CN111821585A - Neutron capture therapy system and beam shaper for neutron capture therapy system - Google Patents

Abstract

A neutron capture therapy system and a beam shaping body for the neutron capture therapy system can prevent deformation and damage of the beam shaping body material itself, and improve the flux and quality of a neutron radiation source. The neutron capture treatment system of the present invention includes a neutron generating device and a beam shaping body, the neutron generating device includes an accelerator and a target, the charged particle beams accelerated by the accelerator interact with the target to generate neutrons, and the neutrons form neutrons The beam, the neutron beam defines a major axis, and the beam shaper includes a support portion and a main body portion filled within the support portion.

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, in particular to a neutron capture therapy system; another aspect of the present invention relates to a beam shaper for a radiation irradiation system, in particular to a neutron capture and treatment system Capture the beam shaper of the treatment system.

Background technique

With the development of atomic science, radiation therapy such as cobalt sixty, linear accelerator, electron beam, etc. has become one of the main means of cancer treatment. However, traditional photon or electron therapy is limited by the physical conditions of radiation itself. While killing tumor cells, it will also cause damage to a large number of normal tissues along the beam path. In addition, due to the different sensitivity of tumor cells to radiation, traditional radiation therapy For more radiation-resistant malignant tumors (eg: glioblastoma multiforme (glioblastoma multiforme), melanoma (melanoma)) treatment results are often poor.

In order to reduce the radiation damage to the normal tissues around the tumor, the concept of targeted therapy in chemotherapy has been applied to radiation therapy; and for tumor cells with high radiation resistance, it is also actively developed with a high relative biological effect (relative biological effect). biological effectiveness, RBE) radiation sources, such as proton therapy, heavy particle therapy, neutron capture therapy, etc. Among them, neutron capture therapy is a combination of the above two concepts, such as boron neutron capture therapy, through the specific accumulation of boron-containing drugs in tumor cells, with precise neutron beam regulation, to provide better than traditional radiation. Cancer treatment options.

Boron Neutron Capture Therapy (BNCT) utilizes the properties of boron ( ¹⁰ B) ^-containing drugs to capture thermal neutrons with a high cross ^- section. Two heavily charged particles, ⁴ He and ⁷ Li, are produced. Referring to Figure 1 and Figure 2, which show the schematic diagram of the boron neutron capture reaction and the ¹⁰ B(n,α) ⁷ Li neutron capture nuclear reaction equation, respectively, the average energy of the two charged particles is about 2.33MeV, with high linearity Transfer (Linear EnergyTransfer,

LET) and short range characteristics, the linear energy transfer and range of α particles are 150keV/μm and 8μm, respectively, while those of ⁷ Li heavy particles are 175keV/μm and 5μm. The total range of the two particles is about the size of a cell, so for Radiation damage caused by organisms can be limited to the cellular level. When boron-containing drugs selectively accumulate in tumor cells, with an appropriate neutron radiation source, local killing can be achieved without causing too much damage to normal tissues. The purpose of dead tumor cells.

Because the effectiveness of boron neutron capture therapy depends on the concentration of boron-containing drugs and the number of thermal neutrons in tumor cells, it is also called binary cancer therapy. It can be seen that, in addition to the development of boron-containing drugs, The improvement of flux and quality of neutron source plays an important role in the research of boron neutron capture therapy.

Therefore, it is necessary to propose a new technical solution to solve the above problems.

SUMMARY OF THE INVENTION

In order to improve the flux and quality of a neutron radiation source, one aspect of the present invention provides a neutron capture therapy system, including a neutron generating device and a beam shaping body, the neutron generating device including an accelerator and a target, so The charged particle beams accelerated by the accelerator interact with the target to generate neutrons, the neutrons form a neutron beam, and the neutron beam defines a main axis, and the beam shaping body includes a support portion and a filling in the target material. The main body part in the support part, the main body part includes a retarder, a reflector and a radiation shield, the retarder decelerates the neutrons generated from the target material to the epithermal neutron energy region, the reflection A body surrounds the retarder and guides neutrons that deviate from the main axis back to the main axis to increase epithermal neutron beam intensity, and the radiation shield serves to shield leaking neutrons and photons to reduce non-irradiation normal tissue dose in the region. By arranging the support part, the deformation and damage of the material of the main body part itself can be prevented, which affects the target changing and the beam quality.

Further, the support portion includes an outer wall circumferentially closed around the main shaft, the outer wall surrounds a receiving portion, the main body portion is arranged in the receiving portion, and the receiving portion includes at least one receiving unit, each of which is The accommodating unit accommodates at least one of the retarder, the reflector and the radiation shield.

Further, the support part further includes first and second side plates respectively arranged on both sides of the outer wall along the neutron beam direction and connected with the outer wall, and arranged along the neutron beam direction at the outer wall. At least one transverse plate between the first and second side plates and circumferentially closed around the main axis and extending between the first and second side plates or between the transverse plate and the first/second side plate Occasionally or at least one inner wall between the transverse plate and the transverse plate, the first side plate is provided with a hole through which the transmission tube of the accelerator passes, and the second side plate is provided with a hole forming a beam outlet, so A plurality of accommodating units are formed between the outer wall, the inner wall, the transverse plate and the first and second side plates, the radiation shielding body includes a neutron shielding body and a photon shielding body, and at least one of the accommodating units simultaneously accommodates the retarder Bulk/neutron shields and reflectors.

As a preferred option, the inner wall includes first and second inner walls, the transverse plate includes a first transverse plate, and the first inner wall extends between the first side plate and the first transverse plate and is used together When installing the transmission tube, the second inner wall extends from the first transverse plate in the direction of the neutron beam and is used for accommodating at least a part of the retarder.

Further, the retarding body includes a basic part and a supplementary part, the accommodating unit includes an adjacent first accommodating unit and a second accommodating unit, the basic part is accommodated in the first accommodating unit, and the basic part is A central hole is provided at one end facing the first side plate, and the central hole is used for accommodating the transmission tube and the target material, and at least a part of the supplementary part and the reflector is accommodated in the second accommodating unit , the first accommodating unit is formed by being surrounded by the second inner wall, and the radial distance from the first inner wall to the main shaft is smaller than the radial distance from the second inner wall to the main shaft. The basic part of the retarder surrounds the target, so that the neutrons generated by the target can be effectively retarded in all directions, which can further improve the neutron flux and beam quality.

Further, the material of the basic part is magnesium fluoride containing Li-6, the basic part acts as a thermal neutron absorber at the same time, the supplementary part includes first and second supplementary units, and the first supplementary The material of the unit is aluminum alloy, the material of the second supplementary unit is Teflon, the material of the reflector is lead, the reflector is also used as a photon shielding body, and the first and second supplementary units are integrally arranged forming two adjacent cones in opposite directions and dividing the reflector in the second accommodating unit into two parts, the first and second supplementary units are arranged in sequence along the direction of the neutron beam, The interface between the first and second supplementary units is perpendicular to the direction of the neutron beam. The aluminum alloy block and the Teflon block are used as the first and second supplementary units of the retarder respectively, which can reduce the manufacturing cost of the retarder, and at the same time, will not have a great impact on the beam quality. The supplementary part units are arranged as a whole in the shape of two cones adjacent to each other in opposite directions, which can obtain better beam quality and treatment effect. Teflon also has better fast neutron absorption, which can reduce the fast neutron content in the beam.

Further, a lead plate shielding plate is also arranged between the magnesium fluoride block and the positioning ring/stop ring in the first accommodating unit, and the basic part and the shielding plate are arranged in sequence along the direction of the neutron beam, The positioning ring and the stop ring are made of materials with a very short intrinsic half-life of the activated nucleus generated after the activation reaction, the material of the shielding plate is lead, and the lead shielding plate is in the direction of the neutron beam. If the thickness is less than or equal to 5cm, the neutrons passing through the retarder will not be reflected, and the lead can absorb the gamma rays released in the retarder. The outer wall, at least one of the inner walls and at least one of the transverse plates integrally form a main frame, and the half-life of radioisotopes generated after the materials of the main frame, the first and second side plates are activated by neutrons is less than 7 days, so The materials of the main frame and the first and second side plates are aluminum alloy, titanium alloy, lead-antimony alloy, cast aluminum, steel without cobalt, carbon fiber, PEEK or high molecular polymer. When the material of the main frame is selected from aluminum alloy, it has better mechanical properties and the half-life of radioisotopes generated after being activated by neutrons is short; when the material of the first and second side plates is selected from lead-antimony alloy, lead can play a To further shield the radiation, while the lead-antimony alloy has a higher strength.

As a preferred example, the accommodating unit includes a third accommodating unit, at least a part of the neutron shield and at least a part of the reflector are accommodated in the third accommodating unit, and the neutron shield is The material is PE, the material of the reflector is lead, the reflector serves as a photon shield at the same time, the reflector and the neutron shield in the third accommodating unit are arranged in sequence along the direction of the neutron beam, the The interface between the reflector and the neutron shield in the third accommodating unit is perpendicular to the direction of the neutron beam.

As a preferred option, the support part further comprises a radial partition plate that divides the accommodating unit into several sub-regions in the circumferential direction, and the radial partition plate is arranged between the first and second side plates or Between the transverse plate and the first/second side plate or between the transverse plate and the transverse plate, and extending from the outer wall to the inner wall or between the two inner walls.

Another aspect of the present invention provides a beam shaper for use in a neutron capture therapy system, the neutron capture therapy system comprising a neutron generating device, the neutrons generated by the neutron generating device form a neutron beam, The beam shaper can adjust the beam quality of the neutron beam, the beam shaper includes a support part and a main body part filled in the support part, the support part forms at least one accommodating unit, each The accommodating unit accommodates at least a portion of the main body portion. By arranging the support part, the deformation and damage of the material of the main body part itself can be prevented, which affects the target changing and the beam quality.

The neutron capture treatment system and the beam shaping body of the present invention can prevent deformation and damage of the material of the beam shaping body itself, and improve the flux and quality of the neutron radiation source.

Description of drawings

Fig. 1 is the schematic diagram of boron neutron capture reaction;

Fig. 2 is the nuclear reaction equation of ¹⁰ B(n,α) ⁷ Li neutron capture;

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

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 the schematic diagram of the support part in Fig. 4;

Fig. 6 is the exploded schematic diagram of the retarder in Fig. 4;

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

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

FIG. 9 is a flowchart of an embodiment of the main frame machining process in FIG. 5 .

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement it with reference to the description.

As shown in FIG. 3 , the neutron capture therapy system in this embodiment is preferably a boron neutron capture therapy system 100 , which includes a neutron generating device 10 , a beam shaping body 20 , a collimator 30 and a treatment table 40 . The neutron generating device 10 includes an accelerator 11 and a target T. The accelerator 11 accelerates charged particles (such as protons, deuterons, etc.) to generate a charged particle beam P such as a proton beam. The target material T acts to generate neutrons, the neutrons form a neutron beam N, and the neutron beam N defines a main axis X, and the target material T is preferably a metal target material. The neutron beam N direction shown in the figure and described below does not represent the actual neutron movement direction, but represents the direction of the overall movement trend of the neutron beam N. According to the required neutron yield and energy, the available accelerated charged particle energy and current, and the physical and chemical properties of the metal target, the appropriate nuclear reaction is selected. The nuclear reactions that are often discussed are ⁷ Li(p,n) ⁷ Be and ⁹ Be(p,n) ⁹ B, both of which are endothermic reactions. The energy thresholds of the two nuclear reactions are 1.881MeV and 2.055MeV, respectively. Since the ideal neutron source for boron neutron capture therapy is epithermal neutrons with keV energy level, theoretically, if proton bombardment with energy only slightly higher than the threshold is used Lithium metal targets can generate relatively low-energy neutrons and can be used clinically without too much retardation. However, the proton interaction cross-sections between lithium metal (Li) and beryllium metal (Be) targets and threshold energy Not high, in order to generate a sufficiently large neutron flux, usually higher energy protons are used to initiate nuclear reactions. The ideal target material should have the characteristics of high neutron yield, neutron energy distribution close to epithermal neutron energy region (described in detail below), no generation of too much strong penetrating radiation, safe, cheap, easy to operate, and high temperature resistance. But in practice it is not possible to find a nuclear reaction that meets all requirements. As known to those skilled in the art, the target T can also be made of metal materials other than Li and Be, for example, Ta or W and alloys thereof. The accelerator 11 may be a linear accelerator, a cyclotron, a synchrotron, a synchrocyclotron.

The neutron source of boron neutron capture therapy produces a mixed radiation field, that is, the beam contains low-energy to high-energy neutrons and photons; for boron neutron capture therapy of deep tumors, except for epithermal neutrons, the rest of the radiation The higher the line content, the greater the proportion of non-selective dose deposition in normal tissue, so these unnecessary doses of radiation 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, in the embodiment of the present invention, the human head tissue prosthesis is used for dose calculation, and the prosthesis beam quality factor is used as the neutron beam quality factor. The design reference for the bundle will be described in detail below.

The International Atomic Energy Agency (IAEA) has given five air beam quality factor recommendations for neutron sources for clinical boron neutron capture therapy. These five recommendations can be used to compare the pros and cons of different neutron sources, and serve as Reference basis for selecting neutron generation paths and designing beam shapers. The five recommendations are as follows:

Epithermal neutron flux>1x 10 ⁹ n/cm ² s

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

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

Thermal to epithermal neutron flux ratio<0.05

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

Note: The epithermal 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 40keV.

1. Epithermal neutron beam flux:

The neutron beam flux and the concentration of boron-containing drugs in the tumor together determine the clinical treatment time. If the concentration of boron-containing drug in the tumor is high enough, the requirement for the neutron beam flux can be reduced; conversely, if the concentration of boron-containing drug in the tumor is low, high-flux epithermal neutrons are required to deliver a sufficient dose to the tumor. The IAEA's requirement for the flux of epithermal neutron beams is that the number of epithermal neutrons per second per square centimeter is greater than 10 ⁹ , and the neutron beam at this flux can roughly control the treatment of current boron-containing drugs In addition to the advantages of patient positioning and comfort, the short treatment time is less than one hour, and it can also more effectively utilize the limited residence time of boron-containing drugs in the tumor.

2. Fast neutron pollution:

Since fast neutrons will cause unnecessary dose to normal tissues, they are regarded as contamination. The dose size is positively correlated with neutron energy, so the content of fast neutrons should be minimized in the design of neutron beams. Fast neutron contamination is defined as the fast neutron dose accompanying a unit of epithermal neutron flux, and the IAEA recommends fast neutron contamination to be less than 2x 10 ^-13 Gy-cm ² /n.

3. Photon pollution (gamma ray pollution):

Gamma rays are strong penetrating radiation and will non-selectively cause dose deposition in all tissues along the beam path. Therefore, reducing the gamma ray content is also a necessary requirement for neutron beam design. Gamma ray contamination is defined as the unit epithermal neutron flux accompanying The gamma ray dose, the IAEA's recommendation for gamma ray contamination is less than 2x 10 ^-13 Gy-cm ² /n.

4. The ratio of thermal neutron to epithermal neutron flux:

Due to the fast decay rate and poor penetration ability of thermal neutrons, most of the energy is deposited in the skin tissue after entering the human body. Except for melanoma and other epidermal tumors, thermal neutrons need to be used as the neutron source for boron neutron capture therapy. Deep tumors such as tumors should reduce the thermal neutron content. The IAEA recommends that the ratio of thermal neutron to epithermal neutron flux be less than 0.05.

5. The ratio of neutron current to flux:

The ratio of neutron current to flux represents the directionality of the beam. The larger the ratio, the better the forwardness of the neutron beam. The high forwardness of the neutron beam can reduce the dose to surrounding normal tissues caused by neutron divergence. It also improves the depth of treatment and the flexibility of the posture. The IAEA recommends that the ratio of neutron current to flux be greater than 0.7.

The dose distribution in the tissue is obtained by using the prosthesis, and the beam quality factor of the prosthesis is deduced according to the dose-depth curves of normal tissue and tumor. The following three parameters can be used to compare the benefits of different neutron beam treatments.

1. Effective treatment depth:

The tumor dose is equal to the depth of the maximum dose to normal tissue, after this depth, the dose to tumor cells is less than the maximum dose to normal tissue, ie the advantage of boron neutron capture is lost. This parameter represents the penetration ability of the neutron beam. The greater the effective treatment depth, the deeper the treatable tumor depth, the unit is cm.

2. Effective treatment depth dose rate:

That is, the tumor dose rate at the effective treatment depth is also equal to the maximum dose rate of normal tissues. Because the total dose received by normal tissues is a factor that affects the total dose that can be given to the tumor, the parameters affect the length of the treatment time. The greater the effective treatment depth dose rate, the shorter the irradiation time required to give a certain dose to the tumor, and the unit is cGy/mA. -min.

3. Effective therapeutic dose ratio:

From the brain surface to the effective treatment depth, the ratio of the average dose received by the tumor to the normal tissue is called the effective treatment dose ratio; the calculation of the average dose can be obtained 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 provide a comparative basis for the design of the beam shaper, in addition to the five IAEA-recommended air beam quality factors and the above three parameters, the embodiment of the present invention also uses the following for evaluating the neutron beam dose performance Advantages and disadvantages of parameters:

1. Irradiation time ≤ 30min (the proton current used by the accelerator is 10mA)

2. 30.0RBE-Gy treatable depth≥7cm

3. The maximum dose of tumor ≥60.0RBE-Gy

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

5. The maximum dose to the skin is less than or equal to 11.0RBE-Gy

Note: RBE (Relative Biological Effectiveness) is a relative biological effect, caused by photons and neutrons

The biological effects are different, so 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 generating device 10 is irradiated to the patient 200 on the treatment table 40 through the beam shaping body 20 and the collimator 30 in sequence. 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 a higher quality during the treatment process. targeting. The beam shaping body 20 further includes a support portion 21 (not shown in FIG. 1 , described in detail below) and a main body portion 23 filled in the support portion 21, the support portion 21 forming at least one accommodating unit C1-C4, each accommodating The unit accommodates at least a part of the main body portion 23 . Setting the support part can prevent the deformation and damage of the material of the main body part, which affects the target changing and beam quality. The main body 23 includes a retarder 231, a reflector 232 and a radiation shielding body 233. Due to the wide energy spectrum of neutrons generated by the neutron generating device 10, in addition to the epithermal neutrons that meet the treatment needs, other types of neutrons need to be reduced as much as possible. Therefore, the neutrons from the neutron generating device 10 need to pass through the retarder 231 to adjust the fast neutron energy to the epithermal neutron energy region, and the retardation The body 231 is made of a material with a large cross-section with fast neutrons and a small cross-section with epithermal neutrons, such as D ₂ O, Al, AlF ₃ , MgF ₂ , CaF ₂ , LiF, Li ₂ CO ₃ or Al ₂ O At least one of ₃ ; the reflector 232 surrounds the retarder 231, and reflects the neutrons diffused around the retarder 231 back to the neutron beam N to improve the utilization rate of neutrons. Made of materials with strong sub-reflection ability, such as including at least one of Pb or Ni; the radiation shield 233 is used to shield leaking neutrons and photons to reduce the normal tissue dose in the non-irradiated area, the material of the radiation shield 233 At least one of photon shielding material and neutron shielding material is included, such as photon shielding material lead (Pb) and neutron shielding material polyethylene (PE). It can be understood that the main body can also have other structures, as long as the epithermal neutron beam required for the treatment can be obtained. The target T is set between the accelerator 11 and the beam shaping body 20 , and the accelerator 11 has a transmission tube 111 for transporting the charged particle beam P. In this embodiment, the transmission tube 111 extends into the beam shaping body 20 along the charged particle beam P direction. , and pass through the retarder 231 and the reflector 232 in sequence, and the target T is arranged in the retarder 231 and at the end of the transmission tube 111 to obtain better neutron beam quality. In this embodiment, first and second cooling pipes D1 and D2 are arranged between the transmission pipe 111 , the retarder 231 and the reflector 232 . The inlet (not shown) is connected to a cooling outlet (not shown), and the other end is connected to an external cooling source (not shown). It can be understood that the first and second cooling pipes can also be arranged in the beam shaping body in other ways, and can also be eliminated when the target material is placed outside the beam shaping body.

Referring to FIGS. 4 and 5 , the support portion 21 includes an outer wall 211 circumferentially closed around the main axis X, and first and second side plates 221 and 222 respectively disposed on both sides of the outer wall 211 along the neutron beam N direction and connected to the outer wall 211 , the first side plate 221 is provided with a hole 2211 through which the transmission pipe 111 passes, the second side plate 222 is provided with a hole 2221 for forming the beam outlet, and a receiving portion is formed between the outer wall 211 and the first and second side plates 221 and 222 C, the main body portion 23 is provided in the accommodating portion C. The accommodating part C includes at least one accommodating unit C1-C4 (detailed below), each accommodating unit C1-C4 accommodates at least one of the retarder 231, the reflector 232 and the radiation shielding body 233, and at least one accommodating unit C1- C4 contains at least 2 of, retarder, reflector and radiation shield at the same time or at least two different materials at the same time. It can be understood that the first and second side plates may not be provided, and the accommodating portion may be surrounded by the outer wall.

The support portion 21 also includes at least one inner wall circumferentially closed around the main axis X and extending between the first and second side plates 221 and 222. In this embodiment, the first and second inner walls 212 and 213 are respectively provided radially inward. , which defines the radial direction as the direction perpendicular to the main axis X. The support portion 21 further includes a first transverse plate 223 disposed between the first and second side plates 221 and 222 along the neutron beam N direction, and is circumferentially closed around the main axis X and extends between the first transverse plate 223 and the first side A third inner wall 214 between the plates 221 and a fourth inner wall 215 circumferentially closed around the main axis X and extending from the first transverse plate 223 to the second side plate 222 . The third inner wall 214 is radially closer to the main axis X than the second inner wall 213, the fourth inner wall 215 is located radially between the second inner wall 213 and the third inner wall 214, and the first transverse plate 223 extends between the third inner wall 214 and the fourth inner wall 214. between the inner walls 215 . The inner surface of the third inner wall 214 is on the same surface as the side wall of the hole 2211 on the first side plate 221 . A second transverse plate 224 is provided between the fourth inner wall 215 and the second side plate 222 along the N direction of the neutron beam adjacent to the fourth inner wall 215, the second transverse plate 224 extends radially inward from the second inner wall 213, and the second transverse plate 224 extends radially inward from the second inner wall 213. The plate 224 is provided with a hole 2241 through which the neutron beam N passes, 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 can be 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 also be provided between the outer wall and the inner wall, and between the inner wall and the inner wall.

In this embodiment, the beam shaping body is cylindrical as a whole, and the cross-sections of the outer wall and the inner wall in the direction perpendicular to the main axis X are circular rings around the main axis X and extend parallel to the main axis X, and the side plates and the horizontal plates are perpendicular to the main axis X. It can be understood that the flat plate extending from the main axis X can also have other settings, such as the extension direction is inclined to the main axis, and the outer contour of the outer wall in the direction perpendicular to the main axis can also be square, rectangular or polygonal, which is convenient for transportation and installation. A first accommodating unit C1 is formed between the outer wall 211, the first inner wall 212, the first side plate 221 and the second side plate 222, and the first inner wall 212, the second inner wall 213, the first side plate 221 and the second side plate 222 A second accommodating unit C2 is formed therebetween, and a third accommodating unit C3 is formed between the second inner wall 213 , the third inner wall 214 , the fourth inner wall 215 , the first side plate 221 , the first transverse plate 223 and the second transverse plate 224 .

In this embodiment, PE blocks 241 of corresponding shapes are arranged in the first accommodating unit C1; lead blocks 242 and PE blocks 241 are arranged in the second accommodating unit C2 in sequence along the N direction of the neutron beam, and the volume ratio of the lead blocks and the PE blocks is less than Equal to 10, the interface between the lead block and the PE block is perpendicular to the N direction of the neutron beam, and it can be understood that other ratios or other distributions are also possible. In this embodiment, the radiation shield 233 includes a neutron shield and a photon shield, the PE block 241 serves as the neutron shield, and the lead block 242 serves as both the reflector 231 and the photon shield.

In this embodiment, a lead block 242, an aluminum alloy block 243, a Teflon block 244 and a PE block 241 are arranged in the third accommodating unit C3, and the aluminum alloy block 243 and the Teflon block 244 are integrally arranged to include at least one cone-shaped block The PE block 241 is arranged adjacent to the second horizontal plate 224, the lead block 242 fills the remaining area, and the aluminum alloy block 243 and the Teflon block 244 as a whole divide the lead block 242 in the third accommodating 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, which can reduce the manufacturing cost of the retarder, and at the same time, will not have a great impact on the beam quality. and the second supplementary part is integrally arranged to include at least one cone-like shape, so that better beam quality and treatment effect can be obtained. The Teflon block 244 also has better fast neutron absorption effect, which can reduce the fast neutron content in the beam. The lead block 242 acts as both the reflector 231 and the photon shield. The PE block 241 is used as a neutron shield, and it can be understood that the PE block may not be provided.

6, in this embodiment, the aluminum alloy block 243 and the Teflon block 244 are arranged in sequence along the N direction of the neutron beam, and the aluminum alloy block 243 and the Teflon block 244 are integrally arranged into two cones adjacent to each other in opposite directions. The aluminum alloy block 243 itself is also arranged in two conical shapes adjacent to each other in opposite directions. The aluminum alloy block 243 includes a first cone portion 2431 and a second cone portion 2432 arranged in sequence along the N direction of the neutron beam. The radial dimension of the outer contour of the first cone portion 2431 gradually increases along the overall trend of the neutron beam N direction. The parts 2431 are connected, and the radial dimension of the outer contour of the second cone part 2432 is gradually reduced along the N direction of the neutron beam. The Teflon block 244 is adjacent to the second conical portion 2432 at the position where the radial dimension of the outer contour of the second conical portion 2432 is the smallest, and the radial dimension of the outer contour of the Teflon block 244 gradually decreases along the overall trend of the neutron beam N direction. , and is in contact with the PE block 241 where the radial dimension of the outer contour is the smallest. The cross-sectional contour of the aluminum alloy block 243 and the Teflon block 244 along the plane where the main axis X is located is a trapezoid or a polygon. The aluminum alloy block 243 has a first side A1 in contact with the lead block 242 in the first cone portion 2431 , a second side A2 in contact with the lead block 242 in the second cone portion 2432 , and a third side A2 in contact with the graphite block 244 . On the side A3, the first and second cone portions together have a fourth side A4 in contact with the third inner wall 214, the fourth inner wall 215 and the first transverse plate 223. In this embodiment, the fourth side A4 is a stepped surface. The Teflon block 244 has a fifth side A5 in contact with the aluminum alloy block 243 , a sixth side A6 in contact with the lead block 242 , a seventh side A7 in contact with the fourth inner wall 215 , and an eighth side in contact with the PE block 241 A8. The third side A3 and the fifth side A5 are adjacent to each other and serve as the interface between the aluminum alloy block 243 and the Teflon block 244 . In this embodiment, the interface is perpendicular to the N direction of the neutron beam. In this embodiment, the volume ratio of the aluminum alloy block 243 to the Teflon block 244 is 5-20. It can be understood that other ratios or other distributions can also be used according to the neutron beam required for treatment, such as different irradiation depths.

A region from the first transverse plate 223 to the second transverse plate 224 in the neutron beam N direction and surrounded by the fourth inner wall 215 forms a fourth accommodating unit C4 which radially adjoins the third accommodating unit C3. In this embodiment, a magnesium fluoride block 245 is set in the fourth accommodating unit C4 as a basic part of the retarder 232, and the magnesium fluoride block 245 contains Li-6, which can be a thermal neutron absorber at the same time, so it is arranged in the third accommodating unit C4. The first and second supplementary parts of the retarding body in the unit C3 surround the basic part of the retarding body arranged in the fourth accommodating unit C4. The magnesium fluoride block 245 is columnar as a whole, and includes first and second end faces A9 and A10 that are substantially perpendicular to the N direction of the neutron beam. The first and second end faces A9 and A10 are arranged in sequence along the neutron beam direction. The first end face A9 A central hole 2451 is provided facing the first side plate 221. The central hole 2451 is used to accommodate the transfer pipe 111, the first and second cooling pipes D1, D2 and the target T, etc. The central hole 2451 is a cylindrical hole, and the side wall of the central hole is 2451a is on the same surface as the inner surface of the third inner wall, and the radial distance L1 from the third inner wall 214 to the main axis X is smaller than the radial distance L2 from the fourth inner wall 215 to the main axis X, so that the basic part of the retarder 232 surrounds the target material T, so that the neutrons generated by the target T can be effectively retarded in all directions, which can further improve the neutron flux and beam quality. A lead plate 246 is arranged between the magnesium fluoride block 245 and the second horizontal plate 224. The lead plate 246 is used as a photon shield. The lead can absorb the gamma rays released from the retarder, while the lead plate 246 is in the N direction of the neutron beam. The thickness is less than or equal to 5cm, which will not reflect the neutrons passing through the retarder. It can be understood that other settings are also possible. For example, the magnesium fluoride block 245 does not contain Li-6, but the magnesium fluoride block 245 and the first A thermal neutron absorber composed of a separate Li-6 is arranged between the two transverse plates 224, and the lead plate can also be eliminated.

It can be understood that the PE used as the neutron shield in this embodiment can be replaced with other neutron shielding materials; the lead used as the photon shield can be replaced with other photon shielding materials; the lead used as the reflector can be replaced with other neutron reflecting capabilities Strong material; magnesium fluoride as the basic part of retarder can be replaced by other materials with large cross-section of fast neutron action and small cross-section of epithermal neutron action; Li-6 as thermal neutron absorber can be replaced by other materials A material with a large cross section that interacts with thermal neutrons; the aluminum alloy as the first supplementary part of the retarder can be replaced with at least one of Zn, Mg, Al, Pb, Ti, La, Zr, Bi, Si, and C. The material, which is easier to obtain, can reduce the manufacturing cost of the retarder, and at the same time has a certain neutron retardation effect, which will not have a great impact on the beam quality; as the second supplementary part of the retarder. Flon can be replaced with graphite, etc., and the second supplementary part selects a material with better fast neutron absorption effect than the first supplementary part, which can reduce the fast neutron content in the beam. It can be understood that at least two of the first and second supplementary parts and the basic part of the retarding body can also be made of the same material.

7 and 8, the support portion 21 is further provided with a radial partition plate 210, and the plane where the radial partition plate 210 is located extends through the main shaft X, and divides each accommodating unit C1-C3 into at least two sub-regions in the circumferential direction, Therefore, the PE blocks, lead blocks, aluminum alloy blocks, and graphite blocks arranged in each of the accommodating units C1-C3 are equally divided into at least two sub-modules in the circumferential direction. In this embodiment, the first radial partition plate 2101 is arranged between the first side plate 221 and the second side plate, extending from the outer wall 211 to the second inner wall 213; the second radial partition plate 2102 is arranged on the first side plate 221 and the second transverse plate 224, extending from the second inner wall 213 to the third inner wall 214 or the fourth inner wall 215. In this embodiment, the number of the first radial partitions is 8, and the number of the second radial partitions is 4, which are evenly distributed along the circumferential direction; the first and second radial partitions are both flat plates, and the second radial partitions are Four of the radial partitions and the first radial partitions are on the same plane; it can be understood that the radial partitions may also be in other numbers or in other arrangements, or no radial partitions are provided.

In this embodiment, the radial partition 210 , the outer wall 211 , the first transverse plate 223 and the first, second, third and fourth inner walls 212 - 215 are integrated, and the main frame 21 a is made of aluminum alloy and has Good mechanical properties and short half-life of radioisotopes generated after being activated by neutrons. The casting process can be used, and the supporting mold is integrally formed, in which the template is selected from wood mold or aluminum mold, and the sand core can be selected from red sand or resin sand, and the specific process adopts the method commonly used in the industry. Since casting will be accompanied by draft slope, depending on the design and beam quality requirements, machining needs to remove it completely. The structural form and casting process make the frame structure have the advantages of good integrity, high rigidity and high bearing capacity. All corners are rounded to account for the limitations of the machined tool and the stress concentration on the right-angled edges. It is also possible to coil and weld the sheet, or to forge an aluminum alloy cylinder, and then to machine the cylinder.

As shown in FIG. 9, an embodiment of the main frame processing process is shown. In this embodiment, the main frame 21a is made of 6061 aluminum alloy, which can meet the chemical composition and mechanical performance requirements of the main frame material. In order to meet the requirement of short half-life of radioisotopes generated after the main frame is activated by neutrons, the types of aluminum alloy constituent elements and the mass ratio of each element should be controlled, such as the mass percentage of Cu element ≤7%. According to the relevant calculation and experience accumulation, in this implementation, the chemical composition of the main frame material is selected to satisfy Cu≤1.0%, Mn≤1.5%, Zn≤1.0% (mass percentage); the chemical composition table of 6061 aluminum alloy is shown in Table 1, for comparison It can be seen that the 6061 aluminum alloy can meet the chemical composition required for the material of the main frame 21a.

Table 1. Chemical Composition (%)

In order to meet the support of the main frame 21a to the main body portion 23 of the beam shaping body, the mechanical properties of the main frame must meet the requirements; according to CAE simulation calculation and experience adjustment, in this implementation, the tensile strength of the aluminum alloy main frame is selected to be ≥150MPa, and the yield strength ≥100MPa.

Since the 6061 aluminum alloy is a deformed aluminum alloy, the free forging method is adopted in this embodiment, and the structure and properties of the aluminum alloy are changed by the plastic forming method, and the raw materials can be saved at the same time. For the free forging process scheme, the quality of the forgings largely depends on the metal structure obtained during the deformation process, especially the uniformity of the deformation of the forgings. Because the deformation is not uniform, not only the plasticity of the metal is reduced, but also due to the uneven recrystallization, the uneven structure will be obtained, which will make the performance of the forging worse. Well, the less heat the better. The processing process of this embodiment is as follows:

1. Billet preparation: Aluminum plants and other manufacturers process aluminum ore into aluminum ingots, and cast them into billets, which are formulated to meet the national standard 6061 aluminum alloy composition. Data and experimental results of homogenization annealing, low magnification and oxide film inspection;

2. Blanking: Process the blanks that meet the requirements by shearing, sawing, gas cutting, etc., such as end face cutting, and remove burrs, oil stains and sawdust in time to meet the processing needs of forging equipment;

3. Heating: The billet is heated before forging to reduce deformation resistance and improve plasticity. If a radiant resistance heating furnace is used, the furnace has circulating air, which can keep the temperature accurate and uniform, and the furnace temperature deviation can be controlled within the range of ±10 °C. In this embodiment, the maximum opening forging temperature is 520 °C, and the final forging temperature is 450°C, and the allowable limit temperature is 530°C. It will be appreciated that other heating devices may also be used. The determination of the heating and holding time should fully consider factors such as the thermal conductivity of the alloy, the specification of the billet, the heat transfer method of the heating equipment, etc. In this embodiment, the heating time is determined according to the dissolution of the strengthening phase and the obtaining of a homogenized structure. In this state It has good plasticity and can improve the forging properties of aluminum alloys. It can be understood that the billet can also be heated before cutting in step 2. At this time, before the billet is heated, such as before entering the heating furnace, oil, debris and other dirt should be removed to avoid polluting the air in the furnace.

4. Forging: The material of 6061 aluminum alloy is polycrystalline, there are grain boundaries between the grains, and there are subgrains and phase boundaries inside the grains. Therefore, the plasticity of the material is used to make it plastically deformed by the action of external force. , can obtain forgings of desired shape (such as cylinder), size and certain structure and properties. The as-cast structure of the metal billet is eliminated by forging deformation, which greatly improves the plasticity and mechanical properties. In the present embodiment, the free forging method is adopted, such as upsetting and drawing, and the above two methods are repeatedly carried out under the condition that the temperature of the forging is not lower than the specified temperature, and the static forging is carried out according to the process, so as to obtain precise grains inside the structure, Forging equipment has the precision of forging blanks.

5. Roughing and heat treatment: In order to finally obtain the mechanical properties that meet the requirements of use, it is also necessary to change the structure and properties of the metal material and the internal quality of the metal through heat treatment. In this embodiment, a cylinder is obtained by forging in step 4, and it is difficult to ensure the performance of the material in the center of the cylinder by directly heat-treating the cylinder. Therefore, the center position of the forged cylinder (that is, the area corresponding to the fourth accommodating unit C4) is punched by rough machining, and then deep heat treatment is performed to ensure that the main frame is close to the center position after heat treatment (forming the fourth accommodating unit C4). The main frame part of the accommodating unit C4) and the overall material properties; at the same time, the fourth accommodating unit C4 accommodates the basic part of the retarder, which can ensure the support of the retarder at this time, prevent the retarder from being deformed and damaged, and affect the target change and beam quality. It can be understood that the rough machining may also include preliminary machining of the hollow area between the outer wall 211 and the inner walls 212-215 of the main frame (ie, the area of the column corresponding to the first, second, and third accommodation units C1, C2, and C3). , such as the solid part of the cylinder obtained by drilling, milling, cutting and forging in this area; in this embodiment, no rough machining is performed on the area, to prevent the thin wall thickness and easy deformation when heat treatment is performed after rough machining. In the case that the process can guarantee the material properties of the central area and other areas, rough machining may not be performed; the rough machining should leave a margin for subsequent further machining.

The heat treatment process adopted in this embodiment is T6 (solution + aging). Solution treatment is the first step in precipitation hardening of the alloy. The solid solution formed during solid solution is rapidly cooled to obtain a metastable supersaturated solid solution, which creates conditions for natural aging and artificial aging, and significantly improves the strength and hardness. After solution treatment, aging treatment is also required. The aluminum after solution treatment is placed at a certain temperature for a certain period of time, and the supersaturated solid solution will decompose, resulting in a substantial increase in the strength and hardness of the alloy, which can be room temperature. Hold or heat. Aging treatment is the last process of heat treatment, which can improve and determine the final mechanical properties of aluminum alloy. The heating temperature and holding time can be selected according to the actual situation. It can be understood that other heat treatment processes can also be used, as long as the mechanical properties required for use can be met.

6. Physical and chemical inspection and inspection: After the heat treatment is completed, physical and chemical inspection and inspection are required, including size inspection, element inspection, mechanical property inspection, ultrasonic flaw detection and non-destructive inspection, etc. This can be an inspection by a person involved in heat treatment after heat treatment, or an inspection by a person involved in machining (see below) before machining. The mechanical property test can be performed by cutting a part of the material in the relevant area of the workpiece after heat treatment. In this embodiment, the part that is punched and removed at the center position during rough machining can be heat treated at the same time, and the inspection of this part approximately represents the part close to the spindle X. The properties of the inner walls 214, 215; the area between the outer wall 211 and the inner walls 212-215 were tested by cutting the material of the heat treated forged cylinder in this area. It can be understood that when rough machining is performed on the hollow area between the outer wall 211 and the inner walls 212-215, the inspection after heat treatment is performed on the rough-cut part of the area can also approximately represent the performance of the area. Selection can be marked on the drawing. Mechanical experiments were carried out on samples from the above regions to obtain yield strength and tensile strength. The non-destructive testing adopts ultrasonic flaw detection, which can be a comprehensive inspection or a divisional inspection. In this embodiment, ultrasonic flaw detection is performed on the inner wall near the center.

7. Machining: After testing and inspection, after the heat-treated forged body meets the requirements, machining is performed to obtain the main frame of the final required shape and size. It is understood that machining can include conventional machining methods such as drilling, milling, and turning. , This implementation uses a large gantry milling machine for milling and automatic processing with programming software.

The main frame 21a and the second transverse plate 224 are connected by bolts, and the first threaded holes are uniformly machined on the end surface of the fourth inner wall 215 facing the second side plate 222, and the positions corresponding to the first threaded holes on the second transverse plate 224 The first through hole is uniformly machined on the upper surface, and the bolt passes through the first through hole and is connected with the first threaded hole. Considering the assembly of the bolts, the diameter of the first through hole is slightly larger than that of the first threaded hole, and the number of the first threaded hole and the first through hole can satisfy the connection strength. The first and second side plates 221 , 222 and the second horizontal plate 224 are made of lead-antimony alloy material. Lead can further shield radiation, and at the same time, lead-antimony alloy has high strength. The outer contours of the first and second side plates 221 and 222 are consistent with the outer contour of the outer wall 211 . The first and second side plates 221, 222 and the second transverse plate 224 are connected with the main frame by bolts, and the end faces of the inner wall of the main frame 21a facing the first and second side plates and the second transverse plate are machined uniformly respectively. Two threaded holes, the second through holes are machined uniformly at the positions corresponding to the second threaded holes on the first and second side plates 221, 222 and the second transverse plate 224. Considering the assembly of the bolts, the The hole diameter is slightly larger than that of the second threaded hole, and the number of the second threaded hole and the second through hole can satisfy the connection strength.

It can be understood that as long as the materials of the main frame, side plate, and end plate (second transverse plate) in this embodiment have a certain strength and are activated by neutrons, the radioisotope has a short half-life (for example, less than 7 days), and the The material properties are sufficient to support the beam shaping body, such as aluminum alloy, titanium alloy, lead-antimony alloy, cobalt-free steel, carbon fiber, PEEK, polymer, etc.; side plate, end plate (second horizontal plate) Other detachable connections or non-detachable connections can be used with the main frame. When detachable connections are used, it is convenient to replace various parts of the main body. In this embodiment, the support portion of the beam shaping body and the main body portion filled in the support portion may also have other configuration modes.

During construction, first put the main frame 21a into the mounting holes reserved for the beam shaping body support part, and connect the outer wall 211 of the main frame 21a and the beam shaping body support part with bolts or the like. Then carry out the filling of the main body and the installation of the first, second side plates and the second horizontal plate. Due to the low density of PE, aluminum alloy and graphite, the corresponding area can be filled as a whole; The beams can be manually filled in N-direction slices, or integrally filled by means of machinery; magnesium fluoride can also be integrally filled or sliced. After the beam shaping body is installed, install other components such as the transmission tube, target, collimator, etc. The collimator 30 is arranged at the rear of the beam exit, and the epithermal neutron beam from the collimator 30 is irradiated to the patient 200 , after passing through the superficial normal tissue, it is slowed to reach the tumor cell M as thermal neutrons. In this embodiment, the collimator is fixed to the main frame 21a by bolts, etc., a third threaded hole is reserved on the end face of the second inner wall 213 facing the second side plate, and the second side plate 222 corresponds to the third threaded hole. The third through hole is machined uniformly in position. Considering the assembly of the bolt, the diameter of the third through hole is slightly larger than that of the third threaded hole, and the number of the third threaded hole and the third through hole can meet the connection strength. It can be understood that the collimator 30 can also be fixed by other connection methods, the collimator 30 can also be eliminated or replaced by other structures, and the neutron beam exits from the beam outlet and directly irradiates the patient 200 . In this embodiment, a radiation shielding device 50 is further arranged between the patient 200 and the beam exit to shield the radiation from the beam exiting the beam exit to the normal tissue of the patient. It can be understood that the radiation shielding device 50 may not be arranged.

The "column" or "columnar-shaped" mentioned in the embodiments of the present invention refers to a structure in which the overall trend of the outer contour is basically unchanged from one side to the other along the direction shown in the figure, and one of the outer contours The line can be a line segment, such as the corresponding contour line of a cylinder, or it can be an arc with a large curvature close to the line segment, such as a corresponding contour line of a spherical shape with a large curvature, and the entire surface of the outer contour can be smooth. The transition can also be a non-smooth transition, such as making a lot of protrusions and grooves on the surface of a cylinder or a sphere with large curvature.

The "cone" or "cone-shaped" mentioned in the embodiments of the present invention refers to a structure whose overall trend of the outer contour gradually decreases from one side to the other in the direction of the drawing, and one of the outer contours The line can be a line segment, such as the corresponding contour of a cone, or an arc, such as the corresponding contour of a sphere, and the entire surface of the outer contour can be a smooth transition, or a non-smooth transition, such as Many bumps and grooves are made on the cone-shaped or spherical surface.

Although the illustrative specific embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, Various changes, which are obvious, are within the scope of the claimed invention, provided they are within the spirit and scope of the invention as defined and determined by the appended claims.

Claims (10)

1. A neutron capture treatment system, comprising a neutron generating device and a beam shaping body, the neutron generating device comprising an accelerator and a target, and the charged particle beams generated by the accelerator are accelerated and generated by the action of the target. The neutrons form a neutron beam, and the neutron beam defines a main axis, wherein the beam shaping body includes a support part and a main body part filled in the support part, and the main body part includes A retarder, a reflector, and a radiation shield that decelerates neutrons generated from the target to an epithermal neutron energy region, the reflector surrounding the retarder and will deviate from the retarder The neutrons of the main shaft are directed back to the main shaft to increase epithermal neutron beam intensity, and the radiation shield is used to shield leaking neutrons and photons to reduce normal tissue dose in non-irradiated regions. 2 . The neutron capture therapy system according to claim 1 , wherein the support portion comprises an outer wall circumferentially closed around the main shaft, the outer wall surrounds and forms a receiving portion, and the main body portion is disposed on the main shaft. 3 . In the accommodating part, the accommodating part includes at least one accommodating unit, and each of the accommodating units accommodates at least one of the retarding body, the reflector and the radiation shielding body. 3. The neutron capture therapy system according to claim 2, wherein the support part further comprises first, A second side plate, at least one transverse plate disposed between the first and second side plates in the direction of the neutron beam, and circumferentially closed around the main axis and extending between the first and second side plates At least one inner wall between the transverse plate and the first/second side plate or between the transverse plate and the transverse plate, the first side plate is provided with a hole through which the transmission tube of the accelerator passes, so The second side plate is provided with a hole for forming a beam outlet, a plurality of accommodating units are formed between the outer wall, the inner wall, the transverse plate and the first and second side plates, and the radiation shielding body includes a neutron shielding body and a photon shielding body. A shield, at least one of the accommodating units accommodates the retarder/neutron shield and the reflector at the same time. 4 . The neutron capture therapy system according to claim 3 , wherein the inner wall comprises first and second inner walls, the transverse plate comprises a first transverse plate, and the first inner wall extends over the first inner wall. 5 . Between one side plate and the first transverse plate and used for installing the transmission tube, the second inner wall extends from the first transverse plate along the neutron beam direction and is used for accommodating at least a portion of the retarder. part. 5 . The neutron capture therapy system according to claim 4 , wherein the retarding body comprises a basic part and a supplementary part, the accommodating unit comprises an adjacent first accommodating unit and a second accommodating unit, the The basic part is accommodated in the first accommodating unit, and the basic part is provided with a central hole at one end facing the first side plate, and the central hole is used for accommodating the transfer tube and the target material, the supplementary part and At least a part of the reflector is accommodated in the second accommodating unit, the first accommodating unit is formed by being surrounded by the second inner wall, and the radial distance from the first inner wall to the main axis is smaller than the second accommodating unit The radial distance from the inner wall to the main shaft. 6 . The neutron capture therapy system according to claim 5 , wherein the material of the basic part is magnesium fluoride containing Li-6, the basic part simultaneously acts as a thermal neutron absorber, and the supplementary The part includes a first and a second supplementary unit, the material of the first supplementary unit is aluminum alloy, the material of the second supplementary unit is Teflon, the material of the reflector is lead, and the reflector also serves as a A photon shielding body, the first and second supplementary units are integrally arranged in two conical shapes adjacent to each other in opposite directions, and the reflector in the second accommodating unit is divided into two parts, the first The second supplementary units are arranged in sequence along the direction of the neutron beam, and the interface between the first and second supplementary units is perpendicular to the direction of the neutron beam. 7 . The neutron capture therapy system according to claim 6 , wherein a shielding plate is further arranged in the first accommodating unit, the basic part and the shielding plate are arranged in sequence along the neutron beam direction, and the The material of the shielding plate is lead, the thickness of the shielding plate in the direction of the neutron beam is less than or equal to 5 cm, the outer wall, at least one of the inner walls and at least one of the transverse plates integrally form a main frame, the main frame, The half-life of radioisotopes generated after the materials of the first and second side plates are activated by neutrons is less than 7 days, and the materials of the main frame and the first and second side plates are aluminum alloy, titanium alloy, lead-antimony alloy, cast aluminum , Cobalt-free steel, carbon fiber, PEEK or polymer. 8. The neutron capture therapy system according to claim 3, wherein the accommodating unit comprises a third accommodating unit, and at least a part of the neutron shield and at least a part of the reflector are accommodated in the In the third accommodating unit, the material of the neutron shield is PE, the material of the reflector is lead, the reflector serves as a photon shield at the same time, and the reflector and neutron shield in the third accommodating unit The bodies are arranged in sequence along the neutron beam direction, and the interface between the reflector and the neutron shielding body in the third accommodating unit is perpendicular to the neutron beam direction. 9 . The neutron capture therapy system according to claim 3 , wherein the support part further comprises a radial partition that divides the accommodating unit into several sub-regions in the circumferential direction, the radial partition It is arranged between the first and second side panels or between the transverse panel and the first/second side panel or between the transverse panel and the transverse panel, and extends from the outer wall to the inner wall or extends at between the two inner walls. 10. A beam shaper for a neutron capture therapy system, the neutron capture therapy system comprising a neutron generating device, the neutrons generated by the neutron generating device forming a neutron beam, the beam shaping The beam shaping body can adjust the beam quality of the neutron beam, and is characterized in that the beam shaping body comprises a support part and a main body part filled in the support part, the support part forms at least one accommodating unit, each of which The accommodating unit accommodates at least a part of the main body portion.

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