Boron neutron capture therapy beam shaping device and boron neutron capture therapy system

Abstract

The invention relates to the technical field of radiation therapy, in particular to a boron neutron capture therapy beam shaping device and a boron neutron capture therapy system. The beam shaping device for boron neutron capture therapy is used for beam shaping of a DT neutron tube generator. The interior of the beam shaping device is provided with a particle beam channel, and the particle beam channel is used for generating an initial neutron source through an incident proton beam. The beam shaping device comprises a value-added layer, a moderator, a filter layer, a reflecting layer, a collimator and a shielding layer, wherein the value-added layer, the moderator, the filter layer and the collimator are sequentially arranged from a target material to an outlet. And the axes of the particle beam channel, the value-added layer, the moderator and the collimator coincide. According to the beam shaping device, 14Mev high-energy neutrons from the DT neutron tube generator are shaped into hot / slow neutron beams meeting the BNCT treatment requirements, and impurities of fast neutrons and gamma rays are reduced to the maximum extent, so that the dosage precision and biological selectivity of treatment are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of radiotherapy technology, and more particularly to a boron neutron capture therapy beam shaping device and a boron neutron capture therapy system. Background Technology

[0002] In recent years, cancer has become the primary threat to human life. With the rapid development of cancer treatment technologies, BNCT (Boron Neutron Capture Therapy) has been widely used in clinical medicine.

[0003] The basic principle of BNCT is to irradiate patients who have been injected with boron carriers using a neutron beam. 10 When B is enriched in cancer cells, neutrons and... 10 B occurs (n, α) 7 Li reacts, compared to other common elements in the human body, 10 B has a larger thermal neutron absorption cross section, and 10 B(n,α) 7 Li reacts to release 7 Li and α ions have advantages such as high linear energy transfer (LET), high relative biological effect (RBE), and short range, which makes BNCT have a strong killing effect on cancer cells. Moreover, its killing power is limited to boron-containing cells, which can kill cancer cells while protecting normal tissue cells to the maximum extent. It has the advantages of precise targeting, short treatment course and less pain.

[0004] Initially, boron neutron transplantation (BNCT) primarily relied on reactor-based neutron sources. However, with the development of accelerator technology, accelerator-based neutron sources have become a new research hotspot due to their advantages such as miniaturized treatment facilities and easily controllable neutron beam quality. However, the neutron energies produced by accelerators are too high to be directly used in boron neutron capture reactions; they need to be reduced to a suitable level using a beam shaping assembly (BSA). Existing BNCT devices are all based on reactors or accelerators, which are large in size and expensive. Using neutron tubes as neutron sources can not only reduce costs but also facilitate the promotion of BNCT, benefiting more people. Existing neutron generators mainly include deuterium-deuterium tube neutron generators (DD neutron tube generators) and deuterium-tritium tube neutron generators (DT neutron tube generators). However, the yield of deuterium-deuterium neutron generators is far from meeting the demand; the stable yield of deuterium-tritium neutron generators is only 5 x 10⁻⁶. 12 / s, with a neutron energy of 14 MeV.

[0005] Different types of accelerators, accelerated particles, energy and current, and target materials all affect the characteristics of neutrons, so it is essential to design a BSA suitable for the conditions of a specific accelerator. SUMMARY

[0006] Based on the current technical situation, the purpose of the present application is to provide a boron neutron capture therapy beam shaping device and a boron neutron capture therapy system, which "shapes" 14Mev high-energy neutrons from a DT neutron tube generator into a hot / slow neutron beam that meets the requirements of BNCT treatment, and maximally reduces the impurities of fast neutrons and gamma rays, so as to effectively improve the dose accuracy and biological selectivity of treatment.

[0007] The present application solves the above technical problems by the following technical means:

[0008] In a first aspect, the embodiments of the present application provide a boron neutron capture therapy beam shaping device, which is internally provided with a particle beam channel, and is used for beam shaping of a DT neutron tube generator, and comprises:

[0009] A value-added layer is arranged at the outlet end of the particle beam channel, and is used for increasing the flux of epithermal neutrons and reducing the components of fast neutrons and gamma rays.

[0010] A moderator is arranged at the end of the moderator away from the value-added layer, and is used for slowing down the incident fast neutron beam to emit a thermal neutron beam or an epithermal neutron beam.

[0011] A filter layer is arranged at the end of the filter layer away from the moderator, and is used for filtering the components of thermal neutrons, fast neutrons and gamma rays.

[0012] A reflector layer is wrapped outside the particle beam channel, the value-added layer, the moderator and the filter layer, and is used for reflecting the scattered and escaped neutrons back to the moderator.

[0013] A collimator is arranged at the end of the collimator away from the moderator, and is used for collimating the thermal neutron beam or the epithermal neutron beam.

[0014] A shielding layer is in contact with the moderator, and is wrapped outside the collimator, and is used for absorbing or reflecting the leaked neutrons and photons and reducing the components of gamma rays.

[0015] The axes of the particle beam channel, the value-added layer, the moderator and the collimator are coincident.

[0016] In combination with the first aspect, in some embodiments, the value-added layer is a sphere, and the radius of the value-added layer is 3-11cm.

[0017] In combination with the first aspect, in some embodiments, the value-added layer is formed of tungsten.

[0018] When the neutron energy reaches 7-8 Mev, the stable isotopes of tungsten will undergo neutron value-added reactions, as follows:

[0019] A W + n → A-1 W + 2n

[0020] The neutron energy generated by the DT neutron tube is basically around 14 Mev, which meets the threshold value of metal tungsten value-added. In addition, metals Mo, Pb, and U can also undergo value-added reactions.

[0021] In combination with the first aspect, in some embodiments, the moderator is formed of aluminum fluoride, and the axial thickness of the moderator is 43-46 cm.

[0022] In combination with the first aspect, in some embodiments, the filter layer includes a thermal neutron filter layer and a gamma filter layer, and the thermal neutron filter layer is in contact with the moderator.

[0023] In combination with the first aspect, in some embodiments, the thickness of the thermal neutron filter layer is 0.08-0.12 mm, and the thermal neutron filter layer is formed of cadmium; the thickness of the gamma filter layer is 1.5-2.5 cm, and the gamma filter layer is formed of lead or bismuth.

[0024] In combination with the first aspect, in some embodiments, the axial thickness of the reflector layer is 60-80 cm, and the radial thickness of the reflector layer is set to 55-75 cm, and the reflector layer is formed of lead.

[0025] In combination with the first aspect, in some embodiments, the collimator has a collimating cavity inside, the collimating cavity has a structure of a truncated cone, and the end of the collimating cavity with a larger inner diameter is arranged on the filter layer.

[0026] In combination with the first aspect, in some embodiments, the shielding layer includes a first shielding layer and a second shielding layer, the first shielding layer is in contact with the reflector layer, the first shielding layer is formed of nickel, and the second shielding layer is formed of boron-containing polyethylene.

[0027] The second aspect provides a boron neutron capture therapy system, which includes a DT neutron tube generator and the boron neutron capture therapy beam shaping device of the first aspect.

[0028] The boron neutron capture therapy beam shaping device of the present application can improve the flux of epithermal neutrons at the outlet and reduce the content of fast neutrons and gamma rays by setting the value-added layer at the outlet end of the particle beam channel. The boron neutron capture therapy beam shaping device of the present application can shape the 14Mev high-energy neutrons from the DT neutron tube generator into a hot / slow neutron beam meeting the requirements of BNCT treatment, and minimize the impurities of fast neutrons and gamma rays, thereby improving the dose accuracy and biological selectivity of the treatment. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a table of recommended values of neutron beam parameters at the outlet set by the International Atomic Energy Agency;

[0030] Figure 2 is a structural schematic diagram of the boron neutron capture therapy beam shaping device;

[0031] wherein the particle beam channel 100, the moderator 200, the value-added layer 300, the thermal neutron filter layer 410, the gamma filter layer 420, the reflector 500, the collimator 600, the first shielding layer 710, and the second shielding layer 720;

[0032] Figure 3 is a curve graph of the change of the flux of epithermal neutrons at the outlet of the value-added layer with different radial sizes;

[0033] Figure 4 is a curve graph of the change of the content of fast neutrons and gamma rays at the outlet of the value-added layer with different radial sizes;

[0034] Figure 5 is a result graph of the influence of different moderator materials on the neutron beam;

[0035] Figure 6 is a result graph of the influence of different axial thicknesses of the reflector on the flux of epithermal neutrons;

[0036] Figure 7 is a result graph of the influence of different radial thicknesses of the reflector on the flux of epithermal neutrons;

[0037] Figure 8 is a curve graph of the influence of different thicknesses of the collimator on the flux of epithermal neutrons;

[0038] Figure 9 is a curve graph of the influence of different thicknesses of the collimator on the dose ratio of fast neutrons;

[0039] Figure 10 is a curve graph of the influence of different thicknesses of the collimator on the Q value. DETAILED DESCRIPTION

[0040] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0041] In the embodiments of the present application, the word "exemplary" or "for example" is used to represent an example, illustration or description. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or having more advantages than other embodiments or design solutions. Rather, the word "exemplary" or "for example" is used in the specific manner to present the relevant concept.

[0042] The International Atomic Energy Agency (IAEA) sets a series of standards for the neutron beam required for clinical BNCT, including the dose contamination of epithermal neutron, thermal neutron, fast neutron and γ ray. For details, please refer to Figure 1 . Among them, the energy range of epithermal neutron is between 0.5 eV and 10 keV, the energy range of thermal neutron is lower than 0.5 eV, and the energy range of fast neutron is higher than 10 keV.

[0043] The epithermal neutron flux and the concentration of boronated drugs at the tumor site jointly determine the clinical treatment time. If the concentration of boronated drugs at the tumor site is high enough, the epithermal neutron flux can be reduced. Conversely, if the concentration of boronated drugs in the tumor is low, the epithermal neutron in the high epithermal neutron flux is required to provide sufficient dose to the tumor. The epithermal neutron flux standard given by the International Atomic Energy Agency is greater than 10 9 epithermal neutrons per square centimeter per second. At this neutron flux, the treatment time of boronated drugs can be controlled within about 1 hour. In this way, in addition to the patient's body position being appropriate and feeling more comfortable in a shorter treatment time, the limited residence time of boronated drugs in the tumor can also be effectively utilized.

[0044] The unnecessary dose generated by fast neutrons to normal tissues is considered as contamination. The dose is positively correlated with the neutron energy, so the number of fast neutrons in the neutron beam should be reduced as much as possible. The fast neutron dose in unit epithermal neutron flux is defined as fast neutron contamination, which is required to be less than 2*10 −13 Gy·cm 2 .

[0045] Gamma-ray long-range penetrating radiation will selectively cause dose deposition of all tissues in the beam path, so reducing the amount of gamma-ray is the only requirement of neutron beam design, the gamma-ray dose accompanied by unit epithermal neutron flux is defined as gamma-ray contamination, IAEA suggests less than 2*10 −13 Gy·cm 2 .

[0046] Thermal neutron and epithermal neutron flux ratio, thermal neutron decay rate is fast, poor penetration, into the human body, most of the energy will remain in the skin tissue. In addition to melanoma and other skin tumors, BNCT neutron source is mostly thermal neutron, brain tumor and other conditions require to reduce the number of thermal neutrons. International Atomic Energy Agency suggests that the ratio of thermal neutron to epithermal neutron flux is less than 0.05.

[0047] Epithermal neutron flux ratio, epithermal neutron flux ratio represents the beam direction, the higher the ratio, the better the advancing direction of the neutron beam, the neutron beam with good advancing direction can reduce the dose of normal tissue around the neutron scattering, and can improve the treatment depth and positioning posture. International Atomic Energy Agency suggests that the epithermal neutron flux ratio is preferably greater than 0.7.

[0048] Beam shaping assembly (BSA) is a key neutron control device between DT neutron tube generator and patient irradiation. The core functions of BSA are as follows:

[0049] (1) Neutron energy spectrum adjustment, converting primary neutrons into thermal neutrons (about 0.025 eV) or epithermal neutrons (neutron energy about 0.5 eV~10 keV) required for treatment, depending on the depth of the target area; (2) Ray impurity filtering, filtering out non-therapeutic fast neutrons (>10 keV) and gamma rays, reducing the side irradiation of normal tissues; (3) Beam collimation and shaping, forming a neutron beam with good collimation, uniform spatial distribution and controllable cross section, which is convenient for patient positioning and dose control; (4) Neutron flux enhancement, increasing neutron flux through reflection layer and focusing structure to improve treatment efficiency.

[0050] Please refer to Figure 2 The application provides a boron neutron capture therapy beam shaping device for beam shaping of a DT neutron tube generator. The beam shaping device is internally provided with a particle beam channel 100 for generating an initial neutron source by using an incident proton beam. The beam shaping device comprises a value-added layer 300, a moderator 200, a filter layer, a reflection layer 500, a collimator 600 and a shielding layer, and the value-added layer 300, the moderator 200, the filter layer and the collimator 600 are arranged in sequence along the target material to the outlet. The axes of the particle beam channel 100, the value-added layer 300, the moderator 200 and the collimator 600 are coincident.

[0051] The value-added layer 300 is used to increase the flux of epithermal neutrons and reduce the fast neutron and gamma components, and is arranged at the outlet end of the particle beam channel. The moderator 200 is used to slow down the incident fast neutron beam to surface thermal neutrons or thermal neutrons, so as to emit a thermal neutron beam or an epithermal neutron beam, and the value-added layer 300 is partially embedded in the moderator 200. The filtering layer is used to filter thermal neutrons, fast neutrons, and high-energy gamma rays generated in the Li(p,n) reaction or neutron moderation process, and to reduce damage to the skin surface. The filtering layer is arranged at the end of the moderator 200 away from the value-added layer 300. The reflector 500 is wrapped outside the particle beam channel 100, the value-added layer 300, the moderator 200, and the filtering layer, and is used to reflect the scattered escaping neutrons back to the moderator 200, so as to recover the escaped neutrons and reflect them to the irradiation beam direction, thereby increasing the flux. The collimator 600 is used to collimate the thermal neutron beam or the epithermal neutron beam, and control the spatial distribution and the shape of the irradiation field of the neutron beam. The collimator 600 is arranged at the end of the filtering layer away from the moderator 200. The collimator 600 is usually a conical channel structure, and is lined with a boron-containing material to absorb scattered neutrons. The shielding layer is used to absorb or reflect leaked neutrons and photons, and to reduce the gamma component. The shielding layer is in contact with the reflector 500 and the filtering layer, and is wrapped outside the collimator 600. 7 The value-added layer 300 is used to increase the flux of epithermal neutrons and reduce the fast neutron and gamma components, and is arranged at the outlet end of the particle beam channel. The moderator 200 is used to slow down the incident fast neutron beam to surface thermal neutrons or thermal neutrons, so as to emit a thermal neutron beam or an epithermal neutron beam, and the value-added layer 300 is partially embedded in the moderator 200. The filtering layer is used to filter thermal neutrons, fast neutrons, and high-energy gamma rays generated in the Li(p,n) reaction or neutron moderation process, and to reduce damage to the skin surface. The filtering layer is arranged at the end of the moderator 200 away from the value-added layer 300. The reflector 500 is wrapped outside the particle beam channel 100, the value-added layer 300, the moderator 200, and the filtering layer, and is used to reflect the scattered escaping neutrons back to the moderator 200, so as to recover the escaped neutrons and reflect them to the irradiation beam direction, thereby increasing the flux. The collimator 600 is used to collimate the thermal neutron beam or the epithermal neutron beam, and control the spatial distribution and the shape of the irradiation field of the neutron beam. The collimator 600 is arranged at the end of the filtering layer away from the moderator 200. The collimator 600 is usually a conical channel structure, and is lined with a boron-containing material to absorb scattered neutrons. The shielding layer is used to absorb or reflect leaked neutrons and photons, and to reduce the gamma component. The shielding layer is in contact with the reflector 500 and the filtering layer, and is wrapped outside the collimator 600.

[0052] In this application, the structure of the beam shaping device shown in Figure 2 is taken as a reference model. The materials and thickness dimensions of the value-added layer 300, the moderator 200, the filtering layer, the reflector 500, the collimator 600, and the shielding layer along the target material to the outlet direction are determined by Monte Carlo simulation. Specifically as follows:

[0053] In the embodiments of the present application, the value-added layer 300 is used to increase the flux of epithermal neutrons and reduce the fast neutron and gamma components, and the value-added layer 300 is a spherical body made of tungsten. The influence of the value-added layer 300 with different radial sizes on the flux of epithermal neutrons, fast neutrons, and gamma components is simulated by Monte Carlo simulation, and the Monte Carlo simulation results are shown in Figure 3 and Figure 4 . Figure 3 is a curve graph of the change of the flux of epithermal neutrons at the outlet of the value-added layer with different radial sizes, Figure 4 is a curve graph of the change of the fast neutron and gamma components at the outlet of the value-added layer with different radial sizes.

[0054] It can be seen from Figure 3 that the metal W can increase the flux of epithermal neutrons at the outlet. With the increase of the thickness of W, the flux of epithermal neutrons increases first and then decreases, and reaches the maximum value at a radius of 7.5 cm. From Figure 4It can be seen that with the increase of the radius of W, the fast neutron dose ratio and the gamma dose ratio are both in a process of obvious decline. Therefore, in the embodiments of the present application, the radius of W is selected as 3-11 cm, and the thickness of W can be fine-tuned according to the detailed fast neutron and gamma components, so as to meet the overall requirements of IAEA.

[0055] In the embodiments of the present application, Al, AlF3, MgF2, Ti, TiF3, CaF2, and Al2O3 are respectively selected as the moderator material, the influence of different moderator materials on the neutron beam is simulated by Monte Carlo, and the results are shown in Figure 5 Figure 5 Among them, hot represents thermal neutron flux, unit: cm -2 ·s -1 ; superhot represents superthermal neutron flux, unit: cm -2 ·s -1 ; Df represents fast neutron. It can be seen from Figure 5 that when AlF3 is used as the moderator material, the superthermal neutron flux, the fast neutron dose ratio, the gamma dose ratio, and the Q value all meet the overall requirements of IAEA. Therefore, the material of the moderator in the present application is aluminum fluoride.

[0056] In the embodiments of the present application, the filter layer includes a thermal neutron filter layer 410 and a gamma filter layer 420, and the thermal neutron filter layer 410 is in contact with the moderator 200. The thermal neutron filter layer 410 is formed of cadmium, and the gamma filter layer 420 is formed of lead or bismuth. Although the filtering effect of bismuth is better than that of lead, lead has more cost advantages. Therefore, in the embodiments of the present application, lead is preferably used as the material of the gamma filter layer. The thickness of the thermal neutron filter layer is 0.08-0.12 mm, and in the embodiments of the present application, the thickness of the thermal neutron filter layer is preferably 0.1 mm. The thickness of the gamma filter layer is 1.5-2.5 cm, and in the embodiments of the present application, the thickness of the gamma filter layer is preferably 2.0 cm.

[0057] In the embodiments of the present application, the reflector layer 500 is used to reflect the scattered and escaped neutrons back to the moderator. Lead is used to prepare the reflector layer in the present application, the influence of different thicknesses of the reflector layer on the superthermal neutron flux is simulated by Monte Carlo, and the results are shown in Figure 6 and Figure 7 Here, the axial thickness of the reflector layer refers to the axial thickness along the direction of the target material to the outlet direction, and the radial thickness of the reflector layer refers to the thickness along the direction perpendicular to the axial thickness. Figure 6 The results show that when the axial thickness of the reflector layer is 70 cm, the superthermal neutron flux at the outlet basically no longer increases, so the axial thickness of the reflector is selected as 60-80 cm, and the axial thickness of the reflector layer is preferably 70 cm. Figure 7 ​The results show that when the radial thickness of the reflecting layer reaches 60 cm, the excess thermal neutron flux will not increase substantially with the increase of the radial thickness of the reflecting layer, and the radial thickness of the reflecting layer is set to 55-75 cm, preferably 60 cm.

[0058] In the embodiment of the present application, the collimator 600 has a collimating cavity inside, the collimating cavity has a truncated cone structure, the end with a larger inner diameter of the collimating cavity is arranged on the filtering layer, and the collimator 600 is made of lead. The influence of different thicknesses of the collimator on the neutron beam is simulated by Monte Carlo simulation, and the results are shown in FIGS. Figure 8 、 Figure 9 and Figure 10 . Figure 8 is a graph of the influence of different thicknesses of the collimator on the excess thermal neutron flux, Figure 9 is a graph of the influence of different thicknesses of the collimator on the fast neutron dose ratio, Figure 10 is a graph of the influence of different thicknesses of the collimator on the Q value.

[0059] Figure 8 、 Figure 9 and Figure 10 The data of FIGS.

[0060] In the embodiment of the present application, the shielding layer includes a first shielding layer 710 and a second shielding layer 720, the first shielding layer 710 is in contact with the reflecting layer 500, and the second shielding layer 720 is in contact with the gamma filtering layer 420. The first shielding layer 710 is formed of nickel, and the second shielding layer 720 is formed of boron-containing polyethylene. In order to greatly reduce the gamma component and improve the excess thermal neutron flux. The thicknesses of the first shielding layer 710 and the second shielding layer 720 are 14 cm and 13 cm, respectively.

[0061] In an embodiment of the present application, tungsten is used as the material of the additive layer, lead is used as the material of the reflecting layer, aluminum fluoride is used as the material of the moderator, cadmium is used as the material of the thermal neutron filtering layer, lead is used as the material of the gamma filtering layer, lead is used as the material of the collimator, boron-containing polyethylene is used as the material of the second shielding layer, and nickel is used as the material of the first shielding layer; and the radius of the additive layer is set to 7.5 cm, the axial thickness of the reflecting layer is set to 70 cm, the radial thickness of the reflecting layer is set to 60 cm, the thickness of the thermal neutron filtering layer is set to 0.1 mm, the thickness of the gamma filtering layer is set to 2 cm, and the thickness of the collimator is set to 2.1 cm. The neutron beam parameters at the outlet obtained in this way are shown in Table 1.

[0062]

[0063] Table 1

[0064] The data in Table 1 shows that the above-mentioned design basically meets the IAEA standard.

[0065] Another embodiment of the present application also provides a boron neutron capture therapy system, comprising a DT neutron tube generator and the above-mentioned boron neutron capture therapy beam shaping device.

[0066] The above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the present application, and all should be covered in the scope of the claims of the present application. The technical, shape and structure parts not described in detail in the present application are all known technologies.

Claims

1. A boron neutron capture therapy beam shaping device, internally equipped with a particle beam channel, characterized in that, The beam shaping device is used for beam shaping of the DT neutron tube generator, and the beam shaping device includes: A booster layer, used to increase the superthermal neutron flux and reduce the fast neutron and gamma components, is disposed at the exit end of the particle beam channel; A moderator is used to slow down an incident fast neutron beam so as to emit a thermal neutron beam or an ultrathermal neutron beam, wherein the value-adding layer is partially embedded in the moderator. A filter layer for filtering thermal neutrons, fast neutrons and gamma components is disposed at the end of the moderator away from the growth layer; The reflector layer, which wraps around the particle beam channel, the booster layer, the moderator, and the filter layer, is used to reflect scattered neutrons back to the moderator. A collimator is used to collimate a thermal neutron beam or an ultrathermal neutron beam, and the collimator is disposed at the end of the filter layer away from the moderator; A shielding layer, used to absorb or reflect leaked neutrons and photons, and to reduce the gamma component, is in contact with a moderator and is wrapped around the outside of the collimator. The axes of the particle beam channel, the booster layer, the moderator, and the collimator all coincide.

2. The boron neutron capture therapy beam shaping device according to claim 1, characterized in that, The enhancement layer is a sphere with a radius of 3 to 11 cm.

3. The boron neutron capture therapy beam shaping device according to claim 2, characterized in that, The enhancement layer is formed using tungsten.

4. The boron neutron capture therapy beam shaping device according to claim 1, characterized in that, The moderating body is formed of aluminum fluoride, and the axial thickness of the moderating body is 43-46 cm.

5. The boron neutron capture therapy beam shaping device according to claim 1, characterized in that, The filter layer includes a thermal neutron filter layer and a gamma filter layer, wherein the thermal neutron filter layer is in contact with the moderator.

6. The boron neutron capture therapy beam shaping device according to claim 5, characterized in that, The thickness of the thermal neutron filter layer is 0.08–0.12 mm, and the thermal neutron filter layer is formed using cadmium; the thickness of the gamma filter layer is 1.5–2.5 cm, and the gamma filter layer is formed using lead or bismuth.

7. The boron neutron capture therapy beam shaping device according to claim 1, characterized in that, The axial thickness of the reflective layer is 60-80 cm, and the radial thickness of the reflective layer is set at 55-75 cm. The reflective layer is made of lead.

8. The boron neutron capture therapy beam shaping device according to claim 1, characterized in that, The collimator has a collimation cavity inside, which has a frustum-shaped structure. The end of the collimation cavity with a larger inner diameter is placed on the filter layer.

9. The boron neutron capture therapy beam shaping device according to claim 1, characterized in that, The shielding layer includes a first shielding layer and a second shielding layer. The first shielding layer is in contact with the reflective layer. The first shielding layer is formed of nickel, and the second shielding layer is formed of boron-containing polyethylene.

10. A boron neutron capture therapy system, characterized in that, It includes a DT neutron tube generator and a boron neutron capture therapy beam shaping device as described in any one of claims 1-9.

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