Neutron capture therapy device based on DT tube
By using a mixture of aluminum fluoride and metallic aluminum as a moderator in the DT tube neutron capture therapy device, combined with a reflector and a filter, the beam shaping system was optimized, solving the problem that a single material cannot meet the needs of multiple neutrons, and improving the therapeutic effect and safety of the neutron beam.
Patent Information
- Application Number
- CN202511140780.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-15
- Publication Date
- 2025-11-14
AI Technical Summary
In existing technologies, a single material cannot simultaneously meet the optimization requirements of DT tube neutron capture therapy devices for fast neutrons, thermal neutrons, and gamma rays, resulting in poor beam quality and affecting treatment efficacy and safety.
A mixture of aluminum fluoride (AlF3) and metallic aluminum (Al) was used as a moderator, and combined with a reflector, a thermal neutron filter, and a gamma-ray shield, to optimize the structural design of the beam shaping system and form a highly efficient beam shaping system.
It increases the ultrathermal neutron flux, reduces the radiation dose of thermal and fast neutrons to healthy tissues, enhances the depth and targeting of treatment, and improves the safety and efficacy of treatment.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of BNCT treatment equipment technology, specifically a neutron capture therapy device based on a DT tube. Background Technology
[0002] Boron neutron capture therapy (BNCT) is a cell-level targeted binary radiotherapy technique. The treatment process involves two key steps: First, the patient is given a stable isotope of boron-10 (¹) that specifically accumulates within tumor cells. 0 B) the drug; then, the tumor region is irradiated using a neutron beam of specific energy. When the tumor cells ¹ 0 When a B atom nucleus captures a neutron, a nuclear fission reaction occurs (¹). 0 B(n,α) 7 Li), releasing alpha particles with high linear energy transfer (LET) and 7 Li ions. These two heavy ions have extremely short ranges, approximately 5-9 micrometers, comparable to the size of a single cell. Therefore, they can precisely release destructive energy inside tumor cells, achieving highly efficient killing of cancer cells with minimal damage to surrounding healthy tissue. Due to their unique biological advantages, BNCT shows great promise in treating invasive, multiple, or refractory tumors that are insensitive to conventional radiotherapy, such as glioblastoma and recurrent head and neck cancer.
[0003] However, the thermal neutron (DT) tube produces fast neutrons with energies up to 14 MeV, far exceeding the hyperthermal neutron energy range (0.5 eV - 40 keV) required for BNCT therapy. Therefore, a highly efficient beam shaping system (BSA) must be designed to moderate these fast neutrons. The core component of the BSA is the moderator, and due to the extremely high initial energy of the DT neutrons, the performance requirements for the moderator are extremely stringent. Existing moderator materials include magnesium fluoride (MgF2), aluminum fluoride (AlF3), alumina (Al2O3), and metallic aluminum (Al). However, a single material often struggles to achieve all performance targets simultaneously. For example, metallic aluminum (Al) effectively suppresses thermal neutron flux but produces excessively high fast neutron contamination; while aluminum fluoride (AlF3) has good moderation capabilities, producing high hyperthermal neutron flux and effectively suppressing fast neutrons, but its thermal neutron content is also relatively high, reducing the depth-dose advantage of the therapy.
[0004] Therefore, there is an urgent need for a new type of moderator design in the current technology to overcome the limitations of a single material and comprehensively optimize the beam quality of BNCT devices based on DT tubes. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a neutron capture therapy device based on a DT tube, which solves the aforementioned problems.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a neutron capture therapy device based on a DT tube, comprising:
[0007] DT neutron tubes for generating fast neutrons; and
[0008] A beam shaping system, which is installed in the neutron emission path of the DT neutron tube, is used to shape the fast neutrons into a therapeutic neutron beam;
[0009] The beam shaping system includes a moderator composed of a mixture of aluminum fluoride (AlF3) and metallic aluminum (Al).
[0010] Preferably, in the mixture, the mass ratio of aluminum fluoride (AlF3) to metallic aluminum (Al) is 40:60.
[0011] Preferably, the beam shaping system further includes a reflector disposed on the outer periphery of the moderator for reflecting neutrons escaping from the moderator back into the moderator.
[0012] Preferably, the reflector is made of lead (Pb) or lead oxide (PbO).
[0013] Preferably, the beam shaping system further includes a thermal neutron filter disposed downstream of the moderator in the beam direction.
[0014] Preferably, the material of the thermal neutron filter is lithium-6 isotope (…). 6 Li) materials.
[0015] Preferably, the beam shaping system further includes a collimator disposed at the exit end of the beam shaping system to limit the irradiation range of the therapeutic neutron beam.
[0016] Preferably, the beam shaping system further includes a gamma-ray shield made of bismuth (Bi) or lead (Pb).
[0017] Preferably, the mixture is a homogeneous composite material produced by powder metallurgy or sintering processes.
[0018] Preferably, the therapeutic neutron beam emitted from the beam shaping system has a superthermal neutron flux to thermal neutron flux ratio greater than 30.
[0019] Beneficial effects
[0020] This invention provides a neutron capture therapy device based on a DT tube. Compared with the prior art, it has the following advantages:
[0021] This DT tube-based neutron capture therapy device overcomes the performance limitations of single materials by employing a specific ratio of aluminum fluoride (AlF3) to metallic aluminum (Al) as a moderator, combined with an optimized beam shaping system (BSA) structure, achieving comprehensive optimization of the emitted neutron beam quality. The invented device increases the hyperthermal neutron flux required for treatment while significantly reducing the thermal neutron flux harmful to superficial tissues, thereby improving the hyperthermal / thermal neutron flux ratio, a key indicator of beam depth therapy capability. This greatly enhances the penetration and therapeutic efficacy of the neutron beam into deep tumors, while significantly reducing unnecessary doses to superficial healthy tissues, thus improving the targeting and depth advantages of treatment. Regarding safety, the design of this invention effectively controls fast neutron contamination, reducing its dose ratio. Even with a slight increase in the gamma dose ratio, its absolute value remains far below international safety standards, ensuring a high level of safety throughout the treatment process. Ultimately, these improvements work together to enhance the Q value, which characterizes the quality of beam-based integrated therapy, enabling the device to deliver superior clinical therapeutic benefits. Detailed Implementation
[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] This invention provides a neutron capture therapy device based on a DT tube. The device includes a DT neutron tube as a neutron source and a beam shaping system. The DT neutron tube generates high-energy fast neutrons with an energy of approximately 14 MeV. The beam shaping system is positioned adjacent to the DT neutron tube and its function is to shape the high-energy fast neutrons into a therapeutic neutron beam, primarily composed of hyperthermic neutrons, suitable for BNCT (Brain-Non-Thermal Neutron Therapy).
[0024] The core component of the beam shaping system is the moderator. The moderator is composed of a mixture of aluminum fluoride (AlF3) and metallic aluminum (Al). In a preferred embodiment, the mass ratio of this mixture is 40% AlF3 and 60% Al. This composite material is manufactured using processes such as powder metallurgy to ensure uniform mixing of the two components.
[0025] The beam shaping system also includes a reflector, typically made of a high-Z material such as lead (Pb), which surrounds the moderator and reflects neutrons scattered laterally and backward back into the moderation region, thereby improving neutron utilization efficiency. Downstream of the moderator in the beam exit direction, a thermal neutron filter is located, typically made of a material containing... 6 Li compounds are used to absorb thermal neutrons that are harmful to superficial tissues. Gamma-ray shields are used to absorb gamma rays. Finally, a collimator is located at the exit of the entire system to define the size and shape of the treatment field, ensuring that the neutron beam precisely irradiates the patient's tumor site.
[0026] Example 1: Performance Comparison Analysis of Single Moderator Materials
[0027] First, under the same BSA geometry, the performance of several single moderator materials was simulated to establish a comparative benchmark. The performance of metallic aluminum (Al) and aluminum fluoride (AlF3) was compared in detail, and the results are shown in Table 1.
[0028] Table 1. Beam parameters of different single moderator materials
[0029]
[0030] Table 1 shows the effects of different moderators on the beam under the same structure. Al effectively suppresses the thermal neutron content while maintaining a relatively high ultrathermal neutron content; however, Al significantly increases the fast neutron content. AlF3 has a high ultrathermal neutron content and also shows significant suppression of fast neutrons, but its thermal neutron content is relatively high. This indicates that a single material cannot simultaneously meet all the requirements of BNCT for the beam.
[0031] Example 2:
[0032] This embodiment provides a technical solution based on Embodiment 1:
[0033] Based on the conclusions of Example 1, this invention proposes mixing AlF3 and Al to combine their advantages. Under the same BSA structure as in Example 1, the performance of the moderator mixtures of AlF3 and Al at different mass ratios was simulated. The mass percentage of AlF3 decreased from 95% to 5% in 5% increments. Some simulation results are shown in Table 2.
[0034] Table 2 Beam parameters at different AlF3 and Al mass ratios
[0035]
[0036] Table 2 shows that the thermal neutron flux decreases monotonically with increasing Al content, while the hyperthermal neutron flux first increases and then decreases, reaching a peak at an AlF3 mass ratio of 40%. Although the fast neutron dose ratio increases, the hyperthermal / heat flux ratio continues to improve. In summary, the mixture with a mass ratio of 40% AlF3 + 60% Al exhibits the best overall potential by significantly improving the hyperthermal / heat flux ratio while maintaining a high hyperthermal neutron flux.
[0037] Example 3:
[0038] This embodiment provides a technical solution based on Embodiment 1 and Embodiment 2:
[0039] This embodiment uses the 40% AlF3 + 60% Al mixture selected in Example 2 as the moderator material. While the 40% AlF3 + 60% Al mixture provides the highest superthermal neutron content, it also increases the fast neutron dose ratio. Therefore, the beam shaper structure needs to be redesigned to ensure the exit beam meets requirements. This embodiment comprehensively optimizes the geometry of the entire BSA (including moderator size, reflector thickness, filter position, etc.) to achieve optimal parameters for the emitted beam. The performance of this final optimized scheme (labeled "Material 2") is compared with that of a similarly optimized scheme using pure AlF3 as the moderator (labeled "Material 1"). The results are shown in Table 3.
[0040] Table 3 Comparison of beam parameters for pure AlF3 and its mixture
[0041]
[0042] Table 3 shows that the thermal neutron flux of the 40% AlF3 + 60% Al mixture decreases by 46%, the ultrathermal neutron flux increases by 3%, the fast neutron dose ratio decreases by 1%, the ultrathermal / thermal neutron ratio increases by 92%, and the Q value increases by 1%. Only the gamma dose ratio increases slightly, but it still meets the IAEA requirements. In summary, by optimizing the results and using a moderator of the 40% ALF3 + 60% Al mixture, the beam parameters at the exit can be optimized.
[0043] In the device of this embodiment, the BSA also integrates other functional components: a 5-10 cm thick lead (Pb) reflector is disposed around the moderating body; and a 0.5-1 mm thick reflector is disposed at the beam exit port. 6 A LiF thermal neutron filter; a bismuth (Bi) gamma-ray shield located near the DT tube target; and a collimator made of lithium-containing polyethylene at the very end. These components, together with the core mixture moderator, constitute the high-performance neutron capture therapy device of this invention.
[0044] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.
[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A neutron capture therapy device based on a DT tube, comprising: DT neutron tubes used to generate fast neutrons; as well as A beam shaping system, which is installed in the neutron emission path of the DT neutron tube, is used to shape the fast neutrons into a therapeutic neutron beam; The feature is that the beam shaping system includes a moderator, which is composed of a mixture of aluminum fluoride and metallic aluminum.
2. The neutron capture therapy device based on a DT tube according to claim 1, characterized in that, In the mixture, the mass ratio of aluminum fluoride to metallic aluminum is 40:
60.
3. The neutron capture therapy device based on a DT tube according to claim 1, characterized in that, The beam shaping system also includes a reflector disposed on the outer periphery of the moderator for reflecting neutrons escaping from the moderator back into the moderator.
4. The neutron capture therapy device based on a DT tube according to claim 3, characterized in that, The reflector is made of lead or lead oxide.
5. A neutron capture therapy device based on a DT tube according to claim 1, characterized in that, The beam shaping system also includes a thermal neutron filter, which is located downstream of the moderator in the beam direction.
6. A neutron capture therapy device based on a DT tube according to claim 5, characterized in that, The thermal neutron filter is made of a material containing the isotope lithium-6.
7. A neutron capture therapy device based on a DT tube according to claim 1, characterized in that, The beam shaping system also includes a collimator disposed at the exit end of the beam shaping system to limit the irradiation range of the therapeutic neutron beam.
8. A neutron capture therapy device based on a DT tube according to claim 1, characterized in that, The beam shaping system also includes a gamma-ray shield, the gamma-ray shield being made of bismuth or lead.
9. A neutron capture therapy device based on a DT tube according to claim 1, characterized in that, The mixture of the moderators is a homogeneous composite material produced by powder metallurgy or sintering processes.
10. A neutron capture therapy device based on a DT tube according to claim 1, characterized in that, The therapeutic neutron beam emitted from the beam shaping system has a superthermal neutron flux to thermal neutron flux ratio greater than 30.