WO2020211583A1 - 中子捕获治疗系统 - Google Patents

中子捕获治疗系统 Download PDF

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Publication number
WO2020211583A1
WO2020211583A1 PCT/CN2020/079731 CN2020079731W WO2020211583A1 WO 2020211583 A1 WO2020211583 A1 WO 2020211583A1 CN 2020079731 W CN2020079731 W CN 2020079731W WO 2020211583 A1 WO2020211583 A1 WO 2020211583A1
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Prior art keywords
neutron
wall
frame
retarder
neutrons
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PCT/CN2020/079731
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English (en)
French (fr)
Inventor
陈韦霖
江涛
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中硼(厦门)医疗器械有限公司
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Priority to EP20791847.5A priority Critical patent/EP3957363A4/en
Priority to JP2021559126A priority patent/JP2022528417A/ja
Priority to CA3135519A priority patent/CA3135519A1/en
Priority to AU2020258593A priority patent/AU2020258593B2/en
Publication of WO2020211583A1 publication Critical patent/WO2020211583A1/zh
Priority to US17/494,876 priority patent/US12023524B2/en
Priority to JP2024021734A priority patent/JP2024050931A/ja

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1077—Beam delivery systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1064—Monitoring, verifying, controlling systems and methods for adjusting radiation treatment in response to monitoring
    • A61N5/1065—Beam adjustment
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1077—Beam delivery systems
    • A61N5/1078—Fixed beam systems
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
    • G21G4/00—Radioactive sources
    • G21G4/02—Neutron sources
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K5/00—Irradiation devices
    • G21K5/02—Irradiation devices having no beam-forming means
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1085—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy characterised by the type of particles applied to the patient
    • A61N2005/1087—Ions; Protons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1085—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy characterised by the type of particles applied to the patient
    • A61N2005/109—Neutrons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1092—Details
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1092—Details
    • A61N2005/1094—Shielding, protecting against radiation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1092—Details
    • A61N2005/1095—Elements inserted into the radiation path within the system, e.g. filters or wedges

Definitions

  • the invention relates to a radiation irradiation system, in particular to a neutron capture treatment system.
  • radiotherapy such as cobalt sixty, linear accelerator, and electron beam has become one of the main methods of cancer treatment.
  • 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.
  • traditional radiotherapy For the more radiation-resistant malignant tumors (such as: glioblastoma multiforme, melanoma), the treatment effect is often poor.
  • 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, combined with precise neutron beam regulation, to provide better than traditional radiation Cancer treatment options.
  • BNCT Boron Neutron Capture Therapy
  • 10 B boron-containing drugs
  • 10 B (n, ⁇ ) 7 Li neutron capture and nuclear fission reaction Two heavily charged particles, 4 He and 7 Li, are produced. 1 and 2, which respectively show the schematic diagram of the boron neutron capture reaction and the 10 B(n, ⁇ ) 7 Li neutron capture nuclear reaction equation.
  • the average energy of the two charged particles is about 2.33 MeV, which has high linearity Transfer (Linear Energy Transfer, LET), short-range characteristics, the linear energy transfer and range of alpha particles are 150keV/ ⁇ m, 8 ⁇ m, and 7 Li heavy-load particles are 175keV/ ⁇ m, 5 ⁇ m, the total range of the two particles is approximately equivalent to The size of a cell, so the radiation damage caused to organisms can be limited to the cell level.
  • boron-containing drugs are selectively aggregated in tumor cells, with an appropriate neutron source, they can not cause too much damage to normal tissues. Under the premise, the purpose of locally killing tumor cells is achieved.
  • boron neutron capture therapy depends on the concentration of boron-containing drugs and the number of thermal neutrons at the tumor cell location, it is also called binary cancer therapy. It can be seen 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.
  • a neutron capture treatment system including a neutron generation device and a beam shaping body
  • the neutron generation device includes an accelerator and a target, so The charged particle beam generated by the accelerator and the target interact to generate neutrons, the neutrons form a neutron beam, the neutron beam defines a main axis
  • the beam shaping body includes a retarder and a reflector And a radiation shield
  • the retarder decelerates the neutrons generated from the target to the superthermal neutron energy zone
  • the reflector surrounds the retarder and guides the neutrons deviated from the main axis back To the main axis to increase the intensity of the superthermal neutron beam
  • the radiation shield is used to shield the leaking neutrons and photons to reduce the normal tissue dose in the non-irradiated area
  • the beam shaping body further includes accommodating the buffer Speed body frame.
  • the frame forms positioning and support for the retarder, which can improve the flux and quality of the
  • the retarder is adjustable, and the frame includes a positioning member and a stop member for fixing the retarder.
  • the half-life of the radioisotope generated by the materials of the positioning member and the stop member is less than 7 days after being activated by neutrons.
  • the materials of the positioning member and the stop member are aluminum alloy, titanium alloy, lead-antimony alloy, cobalt-free steel, carbon fiber, PEEK or high molecular polymer.
  • the positioning member can conveniently adjust the size of the retarder body, thereby adjusting the neutron beam flux, and the stop member can quickly and conveniently realize the packaging of the retarder body after adjustment.
  • the retarder body includes a basic part and a supplementary part, the basic part and the supplementary part have different materials, the frame forms at least one accommodating unit, and the accommodating unit includes a first accommodating unit and a second accommodating unit adjacent to each other.
  • the basic part is accommodated in the first accommodating unit and is adjustable in slices.
  • the positioning member is provided in the first accommodating unit to supplement, The stop member is used to fix the basic part.
  • the supplementary part can reduce the manufacturing cost of the retarder, and at the same time, will not have a greater impact on the beam quality; the positioning member and the stop member can easily adjust the basic part of the retarder.
  • the frame includes a main frame and a secondary frame that are detachably connected, the first accommodating unit is formed by being surrounded by at least a part of the main frame, and the second accommodating unit is formed by at least a part of the main frame and At least a part of the secondary frame is surrounded and formed, the supplementary part is accommodated in the second accommodating unit, and the arrangement of the secondary frame facilitates replacement of the supplementary part of the retarder.
  • the material of the main frame is aluminum alloy, which has good mechanical properties and has a short half-life of radioisotopes generated after being activated by neutrons; preferably, the material of the sub-frame is carbon fiber composite material, which is activated by neutrons.
  • the material of the basic part includes at least one of D 2 O, Al, AlF 3 , MgF 2 , CaF 2 , LiF, Li 2 CO 3 or Al 2 O 3 , which has a large interaction cross-section with fast neutrons, The superthermal neutron action cross section is small and has a better retardation effect; the basic part contains Li-6, and the basic part simultaneously serves as the thermal neutron absorber.
  • the material of the supplementary part includes at least one of Zn, Mg, Al, Pb, Ti, La, Zr, Bi, and C. The material of the supplementary part is easily available, which can reduce the manufacturing cost of the retarder. At the same time, it has a certain neutron slowing effect, which will not have a big impact on the beam quality.
  • the main frame includes a first wall, a second wall which are arranged in sequence along the neutron beam direction and are circumferentially closed around the main axis, and a first horizontal plate connecting the first wall and the second wall,
  • the first horizontal plate extends perpendicular to the direction of the neutron beam
  • the first wall is used to install the transmission tube of the accelerator
  • the second wall surrounds and forms the first containing unit
  • the first wall The radial distance to the main shaft is smaller than the radial distance from the second 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.
  • the main frame includes a third wall circumferentially closed around the neutron beam direction, and the radial distance from the second wall to the main axis is smaller than the radial distance from the third wall to the main axis
  • the frame further includes first and second side plates respectively arranged on both sides of the third wall along the direction of the neutron beam and connected to the third wall, and the sub-frame includes A second horizontal plate arranged between the second wall and the second side plate.
  • the sub-frame further includes a fourth wall which is circumferentially closed around the neutron beam direction and extends between the second transverse plate and the second side plate, and the neutron capture treatment system It also includes a collimator.
  • the fourth wall forms the installation part and/or the beam exit of the collimator.
  • the secondary frame made of carbon fiber is used in the beam exit direction. Compared with aluminum alloy, the activation degree is smaller. It has high strength and has a certain retarding effect.
  • the sub-frame also serves as the installation part of the collimator.
  • the main frame also includes a radial partition arranged between the first side plate and the second horizontal plate and extending from the first wall to the second wall or the third wall, the first wall , A second wall, a third wall, a first horizontal plate, a second horizontal plate and a first side plate surround the second accommodating unit, and the radial partition divides the second accommodating unit in the circumferential direction A number of sub-regions, the third wall, the fourth wall, the second horizontal plate and the second side plate surround to form a third accommodating unit.
  • the second accommodating unit is also provided with at least the reflector/radiation shield In one part, at least part of the radiation shield is provided in the third accommodating unit, and the material of the first and second side plates is lead-antimony alloy. Lead can further shield the radiation. At the same time, the strength of the lead-antimony alloy is higher. high.
  • the basic part is provided with a central hole on the first end surface facing the first side plate, and the central hole is used to accommodate the transmission tube and the target of the accelerator.
  • the first end surface of the supplementary unit close to the second side plate is flush with the second end surface of the basic part close to the second side plate.
  • a shielding plate is arranged adjacent to the second end surface of the basic part, the shielding plate is a lead plate, and the lead can absorb gamma rays released from the retarder, and the shielding plate is in the direction of the neutron beam.
  • the stop member is arranged adjacent to the second horizontal plate, and the stop member is detachably connected to the main frame and/or the secondary frame to facilitate adjustment and replacement of the basic part of the retarder.
  • a neutron capture treatment system including a neutron generating device and a beam shaping body, the neutrons generated by the neutron generating device form a neutron beam, and the neutron beam defines a main axis,
  • the beam shaping body can adjust the beam quality of the neutron beam, the beam shaping body includes a retarder, a reflector and a radiation shielding body, and the retarder will be generated from the neutron generator
  • the neutrons decelerate to the superthermal neutron energy zone
  • the reflector surrounds the retarder and guides the neutrons that deviate from the main axis back to the main axis to increase the intensity of the superthermal neutron beam
  • the radiation shield The body is used to shield the leaking neutrons and photons to reduce the normal tissue dose in the non-irradiated area.
  • the beam shaping body also includes a frame for accommodating the retarder body.
  • the frame includes a detachable main frame and a secondary frame. frame.
  • the frame forms the positioning and support for the retarder, which can improve the flux and quality of the neutron radiation source; the main frame and the secondary frame can be detachably connected to facilitate the replacement of the retarder.
  • the frame of the beam shaping body forms the positioning and support for the slow body, which can improve the flux and quality of the neutron radiation source.
  • Figure 1 is a schematic diagram of the boron neutron capture reaction
  • Figure 2 is the 10 B(n, ⁇ ) 7 Li neutron capture nuclear reaction equation
  • Figure 3 is a schematic diagram of a neutron capture therapy system according to an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of a beam shaping body and a collimator of a neutron capture therapy system according to an embodiment of the present invention
  • Fig. 5 is a schematic diagram of the frame in Fig. 4;
  • Fig. 6 is a schematic diagram of the main frame in Fig. 5 viewed from the direction of the neutron beam N;
  • Fig. 7 is a schematic diagram of the main frame in Fig. 5 viewed from the direction opposite to the direction of the neutron beam N.
  • the neutron capture treatment system in this embodiment is preferably a boron neutron capture treatment system 100, which includes a neutron generator 10, a beam shaping body 20, a collimator 30 and a treatment table 40.
  • the neutron generator 10 includes an accelerator 11 and a target T.
  • the accelerator 11 accelerates charged particles (such as protons, deuterons, etc.) to produce a charged particle beam P such as a proton beam.
  • the charged particle beam P irradiates the target T and interacts with
  • the target material T acts to generate neutrons, the neutrons form a neutron beam N, the neutron beam defines a main axis X, and the target material T is preferably a metal target material.
  • the direction of the neutron beam N in the figure and below does not represent the actual neutron movement direction, but the direction of the overall movement trend of the neutron beam N.
  • Select the appropriate nuclear reaction according to the required neutron yield and energy, the available accelerated charged particle energy and current size, and the physical and chemical properties of the metal target.
  • the nuclear reactions that are often discussed are 7 Li(p,n) 7 Be and 9 Be(p,n) 9 B, both of these reactions are endothermic reactions.
  • the energy thresholds of the two nuclear reactions are 1.881 MeV and 2.055 MeV, respectively.
  • the ideal neutron source for boron neutron capture therapy is superthermal neutrons with keV energy level, theoretically, if proton bombardment with an energy slightly higher than the threshold is used
  • the metallic lithium target can generate relatively low-energy neutrons and can be used in clinics without too much slowing treatment.
  • the two target materials of lithium metal (Li) and beryllium metal (Be) have proton interaction cross-sections with threshold energy Not high, in order to generate a large enough 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 the superthermal neutron energy region (described in detail below), no strong penetrating radiation, safe, cheap, easy to operate, and high temperature resistance.
  • the target material T may 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, or a synchrocyclotron.
  • the neutron source of the boron neutron capture therapy produces a mixed radiation field, that is, the beam contains low to high energy neutrons and photons; for the boron neutron capture therapy of deep tumors, except for the superthermal neutrons, the rest of the radiation
  • the human head tissue prosthesis is used for dose calculation, and the prosthetic beam quality factor is used as the neutron radiation
  • the design reference of the bundle will be described in detail below.
  • the International Atomic Energy Agency has given five recommendations for air beam quality factors 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 methods and designing beam shaping bodies. The five recommendations are as follows:
  • Thermal neutron to epithermal neutron flux ratio thermal to epithermal neutron flux ratio ⁇ 0.05
  • the superthermal neutron energy range is between 0.5eV and 40keV, the thermal neutron energy range is less than 0.5eV, and the fast neutron energy range is greater than 40keV.
  • the neutron beam flux and the concentration of boron-containing drugs in the tumor jointly determine the clinical treatment time. If the concentration of boron-containing drugs in the tumor is high enough, the requirement for neutron beam flux can be reduced; conversely, if the concentration of boron-containing drugs in the tumor is low, high flux superthermal neutrons are required to give the tumor a sufficient dose.
  • the IAEA's requirement for the flux of the superthermal neutron beam is that the number of superthermal neutrons per square centimeter per second is greater than 10 9.
  • the neutron beam under this flux can roughly control the treatment of current boron-containing drugs Within one hour, short treatment time not only has advantages in patient positioning and comfort, but also can effectively utilize the limited residence time of boron-containing drugs in tumors.
  • fast neutrons can cause unnecessary normal tissue doses, they are regarded as pollution.
  • the dose is positively correlated with neutron energy. Therefore, the content of fast neutrons should be minimized in the design of neutron beams.
  • Fast neutron pollution is defined as the dose of fast neutrons per unit of superthermal neutron flux.
  • the IAEA's recommendation for fast neutron pollution is less than 2x 10 -13 Gy-cm 2 /n.
  • Gamma rays are strong penetrating radiation, which will non-selectively cause the dose deposition of all tissues in the beam path. Therefore, reducing the content of gamma rays is also a necessary requirement for neutron beam design.
  • Gamma-ray pollution is defined as the unit superheated neutron flux accompanying The IAEA’s recommendation for ⁇ -ray pollution is less than 2x 10 -13 Gy-cm 2 /n.
  • thermal neutrons Due to the fast attenuation speed and poor penetration ability of thermal neutrons, most of the energy is deposited in the skin tissue after entering the human body. Except for epidermal tumors such as melanoma, which need to use thermal neutrons as the neutron source for boron neutron capture therapy, it is targeted at the brain Deep tumors such as tumors should reduce thermal neutron content.
  • the IAEA recommends that the ratio of thermal neutron to superthermal neutron flux is less than 0.05.
  • the ratio of neutron current to flux represents the directionality of the beam. The larger the ratio, the better the forward direction of the neutron beam.
  • the high forward neutron beam can reduce the normal tissue dose caused by neutron divergence. It also improves the treatment depth and the flexibility of the posture.
  • the IAEA recommends that the ratio of neutron current to flux is greater than 0.7.
  • the prosthesis is used to obtain the dose distribution in the tissue, and the beam quality factors of the prosthesis are derived according to the dose-depth curve of the normal tissue and the tumor.
  • the following three parameters can be used to compare the therapeutic benefits of different neutron beams.
  • the tumor dose is equal to the depth of the maximum dose of normal tissue. After this depth, the dose of tumor cells is less than the maximum dose of normal tissue, that is, the advantage of boron neutron capture is lost. This parameter represents the penetration ability of the neutron beam. The larger the effective treatment depth, the deeper the tumor can be treated, and the unit is cm.
  • the effective treatment depth of tumor dose rate is also equal to the maximum dose rate of normal tissue. Because the total dose received by normal tissue is a factor that affects the total dose that can be given to the tumor, the parameter affects the length of the treatment time. The greater the effective treatment depth and the dose rate, the shorter the irradiation time required to give a certain dose to the tumor.
  • the unit is cGy/mA -min.
  • the effective treatment dose ratio received by the tumor and normal tissue is called the effective treatment dose ratio; the average dose can be calculated by integrating the dose-depth curve.
  • RBE Relative Biological Effectiveness
  • the neutron beam N generated by the neutron generator 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 shaping body 20 can adjust the beam quality of the neutron beam N generated by the neutron generator 10, and the collimator 30 is used to converge the neutron beam N so that the neutron beam N has a higher Targeting.
  • the beam shaping body 20 further includes a frame 21 and a main body 23. At least part of the main body 23 is accommodated in the frame 21.
  • the frame 21 supports the main body 23 to prevent deformation and damage of the material itself, which affects target replacement and beam quality.
  • the main body 23 includes a retarder 231, a reflector 232, and a radiation shield 233.
  • the neutrons generated by the neutron generator 10 have a wide energy spectrum. Except for the superthermal neutrons to meet the needs of treatment, it is necessary to reduce other types as much as possible. The neutron and photon content of the neutron to avoid harm to operators or patients.
  • the body 231 is made of materials with a large interaction cross section with fast neutrons and a small interaction cross section with superthermal 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 through the retarder 231 back to the neutron beam N to improve the utilization of neutrons, and has the ability to reflect neutrons Made of strong materials, such as including at least one of Pb or Ni;
  • the radiation shield 233 is used to shield the leaking neutrons and photons to reduce the normal tissue dose in the non-irradiated area, and the material of the radiation shield 233 includes photon shielding At least one of materials and neutron shielding materials, such as photon shielding material
  • the main body can also have other structures, as long as the superthermal neutron beam required for treatment can be obtained.
  • the target T is arranged between the accelerator 11 and the beam shaping body 20.
  • the accelerator 11 has a transmission tube 111 for transmitting the charged particle line P.
  • the transmission tube 111 extends along the direction of the charged particle line P and enters the beam shaping body 20.
  • the target T is set in the retarder 231 and at the end of the transmission tube 111 to obtain a better neutron beam quality.
  • the first and second cooling tubes D1 and D2 are arranged between the transmission tube 111 and the retarder 231 and the reflector 232.
  • first and second cooling tubes D1 and D2 are respectively connected to the cooling target T
  • the inlet (not shown) is connected to the cooling outlet (not shown), and the other end is connected to an external cooling source (not shown).
  • first and second cooling pipes can also be arranged in the beam shaping body in other ways, and when the target is placed outside the beam shaping body, it can also be eliminated.
  • the frame 21 includes a first wall 211 that is circumferentially closed around the main axis X, and a first wall 211 that is arranged on both sides of the first wall 211 along the neutron beam N direction and connected to the first wall 211.
  • the side plates 221, 222, 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 exit, the first wall 211 and the first and second side plates 221
  • a accommodating portion C of the retarder is formed between 222 and 222, and at least a part of the reflector and/or radiation shielding body is also arranged in the accommodating portion C.
  • the accommodating part C includes at least one accommodating unit C1-C3 (detailed below), each accommodating unit C1-C3 accommodates at least one of the retarder 231, the reflector 232 and the radiation shielding body 233, and at least one accommodating unit simultaneously accommodates At least two of the retarder, the reflector and the radiation shielding body or contain at least two different materials at the same time.
  • the retarder 231 includes a basic part and a supplementary part, and the basic part and the supplementary part are respectively accommodated in different accommodating units. It can be understood that the first and second side plates may not be provided, and the receiving part is surrounded by the first wall.
  • the frame 21 also includes a first horizontal plate 223 arranged 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 horizontal plate 223 and the first side plate
  • the second wall 212 between 221 and the third wall 213 circumferentially closed around the main axis X and extending from the first horizontal plate 223 to the second side plate 222.
  • the second wall 212 is radially closer to the main axis X than the third wall 213.
  • the third wall 213 is located between the first wall 211 and the second wall 212 in the radial direction.
  • the first transverse plate 223 extends between the second wall 212 and the third wall 212. Between walls 213.
  • the inner surface of the second wall 212 is on the same surface as the side wall of the hole 2211 on the first side plate 221, and the second wall 212 forms the installation part of the transmission pipe 111, the first and second cooling pipes D1, D2, etc. It can be understood that the first transverse plate may extend to the first wall.
  • the frame 21 also includes a second horizontal plate 224 arranged between the third wall 213 and the second side plate 222 along the neutron beam N direction, which is circumferentially closed around the main axis X and extends on the second horizontal plate 224 and the second side plate
  • the fourth wall 214 between 222 is adjacent to the third horizontal plate 225 arranged between the second horizontal plate 224 and the second side plate 222 adjacent to the second horizontal plate 224.
  • the second horizontal plate 224 extends from the first wall 211 to the inner side of the third wall 213.
  • the fourth wall 214 is located between the first wall 211 and the third wall 213 in the radial direction.
  • the inner surface of the fourth wall 214 and the second side plate The side walls of the upper hole 2221 on the 222 are on the same surface.
  • the fourth wall 214 and the hole 2221 on the second side plate 222 together form a beam exit.
  • the third horizontal plate 225 forms a hole 2251 through which the neutron beam N passes.
  • the third wall 213 is located radially between the fourth wall 214 and the inner wall of the hole 2251 on the third horizontal plate 225, and the outer wall of the third horizontal plate 225 is located between the inner surface of the fourth wall 214 and the inner surface of the third wall 213 .
  • the cross-sections of the first, second, third, and fourth walls in the direction perpendicular to the main axis X are all rings around the main axis X and extend parallel to the main axis X, and the side plates and horizontal plates are all perpendicular to the main axis X.
  • 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;
  • the frame can also include multiple walls that are circumferentially closed around the main axis X and multiple horizontal plates arranged between the walls. Used to accommodate or support other parts of the beam shaping body.
  • a columnar first housing unit C1 is formed in the direction of the neutron beam N.
  • the first wall 211, the second wall 212, and the A second receiving unit C2 is formed between the three walls 213, the first side plate 221, the first horizontal plate 223, and the second horizontal plate 224, the first wall 211, the fourth wall 214, the second horizontal plate 224 and the second side plate
  • a second containing unit C3 is formed between 222.
  • the magnesium fluoride block 241 is provided in the first containing unit C1 as the basic part of the retarder 231.
  • the magnesium fluoride block 241 contains Li-6 and can be used as a thermal neutron absorber at the same time.
  • the magnesium fluoride block 241 is cylindrical as a whole.
  • a central hole 2411 is provided facing the end surface of the first side plate 221.
  • the central hole 2411 is used to accommodate the transfer pipe 111, the first and second cooling pipes D1, D2 and the target material T.
  • the central hole 2411 is a cylindrical hole.
  • the inner surface of the wall 2411a and the second wall 212 are on the same surface.
  • the radial distance L1 from the second wall 212 to the main axis X is smaller than the radial distance L2 from the third wall 213 to the main axis X, so that the basic part of the retarder 231 surrounds
  • the target material T enables the neutrons generated by the target material T to be effectively slowed down in all directions, which can further improve the neutron flux and beam quality.
  • a lead plate 242 is arranged between the magnesium fluoride block 241 and the third horizontal plate 225. The lead plate 242 serves as a photon shield.
  • the lead can absorb the gamma rays released from the retarder body, and the lead plate 242 is in the neutron beam N direction
  • the thickness is less than or equal to 5cm, and the neutrons passing through the retarder will not be reflected. It is understood that other settings are also possible.
  • the magnesium fluoride block 241 does not contain Li-6, but the magnesium fluoride block 241 and the second A separate thermal neutron absorber composed of Li-6 is arranged between the three horizontal plates 225, and the lead plate can also be eliminated.
  • An aluminum alloy block 243 and a lead block 244 are arranged in the second accommodating unit C2.
  • the aluminum alloy block 243 has surfaces in contact with the second wall 212, the third wall 213, and the first horizontal plate 223, so that the aluminum alloy block 243 serves as a retarder
  • the supplementary part of 231 surrounds the basic part of the retarder 231 provided in the first accommodating unit C1.
  • the aluminum alloy block 243 is used as a supplementary part of the retarder 231, which can reduce the manufacturing cost of the retarder, and at the same time, it will not greatly affect the beam quality.
  • a PE block 245 of corresponding shape is provided in the third accommodating unit C3.
  • the radiation shield 233 includes a neutron shield and a photon shield.
  • the PE block 245 serves as the neutron shield
  • the lead block 244 serves as both the reflector 232 and the photon shield. It can be understood that a PE block can also be provided in the second accommodating unit C2 as a neutron shield.
  • Magnesium fluoride block 241 is made of slices, which is convenient for quality control and the beam intensity can be adjusted by increasing or decreasing the number of slices. As shown in the embodiment in Figure 4, when the magnesium fluoride block 241 is full, the magnesium fluoride block 241 and aluminum The end surface of the alloy block 243 close to the second side plate 222 is flush, and the lead plate 242 is arranged adjacent to the end surface of the magnesium fluoride block 241 close to the second side plate 222 and is in contact with the third horizontal plate 225. When the number of magnesium fluoride blocks 241 is reduced, a positioning ring 226 (as shown in FIG. 5) is provided between the lead plate 242 and the third horizontal plate 225 for corresponding supplementation.
  • the positioning ring 226 can also be provided in the fluorine Between the magnesium block 241 and the lead plate 242, the third horizontal plate 225 serves as a stop ring, and the positioning ring 226 also has a hole 2261 for passing the neutron beam N with the same aperture as the stop ring.
  • the positioning ring 226 of different thicknesses can be set in advance to play the role of positioning the magnesium fluoride block 241.
  • the positioning ring 226 and the stop ring (third horizontal plate 225) are made of carbon fiber, which is a radioactive isotope generated after being activated by neutrons. The half-life is short. It can be understood that the positioning ring and the stop ring can also be replaced with other types of positioning and stop members.
  • the positioning member can conveniently adjust the size of the retarder body, thereby adjusting the neutron beam flux, and the stop member can quickly and conveniently realize the packaging of the retarder body after adjustment.
  • the PE as the neutron shield in this embodiment can be replaced with other neutron shielding materials; the lead as the photon shield can be replaced with other photon shielding materials; the lead as the reflector can be replaced with other neutron reflection capabilities Strong material; magnesium fluoride, which is the basic part of the retarder, can be replaced with other materials with a large fast neutron cross section and a small superthermal neutron cross section; Li-6 as a thermal neutron absorber can be replaced with other materials A material with a large cross-section with thermal neutrons; the aluminum alloy as a supplementary part of the retarder can be replaced with a material including at least one of Zn, Mg, Al, Pb, Ti, La, Zr, Bi, Si, and C, The supplementary part uses easily available materials, which can reduce the manufacturing cost of the retarder, and at the same time has a certain neutron retardation effect, which will not have a greater impact on the beam quality.
  • the frame 21 is further provided with a radial partition 210.
  • the plane on which the radial partition 210 is located extends through the main shaft X, and divides the second containing unit C2 into at least two sub-regions in the circumferential direction.
  • the lead block and the aluminum alloy block arranged in the second containing unit C2 are equally divided into at least two sub-modules in the circumferential direction.
  • the radial partition 210 is arranged between the first side plate 221 and the second horizontal plate 224, and extends from the first wall 211 to the second wall 212 or the third wall 213.
  • the radial partition 210 is 4 There are a number of flat plates evenly distributed along the circumferential direction; it can be understood that there can be other numbers or arrangements, or no radial partitions.
  • the radial partition 210, the first horizontal plate 223 and the first, second, and third walls 211-213 are integrated.
  • the material is aluminum alloy, which has good mechanical properties and The radioisotope produced after being activated by neutrons has a short half-life.
  • the casting process can be used, and the supporting mold is integrally formed.
  • the template is wooden or aluminum mold, and the sand core can be red sand or resin sand.
  • the specific process is a common method in the industry. Since casting will be accompanied by a draft angle, according to the design and beam quality requirements, machining needs to remove them all.
  • the structure and casting process make the frame structure have the advantages of good integrity, high rigidity and high bearing capacity.
  • the sub-frame 21b a carbon fiber composite material is used, and the specific process is a method commonly used in the industry.
  • the radioisotopes produced by aluminum alloy and carbon fiber composite materials activated by neutrons have a short half-life and low radiation. Carbon fiber is used in the beam exit direction. Compared with aluminum alloy, the activation degree is smaller, and the strength is higher, and there is a certain retarding effect.
  • the main frame 21a and the secondary frame 21b are connected by bolts.
  • the first threaded hole is uniformly machined on the end surface of the third wall 213 facing the second side plate 222, and the position corresponding to the first threaded hole on the second horizontal plate 224 is evenly machined.
  • the first through hole is machined, and the bolt passes through the first through hole to connect with the first threaded hole.
  • a second threaded hole is uniformly reserved on the end surface of the third wall 213 facing the second side plate 222, and the second threaded hole is different from the first threaded hole.
  • a second through hole is reserved at the position corresponding to the second threaded hole on the second horizontal plate 224, and the third through hole is machined on the stop ring (the third horizontal plate 225).
  • the through holes correspond, the bolts pass through the third through holes, the second through holes and the second threaded holes in sequence, and the stop ring (third horizontal plate 225) is fixed to the main frame 21a by bolts. It can be understood that the stop ring is also Can be fixed to the subframe.
  • a fourth through hole is machined on the stop ring (third horizontal plate 225). The position of the fourth through hole corresponds to the first through hole, and the hole diameter is slightly larger than the maximum of the head of the connecting bolt between the main frame 21a and the secondary frame 21b. The radial dimension is used to accommodate the bolt head. It is understood that the fourth through hole may also be a blind hole.
  • the aperture of the first through hole is slightly larger than the aperture of the first threaded hole
  • the aperture of the second and third through holes are slightly larger than the aperture of the second threaded hole
  • the first threaded hole, the first through hole and the second threaded hole The number of the two threaded holes, the second through holes, and the third through holes may satisfy the connection strength. It is understandable that the secondary frame, positioning ring and stop ring may not be provided.
  • the first and second side plates 221 and 222 are made of lead-antimony alloy materials. Lead can further shield radiation, and the lead-antimony alloy has higher strength.
  • the first and second side plates 221, 222 and the main frame are connected by bolts, and the third threaded holes are uniformly machined on the inner wall of the main frame 21a facing the first and second side plates.
  • the fourth through hole is uniformly machined at the position corresponding to the third threaded hole on the plates 221, 222. Considering the assembly of the bolt, the hole diameter of the fourth through hole is slightly larger than that of the third threaded hole. The number of through holes only needs to satisfy the connection strength.
  • the materials of the main frame, sub-frame, side plate, positioning ring, and stop ring in this embodiment have a certain strength and the radioisotope produced by neutron activation has a short half-life (such as less than 7 days).
  • the material performance can meet the support beam shaping body, such as aluminum alloy, titanium alloy, lead antimony alloy, cobalt-free steel, carbon fiber, PEEK, polymer, etc.; other connection methods can also be used, as long as the The detachable connection between the bit ring and the frame makes it easy to adjust and replace the basic part of the retarder; the secondary frame and the side plate and the main frame adopt a detachable connection or a non-detachable connection. When the detachable connection is adopted, it is easy to replace the main body. Parts.
  • the frame and main body of the beam shaping body in this embodiment can also have other structures.
  • the collimator 30 is arranged at the back of the beam exit, and the superthermal neutron beam from the collimator 30 irradiates the patient 200, and after passing through the shallow normal tissue, it is slowly turned into thermal neutrons to reach the tumor cell M.
  • the collimator 30 and the sub-frame 21b are fixed by threaded connection, and the fourth wall 214 of the sub-frame 21b forms the mounting part of the collimator 30, and the collimator 30 is close to the beam shaping
  • the end of the body 20 has a flange 31 surrounding the main shaft X.
  • the outer wall of the flange 31 has an external thread (not shown), and the inner wall of the fourth wall 214 is provided with an internal thread (not shown) matching the external thread.
  • the collimator 30 can also be fixed by other connection methods, and the collimator 30 can also be eliminated or replaced by other structures, and the neutron beam exits the beam exit to directly irradiate the patient 200.
  • a radiation shielding device 50 is further provided between the patient 200 and the beam exit to shield the radiation from the beam exit to the normal tissue of the patient. It is understandable that the radiation shielding device 50 may not be provided.
  • the "cylinder” or “cylinder-shaped” in the embodiment of the present invention refers to a structure whose overall trend of the outer contour is basically unchanged from one side to the other side of the direction shown in the figure.
  • One of the outer contours The line can be a line segment, such as a corresponding contour line in a cylindrical shape, or a circular arc close to the line segment with a larger curvature, such as a corresponding contour line in a spherical shape with a larger curvature.
  • the entire surface of the outer contour can be smooth Transitions can also be non-smooth transitions, for example, many protrusions and grooves are made on the surface of a cylinder or a spherical body with a larger curvature.

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Abstract

一种中子捕获治疗系统，能够防止射束整形体(20)材料本身变形损坏，改善中子射源的通量与品质。硼中子捕获治疗系统(100)，包括中子产生装置(10)和射束整形体(20)，中子产生装置(10)包括加速器(11)和靶材(T)，加速器(11)加速产生的带电粒子线(P)与靶材(T)作用产生中子，中子形成中子束(N)，中子束(N)限定一根主轴(X)，射束整形体(20)包括缓速体(231)、反射体(232)和辐射屏蔽体(233)，射束整形体(20)还包括容纳缓速体(231)的框架(21)。

Description

中子捕获治疗系统 技术领域
本发明涉及一种辐射线照射系统，尤其涉及一种中子捕获治疗系统。
背景技术
随着原子科学的发展，例如钴六十、直线加速器、电子射束等放射线治疗已成为癌症治疗的主要手段之一。然而传统光子或电子治疗受到放射线本身物理条件的限制，在杀死肿瘤细胞的同时，也会对射束途径上大量的正常组织造成伤害；另外由于肿瘤细胞对放射线敏感程度的不同，传统放射治疗对于较具抗辐射性的恶性肿瘤(如：多行性胶质母细胞瘤(glioblastoma multiforme)、黑色素细胞瘤(melanoma))的治疗成效往往不佳。
为了减少肿瘤周边正常组织的辐射伤害，化学治疗(chemotherapy)中的标靶治疗概念便被应用于放射线治疗中；而针对高抗辐射性的肿瘤细胞，目前也积极发展具有高相对生物效应(relative biological effectiveness,RBE)的辐射源，如质子治疗、重粒子治疗、中子捕获治疗等。其中，中子捕获治疗便是结合上述两种概念，如硼中子捕获治疗，借由含硼药物在肿瘤细胞的特异性集聚，配合精准的中子射束调控，提供比传统放射线更好的癌症治疗选择。
硼中子捕获治疗(Boron Neutron Capture Therapy,BNCT)是利用含硼( 10B)药物对热中子具有高捕获截面的特性，借由 10B(n,α) 7Li中子捕获及核分裂反应产生 4He和 7Li两个重荷电粒子。参照图1和图2，其分别示出了硼中子捕获反应的示意图和 10B(n,α) 7Li中子捕获核反应方程式，两荷电粒子的平均能量约为2.33MeV，具有高线性转移(Linear Energy Transfer,LET)、短射程特征，α粒子的线性能量转移与射程分别为150keV/μm、8μm，而 7Li重荷粒子则为175keV/μm、5μm，两粒子的总射程约相当于一个细胞大小，因此对于生物体造成的辐射伤害能局限在细胞层级，当含硼药物选择性地聚集在肿瘤细胞中，搭配适当的中子射源，便能在不对正常组织造成太大伤害的前提下，达到局部杀死肿瘤细胞的目的。
因硼中子捕获治疗的成效取决于肿瘤细胞位置含硼药物浓度和热中子数量，故又被称为二元放射线癌症治疗(binary cancer therapy)；由此可知，除了含硼药物的开发，中子射源通量与品质的改善在硼中子捕获治疗的研究中占有重要角色。
因此，有必要提出一种新的技术方案以解决上述问题。
发明内容
为了改善中子射源的通量与品质，本发明的一个方面提供一种中子捕获治疗系统，包括 中子产生装置和射束整形体，所述中子产生装置包括加速器和靶材，所述加速器加速产生的带电粒子线与所述靶材作用产生中子，所述中子形成中子束，所述中子束限定一根主轴，所述射束整形体包括缓速体、反射体和辐射屏蔽体，所述缓速体将自所述靶材产生的中子减速至超热中子能区，所述反射体包围所述缓速体并将偏离所述主轴的中子导回至所述主轴以提高超热中子束强度，所述辐射屏蔽体用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量，所述射束整形体还包括容纳所述缓速体的框架。框架对缓速体形成定位和支撑，能够改善中子射源通量与品质。
进一步地，所述缓速体为可调整的，所述框架包括固定所述缓速体的定位构件和止位构件。优选地，所述定位构件和止位构件的材料被中子活化后产生的放射性同位素半衰期小于7天。优选地，所述定位构件和止位构件的材料为铝合金、钛合金、铅锑合金、不含钴的钢材、碳纤维、PEEK或高分子聚合物。定位构件可以方便地调整缓速体的尺寸，从而调整中子束通量，止位构件在调整完后可以快速、方便地实现缓速体的封装。
进一步地，所述缓速体包括基本部分和补充部分，所述基本部分和补充部分材料不同，所述框架形成至少一个容纳单元，所述容纳单元包括邻接的第一容纳单元和第二容纳单元，所述基本部分容纳在所述第一容纳单元内且为分片式可调整的，当减少所述基本部分的片数时，在所述第一容纳单元内设置所述定位构件进行补充，所述止位构件用于固定所述基本部分。补充部分可以降低缓速体的制造成本，同时，不会对射束品质有较大的影响；定位构件和止位构件可以方便地调整缓速体的基本部分。
进一步地，所述框架包括可拆卸连接的主框架和次框架，所述第一容纳单元由所述主框架的至少一部分包围形成，所述第二容纳单元由所述主框架的至少一部分和所述次框架的至少一部分包围形成，所述补充部分容纳在所述第二容纳单元内，次框架的设置便于更换缓速体的补充部分。优选地，所述主框架的材料为铝合金，具有较好的力学性能且被中子活化后产生的放射性同位素半衰期短；优选地，所述次框架的材料为碳纤维复合材料，被中子活化后产生的放射性同位素半衰期短，带来的辐射低。优选地，所述基本部分的材料包括D 2O、Al、AlF 3、MgF 2、CaF 2、LiF、Li 2CO 3或Al 2O 3中的至少一种，与快中子作用截面大、超热中子作用截面小，具有较好的缓速作用；所述基本部分含Li-6，所述基本部分同时作为所述热中子吸收体。优选地，所述补充部分的材料包括Zn、Mg、Al、Pb、Ti、La、Zr、Bi、C中的至少一种，补充部分选用较易获得的材料，可以降低缓速体的制造成本，同时具有一定的中子缓速作用，不会对射束品质有较大的影响。
进一步地，所述主框架包括沿所述中子束方向依次设置并围绕所述主轴周向封闭的第一 壁、第二壁及连接所述第一壁和第二壁的第一横板，所述第一横板垂直于所述中子束方向延伸，所述第一壁用于安装所述加速器的传输管，所述第二壁包围形成所述第一容纳单元，所述第一壁到所述主轴的径向距离小于所述第二壁到所述主轴的径向距离。缓速体的基本部分包围靶材，使得由靶材产生的中子在各个方向均能被有效缓速，能进一步提升中子通量和射束品质。
进一步地，所述主框架包括围绕所述中子束方向周向封闭的第三壁，所述第二壁到所述主轴的径向距离小于所述第三壁到所述主轴的径向距离，所述框架还包括沿所述中子束方向分别设置在所述第三壁两侧并与第三壁连接的第一、第二侧板，所述次框架包括沿所述中子束方向在所述第二壁和第二侧板之间设置的第二横板。
作为一种优选地，所述次框架还包括围绕所述中子束方向周向封闭并延伸在所述第二横板和第二侧板之间的第四壁，所述中子捕获治疗系统还包括准直器，所述第四壁形成所述准直器的安装部和/或射束出口，在射束出口方向采用碳纤维制成的次框架，相比铝合金，活化程度更小，且强度高，还有一定的缓速作用，次框架同时作为准直器的安装部。所述主框架还包括设置在所述第一侧板和第二横板之间并从所述第一壁延伸到所述第二壁或第三壁的径向隔板，所述第一壁、第二壁、第三壁、第一横板、第二横板和第一侧板包围形成所述第二容纳单元，所述径向隔板将所述第二容纳单元在周向分为若干子区域，所述第三壁、第四壁、第二横板和第二侧板包围形成第三容纳单元，所述第二容纳单元内还设置有所述反射体/辐射屏蔽体的至少一部分，所述第三容纳单元内设置至少部分所述辐射屏蔽体，所述第一、第二侧板的材料为铅锑合金，铅能够起到进一步屏蔽辐射的作用，同时铅锑合金强度较高。
作为另一种优选地，所述基本部分在朝向所述第一侧板的第一端面设置中心孔，所述中心孔用于容纳所述加速器的传输管和靶材，当所述基本部分满装时，所述补充单元靠近所述第二侧板的第一端面与所述基本部分靠近所述第二侧板的第二端面平齐。进一步地，与所述基本部分的第二端面邻接设置屏蔽板，所述屏蔽板为铅板，铅可以吸收缓速体中释放的伽玛射线，所述屏蔽板在所述中子束方向的厚度小于等于5cm，不会反射穿过缓速体的中子；当减少所述基本部分的片数时，邻接所述屏蔽板设置定位构件。所述止位构件邻接所述第二横板设置，所述止位构件可拆卸连接到所述主框架和/或次框架，便于调整和更换缓速体的基本部分。
本发明另一方面提供一种中子捕获治疗系统，包括中子产生装置和射束整形体，所述中子产生装置产生的中子形成中子束，所述中子束限定一根主轴，所述射束整形体能够调整所述中子束的射束品质，所述射束整形体包括缓速体、反射体和辐射屏蔽体，所述缓速体将自 所述中子产生装置产生的中子减速至超热中子能区，所述反射体包围所述缓速体并将偏离所述主轴的中子导回至所述主轴以提高超热中子束强度，所述辐射屏蔽体用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量，所述射束整形体还包括容纳所述缓速体的框架，所述框架包括可拆卸连接的主框架和次框架。框架对缓速体形成定位和支撑，能够改善中子射源通量与品质；主框架和次框架可拆卸连接，便于更换缓速体。
本发明所述的中子捕获治疗系统，其射束整形体的框架对缓速体形成定位和支撑，能够改善中子射源的通量与品质。
附图说明
图1为硼中子捕获反应示意图；
图2为 10B(n,α) 7Li中子捕获核反应方程式；
图3为本发明实施例的中子捕获治疗系统示意图；
图4为本发明实施例的中子捕获治疗系统的射束整形体及准直器的示意图；
图5为图4中的框架的示意图；
图6为图5中的主框架从中子束N方向看过去的示意图；
图7为图5中的主框架从与中子束N方向相反的方向看过去的示意图。
具体实施方式
下面结合附图对本发明做进一步的详细说明，以令本领域技术人员参照说明书文字能够据以实施。
如图3，本实施例中的中子捕获治疗系统优选为硼中子捕获治疗系统100，包括中子产生装置10、射束整形体20、准直器30和治疗台40。中子产生装置10包括加速器11和靶材T，加速器11对带电粒子(如质子、氘核等)进行加速，产生如质子线的带电粒子线P，带电粒子线P照射到靶材T并与靶材T作用产生中子，中子形成中子束N，中子束限定一根主轴X，靶材T优选为金属靶材。图示及下文所述中子束N方向不代表实际的中子运动方向，而是代表中子束N整体运动趋势的方向。依据所需的中子产率与能量、可提供的加速带电粒子能量与电流大小、金属靶材的物化性等特性来挑选合适的核反应，常被讨论的核反应有 7Li(p,n) 7Be及 9Be(p,n) 9B，这两种反应皆为吸热反应。两种核反应的能量阀值分别为1.881MeV和2.055MeV，由于硼中子捕获治疗的理想中子源为keV能量等级的超热中子，理论上若使用能量仅稍高于阀值的质子轰击金属锂靶材，可产生相对低能的中子，不需太多的缓速处理便可用于临床，然而锂金属(Li)和铍金属(Be)两种靶材与阀值能量的质子作用截面不高，为产生足够大的中子通量，通常选用较高能量的质子来引发核反应。理想的靶材应具备高中子产率、产生的中子能量分布接近超热中子能区(将在下文详细描述)、无太多强穿辐射产生、 安全便宜易于操作且耐高温等特性，但实际上并无法找到符合所有要求的核反应。本领域技术人员熟知的，靶材T也可以由Li、Be之外的金属材料制成，例如由Ta或W及其合金等形成。加速器11可以是直线加速器、回旋加速器、同步加速器、同步回旋加速器。
硼中子捕获治疗的中子源产生的为混合辐射场，即射束包含了低能至高能的中子、光子；对于深部肿瘤的硼中子捕获治疗，除了超热中子外，其余的辐射线含量越多，造成正常组织非选择性剂量沉积的比例越大，因此这些会造成不必要剂量的辐射应尽量降低。除了空气射束品质因素，为更了解中子在人体中造成的剂量分布，本发明的实施例中使用人体头部组织假体进行剂量计算，并以假体射束品质因素来作为中子射束的设计参考，将在下文详细描述。
国际原子能机构(IAEA)针对临床硼中子捕获治疗用的中子源，给定了五项空气射束品质因素建议，此五项建议可用于比较不同中子源的优劣，并供以作为挑选中子产生途径、设计射束整形体时的参考依据。这五项建议分别如下：
超热中子射束通量Epithermal neutron flux>1x 10 9n/cm 2s
快中子污染Fast neutron contamination<2x 10 -13Gy-cm 2/n
光子污染Photon contamination<2x 10 -13Gy-cm 2/n
热中子与超热中子通量比值thermal to epithermal neutron flux ratio<0.05
中子电流与通量比值epithermal neutron current to flux ratio>0.7
注：超热中子能区在0.5eV到40keV之间，热中子能区小于0.5eV，快中子能区大于40keV。
1、超热中子射束通量：
中子射束通量和肿瘤中含硼药物浓度共同决定了临床治疗时间。若肿瘤含硼药物浓度够高，对于中子射束通量的要求便可降低；反之，若肿瘤中含硼药物浓度低，则需高通量超热中子来给予肿瘤足够的剂量。IAEA对于超热中子射束通量的要求为每秒每平方厘米的超热中子个数大于10 9，此通量下的中子射束对于目前的含硼药物而言可大致控制治疗时间在一小时内，短治疗时间除了对病人定位和舒适度有优势外，也可较有效利用含硼药物在肿瘤内有限的滞留时间。
2、快中子污染：
由于快中子会造成不必要的正常组织剂量，因此视之为污染，此剂量大小和中子能量呈正相关，因此在中子射束设计上应尽量减少快中子的含量。快中子污染定义为单位超热中子通量伴随的快中子剂量，IAEA对快中子污染的建议为小于2x 10 -13Gy-cm 2/n。
3、光子污染(γ射线污染)：
γ射线属于强穿辐射，会非选择性地造成射束路径上所有组织的剂量沉积，因此降低γ射线含量也是中子束设计的必要要求，γ射线污染定义为单位超热中子通量伴随的γ射线剂量，IAEA对γ射线污染的建议为小于2x 10 -13Gy-cm 2/n。
4、热中子与超热中子通量比值：
由于热中子衰减速度快、穿透能力差，进入人体后大部分能量沉积在皮肤组织，除黑色素细胞瘤等表皮肿瘤需用热中子作为硼中子捕获治疗的中子源外，针对脑瘤等深层肿瘤应降低热中子含量。IAEA对热中子与超热中子通量比值建议为小于0.05。
5、中子电流与通量比值：
中子电流与通量比值代表了射束的方向性，比值越大表示中子射束前向性佳，高前向性的中子束可减少因中子发散造成的周围正常组织剂量，另外也提高了可治疗深度及摆位姿势弹性。IAEA对中子电流与通量比值建议为大于0.7。
利用假体得到组织内的剂量分布，根据正常组织及肿瘤的剂量-深度曲线，推得假体射束品质因素。如下三个参数可用于进行不同中子射束治疗效益的比较。
1、有效治疗深度：
肿瘤剂量等于正常组织最大剂量的深度，在此深度之后的位置，肿瘤细胞得到的剂量小于正常组织最大剂量，即失去了硼中子捕获的优势。此参数代表中子射束的穿透能力，有效治疗深度越大表示可治疗的肿瘤深度越深，单位为cm。
2、有效治疗深度剂量率：
即有效治疗深度的肿瘤剂量率，亦等于正常组织的最大剂量率。因正常组织接收总剂量为影响可给予肿瘤总剂量大小的因素，因此参数影响治疗时间的长短，有效治疗深度剂量率越大表示给予肿瘤一定剂量所需的照射时间越短，单位为cGy/mA-min。
3、有效治疗剂量比：
从大脑表面到有效治疗深度，肿瘤和正常组织接收的平均剂量比值，称之为有效治疗剂量比；平均剂量的计算，可由剂量-深度曲线积分得到。有效治疗剂量比值越大，代表该中子射束的治疗效益越好。
为了使射束整形体在设计上有比较依据，除了五项IAEA建议的空气中射束品质因素和上述的三个参数，本发明实施例中也利用如下的用于评估中子射束剂量表现优劣的参数：
1、照射时间≤30min(加速器使用的质子电流为10mA)
2、30.0RBE-Gy可治疗深度≥7cm
3、肿瘤最大剂量≥60.0RBE-Gy
4、正常脑组织最大剂量≤12.5RBE-Gy
5、皮肤最大剂量≤11.0RBE-Gy
注：RBE(Relative Biological Effectiveness)为相对生物效应，由于光子、中子会造成的生物效应不同，所以如上的剂量项均分别乘上不同组织的相对生物效应以求得等效剂量。
中子产生装置10产生的中子束N依次通过射束整形体20和准直器30照射向治疗台40上的患者200。射束整形体20能够调整中子产生装置10产生的中子束N的射束品质，准直器30用以汇聚中子束N，使中子束N在进行治疗的过程中具有较高的靶向性。射束整形体20进一步包括框架21和主体部23，至少部分主体部23容纳在框架21内，框架21对主体部23形成支撑，防止材料本身变形损坏，影响换靶及射束品质。主体部23包括缓速体231、反射体232和辐射屏蔽体233，中子产生装置10生成的中子由于能谱很广，除了超热中子满足治疗需要以外，需要尽可能的减少其他种类的中子及光子含量以避免对操作人员或患者造成伤害，因此从中子产生装置10出来的中子需要经过缓速体231将其中的快中子能量调整到超热中子能区，缓速体231由与快中子作用截面大、超热中子作用截面小的材料制成，如包括D 2O、Al、AlF 3、MgF 2、CaF 2、LiF、Li 2CO 3或Al 2O 3中的至少一种；反射体232包围缓速体231，并将穿过缓速体231向四周扩散的中子反射回中子束N以提高中子的利用率，由具有中子反射能力强的材料制成，如包括Pb或Ni中的至少一种；辐射屏蔽体233用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量，辐射屏蔽体233的材料包括光子屏蔽材料和中子屏蔽材料中的至少一种，如光子屏蔽材料铅(Pb)和中子屏蔽材料聚乙烯(PE)。可以理解，主体部还可以有其他的构造，只要能够获得治疗所需超热中子束即可。靶材T设置在加速器11和射束整形体20之间，加速器11具有传输带电粒子线P的传输管111，本实施例中，传输管111沿带电粒子线P方向伸入射束整形体20，并依次穿过缓速体231和反射体232，靶材T设置在缓速体231内并位于传输管111的端部，以得到较好的中子射束品质。本实施例中，传输管111与缓速体231和反射体232之间设置第一、第二冷却管D1、D2，第一、第二冷却管D1、D2的一端分别与靶材T的冷却进口(图未示)和冷却出口(图未示)连接，另一端连接到外部冷却源(图未示)。可以理解，第一、第二冷却管还可以以其他方式设置在射束整形体内，当靶材置于射束整形体之外时，还可以取消。
参阅图4和图5，框架21包括围绕主轴X周向封闭的第一壁211和沿中子束N方向分别设置在第一壁211两侧并与第一壁211连接的第一、第二侧板221、222，第一侧板221上设置传输管111穿过的孔2211，第二侧板222上设置形成射束出口的孔2221，第一壁211和第一、第二侧板221、222之间形成缓速体的容纳部C，反射体和/或辐射屏蔽体的至少一部分也设置在容纳部 C内。容纳部C包括至少一个容纳单元C1-C3(下文详述)，每个容纳单元C1-C3容纳缓速体231、反射体232和辐射屏蔽体233中的至少1个，至少一个容纳单元同时容纳缓速体、反射体和辐射屏蔽体中的至少2个或同时容纳至少两种不同的材料，缓速体231包括基本部分和补充部分，基本部分和补充部分分别容纳在不同的容纳单元内。可以理解，也可以不设置第一、第二侧板，由第一壁包围形成容纳部。
框架21还包括沿中子束N方向设置在第一、第二侧板221、222之间的第一横板223，围绕主轴X周向封闭并延伸在第一横板223和第一侧板221之间的第二壁212及围绕主轴X周向封闭并从第一横板223向第二侧板222延伸的第三壁213。第二壁212比第三壁213在径向上更靠近主轴X，第三壁213径向上位于第一壁211和第二壁212之间，第一横板223延伸在第二壁212和第三壁213之间。第二壁212的内表面与第一侧板221上孔2211的侧壁在同一表面上，第二壁212形成传输管111、第一、第二冷却管D1、D2等的安装部。可以理解，第一横板可以延伸到第一壁。
框架21还包括沿中子束N方向在第三壁213和第二侧板222之间设置的第二横板224，围绕主轴X周向封闭并延伸在第二横板224和第二侧板222之间的第四壁214，邻接第二横板224设置在第二横板224和第二侧板222之间的第三横板225。第二横板224从第一壁211延伸到第三壁213的内侧，第四壁214径向上位于第一壁211和第三壁213之间，第四壁214的内表面与第二侧板222上孔2221的侧壁在同一表面上，第四壁214与第二侧板222上的孔2221共同形成射束出口，第三横板225上形成中子束N穿过的孔2251，第三壁213径向上位于第四壁214和第三横板225上的孔2251的内壁之间，第三横板225的外壁位于第四壁214的内表面和第三壁213的内表面之间。
本实施例中，第一、第二、第三、第四壁在垂直于主轴X方向的横截面均为围绕主轴X的圆环并平行于主轴X延伸，侧板、横板均为垂直于主轴X延伸的平板，可以理解，也可以有其他设置，如延伸方向与主轴倾斜；框架还可以包括围绕主轴X周向封闭的多个壁及在壁之间设置的多个横板，还可以用于容纳或支撑射束整形体的其他部分。
在中子束N方向上从第一横板223到第三横板225并由第三壁213包围的区域形成柱体状的第一容纳单元C1，第一壁211、第二壁212、第三壁213、第一侧板221、第一横板223和第二横板224之间形成第二容纳单元C2，第一壁211、第四壁214、第二横板224和第二侧板222之间形成第二容纳单元C3。
第一容纳单元C1内设置氟化镁块241作为缓速体231的基本部分，氟化镁块241含Li-6，可同时作为热中子吸收体，氟化镁块241整体为柱状，其朝向第一侧板221的端面设置中心孔2411， 中心孔2411用于容纳传输管111、第一、第二冷却管D1、D2和靶材T等，中心孔2411为圆柱孔，中心孔的侧壁2411a与第二壁212的内表面在同一表面上，第二壁212到主轴X的径向距离L1小于第三壁213到主轴X的径向距离L2，从而缓速体231的基本部分包围靶材T，使得由靶材T产生的中子在各个方向均能被有效缓速，能进一步提升中子通量和射束品质。在氟化镁块241和第三横板225之间设置铅板242，铅板242作为光子屏蔽体，铅可以吸收缓速体中释放的伽玛射线，同时铅板242在中子束N方向的厚度小于等于5cm，不会反射穿过缓速体的中子，可以理解，也可以有其他的设置，如氟化镁块241不含Li-6，而是在氟化镁块241和第三横板225之间设置单独的Li-6构成的热中子吸收体，铅板也可以取消。
第二容纳单元C2内设置铝合金块243和铅块244，铝合金块243具有与第二壁212、第三壁213、第一横板223接触的面，从而铝合金块243作为缓速体231的补充部分包围设置在第一容纳单元C1内的缓速体231的基本部分。铝合金块243作为缓速体231的补充部分，可以降低缓速体的制造成本，同时，不会对射束品质有较大的影响。第三容纳单元C3内设置相应形状的PE块245。本实施例中辐射屏蔽体233包括中子屏蔽体和光子屏蔽体，PE块245作为中子屏蔽体，铅块244同时作为反射体232和光子屏蔽体。可以理解，第二容纳单元C2内还可以设置PE块作为中子屏蔽体。
氟化镁块241采用分片制作，便于质量控制及通过增减片数来调整射束强度，如图4所示实施例，氟化镁块241满装的时候，氟化镁块241与铝合金块243靠近第二侧板222的端面平齐，铅板242与氟化镁块241靠近第二侧板222的端面邻接设置并与第三横板225接触。当减少氟化镁块241的片数时，在铅板242和第三横板225之间设置定位环226(如图5)进行相应的补充，可以理解，定位环226也可也设置在氟化镁块241和铅板242之间，第三横板225作为止位环，定位环226也具有与止位环相同孔径的用于中子束N通过的孔2261。可预先设置不同厚度的定位环226，以起到定位氟化镁块241的作用，定位环226和止位环(第三横板225)的材料为碳纤维，被中子活化后产生的放射性同位素半衰期较短。可以理解，定位环和止位环还可以替换为其他形式的定位和止位构件。定位构件可以方便地调整缓速体的尺寸，从而调整中子束通量，止位构件在调整完后可以快速、方便地实现缓速体的封装。
可以理解，本实施例中作为中子屏蔽体的PE可以替换为其他中子屏蔽材料；作为光子屏蔽体的铅可以替换为其他光子屏蔽材料；作为反射体的铅可以替换为其它中子反射能力强的材料；作为缓速体基本部分的氟化镁可以替换为其它与快中子作用截面大、超热中子作用截面小的材料；作为热中子吸收体的Li-6可以替换为其它与热中子作用截面大的材料；作为缓速体补充部分的铝合金可以替换为包括Zn、Mg、Al、Pb、Ti、La、Zr、Bi、Si、C中的至少一种的材料，补充部分选用较易获得的材料，可以降低缓速体的制造成本，同时具有一定的中子 缓速作用，不会对射束品质有较大的影响。
参阅图6和图7，框架21还设置有径向隔板210，径向隔板210所在的平面延伸穿过主轴X，将第二容纳单元C2在周向分为至少两个子区域，从而第二容纳单元C2内设置的铅块、铝合金块在周向上均分为至少两个子模块。本实施例中，径向隔板210设置在第一侧板221和第二横板224之间，从第一壁211延伸到第二壁212或第三壁213，径向隔板210为4个沿周向平均分布的平板；可以理解，也可以为其他个数或有其他排布，或不设置径向隔板。
本实施例中，径向隔板210、第一横板223和第一、第二、第三壁211-213是一体的，作为主框架21a，材料为铝合金，具有较好的力学性能且被中子活化后产生的放射性同位素半衰期短。可以采用铸造工艺，支模一体成型，其中模板选取木模或铝模，砂芯可选用红砂或树脂砂，具体工艺选用业内常用的方式。由于铸造会伴有脱模斜度，根据设计及射束品质的要求，机加工需要将其全部去除。该结构形式以及铸造工艺使框架结构具有整体性好，刚度大、承载能力高的优点。考虑到机加工的刀具所限及直角边的应力集中，所有拐角处均倒圆角。也可以是板材卷制焊接或者先锻造出一个铝合金圆柱，然后对该圆柱进行机加工成型。第二横板224和第四壁214是一体的，作为次框架21b，采用碳纤维复合材料，具体工艺选用业内常用的方式。铝合金及碳纤维复合材料被中子活化后产生的放射性同位素半衰期短，带来的辐射低。在射束出口方向采用碳纤维，相比铝合金，活化程度更小，且强度高，还有一定的缓速作用。主框架21a与次框架21b采用螺栓连接，在第三壁213朝向第二侧板222的端面上均匀机加工第一螺纹孔，在第二横板224上与第一螺纹孔对应的位置上均匀机加工第一通孔，螺栓穿过第一通孔与第一螺纹孔连接。考虑到止位环(第三横板225)的安装，在第三壁213上朝向第二侧板222的端面上均匀预留第二螺纹孔，第二螺纹孔与第一螺纹孔位置不同，在第二横板224上与第二螺纹孔对应的位置上预留第二通孔，在止位环(第三横板225)上机加工第三通孔，第三通孔位置与第二通孔对应，螺栓依次穿过第三通孔、第二通孔与第二螺纹孔连接，止位环(第三横板225)即通过螺栓固定到主框架21a，可以理解，止位环也可以固定到次框架。同时在止位环(第三横板225)上机加工第四通孔，第四通孔位置与第一通孔对应，且孔径略大于主框架21a与次框架21b连接螺栓的头部的最大径向尺寸，用于容纳螺栓头部，可以理解，第四通孔也可也是盲孔。考虑到螺栓的装配，第一通孔的孔径略大于第一螺纹孔的孔径，第二、第三通孔的孔径略大于第二螺纹孔的孔径，第一螺纹孔、第一通孔和第二螺纹孔、第二通孔、第三通孔的个数满足连接强度即可。可以理解，也可以不设置次框架、定位环、止位环。
第一、第二侧板221、222为铅锑合金材料，铅能够起到进一步屏蔽辐射的作用，同时铅锑合金强度较高。第一、第二侧板221、222与主框架均采用螺栓连接，在主框架21a内壁朝向 第一、第二侧板的端面上分别均匀机加工第三螺纹孔，在第一、第二侧板221、222上与第三螺纹孔相应的位置上均匀机加工第四通孔，考虑到螺栓的装配，第四通孔的孔径略大于第三螺纹孔的孔径，第三螺纹孔、第四通孔的个数满足连接强度即可。
可以理解，本实施例中主框架、次框架、侧板、定位环、止位环的材料只要具有一定的强度并被中子活化后产生的放射性同位素半衰期短(如小于7天)，主框架的材料性能能够满足支撑射束整形体即可，如铝合金、钛合金、铅锑合金、不含钴的钢材、碳纤维、PEEK、高分子聚合物等；还可以采用其他连接方式，只要保证止位环与框架可拆卸的连接，便于调整和更换缓速体的基本部分；次框架及侧板与主框架之间采用可拆卸连接或不可拆卸的连接，当采用可拆卸连接，便于更换主体部的各个部分。本实施例中射束整形体的框架及主体部还可以有其他的构造方式。
准直器30设置在射束出口后部，从准直器30出来的超热中子束向患者200照射，经浅层正常组织后被缓速为热中子到达肿瘤细胞M。结合图4，本实施例中，准直器30与次框架21b通过螺纹连接进行固定，且次框架21b的第四壁214形成准直器30的安装部，准直器30在靠近射束整形体20的端部具有围绕主轴X的凸缘31，凸缘31外壁具有外螺纹(图未示)，第四壁214的内壁上设置与外螺纹配合的内螺纹(图未示)。可以理解，准直器30还可以通过其他连接方式进行固定，准直器30也可以取消或由其他结构代替，中子束从射束出口出来直接向患者200照射。本实施例中，患者200和射束出口之间还设置了辐射屏蔽装置50，屏蔽从射束出口出来的射束对患者正常组织的辐射，可以理解，也可以不设置辐射屏蔽装置50。
本发明实施例中所述的“柱体”或“柱体状”是指沿着图示方向的一侧到另一侧其外轮廓的整体趋势基本不变的结构，外轮廓的其中一条轮廓线可以是线段，如圆柱体状的对应的轮廓线，也可以是曲率较大的接近线段的圆弧，如曲率较大的球面体状的对应的轮廓线，外轮廓的整个表面可以是圆滑过渡的，也可以是非圆滑过渡的，如在圆柱体状或曲率较大的球面体状的表面做了很多凸起和凹槽。
尽管上面对本发明说明性的具体实施方式进行了描述，以便于本技术领域的技术人员理解本发明，但应该清楚，本发明不限于具体实施方式的范围，对本技术领域的普通技术人员来讲，只要各种变化在所附的权利要求限定和确定的本发明的精神和范围内，这些变化是显而易见的，都在本发明要求保护的范围之内。

Claims (15)

  1. 一种中子捕获治疗系统，包括中子产生装置和射束整形体，所述中子产生装置包括加速器和靶材，所述加速器加速产生的带电粒子线与所述靶材作用产生中子，所述中子形成中子束，所述中子束限定一根主轴，其特征在于，所述射束整形体包括缓速体、反射体和辐射屏蔽体，所述缓速体将自所述靶材产生的中子减速至超热中子能区，所述反射体包围所述缓速体并将偏离所述主轴的中子导回至所述主轴以提高超热中子束强度，所述辐射屏蔽体用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量，所述射束整形体还包括容纳所述缓速体的框架。
  2. 根据权利要求1所述的中子捕获治疗系统，其特征在于，所述缓速体为可调整的，所述框架包括固定所述缓速体的定位构件和止位构件。
  3. 根据权利要求2所述的中子捕获治疗系统，其特征在于，所述定位构件和止位构件的材料被中子活化后产生的放射性同位素半衰期小于7天。
  4. 根据权利要求2所述的中子捕获治疗系统，其特征在于，所述定位构件和止位构件的材料为铝合金、钛合金、铅锑合金、不含钴的钢材、碳纤维、PEEK或高分子聚合物。
  5. 根据权利要求2所述的中子捕获治疗系统，其特征在于，所述缓速体包括基本部分和补充部分，所述基本部分和补充部分材料不同，所述框架形成至少一个容纳单元，所述容纳单元包括邻接的第一容纳单元和第二容纳单元，所述基本部分容纳在所述第一容纳单元内且为分片式可调整的，当减少所述基本部分的片数时，在所述第一容纳单元内设置所述定位构件进行补充，所述止位构件用于固定所述基本部分。
  6. 根据权利要求5所述的中子捕获治疗系统，其特征在于，所述框架包括可拆卸连接的主框架和次框架，所述第一容纳单元由所述主框架的至少一部分包围形成，所述第二容纳单元由所述主框架的至少一部分和所述次框架的至少一部分包围形成，所述补充部分容纳在所述第二容纳单元内。
  7. 根据权利要求6所述的中子捕获治疗系统，其特征在于，所述主框架的材料为铝合金，所述次框架的材料为碳纤维复合材料。
  8. 根据权利要求5所述的中子捕获治疗系统，其特征在于，所述基本部分的材料包括D 2O、Al、AlF 3、MgF 2、CaF 2、LiF、Li 2CO 3或Al 2O 3中的至少一种，所述基本部分含Li-6，所述基本部分同时作为所述热中子吸收体。
  9. 根据权利要求5所述的中子捕获治疗系统，其特征在于，所述补充部分的材料包括Zn、Mg、Al、Pb、Ti、La、Zr、Bi、C中的至少一种。
  10. 根据权利要求6所述的中子捕获治疗系统，其特征在于，所述主框架包括沿所述中子束方向依次设置并围绕所述主轴周向封闭的第一壁、第二壁及连接所述第一壁和第二壁的第一横板，所述第一横板垂直于所述中子束方向延伸，所述第一壁用于安装所述加速器的传输管，所述第二壁包围形成所述第一容纳单元，所述第一壁到所述主轴的径向距离小于所述第二壁到所述主轴的径向距离。
  11. 根据权利要求10所述的中子捕获治疗系统，其特征在于，所述主框架包括围绕所述中子束方向周向封闭的第三壁，所述第二壁到所述主轴的径向距离小于所述第三壁到所述主轴的径向距离，所述框架还包括沿所述中子束方向分别设置在所述第三壁两侧并与第三壁连接的第一、第二侧板，所述次框架包括沿所述中子束方向在所述第二壁和第二侧板之间设置的第二横板。
  12. 根据权利要求11所述的中子捕获治疗系统，其特征在于，所述次框架还包括围绕所述中子束方向周向封闭并延伸在所述第二横板和第二侧板之间的第四壁，所述中子捕获治疗系统还包括准直器，所述第四壁形成所述准直器的安装部和/或射束出口，所述主框架还包括设置在所述第一侧板和第二横板之间并从所述第一壁延伸到所述第二壁或第三壁的径向隔板，所述第一壁、第二壁、第三壁、第一横板、第二横板和第一侧板包围形成所述第二容纳单元，所述径向隔板将所述第二容纳单元在周向分为若干子区域，所述第三壁、第四壁、第二横板和第二侧板包围形成第三容纳单元，所述第二容纳单元内还设置有所述反射体/辐射屏蔽体的至少一部分，所述第三容纳单元内设置至少部分所述辐射屏蔽体，所述第一、第二侧板的材料为铅锑合金。
  13. 根据权利要求11所述的中子捕获治疗系统，其特征在于，所述基本部分在朝向所述第一侧板的第一端面设置中心孔，所述中心孔用于容纳所述加速器的传输管和靶材，当所述基本部分满装时，所述补充单元靠近所述第二侧板的第一端面与所述基本部分靠近所述第二侧板的第二端面平齐。
  14. 根据权利要求13所述的中子捕获治疗系统，其特征在于，与所述基本部分的第二端面邻接设置屏蔽板，所述屏蔽板为铅板，所述屏蔽板在所述中子束方向的厚度小于等于5cm，当减少所述基本部分的片数时，邻接所述屏蔽板 设置所述定位构件，所述止位构件邻接所述第二横板设置，所述止位构件可拆卸连接到所述主框架和/或次框架。
  15. 一种中子捕获治疗系统，包括中子产生装置和射束整形体，所述中子产生装置产生的中子形成中子束，所述中子束限定一根主轴，所述射束整形体能够调整所述中子束的射束品质，其特征在于，所述射束整形体包括缓速体、反射体和辐射屏蔽体，所述缓速体将自所述中子产生装置产生的中子减速至超热中子能区，所述反射体包围所述缓速体并将偏离所述主轴的中子导回至所述主轴以提高超热中子束强度，所述辐射屏蔽体用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量，所述射束整形体还包括容纳所述缓速体的框架，所述框架包括可拆卸连接的主框架和次框架。
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