Neutron moderating material and boron neutron capture therapy beam shaping device
By using a mixture of AlF3 and Al as a neutron moderator and combining it with a beam shaping device of a specific structure, the problem of unsatisfactory moderation effect of neutron moderators was solved, achieving efficient neutron beam shaping and improving the dosage accuracy and bioselectivity of BNCT treatment.
Patent Information
- Application Number
- CN202511078231.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-01
- Publication Date
- 2025-11-04
AI Technical Summary
Existing neutron moderators have not shown ideal moderation effects in BNCT therapy, failing to effectively reduce fast neutrons and gamma-ray impurities, resulting in insufficient treatment dose precision and bioselectivity.
A boron neutron capture therapy beam shaping device, which combines a particle beam channel, amplifier, filter layer, reflector, collimator, and shielding layer, uses a mixture of 25–45 wt% AlF3 and 55–75 wt% Al as a neutron moderator. By modulating and filtering the neutron beam, the device improves the dosage accuracy and bioselectivity of the therapy.
It significantly increases the ultrathermal neutron flux, reduces fast neutron and gamma-ray impurities, improves the dosage accuracy and bioselectivity of treatment, and meets the international standard neutron beam requirements.
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Figure CN120895285A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of radiotherapy technology, and more particularly to neutron moderation materials and boron neutron capture therapy beam shaping devices. Background Technology
[0002] As one of the three major methods of clinical cancer treatment, radiotherapy has always pursued precision. In recent years, medical imaging technology has made great strides, and radiotherapy has entered an era of "precise localization, accurate planning, and precise treatment." Traditional radiotherapy mainly uses photons for irradiation. Although most tumors can be treated with photons, the linear energy transfer (LET) of photons is relatively low. While killing tumors, it inevitably causes damage to normal tissues. In addition, for tumors with infiltrative or dendritic growth characteristics, such as gliomas and melanomas, conventional photon radiotherapy is difficult to avoid damaging healthy tissues, resulting in less than ideal radiotherapy effects.
[0003] Boron neutron capture therapy (BNCT), as an emerging radiotherapy method, offers advantages over conventional radiotherapy, including automated targeted guidance and conformal mapping for precise targeting, selectively killing tumor cells at the cellular level. The basic principle of BNCT is to irradiate patients 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] Existing BNCT (Bipolar Non-Terrain Therapy) devices are all based on reactors or accelerators. Accelerator neutron sources generate neutrons by bombarding lithium or beryllium targets with proton beams, utilizing (p,n) nuclear reactions. However, the initial neutron beam energy is too high to be directly used for BNCT therapy; a beam shaping assembly (BSA) is needed to moderate and shape the neutron beam. The moderator material in the BSA needs a high neutron scattering cross section to rapidly moderate neutrons with an average energy of 0.33 MeV. Simultaneously, it needs a small neutron absorption cross section and a small gamma-ray reaction cross section. Therefore, medium-mass nuclides such as Al / Mg / F / O / C are generally chosen. However, existing moderator materials still suffer from unsatisfactory moderation effects. Summary of the Invention
[0005] Based on the current state of technology, the purpose of this invention is to provide a neutron moderation material and a boron neutron capture therapy beam shaping device, which can effectively reduce impurities such as fast neutrons and gamma rays, and improve the dosage accuracy and bioselectivity of the treatment.
[0006] The present invention solves the above-mentioned technical problems through the following technical means:
[0007] In a first aspect, embodiments of this application provide a neutron moderator material for use in a deuterium-tritium neutron tube, the neutron moderator material comprising 25-45 wt% AlF3 and 55-75 wt% Al.
[0008] In conjunction with the first aspect, in some embodiments, the neutron moderator material comprises 40 wt% AlF3 and 60 wt% Al.
[0009] In conjunction with the first aspect, in some embodiments, the density of the neutron moderator material is 2.80–2.88 g / cm³. 3 .
[0010] Secondly, embodiments of this application provide a boron neutron capture therapy beam shaping device, including a moderator prepared using the neutron moderator material described in the first aspect above.
[0011] In conjunction with the second aspect, in some embodiments, the beam shaping device further includes a particle beam channel, a booster, a filter layer, a reflector, a collimator, and a shielding layer. The axes of the particle beam channel, booster, modulator, and collimator are all coincident. The booster is disposed at the exit end of the particle beam channel, and the booster is partially embedded in the modulator. The filter layer is disposed at the end of the modulator away from the booster. The reflector wraps around the outside of the particle beam channel, booster, modulator, and filter layer. The collimator is disposed at the end of the filter layer away from the modulator. The shielding layer wraps around the outside of the collimator.
[0012] In conjunction with the second aspect, in some embodiments, the amplifying body is a sphere with a radius of 7.5 cm, and the amplifying body is made of tungsten.
[0013] In conjunction with the second aspect, in some embodiments, the moderating body is a cylinder with an axial thickness of 35–47.5 cm and a radius of 30–35 cm.
[0014] In conjunction with the second aspect, in some embodiments, the reflector is a cylinder made of lead, the axial thickness of the reflector is 70 cm, and the radius of the reflector is 93 cm.
[0015] In conjunction with the second aspect, in some embodiments, the collimator has a frustum-shaped structure, the end of the collimator with the larger outer diameter is disposed on the filter layer, the collimator is made of lead, and the axial thickness of the collimator is 1.1 to 2.1 cm.
[0016] In conjunction with the second aspect, in some embodiments, the shielding layer is made of boron-containing polyethylene material.
[0017] The neutron moderator material of the present invention is obtained by mixing AlF3 and Al, which can significantly improve the superthermal neutron flux, and the superthermal neutron content is the highest in the neutron moderator material obtained by mixing 40w% AlF3 and 60w% Al.
[0018] The boron neutron capture therapy (BNCT) beam shaping device of the present invention, by setting a booster at the exit end of the particle beam channel, can increase the ultrathermal neutron flux at the exit and reduce the fast neutron and gamma components. This device can "shape" 14 MeV high-energy neutrons from the DT neutron tube generator into a thermal / slow neutron beam that meets the requirements of BNCT treatment, while minimizing fast neutron and gamma-ray impurities, thereby improving the dosage accuracy and bioselectivity of the treatment. Attached Figure Description
[0019] Figure 1 This is a table of recommended values for neutron beam parameters at the exit point set by the International Atomic Energy Agency;
[0020] Figure 2 This is a schematic diagram of the boron neutron capture therapy beam shaping device;
[0021] Among them, there are particle beam channel 100, moderator 200, amplifier 300, Cd filter layer 410, Pb filter layer 420, reflector 500, collimator 600, and shielding layer 700. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0023] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.
[0024] 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 output of deuterium-deuterium neutron generators is far from meeting the demand; the stable output of deuterium-tritium neutron generators is only 5 x 10^6 neutrons. 12 / s, with a neutron energy of 14 MeV. The neutron moderation material and boron neutron capture therapy beam shaping device of this application are both used in DT neutron tube generators.
[0025] The International Atomic Energy Agency (IAEA) has set a series of standards for the neutron beams required for clinical BNCT, including indicators of dose contamination from hyperthermal neutrons, thermal neutrons, fast neutrons, and gamma rays. Please refer to [link to relevant documentation] for details. Figure 1 Among them, the energy range of ultrathermal neutrons is between 0.5 eV and 10 keV, the energy range of thermal neutrons is below 0.5 eV, and the energy range of fast neutrons is above 10 keV.
[0026] The duration of clinical treatment is determined by both the hyperthermic neutron flux and the concentration of boronized drugs at the tumor site. If the concentration of boronized drugs at the tumor site is sufficiently high, the hyperthermic neutron flux can be reduced. Conversely, if the concentration of boronized drugs within the tumor is low, a high hyperthermic neutron flux is required to deliver a sufficient dose of hyperthermic neutrons to the tumor. The International Atomic Energy Agency (IAEA) specifies a hyperthermic neutron flux standard of greater than 10-1. 9 One superthermal neutron per square centimeter per second. At this neutron flux, the treatment time for boronizing drugs can be controlled to within approximately one hour. This not only allows for a more comfortable and appropriate patient position during the shorter treatment period, but also effectively utilizes the limited residence time of the boronizing drug within the tumor.
[0027] Unnecessary doses of fast neutrons to normal tissues are considered contamination. The dose is positively correlated with neutron energy; therefore, the number of fast neutrons in a neutron beam should be minimized. The fast neutron dose per unit hyperthermic neutron flux is defined as fast neutron contamination, and the International Atomic Energy Agency (IAEA) stipulates that it should be less than 2 × 10⁻⁶. −13 Gy·cm 2 .
[0028] Long-range penetrating gamma rays selectively cause dose deposition in all tissues within the beam; therefore, reducing gamma ray levels is the sole requirement for neutron beam design. The gamma ray dose associated with a unit hyperthermic neutron flux is defined as gamma ray contamination, and the IAEA recommends a dose less than 2 × 10⁻⁶. −13 Gy·cm 2 .
[0029] The thermal neutron to ultrathermal neutron flux ratio is crucial. Thermal neutrons decay rapidly and have poor penetrating power; after entering the body, most of their energy remains in skin tissue. Except for skin tumors such as melanoma, BNCT neutron sources are mostly thermal neutrons. However, in other cases such as brain tumors, the thermal neutron quantity needs to be reduced. The International Atomic Energy Agency recommends a thermal neutron to ultrathermal neutron flux ratio of less than 0.05.
[0030] The superthermal neutron flux ratio represents the beam direction. A higher ratio indicates a better beam direction. A neutron beam with a better direction can reduce the dose of neutron scattering to surrounding normal tissues, while also improving treatment depth and positioning. The International Atomic Energy Agency recommends that the superthermal neutron flux ratio should ideally be greater than 0.7.
[0031] The Beam Shaping Assembly (BSA) is a crucial neutron modulation device between the DT neutron tube generator and patient irradiation. The core functions of the BSA are as follows:
[0032] (1) Neutron energy spectrum modulation: converting primary neutrons into thermal neutrons (approximately 0.025 eV) or surface thermal neutrons (epithermAl, neutron energy approximately 0.5 eV to 10 keV), depending on the depth of the target area; (2) X-ray impurity filtering: filtering out non-therapeutic fast neutrons (>10 keV) and gamma rays, reducing the side irradiation to normal tissues; (3) Beam collimation and shaping: forming a neutron beam with good collimation, uniform spatial distribution, and controllable cross-section, facilitating patient positioning and dose control; (4) Neutron flux enhancement: increasing neutron flux through reflectors and focusing structures to improve treatment efficiency.
[0033] Please refer to Figure 2The boron neutron capture therapy beam shaping device of this application includes a particle beam channel 100, a moderator 200, a booster 300, a filter layer, a reflector 500, a collimator 600, and a shielding layer 700. The axes of the particle beam channel 100, booster 300, moderator 200, and collimator 600 are all coincident. The booster 300 is located at the outlet end of the particle beam channel 100, and the booster 300 is partially embedded in the moderator 200. The filter layer is located at the end of the moderator 200 away from the booster 300. The reflector 500 wraps around the outside of the particle beam channel 100, booster 300, moderator 200, and filter layer. The collimator 600 is located at the end of the filter layer away from the moderator 200. The shielding layer 700 wraps around the outside of the collimator 600.
[0034] In this application, all axial thicknesses described refer to the thickness along the particle beam channel 100 towards the exit of the collimator 600. The booster 300 is a sphere with a radius of 7.5 cm and is made of tungsten. The moderator 200 is a cylinder with an axial thickness of 35–47.5 cm and a radius of 30–35 cm. The reflector 500 is a cylinder made of lead with an axial thickness of 70 cm and a radius of 93 cm. The collimator 600 has a frustum-shaped structure, with the larger outer diameter end positioned on the filter layer. The collimator 600 is made of lead and has an axial thickness of 1.1–2.1 cm. The shielding layer 700 is made of boron-containing polyethylene and has an axial thickness of 13 cm. The filter layer includes a Cd filter layer 410 and a Pb filter layer 420. The Cd filter layer 410 is adjacent to the moderator 200. The axial thickness of the Cd filter layer 410 is 0.1 cm, and the axial thickness of the Pb filter layer 420 is 2.0 to 2.5 cm.
[0035] The moderator 200 in this application is made of a neutron moderator material comprising 25–45 wt% AlF3 and 55–75 wt% Al, and the density of the neutron moderator material is 2.80–2.88 g / cm³. 3 .
[0036] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.
[0037] Using the boron neutron capture therapy beam shaping device described above as the equipment for the moderator material experiment, the moderators 200 made of various moderator materials were tested to obtain the neutron beam parameters at the exit. In the experiment, the radius of the booster 300 in the boron neutron capture therapy beam shaping device was 7.5 cm; the axial thickness of the moderator 200 was 39 cm, and the radius of the moderator 200 was 33 cm; the axial thickness of the reflector 500 was 70 cm, and the radius of the reflector 500 was 93 cm. The radius of the collimator 600 at the end with the larger radial dimension was 21 cm, and the radius of the end with the smaller radial dimension was 7 cm; the axial thickness of the collimator 600 was 2.1 cm; the axial thickness of the shielding layer 700 was 13 cm; the axial thickness of the Cd filter layer was 0.1 cm, and the axial thickness of the Pb filter layer was 2.0 cm.
[0038] Using Al, AlF3, MgF2, TiF3, CaF2, and Al2O3 as moderators, the neutron beam parameters at the outlet of the same boron neutron capture therapy beam shaping device were tested using moderators 200 made of different moderators. The results are shown in Table 1.
[0039] Material Name <![CDATA[Thermal neutron flux (cm -2 ·s -1 )]]> <![CDATA[Superthermal neutron flux (cm -2 ·s -1 ).]]> <![CDATA[Df / Superheat (Gy·cm 2 )]]> <![CDATA[Dγ / Superheat (Gy·cm 2 ).]]> Super hot / hot Q value Al 5.43E+06 4.85E+08 5.46E-12 2.01E-13 8.92E+01 0.6934 AlF3 1.82E+07 5.00E+08 6.86 E-13 1.78E-13 2.75E+01 0.70855 <![CDATA[MgF2]]> 2.24E+07 3.81E+08 6.74 E-13 1.83E-13 1.71E+01 0.71265 <![CDATA[TiF3]]> 4.40E+06 3.35E+08 1.24 E-12 5.53E-13 7.61E+01 0.7061 <![CDATA[CaF2]]> 2.46E+07 5.54E+08 1.09 E-12 1.37E-13 2.25E+01 0.70084 <![CDATA[Al2O3]]> 1.71E+07 3.44E+08 8.59 E-13 3.04E-13 2.01E+01 0.71099
[0040] Table 1
[0041] The data in Table 1 show that Al can effectively suppress thermal neutrons, while also having a relatively high ultrathermal neutron content. However, Al significantly increases the fast neutron content. AlF3 has a high ultrathermal neutron content and also shows a significant inhibitory effect on fast neutrons, but its thermal neutron content is relatively high.
[0042] Therefore, a mixture of Al and AlF3 in a certain proportion was selected as the moderator material. Moderator materials with different Al and AlF3 ratios were used to prepare the moderator 200 in the above-mentioned boron neutron capture therapy beam shaping device. The simulated neutron beam parameters at the outlet are shown in Table 2.
[0043] Material Name <![CDATA[Density (g·cm -3 )]]> <![CDATA[Thermal neutron flux (cm -2 ·s -1 )]]> <![CDATA[Superthermal neutron flux (cm -2 ·s -1 )]]> <![CDATA[Df / Superheat (Gy·cm 2 )]]> <![CDATA[Dγ / Superheat (Gy·cm 2 )]]> Super hot / hot Q value <![CDATA[95w%AlF3+5w%Al]]> 3.08 1.72E+07 5.20E+08 7.08E-13 1.75E-13 3.02E+01 7.06E-01 <![CDATA[90w%AlF3+10w%Al]]> 3.06 1.64E+07 5.42E+08 7.19E-13 1.68E-13 3.31E+01 7.04E-01 <![CDATA[85w%AlF3+15w%Al]]> 3.04 1.58E+07 5.61E+08 7.41E-13 1.65E-13 3.55E+01 7.07E-01 <![CDATA[80w%AlF3+20w%Al]]> 3.02 1.48E+07 5.81E+08 7.64E-13 1.60E-13 3.91E+01 7.08E-01 <![CDATA[75w%AlF3+25w%Al]]> 3.00 1.37E+07 5.97E+08 7.96E-13 1.55E-13 4.35E+01 7.03E-01 <![CDATA[70w%AlF3+30w%Al]]> 2.92 1.34E+07 6.18E+08 8.28E-13 1.53E-13 4.61E+01 7.03E-01 <![CDATA[65w%AlF3+35w%Al]]> 2.96 1.24E+07 6.32E+08 8.80 E-13 1.51E-13 5.10E+01 7.04E-01 <![CDATA[60w%AlF3+40w%Al]]> 2.94 1.18E+07 6.46E+08 9.38E-13 1.45E-13 5.49E+01 7.01E-01 <![CDATA[55w%AlF3+45w%Al]]> 2.92 1.11E+07 6.57E+08 1.01E-12 1.43E-13 5.94E+01 7.02E-01 <![CDATA[50w%AlF3+50w%Al]]> 2.90 1.04E+07 6.62E+08 1.09E-12 1.42E-13 6.37E+01 7.03E-01 <![CDATA[45w%AlF3+55w%Al]]> 2.88 9.77E+06 6.65E+08 1.19E-12 1.44E-13 6.80E+01 7.02E-01 <![CDATA[40w%AlF3+60w%Al]]> 2.86 9.42E+06 6.67E+08 1.32E-12 1.43E-13 7.09E+01 7.03E-01 <![CDATA[35w%AlF3+65w%Al]]> 2.84 8.61E+06 6.66E+08 1.46E-12 1.44E-13 7.74E+01 6.98E-01 <![CDATA[30w%AlF3+70w%Al]]> 2.82 8.25E+06 6.57E+08 1.66E-12 1.53E-13 7.97E+01 6.96E-01 <![CDATA[25w%AlF3+75w%Al]]> 2.80 7.68E+06 6.43E+08 1.89E-12 1.54E-13 8.37E+01 6.92E-01 <![CDATA[20w%AlF3+80w%Al]]> 2.78 7.30E+06 6.27E+08 2.21E-12 1.65E-13 8.59E+01 6.96E-01 <![CDATA[15w%AlF3+85w%Al]]> 2.76 6.74E+06 6.06E+08 2.61E-12 1.65E-13 8.98E+01 6.97E-01 <![CDATA[10w%AlF3+90w%Al]]> 2.74 6.45E+06 5.76E+08 3.18E-12 1.65E-13 8.93E+01 6.95E-01 <![CDATA[5w%AlF3+95w%Al]]> 2.72 6.05E+06 5.39E+08 4.02E-12 1.88E-13 8.91E+01 6.93E-01
[0044] Table 2
[0045] The data in Table 2 show that mixing AlF3 and Al can significantly increase the superthermal neutron flux, with the highest superthermal neutron content achieved at 40% AlF3 and 60% Al, but this also increases the fast neutron dose ratio. Therefore, the moderator material in this application comprises 25–45 wt% AlF3 and 55–75 wt% Al.
[0046] Example 1
[0047] This embodiment discloses a boron neutron capture therapy beam shaping device, including a particle beam channel 100, a moderator 200, a booster 300, a filter layer, a reflector 500, a collimator 600, and a shielding layer 700. The axes of the particle beam channel 100, booster 300, moderator 200, and collimator 600 are all coincident. The booster 300 is located at the outlet end of the particle beam channel 100, and the booster 300 is partially embedded in the moderator 200. The filter layer is located at the end of the moderator 200 away from the booster 300. The reflector 500 wraps around the outside of the particle beam channel 100, booster 300, moderator 200, and filter layer. The collimator 600 is located at the end of the filter layer away from the moderator 200. The shielding layer 700 wraps around the outside of the collimator 600.
[0048] In this embodiment, the amplifying element 300 is a sphere with a radius of 7.5 cm and is made of tungsten. The moderating element 200 is a cylinder prepared from 100 wt% AlF3, with an axial thickness of 39 cm and a radius of 33 cm. The reflector 500 is a cylinder made of lead, with an axial thickness of 70 cm and a radius of 93 cm. The collimator 600 has a frustum-shaped structure with a maximum radial radius of 21 cm and a minimum radial radius of 7 cm. The end of the collimator 600 with the larger outer diameter is placed on the filter layer. The collimator 600 is made of lead and has an axial thickness of 2.1 cm. The shielding layer 700 is made of boron-containing polyethylene and has an axial thickness of 13 cm. The filter layer includes a Cd filter layer 410 and a Pb filter layer 420. The Cd filter layer 410 is adjacent to the moderator 200. The axial thickness of the Cd filter layer 410 is 0.1 cm, and the axial thickness of the Pb filter layer 420 is 2.0 cm.
[0049] The neutron beam parameters at the outlet of the boron neutron capture therapy beam shaping device in this embodiment were obtained through simulation experiments, as shown in Table 3.
[0050] Example 2
[0051] This embodiment discloses a boron neutron capture therapy beam shaping device with a structure identical to that of Embodiment 1, except for the dimensions of some structural components. The differences between this embodiment and Embodiment 1 are as follows:
[0052] In this embodiment, the moderator 200 is a cylinder prepared by mixing 40 wt% AlF3 and 60 wt% Al. The axial thickness of the moderator 200 is 47.5 cm, and the radius is 33 cm. The collimator 600 has an axial thickness of 1.1 cm. The filter layer includes a Cd filter layer and a Pb filter layer. The Cd filter layer is adjacent to the moderator 200, and the axial thickness of the Cd filter layer is 0.1 cm, while the axial thickness of the Pb filter layer is 2.5 cm.
[0053] The neutron beam parameters at the outlet of the boron neutron capture therapy beam shaping device in this embodiment were obtained through simulation experiments, as shown in Table 3.
[0054] <![CDATA[Thermal neutron flux (cm -2 ·s -1 )]]> <![CDATA[Superthermal neutron flux (cm -2 ·s -1 )]]> <![CDATA[Df / Superheat (Gy·cm 2 )]]> <![CDATA[Dγ / Superheat (Gy·cm 2 )]]> Super hot / hot Q value Example 1 1.80E+07 4.98E+08 6.87E-13 1.83E-13 2.77E+01 0.7075 Example 2 9.64E+06 5.13E+08 6.81 E-13 2.00E-13 5.32E+01 0.7158
[0055] Table 3
[0056] Table 3 shows that, compared to Example 2, the neutron beam parameters at the exit of the beam shaping device in Example 1 and Example 2 show that, compared to Example 2, the thermal neutron flux in Example 1 decreased by 46%, the hyperthermal neutron flux increased by 3%, the fast neutron dose ratio decreased by 1%, the hyperthermal / thermal neutron ratio increased by 92%, and the Q value increased by 1%. Only the gamma dose ratio increased slightly, but it still meets the IAEA requirements. In summary, by optimizing the results and using a moderator 200 of 40% AlF3 + 60% Al mixture, the beam parameters at the exit of the beam shaping device can be optimized.
[0057] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.
Claims
1. A neutron moderator material, characterized in that, The neutron moderator material is used in a deuterium-tritium neutron tube, and the neutron moderator material comprises 25–45 wt% AlF3 and 55–75 wt% Al.
2. The neutron moderator material according to claim 1, characterized in that, The neutron moderator material comprises 40 wt% AlF3 and 60 wt% Al.
3. The neutron moderator material according to claim 1, characterized in that, The density of the neutron moderator material is 2.80–2.88 g / cm³. 3 .
4. A boron neutron capture therapy beam shaping device, characterized in that, This includes moderators prepared using the neutron moderators described in any one of claims 1-3.
5. The boron neutron capture therapy beam shaping device according to claim 4, characterized in that, The beam shaping device further includes a particle beam channel, a booster, a filter layer, a reflector, a collimator, and a shielding layer. The axes of the particle beam channel, booster, modulator, and collimator are all coincident. The booster is located at the exit end of the particle beam channel, and the booster is partially embedded in the modulator. The filter layer is located at the end of the modulator away from the booster. The reflector wraps around the outside of the particle beam channel, booster, modulator, and filter layer. The collimator is located at the end of the filter layer away from the modulator. The shielding layer wraps around the outside of the collimator.
6. The boron neutron capture therapy beam shaping device according to claim 5, characterized in that, The amplifying body is a sphere with a radius of 7.5 cm, and it is made of tungsten.
7. The boron neutron capture therapy beam shaping device according to claim 5, characterized in that, The moderating body is a cylinder with an axial thickness of 35–47.5 cm and a radius of 30–35 cm.
8. The boron neutron capture therapy beam shaping device according to claim 5, characterized in that, The reflector is a cylinder made of lead, with an axial thickness of 70 cm and a radius of 93 cm.
9. The boron neutron capture therapy beam shaping device according to claim 5, characterized in that, The collimator has a frustum-shaped structure, with the larger outer diameter end of the collimator positioned on the filter layer. The collimator is made of lead, and its axial thickness is 1.1–2.1 cm.
10. The boron neutron capture therapy beam shaping device according to claim 5, characterized in that, The shielding layer is made of boron-containing polyethylene material.