CN211188823U

CN211188823U - Neutron capture therapy system and beam shaper for neutron capture therapy system

Info

Publication number: CN211188823U
Application number: CN201921078947.9U
Authority: CN
Inventors: 闫发智; 江涛; 陈韦霖
Original assignee: China Boron Xiamen Medical Equipment Co ltd
Current assignee: China Boron Xiamen Medical Equipment Co ltd
Priority date: 2019-04-17
Filing date: 2019-07-11
Publication date: 2020-08-07
Anticipated expiration: 2029-07-11
Also published as: CN111821584A; CN111821585A; CN211188822U

Abstract

A neutron capture treatment system and a beam shaper for the neutron capture treatment system can prevent the beam shaper material from deforming and damaging and improve the flux and the quality of a neutron source. The utility model discloses a neutron capture treatment system, including neutron generating device and beam shaping body, neutron generating device includes accelerator and target, and the charged particle ray that the accelerator produced with higher speed produces the neutron with the target effect, and the neutron forms neutron beam, and a main shaft is injectd to the neutron beam, and the beam shaping body includes the supporting part and fills the main part in the supporting part.

Description

Neutron capture therapy system and beam shaper for neutron capture therapy system

Technical Field

One aspect of the present invention relates to a radiation irradiation system, and more particularly, to a neutron capture therapy system; another aspect of the present invention relates to a beam shaper for a radiation irradiation system, and more particularly to a beam shaper for a neutron capture therapy system.

Background

With the development of atomic science, radiation therapy such as cobalt sixty, linacs, electron beams, etc. has become one of the main means of cancer treatment. However, the traditional photon or electron therapy is limited by the physical conditions of the radiation, and can kill tumor cells and damage a large amount of normal tissues in the beam path; in addition, due to the difference in the sensitivity of tumor cells to radiation, conventional radiotherapy is often ineffective in treating malignant tumors with relatively high radiation resistance, such as multiple glioblastoma multiforme (glioblastoma multiforme) and melanoma (melanoma).

In order to reduce the radiation damage of normal tissues around tumor, the target therapy concept in chemotherapy (chemotherapy) is applied to radiotherapy; for tumor cells with high radiation resistance, radiation sources with high Relative Biological Effect (RBE) are also actively developed, such as proton therapy, heavy particle therapy, neutron capture therapy, etc. Wherein, the neutron capture treatment combines the two concepts, such as boron neutron capture treatment, and provides better cancer treatment selection than the traditional radioactive rays by the specific accumulation of boron-containing drugs in tumor cells and the precise neutron beam regulation.

Boron Neutron Capture Therapy (BNCT) utilizes Boron-containing (B: (B-N-C-B-N-C-¹⁰B) The medicine has the characteristic of high capture cross section for thermal neutrons¹⁰B(n,α)⁷L i neutron capture and fission reaction generation⁴He and⁷l i two heavily charged particles referring to figures 1 and 2, there are shown schematic diagrams of boron neutron capture reactions and¹⁰B(n,α)⁷l i neutron capture nuclear reaction equation, the average energy of two charged particles is about 2.33MeV, with high linear transfer (L initial energy transfer, &lTtTtransfer = L "&gTtL &lTt/T &gTtET), short range characteristics, and the linear energy transfer and range of α particles are 150keV/μm, 8 μm respectively, and⁷l i heavy-load particles are 175 keV/mum and 5μm, the total range of the two particles is about equal to one cell size, so the radiation damage to organism can be limited at cell level, when boron-containing medicine selectively gathers in tumor cells, matching with proper neutron source, the purpose of local killing tumor cells can be achieved without causing too much damage to normal tissue.

The effect of boron neutron capture therapy is also called binary cancer therapy (binary cancer therapy) because the effect depends on the boron-containing drug concentration and the quantity of thermal neutrons at the tumor cell position; it is known that, in addition to the development of boron-containing drugs, the improvement of neutron source flux and quality plays an important role in the research of boron neutron capture therapy.

Therefore, a new technical solution is needed to solve the above problems.

SUMMERY OF THE UTILITY MODEL

In order to improve flux and the quality of neutron source, an aspect of the utility model provides a beam integer for neutron capture treatment system, neutron capture treatment system includes neutron generating device, the neutron that neutron generating device produced forms neutron beam, a main shaft is prescribed a limit to the neutron beam, beam integer can be adjusted the beam quality of neutron beam, beam integer includes the supporting part and fills main part in the supporting part, the supporting part includes braced frame, braced frame is forged by forging equipment again after the heating of blank through heating equipment and is processed into the cylinder, the cylinder is by machining equipment machine-shaping after rough machining and thermal treatment. The support part can prevent the main body part material from deforming and damaging to influence the target changing and the beam quality; the support frame adopts less forging process and heating times, has uniform structure and good forging performance, and saves raw materials; the blank is subjected to heating treatment before forging, so that the deformation resistance can be reduced, and the plasticity can be improved; the forged cylinder can ensure the overall material performance of the support frame after heat treatment through rough machining.

Furthermore, the supporting frame is made of aluminum alloy, the mass percent of Cu element in the aluminum alloy is less than or equal to 7%, and the requirement that the half-life period of the radioactive isotope generated after the supporting frame is activated by neutrons is short can be met; the tensile strength of the supporting frame is more than or equal to 150MPa, the yield strength is more than or equal to 100MPa, and the supporting frame can support the main body part of the beam-shaping body. The aluminum alloy is a wrought aluminum alloy, the forging equipment is free forging equipment, and the free forging equipment comprises upsetting and drawing equipment. The free forging changes the structure and the performance of the aluminum alloy through a plastic forming method, and can further save raw materials.

Further, the heating equipment is a radiation type resistance heating furnace, circulating air is filled in the furnace, the temperature can be kept accurate and uniform, the deviation of the furnace temperature is +/-10 ℃, the maximum open forging temperature is 520 ℃, the final forging temperature is 450 ℃, and the allowable limit temperature is 530 ℃. The heating time can be determined according to the dissolution of the strengthening phase and the obtainment of a homogenized structure, and the aluminum alloy has better plasticity in the state and can improve the forging performance of the aluminum alloy.

Further, the main part includes the retarder, the reflector and the radiation shield, the retarder will certainly neutron that neutron production device produced is slowed down to super heat neutron energy district, the reflector surrounds the retarder and will deviate the neutron of main shaft leads back to the main shaft is in order to improve super heat neutron beam intensity, the radiation shield is used for shielding the normal tissue dose in order to reduce non-irradiation region of seepage neutron and photon, braced frame forms at least one and holds the unit, every hold the unit hold at least a part of main part.

Still further, the accommodating unit includes a first accommodating unit accommodating at least a part of the retarder, the first accommodating unit is located radially at the center of the support frame, and the rough machining is to punch a hole in a region of the pillar corresponding to the first accommodating unit. The cylinder is directly subjected to heat treatment, and the performance of the central material of the cylinder is difficult to ensure, so that the central position (namely the area of the cylinder corresponding to the first accommodating unit) of the forged cylinder is punched through rough machining, and then deep heat treatment is carried out, so that the material performance of the support frame close to the central position (forming the main frame part of the first accommodating unit) and the whole support frame after heat treatment can be ensured; simultaneously, the first holding unit holds the retarder, can guarantee the support to the retarder this moment, prevents that the retarder from deforming and damaging, influences target changing and beam quality.

Still further, it holds the unit including holding the second of at least one in retarder, reflector and the radiation shield body, braced frame includes and centers on main shaft circumference confined outer wall and at least one inner wall, form between outer wall and inner wall or inner wall and the inner wall the second holds the unit, rough machining still includes right the cylinder with the second holds the preliminary machining in the corresponding region of unit. It can be understood that the region of the cylinder corresponding to the second accommodating unit does not need to be roughly machined, so that deformation and the like easily caused by the thin wall can be prevented when heat treatment is carried out after rough machining.

Further, the heat treatment comprises solution treatment and aging treatment, the aluminum after the solution treatment is placed under a certain temperature and kept for a certain time, and the supersaturated solid solution is decomposed, so that the strength and the hardness of the alloy are greatly improved.

Another aspect of the present invention provides a beam shaping body support frame processing method, including:

heating, namely heating the blank meeting the requirement of the support frame material at a certain temperature for a certain time;

forging, namely forging and processing the heated blank into a cylinder;

rough machining, namely punching the center position of the column obtained by forging;

heat treatment, the forging body obtained after rough machining is heat treated;

and (4) machining, namely machining the forged body after heat treatment to obtain the support frame with the finally required shape and size.

The support frame can prevent the main body part material from deforming and damaging to influence the target changing and the beam quality; the support frame adopts less forging process and heating times, has uniform structure and good forging performance, and saves raw materials; the blank is subjected to heating treatment before forging, so that the deformation resistance can be reduced, and the plasticity can be improved; the center position of the column obtained by forging is punched and then is subjected to heat treatment, so that the position of the support frame close to the center position and the overall material performance after heat treatment can be ensured.

Further, before the heating step, the blank is inspected to meet the raw material requirements of the support frame material; before the forging step, processing the blank to meet the processing requirement of forging equipment; the forging is free forging, including upsetting and drawing out, the two methods are repeatedly carried out for static forging according to the process under the condition that the temperature of the forging is not lower than the specification temperature, so as to obtain precise crystal grains in the structure, and the forging equipment has the precision of forging a blank; the heat treatment comprises solution treatment and aging treatment, the aluminum after the solution treatment is placed under a certain temperature and kept for a certain time, and supersaturated solid solution can be decomposed, so that the strength and the hardness of the alloy are greatly improved; and carrying out physical and chemical detection and inspection after the heat treatment, wherein the physical and chemical detection and inspection comprise size detection, element detection, mechanical property detection and ultrasonic flaw detection nondestructive detection.

Neutron capture treatment system and beam shaping body thereof, can prevent beam shaping body material itself and warp the damage, improve the flux and the quality of neutron source.

Drawings

FIG. 1 is a schematic diagram of a boron neutron capture reaction;

FIG. 2 is¹⁰B(n,α)⁷L i neutron capture nuclear reaction equation;

fig. 3 is a schematic view of a neutron capture therapy system according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a beam shaper of a neutron capture therapy system according to an embodiment of the present invention;

FIG. 5 is a schematic view of the support portion of FIG. 4;

FIG. 6 is an exploded view of the retarder of FIG. 4;

FIG. 7 is a schematic view of the main frame of FIG. 5 as viewed from the direction of the neutron beam N;

FIG. 8 is a schematic view of the main frame of FIG. 5 as viewed from a direction opposite to the direction of the neutron beam N;

FIG. 9 is a flow chart of an embodiment of a mainframe manufacturing process of FIG. 5.

Detailed Description

The present invention is further described in detail below with reference to the drawings so that those skilled in the art can implement the invention with reference to the description.

Referring to fig. 3, the neutron capture therapy system in the present embodiment is preferably a boron neutron capture therapy system 100, which includes a neutron generating device 10, a beam shaper 20, a collimator 30, and a treatment table 40. The neutron generating apparatus 10 includes an accelerator 11 and a target T, and the accelerator 11 accelerates charged particles (such as protons, deuterons, etc.) to generate a charged particle beam P such as a proton beam, and the charged particle beam P irradiates the target T and reacts with the target T to generate neutrons, which form a neutron beam N, the neutron beam N defining a main axis X, and the target T is preferably a metal target. The illustrated and described later, the neutron beam N direction does not represent the actual neutron motion direction, but represents the direction of the overall motion trend of the neutron beam N. The appropriate nuclear reactions are selected based on the desired neutron yield and energy, the available energy and current for accelerating charged particles, the physical properties of the metal target, and the like, and the nuclear reactions in question include⁷Li(p,n)⁷Be and⁹Be(p,n)⁹the energy thresholds for the two nuclear reactions are 1.881MeV and 2.055MeV, respectively, since the ideal neutron source for boron neutron capture therapy is epithermal neutrons at keV energy levels, theoretically relatively low energy neutrons can Be produced if the metallic lithium target is bombarded with protons at energies only slightly above the threshold, and can Be used clinically without much moderation treatment, whereas the two targets of lithium metal (L i) and beryllium metal (Be) have a low cross-section for proton interaction with the threshold energy, and to produce a sufficiently large neutron flux, protons of higher energy are usually selected to initiate the nuclear reactionThe target T may Be made of a metal material other than L i and Be, for example, Ta or W, an alloy thereof, or the like, and the accelerator 11 may Be a linear accelerator, a cyclotron, a synchrotron, or a synchrocyclotron.

The neutron source for boron neutron capture therapy generates a mixed radiation field, namely a beam contains neutrons with low energy to high energy and photons; for boron neutron capture therapy of deep tumors, the greater the amount of radiation other than epithermal neutrons, the greater the proportion of non-selective dose deposition in normal tissue, and therefore the unnecessary dose of radiation that these would cause should be minimized. In addition to the air beam quality factor, in order to better understand the dose distribution caused by neutrons in the human body, the embodiment of the present invention uses the human head tissue prosthesis to perform dose calculation, and uses the prosthesis beam quality factor as the design reference of the neutron beam, which will be described in detail below.

The International Atomic Energy Agency (IAEA) gives five air beam quality factor suggestions aiming at a neutron source for clinical boron neutron capture treatment, and the five suggestions can be used for comparing the advantages and disadvantages of different neutron sources and serving as reference bases for selecting neutron generation paths and designing beam integrators. The five proposals are as follows:

epithermal neutron beam flux Epithermal neutron flux>1x 10⁹n/cm²s

Fast neutron contamination<2x 10^-13Gy-cm²/n

Photon contamination of Photon contamination<2x 10^-13Gy-cm²/n

Thermal to epithermal neutron flux ratio of thermal to epithermal neutron flux ratio <0.05

Neutron current to flux ratio epithermal neutron current to flux ratio >0.7

Note: the super-thermal neutron energy region is between 0.5eV and 40keV, the thermal neutron energy region is less than 0.5eV, and the fast neutron energy region is greater than 40 keV.

1. Epithermal neutron beam flux:

neutron beam flux and boron-containing drug concentration in tumorsTogether determine the clinical treatment time. If the concentration of the boron-containing drug in the tumor is high enough, the requirement on the neutron beam flux can be reduced; conversely, if the boron-containing drug concentration in the tumor is low, high-throughput epithermal neutrons are required to administer a sufficient dose to the tumor. IAEA requirements for epithermal neutron beam flux are greater than 10 epithermal neutrons per second per square centimeter⁹The neutron beam at this flux can generally control the treatment time within one hour for the current boron-containing drugs, and the short treatment time can effectively utilize the limited residence time of the boron-containing drugs in the tumor besides having advantages on the positioning and comfort of the patient.

2. Fast neutron contamination:

since fast neutrons cause unnecessary normal tissue doses and are therefore considered contamination, the dose magnitude and neutron energy are positively correlated, and the fast neutron content should be minimized in the neutron beam design. Fast neutron contamination is defined as the fast neutron dose accompanied by a unit epithermal neutron flux, and the recommendation for fast neutron contamination by IAEA is less than 2x 10^-13Gy-cm²/n。

3. Photon contamination (gamma ray contamination):

gamma rays belong to intense penetrating radiation and can non-selectively cause the deposition of dose on all tissues on a beam path, so that the reduction of the content of the gamma rays is also a necessary requirement for neutron beam design, the gamma ray pollution is defined as the gamma ray dose accompanied by unit epithermal neutron flux, and the recommendation of IAEA for the gamma ray pollution is less than 2x 10^-13Gy-cm²/n。

4. Thermal neutron to epithermal neutron flux ratio:

because the thermal neutrons have high attenuation speed and poor penetrating power, most energy is deposited on skin tissues after entering a human body, and the thermal neutrons content is reduced aiming at deep tumors such as brain tumors and the like except that the epidermal tumors such as melanoma and the like need to use thermal neutrons as a neutron source for boron neutron capture treatment. The IAEA to thermal neutron to epithermal neutron flux ratio is recommended to be less than 0.05.

5. Neutron current to flux ratio:

the neutron current-to-flux ratio represents the beam directivity, the larger the ratio is, the better the neutron beam directivity is, the neutron beam with high directivity can reduce the dosage of the surrounding normal tissues caused by neutron divergence, and in addition, the treatable depth and the positioning posture elasticity are also improved. The IAEA to neutron current to flux ratio is recommended to be greater than 0.7.

The prosthesis is used to obtain the dose distribution in the tissue, and the quality factor of the prosthesis beam is deduced according to the dose-depth curve of the normal tissue and the tumor. The following three parameters can be used to make comparisons of therapeutic benefits of different neutron beams.

1. Effective treatment depth:

the tumor dose is equal to the depth of the maximum dose of normal tissue, after which the tumor cells receive a dose less than the maximum dose of normal tissue, i.e. the advantage of boron neutron capture is lost. This parameter represents the penetration of the neutron beam, with greater effective treatment depth indicating a greater depth of tumor that can be treated, in cm.

2. Effective treatment depth dose rate:

i.e. the tumor dose rate at the effective treatment depth, is also equal to the maximum dose rate for normal tissue. Because the total dose received by normal tissues is a factor influencing the size of the total dose which can be given to the tumor, the parameter influences the length of the treatment time, and the larger the effective treatment depth dose rate is, the shorter the irradiation time required for giving a certain dose to the tumor is, and the unit is cGy/mA-min.

3. Effective therapeutic dose ratio:

the average dose ratio received from the surface of the brain to the effective treatment depth, tumor and normal tissues, is called the effective treatment dose ratio; the average dose can be calculated by integrating the dose-depth curve. The larger the effective therapeutic dose ratio, the better the therapeutic benefit of the neutron beam.

In order to make the beam shaper design more reliable, in addition to the five IAEA proposed beam quality factors in air and the three parameters mentioned above, the embodiments of the present invention also utilize the following parameters for evaluating the performance of neutron beam dose:

1. the irradiation time is less than or equal to 30min (proton current used by an accelerator is 10mA)

2. 30.0RBE-Gy for treating depth greater than or equal to 7cm

3. Maximum tumor dose is more than or equal to 60.0RBE-Gy

4. Maximum dose of normal brain tissue is less than or equal to 12.5RBE-Gy

5. Maximum skin dose not greater than 11.0RBE-Gy

Note: RBE (relative Biological effect) is the relative Biological effect, and since the Biological effects caused by photons and neutrons are different, the above dose terms are multiplied by the relative Biological effects of different tissues to obtain the equivalent dose. The neutron beam N generated by the neutron generator 10 is irradiated to the patient 200 on the treatment table 40 through the beam shaper 20 and the collimator 30 in this order. The beam shaper 20 can adjust the beam quality of the neutron beam N generated by the neutron generating device 10, and the collimator 30 is used for converging the neutron beam N, so that the neutron beam N has high targeting performance in the treatment process. The beam shaper 20 further comprises a support 21 (not shown in fig. 1, described in detail below) and a body portion 23 filled in the support 21, the support 21 forming at least one receiving cell C1-C4, each receiving at least a part of the body portion 23. The support part can prevent the main body part material from deforming and damaging, and the target changing and the beam quality are influenced. The main body 23 includes a retarder 231, a reflector 232 and a radiation shield 233, neutrons generated by the neutron generating apparatus 10 have a wide energy spectrum, and in addition to epithermal neutrons meeting therapeutic requirements, the content of neutrons and photons of other types needs to be reduced as much as possible to avoid damage to operators or patients, so that neutrons coming from the neutron generating apparatus 10 need to pass through the retarder 231 to adjust fast neutron energy therein to epithermal neutron energy region, the retarder 231 is made of a material having a large fast neutron acting section and a small epithermal neutron acting section, for example, the material includes D₂O、Al、AlF₃、MgF₂、CaF₂、LiF、Li₂CO₃Or Al₂O₃At least one of; the reflector 232 surrounds the retarder 231 and reflects neutrons diffused toward the periphery through the retarder 231 back to the neutron beam N to improve utilization rate of the neutrons, and the reflector 232 is made of a material having a high neutron reflection capability, such as at least one of Pb and Ni(ii) a The radiation shield 233 is used to shield the leaked neutrons and photons to reduce the normal tissue dose in the non-irradiated region, and the material of the radiation shield 233 includes at least one of photon shielding material and neutron shielding material, such as photon shielding material lead (Pb) and neutron shielding material Polyethylene (PE). It will be appreciated that the body portion may have other configurations as long as the desired hyperthermal neutron beam for treatment is obtained. The target T is disposed between the accelerator 11 and the beam shaper 20, the accelerator 11 has a transport tube 111 carrying the charged particle beam P, in this embodiment, the transport tube 111 extends into the beam shaper 20 along the charged particle beam P and sequentially passes through the retarder 231 and the reflector 232, and the target T is disposed in the retarder 231 and at the end of the transport tube 111 to obtain better neutron beam quality. In this embodiment, the first and second cooling tubes D1 and D2 are disposed between the transport tube 111 and the retarder 231 and the reflector 232, one end of each of the first and second cooling tubes D1 and D2 is connected to a cooling inlet (not shown) and a cooling outlet (not shown) of the target T, and the other end is connected to an external cooling source (not shown). It will be appreciated that the first and second cooling tubes may be otherwise disposed within the beam shaper and may be eliminated when the target material is disposed outside of the beam shaper.

Referring to fig. 4 and 5, the support portion 21 includes an outer wall 211 circumferentially enclosed around the main axis X, and first and

second side plates

221, 222 respectively disposed on both sides of the outer wall 211 along the direction of the neutron beam N and connected to the outer wall 211, the first side plate 221 is provided with a hole 2211 through which the transmission tube 111 passes, the second side plate 222 is provided with a hole 2221 forming a beam outlet, a receiving portion C is formed between the outer wall 211 and the first and

second side plates

221, 222, and the main body portion 23 is disposed in the receiving portion C. The container C includes at least one container unit C1-C4 (described in detail below), each container unit C1-C4 contains at least 1 of the retarder 231, the reflector 232, and the radiation shield 233, and at least one container unit C1-C4 contains at least 2 of the retarder, the reflector, and the radiation shield at the same time or at least two different materials at the same time. It is understood that the first and second side plates may not be provided, and the accommodating portion may be surrounded by an outer wall.

The support portion 21 further comprises at least one inner wall circumferentially enclosed around the main axis X and extending between the first and

second side plates

221, 222, in this embodiment the first and second

inner walls

212, 213 are radially inwardly disposed, respectively, and radially defined as a direction perpendicular to the main axis X. The support portion 21 further includes a first cross plate 223 disposed between the first and

second side plates

221, 222 in the direction of the neutron beam N, a third inner wall 214 circumferentially enclosed around the main axis X and extending between the first cross plate 223 and the first side plate 221, and a fourth inner wall 215 circumferentially enclosed around the main axis X and extending from the first cross plate 223 to the second side plate 222. The third inner wall 214 is radially closer to the major axis X than the second inner wall 213, the fourth inner wall 215 is radially between the second inner wall 213 and the third inner wall 214, and the first cross plate 223 extends between the third inner wall 214 and the fourth inner wall 215. The inner surface of the third inner wall 214 is on the same surface as the side wall of the hole 2211 of the first side plate 221, and the third inner wall 214 forms a mounting portion for the transfer tube 111, the first and second cooling tubes D1, D2, and the like. A second cross plate 224 is provided adjacent to the fourth inner wall 215 between the fourth inner wall 215 and the second side plate 222 in the direction of the neutron beam N, the second cross plate 224 extends radially inward from the second inner wall 213, a hole 2241 through which the neutron beam N passes is provided on the second cross plate 224, and the inner wall of the hole 2241 is closer to the main axis X than the inner side of the fourth inner wall 215. It is understood that the second transverse plate may not be provided, the first transverse plate may extend to the outer wall or other inner walls, and a plurality of transverse plates may be provided between the outer wall and the inner wall, and between the inner wall and the inner wall.

In this embodiment, the beam shaper is generally cylindrical, the cross sections of the outer wall and the inner wall in the direction perpendicular to the main axis X are both circular rings surrounding the main axis X and extend parallel to the main axis X, and the side plates and the transverse plates are flat plates extending perpendicular to the main axis X. A first containing unit C1 is formed among the outer wall 211, the first inner wall 212, the first side plate 221 and the second side plate 222, a second containing unit C2 is formed among the first inner wall 212, the second inner wall 213, the first side plate 221 and the second side plate 222, and a third containing unit C3 is formed among the second inner wall 213, the third inner wall 214, the fourth inner wall 215, the first side plate 221, the first horizontal plate 223 and the second horizontal plate 224.

In this embodiment, a PE block 241 having a corresponding shape is provided in the first accommodation unit C1; the lead block 242 and the PE block 241 are sequentially disposed in the second accommodating unit C2 along the neutron beam N direction, a volume ratio of the lead block to the PE block is less than or equal to 10, and an interface of the lead block and the PE block is perpendicular to the neutron beam N direction, which can be understood as other ratios or other distributions. The radiation shield 233 in this embodiment includes a neutron shield and a photon shield, the PE block 241 acting as a neutron shield, and the lead block 242 acting as both the reflector 231 and photon shield.

In this embodiment, the lead block 242, the aluminum alloy block 243, the teflon block 244, and the PE block 241 are provided in the third containing unit C3, the aluminum alloy block 243 and the teflon block 244 are integrally provided to include at least one cone-like shape, the PE block 241 is provided adjacent to the second horizontal plate 224, the lead block 242 fills the remaining region, and the aluminum alloy block 243 and the teflon block 244 integrally divide the lead block 242 in the third containing unit C3 into two parts. The aluminum alloy block 243 and the teflon block 244 are respectively used as the first and second supplementary parts of the retarder 232, so that the manufacturing cost of the retarder can be reduced, meanwhile, the beam quality is not greatly influenced, the first and second supplementary parts are integrally arranged to comprise at least one cone-shaped shape, and better beam quality and treatment effect can be obtained. The teflon block 244 has a better fast neutron absorption effect at the same time, and can reduce the fast neutron content in the beam. The lead 242 serves as both the reflector 231 and the photon shield. The PE block 241 serves as a neutron shield, and it is understood that the PE block may not be provided.

Referring to fig. 6, in the present embodiment, the aluminum alloy block 243 and the teflon block 244 are sequentially disposed along the neutron beam N direction, the aluminum alloy block 243 and the teflon block 244 are integrally disposed in two conical shapes adjacent to each other in opposite directions, the aluminum alloy block 243 is also disposed in two conical shapes adjacent to each other in opposite directions, the aluminum alloy block 243 includes a first conical portion 2431 and a second conical portion 2432 sequentially disposed along the neutron beam N direction, the radial dimension of the outer contour of the first conical portion 2431 gradually increases along the overall trend of the neutron beam N direction, the second conical portion 2432 is connected to the first conical portion 2431 at the position where the radial dimension of the outer contour of the first conical portion 2431 is maximum, and the radial dimension of the outer contour of the second conical portion 2432 gradually decreases along the overall trend of the neutron beam N direction. The teflon block 244 is adjacent to the second cone portion 2432 at the position where the radial dimension of the outer contour of the second cone portion 2432 is the smallest, the radial dimension of the outer contour of the teflon block 244 gradually decreases along the whole trend of the neutron beam N direction, and the teflon block 244 contacts with the PE block 241 at the position where the radial dimension of the outer contour is the smallest. The cross-sectional profiles of the aluminum alloy block 243 and the teflon block 244 in the plane along the major axis X are trapezoids or polygons. The aluminum alloy block 243 has a first side a1 contacting the lead block 242 at the first taper portion 2431, a second side a2 contacting the lead block 242 and a third side A3 contacting the graphite block 244 at the second taper portion 2432, and a fourth side a4 contacting the third inner wall 214, the fourth inner wall 215 and the first cross plate 223 at the first and second taper portions in common, and in this embodiment, the fourth side a4 is a stepped surface. The teflon block 244 has a fifth side a5 contacting the aluminum alloy block 243, a sixth side a6 contacting the lead block 242, a seventh side a7 contacting the fourth inner wall 215, and an eighth side A8 contacting the PE block 241. Wherein the third side A3 and the fifth side a5 are adjacent and serve as an interface of the aluminum alloy block 243 and the teflon block 244, which is perpendicular to the neutron beam N direction in this embodiment. In this embodiment, the volume ratio of the aluminum alloy block 243 to the teflon block 244 is 5-20, and it can be understood that other ratios or other distributions can be adopted according to the neutron beam required for treatment, such as different irradiation depths.

In the direction of neutron beam N, a fourth containing unit C4 is formed from a region surrounded by a fourth inner wall 215 from a first transverse plate 223 to a second transverse plate 224, and the fourth containing unit C4 is radially adjacent to a third containing unit C3, in this embodiment, a magnesium fluoride block 245 is disposed in the fourth containing unit C4 as a basic portion of a buffer 232, the magnesium fluoride block 245 contains L i-6, and a thermal neutron absorber is simultaneously present, so that first and second complementary portions of the buffer disposed in the third containing unit C3 surround a basic portion of the buffer disposed in the fourth containing unit C4, the magnesium fluoride block 245 is generally cylindrical, including first and second end faces A9, a10 substantially perpendicular to the direction of neutron beam N, the first and second end faces A9, a10 are sequentially disposed in the direction of the neutron beam 2455, the first end face A9 faces the first side plate and is disposed with a central hole 2451, a first end face b 1 for receiving the transmission tube 111, the first and second end face D, a cooling tube D38, and a buffer D38, and a central hole 2452 are disposed radially closer to the inner wall of the central hole 2455, so that the inner wall of the buffer can be disposed radially as a distance from the inner wall of a vertical direction of the central hole 245 of the lead fluoride block p, and the inner wall of the central hole 245 b, so that the inner wall of the buffer can be less than the inner wall of the lead fluoride block p 2, and the inner wall of the buffer can be disposed in the inner wall of the lead fluoride block p 2, and the inner wall of the buffer disposed in the inner wall of the inner.

It is understood that in this embodiment, PE as the neutron shield may be replaced with other neutron shield materials, lead as the photon shield may be replaced with other photon shield materials, lead as the reflector may be replaced with other materials having strong neutron reflection capability, magnesium fluoride as the basic portion of the retarder may be replaced with other materials having a large cross section for fast neutron action and a small cross section for epithermal neutron action, L i-6 as the thermal neutron absorber may be replaced with other materials having a large cross section for thermal neutron action, aluminum alloy as the first supplement portion of the retarder may be replaced with a material including at least one of Zn, Mg, Al, Pb, Ti, L a, Zr, Bi, Si, and C, and a material that is easily available is selected, so that the manufacturing cost of the retarder may be reduced, and at the same time, a certain neutron moderation action may not have a large influence on the beam quality, teflon as the second supplement portion of the retarder may be replaced with graphite, and the second supplement portion may be selected from a material having a better neutron absorption effect than the first supplement portion, and the second supplement portion may be at least two materials.

Referring to fig. 7 and 8, the supporting portion 21 is further provided with a radial partition 210, the plane of the radial partition 210 extends through the main axis X to divide each containing unit C1-C3 into at least two sub-areas in the circumferential direction, so that the PE block, the lead block, the aluminum alloy block and the graphite block arranged in each containing unit C1-C3 are divided into at least two sub-modules in the circumferential direction. In this embodiment, a first radial partition 2101 is disposed between the first side plate 221 and the second side plate, extending from the outer wall 211 to the second inner wall 213; a second radial partition 2102 is disposed between the first side plate 221 and the second cross plate 224, extending from the second inner wall 213 to the third inner wall 214 or the fourth inner wall 215. In the embodiment, the number of the first radial partition plates is 8, and the number of the second radial partition plates is 4, and the first radial partition plates and the second radial partition plates are evenly distributed along the circumferential direction; the first radial partition plate and the second radial partition plate are both flat plates, and 4 of the second radial partition plates and 4 of the first radial partition plates are on the same plane; it is understood that the radial partitions may be in other numbers or in other arrangements, or no radial partitions may be provided.

In this embodiment, the radial partition plate 210, the outer wall 211, the first transverse plate 223 and the first, second, third and fourth

inner walls

212 and 215 are integrated, and the main frame 21a is made of aluminum alloy, which has better mechanical properties and short half-life of the radioactive isotope generated after being activated by neutrons. The method can adopt a casting process and a formwork integrated molding, wherein a wooden mold or an aluminum mold is selected as a template, red sand or resin sand is selected as a sand core, and a mode commonly used in the industry is selected as a specific process. Since casting is accompanied by draft, machining requires its complete removal depending on design and beam quality requirements. The structural form and the casting process enable the frame structure to have the advantages of good integrity, high rigidity and high bearing capacity. All corners are rounded off in view of the machining tool limitations and the stress concentration on the right-angled sides. Or the plate is rolled and welded or an aluminum alloy cylinder is forged firstly and then the cylinder is machined and formed.

Referring to fig. 9, an embodiment of the main frame processing procedure is shown, in which the main frame 21a is made of 6061 aluminum alloy, which can meet the requirements of the main frame material on chemical composition and mechanical properties. In order to meet the requirement that the half-life period of the radioactive isotope generated after the main frame is activated by neutrons is short, the types and the mass proportion of the elements of the aluminum alloy should be controlled, for example, the mass percentage of the Cu element is less than or equal to 7%. According to the accumulation of relevant calculation and combined experience, the chemical components of the main frame material are selected to meet the requirements that Cu is less than or equal to 1.0 percent, Mn is less than or equal to 1.5 percent and Zn is less than or equal to 1.0 percent (mass percentage); the chemical composition table of the 6061 aluminum alloy is shown in table 1, and it is known that the 6061 aluminum alloy can satisfy the chemical composition required for the material of the main frame 21 a.

TABLE 1 chemical composition (%)

In order to support the beam shaper body portion 23 by the main frame 21a, the mechanical properties of the main frame need to meet requirements; according to CAE simulation calculation and experience adjustment, the tensile strength of the aluminum alloy main frame is not less than 150MPa, and the yield strength of the aluminum alloy main frame is not less than 100 MPa.

Since the 6061 aluminum alloy is a wrought aluminum alloy, the free forging method is adopted in the embodiment, the structure and the performance of the aluminum alloy are changed by the plastic forming method, and meanwhile, raw materials can be saved. According to the free forging process scheme, the quality of the forge piece depends on the metal structure obtained in the deformation process to a great extent, particularly the deformation uniformity of the forge piece. Because the deformation is uneven, the plasticity of the metal is reduced, uneven structures are obtained due to uneven recrystallization, the performance of the forged piece is poor, and in order to obtain even deformed structures and optimal mechanical properties, the fewer the working procedures are, the better the heating times are, the fewer the heating times are, the better the forging performance is. The processing procedure of this example is as follows:

1. preparing a blank: aluminum manufacturers such as aluminum factories process aluminum ores into aluminum ingots, cast the aluminum ingots into blanks, prepare the blanks into 6061 aluminum alloy components meeting the national standard, and detect the blanks, such as materials and experimental results in alloy brands, smelting furnaces, batch numbers, specifications, homogenizing annealing, low power and oxide film inspection and the like;

2. blanking: the blank meeting the detection requirements is processed by methods of shearing, sawing, gas cutting and the like, for example, end face cutting is carried out, burrs, oil stains, sawdust and the like are removed in time, and the processing requirements of forging equipment are met;

3. heating: the blank is subjected to a heat treatment prior to forging to reduce deformation resistance and improve plasticity. If a radiation type resistance heating furnace is adopted, circulating air is filled in the furnace, the temperature can be kept accurate and uniform, the furnace temperature deviation can be controlled within the range of +/-10 ℃, in the embodiment, the maximum open forging temperature is 520 ℃, the final forging temperature is 450 ℃, and the allowable limit temperature is 530 ℃. It will be appreciated that other heating devices may be employed. The heating and heat preservation time needs to be determined by fully considering the factors such as the heat conductivity of the alloy, the specification of the blank, the heat transfer mode of heating equipment and the like. It will be appreciated that the blank may also be subjected to a heat treatment prior to blanking in step 2, in which case the blank is cleaned of oil, debris and other contaminants prior to heating, for example, prior to entering the furnace, so as not to contaminate the furnace atmosphere.

4. Forging: the 6061 aluminum alloy is polycrystal, crystal boundaries exist among crystal grains, and sub-crystal grains and phase boundaries exist in the crystal grains, so that the forging with the required shape (such as a column), size and certain structure performance can be obtained by utilizing the plasticity of the material and generating plastic deformation under the action of external force. The cast structure of the metal blank is eliminated through forging deformation, and the plasticity and the mechanical property are greatly improved. In this embodiment, a free forging method such as upsetting and elongation is adopted, and the above two methods are repeatedly performed to perform static forging according to the process under the condition that the temperature of the forging is not lower than the schedule temperature, so as to obtain precise crystal grains inside the structure, and the forging equipment has the precision of forging a blank.

5. Rough machining and heat treatment: in order to finally obtain mechanical properties meeting the use requirements, the structure and the properties of the metal material are required to be changed through heat treatment, and the internal quality of the metal is also required to be changed. In this embodiment, the cylinder obtained by forging in step 4 is directly subjected to heat treatment, and it is difficult to ensure the performance of the central material of the cylinder. Therefore, the center position of the cylinder obtained by forging (i.e., the region of the cylinder corresponding to the fourth containing unit C4) is perforated by rough machining, and then deep heat treatment is performed, so that the material properties of the main frame close to the center position (the main frame portion forming the fourth containing unit C4) and the whole after heat treatment can be ensured; meanwhile, the fourth accommodating unit C4 accommodates the basic part of the retarder, so that the support of the retarder can be ensured, and the retarder is prevented from being deformed and damaged to influence the target replacement and the beam quality. It is understood that the rough machining may also include preliminary machining of the hollow region between the outer wall 211 and the

inner wall

212 and 215 of the main frame (i.e., the region where the cylinder corresponds to the first, second and third containing units C1, C2 and C3), such as drilling, milling, cutting and forging to obtain a solid part of the cylinder in the region; in this embodiment, the region is not roughened, and deformation and the like are prevented from easily occurring when the region is heat-treated after rough machining. Under the condition that the process can ensure the material performance of the central area and other areas, rough machining can be omitted; the rough machining should leave a margin for subsequent further machining.

The heat treatment process used in this example was T6 (solution + aging). The solution treatment is a prior process for causing precipitation hardening of the alloy, and the solid solution formed during solution treatment is rapidly cooled to obtain a metastable supersaturated solid solution, thereby creating conditions for natural aging and artificial aging and obviously improving the strength and the hardness. After the solution treatment, aging treatment is needed, the aluminum after the solution treatment is placed below a certain temperature and kept for a certain time, the supersaturated solid solution is decomposed, so that the strength and the hardness of the alloy are greatly improved, and the aluminum can be kept at room temperature or heated. The aging treatment is the last process of the heat treatment, and can improve and determine the final mechanical property of the aluminum alloy. The heating temperature and the holding time can be selected according to actual conditions. It is understood that other heat treatment processes may be used as long as the mechanical properties required for use are met.

6. Physical and chemical detection and inspection: after the heat treatment is finished, physical and chemical detection and inspection, including size detection, element detection, mechanical property detection, ultrasonic flaw detection nondestructive detection and the like, are required. Either as a result of testing by those associated with heat treatment after heat treatment or as a result of testing by those associated with machining (described below) prior to machining. The mechanical property detection can be to detect the material of the cutting part in the relevant area of the workpiece after heat treatment, in this embodiment, the part punched and taken off at the central position during rough machining can be simultaneously heat treated, and the detection of the part approximately represents the property of the

inner walls

214 and 215 close to the main shaft X; the region between the outer wall 211 and the

inner wall

212 and 215 is examined by cutting the material of the heat treated forged cylinder in this region. It is understood that when the hollow region between the outer wall 211 and the

inner wall

212 and 215 is roughly processed, the roughly processed and cut part of the region and the heat-treated part are detected to similarly approximate the performance of the region, and the region can be selected and labeled on the drawing. And (4) sampling the area, and performing a mechanical experiment to obtain the yield strength and the tensile strength. The nondestructive inspection adopts ultrasonic flaw detection, can be comprehensive inspection or partition inspection, and in the embodiment, the ultrasonic flaw detection is carried out on the inner wall close to the center.

7. And (3) machining: after detection and inspection, the forging body after heat treatment meets the requirements, and then the main frame with the finally needed shape and size is obtained through machining.

The main frame 21a is connected to the second horizontal plate 224 by bolts, first threaded holes are uniformly machined in the end surface of the fourth inner wall 215 facing the second side plate 222, first through holes are uniformly machined in the position of the second horizontal plate 224 corresponding to the first threaded holes, and bolts pass through the first through holes and are connected to the first threaded holes. Considering the assembly of the bolt, the aperture of the first through hole is slightly larger than that of the first threaded hole, and the number of the first threaded holes and the number of the first through holes can meet the requirement of connection strength. The first and

second side plates

221, 222 and the second transverse plate 224 are made of lead-antimony alloy, lead can further shield radiation, and the strength of the lead-antimony alloy is high. The outer contours of the first and

second side plates

221, 222 are identical to the outer contour of the outer wall 211. The first side plate 221, the second side plate 222 and the second transverse plate 224 are connected with the main frame through bolts, second threaded holes are machined in the end faces, facing the first side plate, the second side plate and the second transverse plate, of the inner wall of the main frame 21a respectively, second through holes are machined in the positions, corresponding to the second threaded holes, of the first side plate 221, the second side plate 222 and the second transverse plate 224 respectively, the hole diameter of each second through hole is slightly larger than that of each second threaded hole in consideration of assembly of the bolts, and the number of the second threaded holes and the number of the second through holes can meet connection strength.

It can be understood that, in this embodiment, as long as the materials of the main frame, the side plates, and the end plates (the second transverse plate) have certain strength and the half-life of the radioisotope generated after neutron activation is short (for example, less than 7 days), the material properties of the main frame can satisfy the requirement of supporting the beam shaper, such as aluminum alloy, titanium alloy, lead-antimony alloy, cobalt-free steel, carbon fiber, PEEK, and high molecular polymer; the side plates, the end plates (second transverse plates) and the main frame can be detachably connected or non-detachably connected, and when the side plates and the end plates are detachably connected, all parts of the main body part can be conveniently replaced. The beam shaper of the present embodiment may have other configurations of the support portion and the body portion filling the support portion.

In the construction, the main frame 21a is first placed in the mounting hole provided in the beam shaper support, and the outer wall 211 of the main frame 21a and the beam shaper support are connected by bolts or the like. Then, the main body part is filled and the first side plate, the second side plate and the second transverse plate are installed, and the corresponding areas can be integrally filled due to the fact that the density of PE, aluminum alloy and graphite is small; the lead is heavier, so that the lead can be manually filled in a sub-slice mode along the N direction of the neutron beam or can be integrally filled by means of machinery; the magnesium fluoride may also be filled in bulk or in pieces. After the beam shaper is installed, other components such as a transmission tube, a target material, a collimator and the like are installed, the collimator 30 is arranged at the rear part of a beam outlet, the hyperthermo neutron beam coming out of the collimator 30 irradiates the patient 200, and the hyperthermo neutron beam is slowed down into thermal neutrons to reach the tumor cells M after passing through a shallow normal tissue. In this embodiment, the collimator is fixed to the main frame 21a by bolts or the like, third threaded holes are reserved on the end surface of the second inner wall 213 facing the second side plate, third through holes are uniformly machined in positions on the second side plate 222 corresponding to the third threaded holes, the hole diameter of the third through holes is slightly larger than that of the third threaded holes in consideration of the assembly of the bolts, and the number of the third threaded holes and the third through holes satisfies the connection strength. It will be appreciated that the collimator 30 may be fixed by other means of attachment, and that the collimator 30 may be eliminated or replaced by other structures, with the neutron beam exiting the beam outlet and directed towards the patient 200. In this embodiment, a radiation shield 50 is disposed between the patient 200 and the beam outlet to shield the beam exiting the beam outlet from normal tissue of the patient, although it is understood that the radiation shield 50 may or may not be disposed.

The embodiment of the present invention provides a "column" or "column" is a structure whose overall trend from one side to the other side along the direction shown in the figure is basically unchanged, one of the contour lines of the outer contour may be a line segment, such as a corresponding contour line of the cylindrical shape, or a circular arc close to the line segment with a large curvature, such as a corresponding contour line of the spherical shape with a large curvature, the whole surface of the outer contour may be in smooth transition, or in non-smooth transition, such as a plurality of bulges and grooves are made on the surface of the cylindrical shape or the spherical shape with a large curvature.

In the embodiment of the present invention, the "cone" or "cone-shaped" refers to a structure in which the overall trend of the outer contour gradually decreases from one side to the other side along the direction shown in the figure, and one of the contour lines of the outer contour may be a line segment, such as a corresponding contour line of a cone shape, or an arc, such as a corresponding contour line of a sphere shape, and the entire surface of the outer contour may be in smooth transition, or in non-smooth transition, such as making a plurality of protrusions and grooves on the surface of a cone shape or a sphere shape.

Although illustrative embodiments of the invention have been described above to facilitate the understanding of the invention by those skilled in the art, it should be understood that the invention is not limited to the scope of the embodiments, and that various changes may be apparent to those skilled in the art without departing from the spirit and scope of the invention as defined and defined in the appended claims.

Claims

1. A beam shaper for a neutron capture therapy system, the neutron capture therapy system comprising a neutron generating device, neutrons generated by the neutron generating device forming a neutron beam, the neutron beam defining a main axis, the beam shaper being capable of adjusting the beam quality of the neutron beam, the beam shaper comprising a support part and a main body part filled in the support part, the support part comprising a support frame, the support frame being heated by a heating device from a blank and forged by a forging device into a cylinder, the cylinder being machined and formed by a machining device after rough machining and heat treatment.

2. The beam shaper for a neutron capture therapy system of claim 1, wherein: the supporting frame is made of aluminum alloy, the mass percentage of Cu element in the aluminum alloy is less than or equal to 7%, the tensile strength of the supporting frame is more than or equal to 150MPa, and the yield strength of the supporting frame is more than or equal to 100 MPa.

3. The beam shaper for a neutron capture therapy system of claim 2, wherein: the aluminum alloy is a wrought aluminum alloy, the forging equipment is free forging equipment, and the free forging equipment comprises upsetting and drawing equipment.

4. The beam shaper for a neutron capture therapy system of claim 1, wherein: the heating device is a radiation type resistance heating furnace, the deviation of the furnace temperature is +/-10 ℃, the maximum open forging temperature is 520 ℃, the finish forging temperature is 450 ℃, and the allowable limit temperature is 530 ℃.

5. The beam shaper for a neutron capture therapy system of claim 1, wherein: the main part includes the retarder, reflector and radiation shield, the retarder will certainly neutron that neutron production device produced slows down to super heat neutron energy district, the reflector surrounds the retarder and will deviate the neutron of main shaft is led back to the main shaft is in order to improve super heat neutron beam intensity, radiation shield is used for shielding the normal tissue dose of seepage neutron and photon in order to reduce non-irradiation area, braced frame forms at least one and holds the unit, at least one hold the unit hold at least partly of main part.

6. The beam shaper for a neutron capture therapy system of claim 5, wherein: the accommodating unit comprises a first accommodating unit for accommodating at least part of the retarder, the first accommodating unit is located at the center of the supporting frame in the radial direction, and the rough machining is to punch holes in the corresponding areas of the cylinder and the first accommodating unit.

7. The beam shaper for a neutron capture therapy system of claim 6, wherein: the holding unit is including holding the second of at least one in retarder, reflector and the radiation shield holds the unit, braced frame includes and centers on main shaft circumference confined outer wall and at least one inner wall, form between outer wall and inner wall or inner wall and the inner wall the second holds the unit, rough machining still includes right the cylinder with the second holds the rough machining in the corresponding region of unit.