CN115120894A

CN115120894A - Neutron generating device

Info

Publication number: CN115120894A
Application number: CN202211056609.1A
Authority: CN
Inventors: 顾龙; 苏兴康
Original assignee: Lanzhou University
Current assignee: Lanzhou University
Priority date: 2022-08-31
Filing date: 2022-08-31
Publication date: 2022-09-30
Anticipated expiration: 2042-08-31
Also published as: CN115120894B

Abstract

The application discloses neutron generating device relates to radiotherapy technical field. The device comprises an accelerator, a neutron generator and a neutron beam shaper; an accelerator for generating a proton beam; the neutron generator is used for generating a first neutron beam under the action of the proton beam; the neutron beam shaper is used for moderating the first neutron beam to form a second neutron beam; the neutron generator comprises a rotary base plate and a bearing body, targets are distributed on the rotary base plate at intervals and are connected with the bearing body, the distribution of the extraction frequency and the duty ratio of the accelerator is changed based on the distribution of the targets and the rotation rate of the rotary base plate, and a coolant circulation passage is embedded in the bearing body. The device can reduce the action probability of non-target materials, reduce pollution, ensure that the proton beam continuously and stably reacts with the target materials, provide the utilization rate of the beam, be beneficial to obtaining the neutron beam with higher yield and higher purity, improve the treatment effect and improve the treatment gain.

Description

Neutron generating device

Technical Field

The present application relates to the field of radiation therapy, and more particularly, to a neutron generation device.

Background

The malignant tumor becomes the leading cause of death of residents in China, and it is estimated that 392.9 ten thousands of new malignant tumors are generated in the whole country in 2015 as an example, wherein 233.8 thousands of death cases are generated. Surgery, radiation therapy and chemotherapy are one of the three major approaches to cancer treatment. Among them, radiotherapy is one of the most widely used therapeutic methods because of its advantages of less damage, less pain in treatment, and easy acceptance by patients.

In the twenty-first century, accelerator-based Boron Neutron Capture Therapy (BNCT) devices have become the predominant form of radiation TherapyFig. 1 is a schematic diagram of a prior art accelerator-based boron neutron capture treatment device, as shown in fig. 1. In fig. 1, the boron neutron capture treatment apparatus includes an accelerator 200, a neutron generation unit 10, a beam shaper 20, a support 21, a reflector 22, and a collimator 30. The principle is based on thermal neutrons and ¹⁰ b (boron) reaction. After the capture of the thermal neutrons, ¹⁰ b becomes in an excited state ¹¹ B, produced in this process ⁷ Li (lithium) and ⁴ he (helium) is a particle having high Linear Energy Transfer (LET) and Relative Biological Effect (RBE) characteristics, has strong cytocidal power, and its Energy deposition is in the range of about 10 μm, which is equivalent to the diameter of one cell. Therefore, if so ¹⁰ And B is enriched in tumor cells, so that accurate killing of the tumor cells can be realized, and healthy cells around the tumor are protected. Therefore, the boron neutron capture therapy has good application prospect in the aspect of treating tumors such as malignant liver cancer, brain glioma, chondrosarcoma and the like.

However, the neutron utilization rate of the boron neutron capture treatment device in the prior art is low, and impurities such as thermal neutrons, fast neutrons and the like are more in the neutron beam current.

Disclosure of Invention

The application provides a neutron generating device, can reduce the neutron beam extravagant, improves the utilization efficiency of neutron.

The application discloses following technical scheme:

the application provides a neutron generating device, which comprises an accelerator, a neutron generator and a neutron beam shaper;

the outlet of the accelerator is aligned with the neutron generator, and the neutron beam shaper is wrapped outside the neutron generator;

the accelerator is used for generating proton beams;

the neutron generator is used for acting with the proton beam to generate a first neutron beam, and the energy of the first neutron beam is larger than a first preset threshold;

the neutron beam shaper is used for moderating the first neutron beam to form a second neutron beam, wherein the energy of the second neutron beam is smaller than a second preset threshold, and the energy of the second neutron beam is larger than a third preset threshold;

the neutron generator comprises a rotary chassis and a bearing body, targets are distributed on the rotary chassis at intervals and are connected with the bearing body, the leading-out frequency and duty ratio distribution of the accelerator are changed based on the distribution of the targets and the rotation rate of the rotary chassis, and a coolant circulation passage is embedded in the bearing body.

Optionally, the neutron beam shaper, comprising a moderator;

the moderating body is positioned behind the neutron generator;

the moderating body is used for generating inelastic collision with the first neutron beam to enable the first neutron beam to lose energy and form a second neutron beam.

Optionally, the neutron beam shaper further comprises a shielding reflector;

the shielding reflector is wrapped outside the slowing body and the neutron generator;

the shielding reflector is used for shielding neutrons scattered by the moderator when the moderator is subjected to inelastic collision and reflecting neutrons scattered by the moderator when the moderator is subjected to inelastic collision.

Optionally, the shielding reflector comprises a shield and a reflector;

the shielding body is used for shielding neutrons scattered by the moderating body during inelastic collision;

the reflector is used for reflecting neutrons scattered by the moderator when the moderator is subjected to inelastic collision to the moderator.

Optionally, the neutron beam shaper further comprises a filter;

the filter body is aligned with the outlet of the moderator;

the filtering body is used for filtering gamma rays scattered by the moderating body when a second neutron beam current is formed, neutrons with energy smaller than a third preset threshold value and neutrons with energy larger than the first preset threshold value.

Optionally, the filter comprises a thermal neutron filter, a fast neutron filter, and a gamma ray filter;

the thermal neutron filtering body is used for filtering neutrons with the energy smaller than the third preset threshold;

the fast neutron filtering body is used for filtering neutrons with the energy larger than the first preset threshold value.

Optionally, the neutron beam shaper further comprises a collimating body;

the collimator is positioned behind the shielding reflector;

the collimation body is used for generating a radiation field with a certain shape and contour.

Optionally, the moderator material is one or more of fluoride, heavy water, polyethylene, and graphite.

Optionally, the material of the shield is boron-containing polyethylene.

Optionally, the material of the reflector is one or more of polytetrafluoroethylene, beryllium oxide, aluminum oxide and lead.

Compared with the prior art, the method has the following beneficial effects:

the accelerator generates a proton beam, the neutron generator and the proton beam act to generate a first neutron beam, and the neutron beam shaper moderates the first neutron beam to form a second neutron beam. The extraction frequency and duty ratio distribution of the accelerator are synchronous with the distribution of the target and the rotation rate of the rotating chassis, so that the frequency of the target entering a beam streamline is consistent with the extraction frequency and duty ratio distribution of the accelerator, namely, the beam distribution and rotation speed synchronization method reduces the action probability of non-target materials, reduces pollution, ensures that the proton beam continuously and stably reacts with the target, improves the utilization rate of the proton beam, is beneficial to obtaining the neutron beam with higher yield and higher purity, improves the treatment effect and improves the treatment gain.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments of the present application, and for those skilled in the art, other drawings may be obtained according to these drawings without inventive labor.

FIG. 1 is a schematic diagram of a prior art accelerator-based boron neutron capture treatment apparatus;

fig. 2 is a schematic view of a neutron generation apparatus provided in an embodiment of the present application;

FIG. 3 is a schematic view of a neutron generator provided in an embodiment of the present application;

fig. 4 is a schematic front view of a rotating chassis according to an embodiment of the present disclosure.

Detailed Description

The technical terms referred to in the present application will be described below.

An accelerator: accelerators (accelerators) are devices that manually accelerate charged particles to higher energies. Electrons, protons, deuterons, alpha particles and some other heavy ions of various energies can be generated with this device.

A neutron generator: the neutron generator (neutron generator) refers to a reaction target which interacts with charged particles to generate neutrons, a supporting body and a control system thereof, and is used for interacting with the high-energy charged particle beam to generate a first neutron beam, wherein the energy of the first neutron beam is greater than a first preset threshold value.

A neutron beam shaper: the neutron beam shaper comprises a moderator, and also comprises a shielding reflector, a filter and a collimator, and is used for moderating the first neutron beam to form a second neutron beam, wherein the energy of the second neutron beam is smaller than a second preset threshold and larger than a third preset threshold.

Duty ratio: duty cycle refers to the proportion of the time that power is applied to the total time in a pulse cycle.

The accelerator, the neutron generator and the neutron beam shaper can be applied to a neutron generating device so as to carry out boron neutron capture treatment. However, in the prior art, the boron neutron capture treatment device often causes the waste of neutron beam current, which results in low neutron utilization rate and more impurities such as thermal neutrons, fast neutrons and the like in the neutron beam current.

In view of this, the present application provides a neutron generating apparatus, which may generate a proton beam through an accelerator, generate a first neutron beam through an action of a neutron generator and the proton beam, and slow the first neutron beam through a neutron beam shaper to form a second neutron beam. The extraction frequency and the duty ratio distribution of the accelerator are synchronous with the distribution of the target and the rotation rate of the rotating chassis, so that the frequency of the target entering a beam streamline is consistent with the extraction frequency and the duty ratio distribution of the accelerator, namely, the beam distribution and the rotation speed are synchronous, the action probability of a non-target material is reduced, pollution is reduced, the proton beam continuously and stably reacts with the target, the utilization rate of the beam is improved, the neutron beam with higher yield and higher purity can be obtained, the treatment effect is improved, and the treatment gain is improved.

In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 2, the drawing is a schematic view of a neutron generation apparatus provided in an embodiment of the present application.

The neutron generating device comprises an accelerator 201, a neutron generator 202 and a neutron beam shaper 203. The neutron beam shaper 203 includes a moderator 205, and may further include a shielding reflector 204, a filter 206, and a collimator 207. The exit of the accelerator 201 is aligned with the neutron generator 202, and the neutron beam shaper 203 is wrapped outside the neutron generator 202.

The accelerator 201 is configured to generate and accelerate a proton beam, and to extract the proton beam according to a certain duty ratio. The accelerator 201 is used for generating a charged particle beam with appropriate energy and fluence rate and flux rate (flow intensity) by using a magnetic field and an electric field. Since the higher the charged particle flux, the higher the neutron yield, in some embodiments, a radio frequency quadrupole accelerator (RFQ accelerator), a charged particle accelerator, a spherical electrostatic accelerator, a linear accelerator, a cyclotron, etc. may be selected, which is not limited in this application. The radio frequency quadrupole accelerator is a device for realizing charged particle beam acceleration after radio frequency focusing, is used as a low-energy accelerating device of an ion linear accelerator, and is widely applied to the fields of nuclear physics, atomic nuclear physics, material irradiation, biological irradiation, cancer treatment and the like. Because the charged particle flow intensity is higher, the neutron yield is improved.

And a neutron generator 202 for generating a first neutron beam by interacting with the proton beam. The energy of the first neutron beam current is greater than a first preset threshold, which may be 1MeV (megaelectron volts). The neutron generator 202 refers to a reaction target which reacts with charged particles to generate neutrons, a carrier thereof and a control system. As shown in fig. 3, fig. 3 is a schematic diagram of a neutron generator according to an embodiment of the present disclosure, in which the neutron generator 202 includes a rotating base plate 301, a carrier 302, and a target 303. As shown in fig. 4, fig. 4 is a front view of a rotating base plate according to an embodiment of the present invention, wherein targets 303 are spaced apart from each other on the rotating base plate 301 and are connected to a carrier 302. The rotating base plate 301 carries targets 303, the targets 303 are uniformly distributed on the rotating base plate 301 by taking the geometric center of the rotating base plate 301 as a circle center, and the distances from the targets 303 to the geometric center of the rotating base plate 301 are the same. Moreover, a gap exists between the target 303 and the target 303, and the driving component drives the rotating chassis 301 to rotate at a preset speed by taking the bearing as an axis through the bearing, so that each target 303 is aligned with the outlet of the accelerator 201 in sequence, and the target 303 and the proton beam generated by the accelerator 201 act to generate a first neutron beam. The accelerator adopts an extraction control strategy of matching extraction frequency, duty ratio distribution and target material distribution and rotation rate, so that the frequency of the target material entering a beam streamline is consistent with the extraction frequency and the duty ratio distribution of the accelerator, namely, the frequency is matched with the charged particle beam pulse, beam waste is avoided, the utilization efficiency of neutrons is improved, and the neutron beam with higher yield and higher purity is obtained. When the target material is hit with the accelerator 201 to generate neutrons, the material of the target needs to be considered, and the material of the target is not limited in this application. In some embodiments, a proton beam may Be selected to bombard the Li target or Be target to generate neutrons. In some embodiments, there may be more than 3 targets 303 carried on the rotating chassis 301.

In one embodiment, a coolant circulation path is added to the carrier 302. The coolant circulation path is a path for transferring heat from a lower temperature substance (or environment) to a higher temperature substance (or environment) by using external energy. In some embodiments, a freon coolant circulation path, an ammonia coolant circulation path, a mixed working fluid coolant circulation path, and a coolant circulation path for a working fluid such as air may be used depending on the kind of the refrigerant used. Therefore, in the embodiment of the application, on the one hand, the target is rotated through the rotating chassis, so that the charged particles are prevented from irradiating the same position for a long time, on the other hand, the heat dissipation of the target is accelerated by utilizing the circulation of the coolant, namely, the target sheet is protected through a dual mode, the thermal condition of the target is improved, and the heating is not serious any more.

The neutron beam shaper 203 includes a moderator 205, and may further include a shielding reflector 204, a filter 206, and a collimator 207, which are not limited in the present application.

The neutron beam shaper 203 is configured to slow the first neutron beam current to form a second neutron beam current, where energy of the second neutron beam current is smaller than a second preset threshold and larger than a third preset threshold. The moderation refers to a process of losing heat of fast neutrons with large energy in a collision process, so that the energy and the speed of the fast neutrons are gradually reduced to thermal neutrons or epithermal neutrons. The energy of the first neutron beam current is greater than a first preset threshold, which may be 1MeV (megaelectron volts). The energy of the second neutron beam is smaller than a second preset threshold, which may be 10keV (kilo electron volts) or 40keV, and larger than a third preset threshold, which may be 0.5eV (electron volts).

In some embodiments, high-energy neutrons may be moderated to the epithermal neutron energy range, and also to the thermal neutron energy range. The thermal neutrons may be neutrons with an energy range below a third predetermined threshold, which may be 0.5eV, for example, the thermal neutrons may have an energy range E < 0.5 eV. The epithermal neutrons may be neutrons with energies above a third predetermined threshold, below a second predetermined threshold, which may be 10keV or 40keV, for example, epithermal neutrons may have energies in the range 0.5eV < E < 10 keV.

A moderator 205 is positioned behind the neutron generator 202 and can interact with the first neutron beam stream in inelastic collisions or the like, thereby causing the first neutrons to lose energy and moderate it to the thermal neutron energy range or epithermal neutron energy range without producing excessive high-energy neutrons or gamma rays. The material of the moderator 205 needs to satisfy the following conditions: firstly, the fast neutron scattering cross section is large; secondly, the scattering cross section of the epithermal neutrons is small; thirdly, the absorption cross section of fast neutrons, epithermal neutrons and thermal neutrons is small. The fast neutrons are neutrons with energy greater than a first preset threshold, and the thermal neutrons are neutrons with energy less than a third preset threshold; the epithermal neutrons are neutrons with energy less than a second preset threshold and greater than a third preset threshold. Wherein the energy range of the thermal neutrons is E<0.5eV, and the energy range of the epithermal neutron is 0.5eV<E<10keV, and the energy range of fast neutrons is E > 1 MeV. In some embodiments, moderator 205 may be a fluoride, such as MgF ₂ (magnesium fluoride) AlF ₃ (aluminum fluoride), CaF ₂ (calcium fluoride), etc.; D ₂ O (heavy water), polyethylene, graphite, and the like.

The shielding reflector 204 is a material device having a radiation protection shielding effect and a neutron mixed beam filtering and reflecting effect, and the shielding reflector 204 is used for shielding neutrons scattered by the moderator 205 in inelastic collision and reflecting neutrons scattered by the moderator 205 in inelastic collision. The shielding reflector 204 may be further divided into a shielding body and a reflector. The shield serves to shield neutrons scattered by the moderator 205 during inelastic collisions. In some embodiments, a boron-containing polyethylene (mass fraction of B) may be selected for use on the outside10%) and the like as a neutron shield. The reflector is wrapped outside the moderator 205 and the neutron source, and functions to make the neutrons generated by the neutron generator 202 in anisotropic distribution in direction and energy, and when passing through the moderator 205, the neutrons will be diffused in all directions, and the reflector will reflect the scattered neutrons back to the moderator 205, so as to improve the neutron utilization rate, and make the thermal neutrons or epithermal neutron flux at the beam outlet of the collimator 207 as high as possible. Therefore, reflector materials are required to have a high elastic scattering cross-section and a low absorption cross-section within a suitable neutron energy interval. In some embodiments, polytetrafluoroethylene, BeO (beryllium oxide), Al may be selected ₂ O ₃ Materials such as (aluminum oxide) and Pb (lead) are used as reflectors.

The filter 206 is used to filter unwanted beam components such as thermal neutrons, fast neutrons, and gamma rays. The filter 206 includes a thermal neutron filter, a fast neutron filter, and a gamma ray filter; the thermal neutron filtering body is used for filtering thermal neutrons, namely neutrons with energy less than the third preset threshold; the fast neutron filtering body is used for filtering fast neutrons, namely neutrons with energy larger than the first preset threshold; the gamma ray filter is used for filtering gamma rays. After being moderated by the moderator 205, many thermal neutrons are generated, and the thermal neutrons are absorbed by superficial tissues of the human body and deposit energy. In treating deep tumors, the dose to which these superficial tissues are subjected needs to be avoided, and thus the filter 206 is required to filter thermal neutrons. In addition, some fast neutrons may also occur due to the lack of moderation by moderator 205. Therefore, the material of the filter 206 needs to have a high absorption cross-section in the thermal and fast neutron energy range and a small absorption cross-section in the epithermal neutron energy range so as not to reduce the epithermal neutron flux. In some embodiments, Li (lithium), B (boron), Cd (cadmium) materials may be selected to filter thermal neutrons, and Ni (nickel) materials may be selected to filter fast neutrons. In addition, during the slowing process, a part of gamma rays can be generated, and the gamma rays can cause excessive dose on normal tissues, so that a gamma ray filter 206 can be additionally arranged to reduce the component of the gamma rays in the neutron beam. In some embodiments, Pb and Bi may be selected as gamma filter materials.

The collimating body 207 mainly functions to collimate and focus the neutron beam to form a desired neutron beam irradiation field. Collimation, i.e. converting the diverging neutrons into collimated neutrons, produces a radiation field with a certain shape and contour. In some embodiments, a polyethylene polymer containing Li or B may be selected as the collimator material. In some embodiments, the shape of the beam outlet of the collimating body 207 may be various shapes such as a circle, a polygon, and the like, and the shape of the beam outlet may be selected according to actual conditions by changing the shape of the beam outlet of the collimating body 207, so as to meet different requirements.

In some embodiments, the moderator 205, the shielding reflector 204, the filter 206, and the collimator 207 may be adjusted according to the purpose of the acquisition, i.e., whether thermal neutrons or epithermal neutrons are obtained. The materials can be arranged in sequence or in a crossed manner, the core effect is to obtain proper energy and flow intensity, reduce impurity pollution, collimate and focus the neutron beam flow, and finally obtain the neutron beam flow with higher yield and higher purity, thereby achieving the high-quality requirement of the neutron beam flow for treatment.

In summary, the accelerator 201 generates a proton beam, the bombarder 202 generates a first neutron beam, the first neutron beam is moderated to a suitable energy range under the action of the neutron beam shaper 203, and is collimated and focused to finally obtain a second neutron beam. The neutron generator 202 comprises a rotary base plate 301, a carrier 302 and targets 303, wherein the targets 303 are distributed on the rotary base plate 301 at intervals and connected with the carrier 302. The rotating base plate 301 is loaded with at least three targets 303, each target 303 is uniformly distributed on the rotating base plate 301 by taking the geometric center of the rotating base plate 301 as a circle center, and the distances from each target 303 to the geometric center of the rotating base plate 301 are the same. Moreover, a gap exists between the target 303 and the target 303, and the driving component drives the rotating base plate 301 to rotate at a preset speed by taking the bearing as an axis through the bearing, so that the targets 303 are sequentially aligned with the outlet of the accelerator 201, and the targets 303 and the proton beams generated by the accelerator 201 act. The accelerator 201 can control the extraction frequency of the proton beam according to the rotation speed of the rotating chassis 301, so that the frequency of the target 303 entering the beam line is consistent with the extraction frequency and duty ratio distribution of the accelerator 201, that is, the frequency is matched with the charged particle beam pulses, thereby avoiding beam waste, improving the utilization efficiency of neutrons, and obtaining the neutron beam with higher yield and higher purity. The neutron beam shaper 203 includes a moderator 205 and may further include a shielding reflector 204, a filter 206, and a collimator 207. Furthermore, the moderating body 205, the filtering body 206, the shielding and reflecting body 204 and the collimating body 207 can be adjusted structurally according to the purpose of obtaining thermal neutrons or epithermal neutrons, various materials can be arranged in sequence or in a crossed manner, the core effect is to obtain proper energy and current intensity, reduce impurity pollution, collimate and focus neutron beam current, finally obtain neutron beam current with higher yield and higher purity, improve the treatment effect and improve the treatment gain.

It should be noted that, in this specification, each embodiment is described in a progressive manner, and the same and similar parts between the embodiments are referred to each other, and each embodiment focuses on differences from other embodiments. The above-described embodiments are merely illustrative, and the units described as separate components may or may not be physically separate, and the components suggested as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

It should be noted that the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

The above description is only one specific embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The neutron generating device is characterized by comprising an accelerator, a neutron generator and a neutron beam shaper;

the accelerator is used for generating proton beams;

the neutron generator is used for acting with the proton beam to generate a first neutron beam, and the energy of the first neutron beam is larger than a first preset threshold value;

2. The neutron production device of claim 1, wherein the neutron beam shaper comprises a moderator body;

the moderating body is positioned behind the neutron generator;

3. The neutron production device of claim 2, wherein the neutron beam shaper further comprises a shielding reflector;

4. The neutron production device of claim 3, wherein the shielding reflector comprises a shield and a reflector;

5. The neutron production device of claim 3, wherein the neutron beam shaper further comprises a filter;

the filter body is aligned with the outlet of the moderator body;

6. The neutron production device of claim 5, wherein the filter comprises a thermal neutron filter, a fast neutron filter, and a gamma ray filter;

7. The neutron generation device of claim 4, wherein the neutron beam shaper further comprises a collimating body;

the collimator is positioned behind the shielding reflector;

8. The neutron generation device of claim 2, wherein the moderator material is one or more of fluoride, heavy water, polyethylene, and graphite.

9. The neutron generation device of claim 4, wherein the material of the shield is a boron-containing polyethylene.

10. The neutron production device of claim 4, wherein the reflector material is one or more of polytetrafluoroethylene, beryllium oxide, aluminum oxide, and lead.