Energy spectrum measurement system and spectrum unfolding method thereof

Abstract

The embodiment of the invention provides an energy spectrum measurement system and a spectrum unfolding method of the energy spectrum measurement system. The energy spectrum measurement system comprises an energy spectrum measurement device. The energy spectrum measurement device comprises a shielding assembly, a plurality of measurement assemblies and an absorption sheet assembly. The shielding assembly is provided with a mounting cavity, and one end of the mounting cavity is open to form an incident port for X-rays to enter. The measuring assembly comprises a thermoluminescence dosimeter. The absorption piece assembly comprises a first absorption piece and a plurality of second absorption pieces, the first absorption piece is arranged on the outer side of the incident port, the second absorption pieces are arranged in the mounting cavity, and the measuring assembly is arranged between the first absorption piece and the adjacent second absorption piece; the measuring assemblies are arranged between the adjacent second absorbing pieces, and the first absorbing pieces and the second absorbing pieces are made of different materials. The energy spectrum measurement system provided by the embodiment of the invention is good in measurement effect.

Description

Technical Field

[0001] The present application relates to the technical field of ray measurement, and in particular to an energy spectrum measurement system and a spectrum interpretation method of the energy spectrum measurement system. Background Art

[0002] X-rays are a type of electromagnetic wave with a very high frequency, ranging from 3×1016Hz to 3×1019Hz, with the characteristics of good directionality, high single photon energy, and strong penetrating ability. By using pulse power technology, the parameter adjustment function of the X-ray generator can be realized to generate pulsed X-rays of different widths and frequencies, forming a pulsed X-ray radiation field. Pulsed X-rays are mainly generated by X-ray tubes, accelerators and other equipment. The pulse width can cover different orders of magnitude such as milliseconds, microseconds, and nanoseconds. They are widely used in medical diagnosis, radiographic flaw detection, safety inspection, and radiation protection.

[0003] Pulse X-ray radiation field energy spectrum measurement is a necessary prerequisite for related protection research, radiation protection shielding design and dose assessment. Pulse X-ray energy spectrum is an important indicator of X-ray application, which can be used for structural optimization and performance improvement of pulse radiation devices, and can also be used to study the interaction relationship between bremsstrahlung X-rays and effectors.

[0004] In the related art, pulse X-rays have high intensity, wide energy spectrum range, and short pulse duration (ie, pulse width). The energy spectrum measurement system in the related art has great difficulty in measuring pulse X-rays in complex environments, and the measurement effect is poor. Summary of the invention

[0005] In view of this, the main purpose of the embodiments of the present application is to provide an energy spectrum measurement system with good measurement effect and a spectrum interpretation method of the energy spectrum measurement system.

[0006] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0007] A first aspect of an embodiment of the present application provides an energy spectrum measurement system, the energy spectrum measurement system comprising an energy spectrum measurement device, the energy spectrum measurement device comprising a shielding component, a plurality of measurement components and an absorption sheet component;

[0008] The shielding assembly has a mounting cavity, one end of which is open to form an incident port for X-rays to enter;

[0009] The measuring assembly includes a thermoluminescent dosimeter;

[0010] The absorption sheet assembly includes a first absorption sheet and a plurality of second absorption sheets, wherein the first absorption sheet is arranged on the outside of the incident port, and the second absorption sheet is arranged in the mounting cavity, the measurement assembly is arranged between the first absorption sheet and the adjacent second absorption sheet, and the measurement assembly is arranged between adjacent second absorption sheets respectively; the first absorption sheet and the second absorption sheet are made of different materials.

[0011] In one embodiment, the first absorbent sheet is made of PMMA; and / or,

[0012] The second absorption sheet is a metal absorption sheet; and / or,

[0013] The material of the thermoluminescent dosimeter is LiF (Mg, Cu, P).

[0014] In one embodiment, the first absorption sheet comprises a plurality of first sub-absorption sheets stacked along the opening direction of the incident port; and / or,

[0015] The second absorption sheet comprises a plurality of second sub-absorption sheets stacked along the opening direction of the incident port; and / or,

[0016] The second absorption sheet is an aluminum absorption sheet.

[0017] In one embodiment, the measurement component further comprises a polytetrafluoroethylene foil, and the polytetrafluoroethylene foil is arranged on a side of the thermoluminescent dosimeter close to the incident port.

[0018] In one embodiment, the shielding assembly includes a first shielding layer and a second shielding layer, the first shielding layer has the installation cavity and the incident port, the second shielding layer is sleeved on the outside of the first shielding layer, and the materials of the first shielding layer and the second shielding layer are different; wherein the first shielding layer is used to shield the scattering of X-rays in the accommodating cavity; and the second shielding layer is used to shield environmental stray radiation.

[0019] In one embodiment, the first shielding layer is a copper material layer; and / or,

[0020] The second shielding layer is a lead material layer.

[0021] In one embodiment, along the incident direction of the X-ray, the thickness of each of the second absorption sheets gradually increases.

[0022] In one embodiment, the energy spectrum measurement system further includes a processor, which establishes a response matrix equation based on a Monte Carlo simulation method to determine the spectrum distribution of X-rays according to the measurement results of the thermoluminescent dosimeter and the response matrix equation.

[0023] A second aspect of an embodiment of the present application provides a spectrum decomposition method for an energy spectrum measurement system, which is used in any of the above-mentioned energy spectrum measurement systems, wherein the energy spectrum measurement system further includes a processor, and the spectrum decomposition method includes:

[0024] The processor establishes a response matrix equation based on a Monte Carlo simulation method;

[0025] The processor determines the spectrum distribution of X-rays according to the measurement result of the thermoluminescent dosimeter and the response matrix equation.

[0026] In one embodiment, the processor establishes a Monte Carlo model corresponding to the energy spectrum measurement device to simulate and obtain a response function of the X-ray attenuation in the absorption sheet assembly and construct the response matrix equation;

[0027] The processor solves the response matrix equation based on one of a maximum expectation method and a maximum entropy method.

[0028] The embodiment of the present application provides an energy spectrum measurement system and a spectrum interpretation method of the energy spectrum measurement system, wherein the shielding component has an installation cavity, one end of which is open to form an incident port for X-rays to enter. The measurement component includes a thermoluminescent dosimeter. The absorption sheet component includes a first absorption sheet and a plurality of second absorption sheets, wherein the first absorption sheet is arranged outside the incident port, the second absorption sheet is arranged in the installation cavity, a measurement component is arranged between the first absorption sheet and the adjacent second absorption sheet, and a measurement component is arranged between the adjacent second absorption sheets, and the materials of the first absorption sheet and the second absorption sheet are different. On the one hand, the thermoluminescent dosimeter is a mixture of a certain amount of thermoluminescent material or a thermoluminescent material and a non-luminescent material in a certain weight ratio, and has the advantages of good energy response, high sensitivity, wide measuring range, light weight, small volume, stable performance, good reproducibility, and low price. Therefore, the use of a thermoluminescent dosimeter as a measurement component can make the energy spectrum measurement system have a better measurement effect. And by setting up a shielding component, it is possible to better shield external environmental stray radiation, thereby reducing the impact of environmental stray radiation on the measurement results, and thus further improving the measurement effect. On the other hand, the absorption sheet component adopts a composite structure, using two absorption sheets of different materials, which can be suitable for photon attenuation of X-rays of different energies, thereby meeting the measurement requirements and improving the measurement effect. At the same time, the first absorption sheet is arranged on the outside of the incident port, which can facilitate the measurement of low-energy photons, thereby making the measurement lower limit of the energy spectrum measurement system lower and the measurement range of the energy spectrum measurement system wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the energy spectrum measurement system for measuring pulse X-ray energy spectrum based on the absorption method. The straight arrow in the figure is the incident direction of the X-ray.

[0030] Figure 2 This is a schematic structural diagram of an energy spectrum measurement system according to the first embodiment of the present application. The straight arrow in the figure indicates the incident direction of the X-ray, and the processor is not shown in the figure;

[0031] Figure 3 for Figure 2 A schematic diagram of the structure from another perspective;

[0032] Figure 4 for Figure 3 The AA section view, the straight arrow in the figure is the incident direction of the X-ray;

[0033] Figure 5 for Figure 2 Exploded diagram of the medium energy spectrum measurement system;

[0034] Figure 6 for Figure 5 A partial enlarged view of point B in the middle;

[0035] Figure 7 This is a graph showing the response function of the LiF (Mg, Cu, P) crystal in the second embodiment of the present application;

[0036] Figure 8 It is a diagram of energy response data of the energy spectrum measurement system in air simulated by the processor in the third embodiment of the present application;

[0037] Fig. 9 This is a diagram of spectrum decomposition results of the processor based on the maximum expectation method in the fourth embodiment of the present application;

[0038] Fig.10 This is a diagram of spectrum decomposition results of the processor based on the maximum entropy method in the fifth embodiment of the present application;

[0039] Fig.11 This is a flow chart of a spectrum interpretation method of an energy spectrum measurement system in a sixth embodiment of the present application.

[0040] Description of Reference Numerals

[0041] 10. Shielding assembly; 10a. Mounting cavity; 10b. Incident port; 11. First shielding layer; 12. Second shielding layer; 20. Measuring assembly; 21. Thermoluminescent dosimeter; 22. Polytetrafluoroethylene foil; 30. Absorber assembly; 31. First absorber; 32. Second absorber; 40. Absorber; 50. Detector medium. DETAILED DESCRIPTION

[0042] An embodiment of the present application provides an energy spectrum measurement system. Figures 2 to 5 The energy spectrum measurement system includes an energy spectrum measurement device, and the energy spectrum measurement device includes a shielding component 10, a plurality of measurement components 20 and an absorption sheet component 30.

[0043] The shielding assembly 10 has a mounting cavity 10a, one end of which is open to form an incident port 10b for X-rays to enter.

[0044] The measuring assembly 20 comprises a thermoluminescent dosimeter 21 .

[0045] The absorption sheet assembly 30 includes a first absorption sheet 31 and a plurality of second absorption sheets 32. The first absorption sheet 31 is arranged outside the incident port 10b, and the second absorption sheet 32 ​​is arranged in the installation cavity 10a. A measurement assembly 20 is arranged between the first absorption sheet 31 and the adjacent second absorption sheet 32, and a measurement assembly 20 is respectively arranged between the adjacent second absorption sheets 32. The first absorption sheet 31 and the second absorption sheet 32 ​​are made of different materials.

[0046] Specifically, the energy spectrum measurement system of the embodiment of the present application can be applied to the energy spectrum measurement of any X-ray radiation field. For the convenience of description, the present application takes the energy spectrum measurement system for the energy spectrum measurement of the pulsed X-ray radiation field as an example for description.

[0047] The energy spectrum measurement system measures the pulsed X-ray spectrum based on the absorption method. Figure 1 The principle is that the energy deposited on the detector medium 50 by X-rays after passing through the absorbers 40 of different materials and thicknesses is different. By placing absorbers 40 of different mass thicknesses in front of the detector medium 50 array and combining the response function of the detector medium 50, the energy spectrum is obtained. Among them, the selection of the detector medium 50 will directly determine the decomposition effect of the X-ray energy spectrum, which is an important factor in the design of the pulse X-ray energy spectrum measurement system.

[0048] The embodiment of the present application uses a thermoluminescent dosimeter 21 as the detector medium 50, which has a series of advantages such as good energy response, high sensitivity, wide measuring range, light weight, small size, stable performance, good reproducibility, and low price.

[0049] It should be noted that the specific material of the thermoluminescent dosimeter 21 is not limited. For example, the material of the thermoluminescent dosimeter 21 is LiF (Mg, Cu, P), that is, a lithium magnesium copper phosphorus thermoluminescent dose detector.

[0050] Specifically, LiF (Mg, Cu, P) crystal is selected as the detector medium 50. The response function curve of LiF (Mg, Cu, P) crystal changes very smoothly and has no mutation at a specific energy point, which meets the requirement of the spectrum decomposition algorithm for a relatively smooth response function. In a wide dose range, the thermoluminescence signal of LiF (Mg, Cu, P) crystal has a good linear relationship with the X-ray dose rate, and the sensitivity does not change with the absorbed dose, which ensures the reliability of the measurement results of the energy spectrum measurement system and can effectively solve the dose monitoring problem in high-dose places.

[0051] The specific size and performance of the thermoluminescent dosimeter 21 can be set according to actual conditions. For example, the detector medium 50 is set to a 3.2 mm×3.2 mm LiF (Mg, Cu, P) crystal, and its response function curve is as shown in FIG. Figure 7 Its specific performance is shown in the following table:

[0052] Table 1 LiF (Mg, Cu, P) performance

[0053]

[0054] The measuring component 20 is disposed in the installation cavity 10a of the shielding component 10. The shielding component 10 can shield external environmental stray radiation, thereby reducing the risk of environmental stray radiation entering the installation cavity 10a, thereby reducing the impact of environmental stray radiation on test results.

[0055] The incident port 10b of the installation cavity 10a is used for allowing X-rays to enter the installation cavity 10a.

[0056] The absorption sheet assembly 30 is used to attenuate X-rays, so that the energy distribution changes continuously. The absorption sheet assembly 30 uses absorption sheets made of different materials, which is a composite structure, and can be suitable for attenuating photons of different energies.

[0057] For example, the first absorption sheet 31 is a low-energy photon absorption sheet, which corresponds to low-energy photons and is used to attenuate low-energy photons. The second absorption sheet 32 ​​is a medium-high energy photon absorption sheet, which corresponds to medium-high energy photons and is used to attenuate medium-high energy photons.

[0058] Exemplarily, the material of the first absorption sheet 31 is PMMA (polymethyl methacrylate). The use of PMMA absorption sheet can better facilitate the attenuation of low-energy photons of X-rays, so that the measurement lower limit of the energy spectrum measurement system is reduced, thereby having a wider measurement range.

[0059] For another example, the second absorbent sheet 32 ​​is a metal absorbent sheet.

[0060] For example, the second absorption sheet 32 ​​is an aluminum absorption sheet, which can better facilitate the attenuation of medium and high energy photons of X-rays.

[0061] The first absorption sheet 31 is arranged outside the incident port 10b, that is, the first absorption sheet 31 is arranged at the incident port 10b and is located outside the mounting cavity 10a. Therefore, when the first absorption sheet 31 is used for attenuation of low-energy photons, due to the low energy of low-energy photons, if the first absorption sheet 31 is arranged inside the mounting cavity 10a, there will be a problem of poor measurement effect of the first absorption sheet 31. Therefore, the first absorption sheet 31 is arranged outside the mounting cavity 10a, so that low-energy photons can be better passed through and attenuated.

[0062] The second absorption sheet 32 ​​is arranged in the installation cavity 10a, and is used to attenuate medium and high energy photons. Since medium and high energy photons have high energy, the second absorption sheet 32 ​​is arranged in the shielding component 10, which will not have a significant impact on the measurement result. At the same time, the shielding effect of the shielding component 10 can also improve the measurement effect.

[0063] X-rays pass through the incident port 10b from the outside of the shielding component 10 and enter the installation cavity 10a. Along the incident direction of the X-rays, a plurality of second absorption sheets 32 are arranged at intervals in the installation cavity 10a, and a measurement component 20 is correspondingly arranged on the rear side of each absorption sheet (including the first absorption sheet 31 and the second absorption sheet 32). Therefore, when the X-rays are incident on the energy spectrum measurement device, the energy distribution will continuously change due to the attenuation of each layer of absorption sheet and the thermoluminescent dosimeter 21. By measuring the dose deposited in each thermoluminescent dosimeter 21 and inferring it, the energy spectrum information of the incident pulse X-ray can be obtained.

[0064] It should be noted that the specific structure of the first absorbent sheet 31 can be set according to actual conditions.

[0065] For example, see Figures 2 to 5 The first absorption sheet 31 includes multiple first sub-absorption sheets stacked along the opening direction of the incident port 10b. In other words, the first absorption sheet 31 is formed by stacking multiple first sub-absorption sheets along the incident direction of the X-rays, thereby avoiding the problem of unclear attenuation caused by the thickness of a single absorption sheet being too small.

[0066] For example, see Figure 4 and Figure 5 The second absorption sheet 32 ​​includes a plurality of second sub-absorption sheets stacked along the opening direction of the incident port 10b. In other words, the second absorption sheet 32 ​​is formed by stacking a plurality of second sub-absorption sheets along the incident direction of the X-rays, thereby avoiding the problem of unclear attenuation caused by a single absorption sheet being too thin.

[0067] Pulsed X-rays are widely used in the fields of medical diagnosis, radiographic flaw detection, safety inspection and radiation protection. However, compared with continuous X-rays, the research work on pulsed X-rays is temporarily lacking, and the relevant measurement and metrology methods lag seriously behind the application technology requirements, which directly affects the energy efficiency of the pulsed radiation field. At the same time, due to the wide range of sources of uncertainty and the difficulty in quantifying some source terms, the uncertainty analysis of pulsed X-ray energy spectrum measurement is still a technical problem in this field, and only rough estimates and qualitative analysis can be given at present. In the related technology, various types of energy spectrometers are used to measure the energy spectrum of the pulsed X-ray radiation field. The height of the pulse signal output by the detector is proportional to the energy of the incident particles. The pulse height information obtained by the energy spectrometer analysis can be used to obtain the energy spectrum results of the pulsed X-ray radiation field. However, due to the dead time problem, the pulse pile-up effect and the limitation of the back-end circuit analysis time, the energy spectrometer in the related technology cannot achieve the established measurement goals in the pulsed X-ray radiation field and is difficult to be widely used in practice.

[0068] The energy spectrum measurement system of the embodiment of the present application adopts the absorption method to measure the pulse X-ray energy spectrum. On the one hand, the thermoluminescent dosimeter 21 is a mixture of a certain amount of thermoluminescent material or a thermoluminescent material and a non-luminescent material in a certain weight ratio, which has the advantages of good energy response, high sensitivity, wide range, light weight, small size, stable performance, good reproducibility, and low price. Therefore, the use of the thermoluminescent dosimeter 21 as the measurement component 20 can make the energy spectrum measurement system have a better measurement effect. And by setting the shielding component 10, it can better shield the external environmental stray radiation, thereby reducing the influence of environmental stray radiation on the measurement results, and thus can further improve the measurement effect. On the other hand, the absorption sheet component 30 adopts a composite structure, using two absorption sheets of different materials, which can be suitable for the photon attenuation of X-rays of different energies, thereby meeting the measurement requirements to improve the measurement effect. Meanwhile, the first absorption sheet 31 is arranged outside the incident port 10b, which can facilitate the measurement of low-energy photons, thereby making the measurement lower limit of the energy spectrum measurement system lower and the measurement range of the energy spectrum measurement system wider.

[0069] In summary, the energy spectrum measurement system based on the thermoluminescent dosimeter 21 is not only an effective method for carrying out energy spectrum measurement in complex environmental backgrounds, but also can provide a basis for the performance evaluation and structural optimization of pulse radiation devices, improve pulse X-ray measurement and metrology research, and improve the technical difficulties of uncertainty analysis. It is of great significance for shielding design and radiation protection work of related practitioners.

[0070] In one embodiment, please refer to Figure 5 and Figure 6The measuring assembly 20 further includes a polytetrafluoroethylene foil 22, which is disposed on a side of the thermoluminescent dosimeter 21 close to the incident port 10b. Thus, when the electron energy is lower than 200 keV (assuming that there is no boundary effect between the absorber and the thermoluminescent dosimeter 21), the polytetrafluoroethylene foil 22 can prevent the secondary electrons generated by the radiation in the absorber from entering the thermoluminescent dosimeter 21.

[0071] Specifically, when the measuring assembly 20 includes a plurality of thermoluminescent dosimeters 21, a polytetrafluoroethylene foil 22 is disposed in front of each thermoluminescent dosimeter 21. Thus, the measuring effect can be improved.

[0072] For example, the measuring assembly 20 includes three thermoluminescent dosimeters 21, each of which is covered with a Teflon (polytetrafluoroethylene) foil with a thickness of 0.8 mm.

[0073] In one embodiment, please refer to Figure 3 and Figure 4 The shielding assembly 10 includes a first shielding layer 11 and a second shielding layer 12. The first shielding layer 11 has a mounting cavity 10a and an incident port 10b. The second shielding layer 12 is sleeved on the outside of the first shielding layer 11. The first shielding layer 11 and the second shielding layer 12 are made of different materials. The first shielding layer 11 is used to shield the scattering of X-rays in the accommodating cavity. The second shielding layer 12 is used to shield the stray radiation of the environment. Thus, the measurement effect can be further improved.

[0074] Specifically, the shielding assembly 10 is a composite shielding structure, which includes two shielding layers of different materials. The inner layer is the first shielding layer 11, which is mainly used to shield the scattering of X-rays in the accommodating cavity. The outer layer is the second shielding layer 12, which is mainly used to shield the environmental stray radiation outside the accommodating cavity.

[0075] It should be noted that the specific materials of the two shielding layers can be set according to actual conditions.

[0076] For example, the first shielding layer 11 is a copper material layer. The copper material layer can better shield the scattering of X-rays in the accommodating cavity.

[0077] For another example, the second shielding layer 12 is a lead material layer. The lead material layer can better accommodate the environmental stray radiation outside the cavity.

[0078] The thickness of the two shielding layers can be set according to actual conditions.

[0079] For example, the thickness of the first shielding layer 11 is 5 mm, and the thickness of the second shielding layer 12 is 17 mm.

[0080] In one embodiment, please refer to Figure 3 and Figure 4, along the incident direction of the X-ray, the thickness of each second absorption sheet 32 ​​gradually increases. Thus, it is convenient to attenuate the X-ray in the second absorption sheets 32 of different thicknesses, so as to obtain different absorbed doses recorded by the thermoluminescent dosimeter 21 under the second absorption sheets 32 of different thicknesses.

[0081] In one embodiment, the energy spectrum measurement system further includes a processor, which establishes a response matrix equation based on a Monte Carlo simulation method to determine the spectrum distribution of the X-ray according to the measurement result of the thermoluminescent dosimeter 21 and the response matrix equation. Thus, based on the energy spectrum measurement device, the processor obtains the absorbed dose deposited in the thermoluminescent dosimeter 21 and inversely infers the energy spectrum information of the incident pulsed X-ray.

[0082] Another embodiment of the present application provides a spectrum analysis method for a spectrum measurement system, which is used in the spectrum measurement system described in any embodiment of the present application. The spectrum measurement system also includes a processor. Fig.11 , the spectrum decomposition method includes the following steps:

[0083] Step S1: The processor establishes a response matrix equation based on a Monte Carlo simulation method.

[0084] Step S2: The processor determines the spectrum distribution of the X-rays according to the measurement result of the thermoluminescent dosimeter 21 and the response matrix equation.

[0085] Specifically, the spectrum analysis method of the energy spectrum measurement system based on the absorption method is essentially to solve the energy distribution of the incident particles through limited measurement data and the limit values ​​of some physical conditions, and to record different absorbed doses by the measuring component 20 by replacing different absorption sheets. By measuring the dose after a series of absorption sheets, the intensity of the rays is inferred based on the absorbed dose. That is, as mentioned above, a pulsed X-ray spectrum measurement system is established using a thermoluminescent dosimeter 21, and a spectrum analysis method technology study is carried out based on the "few-path method", a response function is constructed using the Monte Carlo simulation method, and a response matrix equation is established; the spectrum distribution of the pulsed X-ray is determined by solving the inverse matrix method.

[0086] In one embodiment, the processor establishes a Monte Carlo model corresponding to the energy spectrum measurement device to simulate and obtain the response function of the X-ray attenuation in the absorption sheet assembly 30 and construct a response matrix equation.

[0087] The processor solves the response matrix equation based on one of a maximum expectation method and a maximum entropy method.

[0088] Specifically, since the response matrix in the spectrum decomposition process is highly ill-conditioned when the absorption method is used to measure the pulse X-ray energy spectrum, it is necessary to study the spectrum decomposition method. The energy spectrum measurement system of this embodiment can perform spectrum decomposition using the maximum expectation method, or the maximum entropy method, or the combination of the maximum expectation method and the maximum entropy method.

[0089] Among them, the maximum expectation method has the advantages of fast iteration speed and good robustness, and the maximum entropy method has the characteristic of optimally recovering the desired quantity with the least amount of information. These two methods can be used to deconstruct the pulse X-ray measurement results based on the absorption method.

[0090] A simple description of the maximum expectation method is as follows: Assume that the response function of the X-ray with energy j after penetrating the i-th material in the measuring component 20 is A(D i |φ j ), denoted as A ij . A ij A is related to the properties of the particle source, the properties of the matrix material, and the material thickness. ij Construct an N×M response matrix A. Assume that the total dose deposited by the i-th material is D i , then:

[0091]

[0092] The writable matrix form is Aφ=D. The task of spectrum analysis is to solve the X-ray energy spectrum distribution intensity φ based on the response matrix A and the measured D.

[0093] Using the maximum expectation method to solve this system of equations:

[0094]

[0095] in:

[0096]

[0097] The maximum entropy method is a maximum probability statistical method that has the characteristic of optimally recovering the quantity to be determined using the least amount of information. When solving a problem with insufficient data, the solution must be consistent with the known data, while at the same time making the least assumptions about the unknown parts. Maximum entropy means the least total information obtained, that is, the least "added" information. In the process of solving the energy spectrum, the relevant physical spectrum should be selected as empirical information to estimate the energy spectrum. Such empirical information as the initial estimate of the solution spectrum is called the default spectrum. The default spectrum and the predicted spectrum φ j To compare them, we use the maximum entropy distribution S to represent the degree of their closeness.

[0098] In fact, after the processor establishes the Monte Carlo model corresponding to the energy spectrum measurement device, the energy response function after the X-ray penetrates the energy spectrum measurement device is simulated, and then the response matrix equation is constructed. Therefore, in the actual measurement process, by obtaining the amount of X-ray deposition in the thermoluminescent dosimeter 21 of the energy spectrum measurement device and substituting it into the response matrix equation, the corresponding X-ray energy spectrum distribution intensity can be obtained.

[0099] In a specific embodiment, after the response matrix is ​​established, the spectrum solution result of solving the response matrix equation based on the maximum expectation method is as follows: Fig. 9 shown.

[0100] In a specific embodiment, after the response matrix is ​​established, the spectrum solution result of solving the response matrix equation based on the maximum entropy method is as follows: Fig.10 shown.

[0101] In a specific embodiment, a processor (such as Geant4) is used to establish a Monte Carlo model to simulate that the first absorber 31 is a PMMA absorber with a diameter of 70 mm. The second absorber 32 is an Al absorber with a diameter of 26 mm, and the thermoluminescent dosimeter 21 is a LiF (Mg, Cu, P) of φ4.5 mm×0.8 mm. The 20 keV to 2 MeV energy range is divided into equal intervals of 1 keV, and the particle source is set to monoenergetic photons of different energies to simulate the energy response. The energy response curves at different energies are shown in FIG. Figure 8 As shown, photons of different energies are completely attenuated in absorbers of different thicknesses, and photons with energies below 335 keV have large differences in energy response in the same layer of absorbers, indicating that the energy spectrum measurement system has a higher energy resolution for medium and low energy photons.

[0102] In a specific embodiment, the processor includes pulse X-ray spectrum analysis software for spectrum analysis, which is based on the Microsoft Visual Studio platform, uses the programming language C#, has a very powerful development language environment (IDE), contains multiple language packages in the document, and requires a running platform on Windows with a large number of users. The pulse X-ray spectrum analysis software adopts a modular design method, and generally includes a login and modification information module, a homepage module, an initial spectrum and parameter setting module, and a spectrum analysis module.

[0103] In the description of the present application, the description with reference to the terms "in one embodiment", "in some embodiments", "in a specific embodiment", or "exemplary" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine different embodiments or examples described in the present application and the features of different embodiments or examples without contradiction.

[0104] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. An energy spectrum measurement system, characterized in that: The energy spectrum measurement system comprises an energy spectrum measurement device, and the energy spectrum measurement device comprises a shielding component, a plurality of measurement components and an absorption sheet component; The shielding assembly has a mounting cavity, one end of which is open to form an incident port for X-rays to enter; The measuring assembly includes a thermoluminescent dosimeter; The absorption sheet assembly includes a first absorption sheet and a plurality of second absorption sheets, wherein the first absorption sheet is arranged on the outside of the incident port, and the second absorption sheet is arranged in the mounting cavity, the measurement assembly is arranged between the first absorption sheet and the adjacent second absorption sheet, and the measurement assembly is arranged between adjacent second absorption sheets respectively; the first absorption sheet and the second absorption sheet are made of different materials.

2. The energy spectrum measurement system according to claim 1, characterized in that: The material of the first absorbent sheet is PMMA; and / or, The second absorption sheet is a metal absorption sheet; and / or, The material of the thermoluminescent dosimeter is LiF (Mg, Cu, P).

3. The energy spectrum measurement system according to claim 1, characterized in that: The first absorption sheet comprises a plurality of first sub-absorption sheets stacked along the opening direction of the incident port; and / or, The second absorption sheet comprises a plurality of second sub-absorption sheets stacked along the opening direction of the incident port; and / or, The second absorption sheet is an aluminum absorption sheet.

4. The energy spectrum measurement system according to any one of claims 1 to 3, characterized in that: The measuring assembly further comprises a polytetrafluoroethylene foil, and the polytetrafluoroethylene foil is arranged on a side of each of the thermoluminescent dosimeters close to the incident port.

5. The energy spectrum measurement system according to any one of claims 1 to 3, characterized in that: The shielding assembly includes a first shielding layer and a second shielding layer, the first shielding layer has the installation cavity and the incident port, the second shielding layer is sleeved on the outside of the first shielding layer, and the materials of the first shielding layer and the second shielding layer are different; wherein the first shielding layer is used to shield the scattering of X-rays in the accommodating cavity; and the second shielding layer is used to shield environmental stray radiation.

6. The energy spectrum measurement system according to claim 5, characterized in that: The first shielding layer is a copper material layer; and / or, The second shielding layer is a lead material layer.

7. The energy spectrum measurement system according to any one of claims 1 to 3, characterized in that: Along the incident direction of the X-rays, the thickness of each of the second absorption sheets gradually increases.

8. The energy spectrum measurement system according to any one of claims 1 to 3, characterized in that: The energy spectrum measurement system also includes a processor, which establishes a response matrix equation based on a Monte Carlo simulation method to determine the spectrum distribution of X-rays according to the measurement result of the thermoluminescent dosimeter and the response matrix equation.

9. A spectrum analysis method for an energy spectrum measurement system, characterized in that: Used in the energy spectrum measurement system according to any one of claims 1 to 7, the energy spectrum measurement system further comprises a processor, and the spectrum decomposition method comprises: The processor establishes a response matrix equation based on a Monte Carlo simulation method; The processor determines the spectrum distribution of X-rays according to the measurement result of the thermoluminescent dosimeter and the response matrix equation.

10. The spectrum interpretation method of the energy spectrum measurement system according to claim 9, characterized in that: include: The processor establishes a Monte Carlo model corresponding to the energy spectrum measuring device to simulate and obtain a response function of the X-ray attenuation in the absorption sheet assembly and construct the response matrix equation; The processor solves the response matrix equation based on one of a maximum expectation method and a maximum entropy method.

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