjusted so that the simulated pulse amplitude spectrum of the reference radiation field changes, and the simulated efficiency value of the detector changes accordingly, until the deviation between the simulated efficiency value and the actual efficiency value of the detector is less than the preset condition. The adjusted dead-layer parameters of the detector are obtained as the dead-layer parameter model.

3. The method for correcting a γ-energy fluence spectrum as described in claim 1, characterized in that, The radiation source parameters of the reference radiation field include γ sources with energies ranging from 0.1 MeV to 11 MeV.

4. The method for correcting a γ-energy fluence spectrum as described in claim 1, characterized in that, The steps for obtaining the gamma energy fluence spectrum by deconstructing the amplitude spectrum of a primary gamma-ray pulse include: Based on the detector's size parameter model, dead layer parameter model, shielding structure parameter model, and monoenergetic gamma radiation source parameters, the detector's response function is established using Monte Carlo simulation. The gamma flux spectrum is obtained by despectrographing the amplitude spectrum of the primary gamma-ray pulse based on the detector's response function.

5. A storage medium, characterized in that, The storage medium stores computer-executable instructions that can be executed by a processor to implement the steps of the correction method according to any one of claims 1 to 4.

6. A correction device, characterized in that, The correction device includes: The first acquisition module is used to perform Monte Carlo simulation based on the parameter model of the detector, the parameter model of the shielding structure, and the neutron source parameters of the irradiation beam to obtain the simulated pulse amplitude spectrum of neutron-induced secondary gamma rays. The second acquisition module is used to acquire the total gamma-ray pulse amplitude spectrum, which is obtained by the detector measuring the irradiation beam through the shielded structure. The correction module is used to correct the total gamma-ray pulse amplitude spectrum based on the simulated pulse amplitude spectrum of the secondary gamma rays to obtain the primary gamma-ray pulse amplitude spectrum. The spectrum decomposition module is used to decompose the amplitude spectrum of the primary gamma-ray pulse to obtain the gamma-ray energy fluence spectrum.

7. A correction system, characterized in that, The correction system includes: A detector used to measure the illumination beam; A shielding structure is disposed upstream of the detector along the emission direction of the irradiation beam. The shielding structure is used to slow down and absorb neutrons from the irradiation beam, shield gamma rays scattered from the detector, and collimate the gamma rays incident on the detector. A memory that stores computer-executable instructions; A processor for executing the computer-executable instructions to implement the steps of the correction method according to any one of claims 1 to 4.

8. A correction system as described in claim 7, characterized in that, The shielding structure includes: A gamma-ray shielding collimator has a shielding cavity and a collimation hole communicating with the shielding cavity. The shielding cavity is used to mount the detector probe and shield scattered gamma rays, and the collimation hole is used to collimate the gamma rays incident on the probe. A neutron shield, located in the outward direction of the collimation aperture, is used to moderate and absorb neutrons.

9. A correction system as described in claim 8, characterized in that, In the extending direction of the collimation aperture, the neutron shield and the γ-shielded collimator maintain a first preset interval.

10. A correction system as described in claim 8, characterized in that, The γ-shielded collimator includes a lead cylinder and a tungsten alloy sealing block at one end of the cylinder. The cylinder and the sealing block form a shielding cavity, and the collimation hole is formed on the sealing block.

11. A correction system as described in claim 8, characterized in that, The neutron shield is made of high-density polyethylene.

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