TWI839257B - Neutron Capture Therapy System - Google Patents

Abstract

The present invention provides a neutron capture therapy system, which can avoid or reduce the leakage of neutrons and other radiations caused by the shielding wall or floor where the components or elements pass through. The neutron capture therapy system of the present invention includes an accelerator, a beam transmission part, a neutron beam generating part and a shielding wall that accommodates the accelerator, the beam transmission part and the neutron beam generating part. A shielding body is provided at the part where the beam transmission part or the neutron beam generating part passes through on the upstream side of the shielding wall in the beam transmission direction. The shielding body is movable and has a first position and a second position. In the aforementioned first position, a receiving hole is formed for the beam transmission part to pass through. In the aforementioned second position, the receiving hole is opened.

Description

Neutron capture therapy system

The present invention relates to a radiation irradiation system, and more particularly to a neutron capture therapy system.

With the development of atomic science, radiation therapy such as cobalt-60, linear accelerator, and electron beam 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 in the beam path. In addition, due to the different sensitivity of tumor cells to radiation, traditional radiotherapy is often not effective for the treatment of malignant tumors that are more resistant to radiation (such as glioblastoma multiforme and melanoma).

In order to reduce radiation damage to normal tissues around tumors, the concept of targeted therapy in chemotherapy has been applied to radiotherapy; and for tumor cells with high radiation resistance, radiation sources with high relative biological effectiveness (RBE) are currently being actively developed, such as proton therapy, heavy particle therapy, and neutron capture therapy. Among them, neutron capture therapy is a combination of the above two concepts, such as boron neutron capture therapy, which provides a better cancer treatment option than traditional radiation by specifically aggregating boron-containing drugs in tumor cells and combining with precise neutron beam control.

Various types of radiation are generated during radiation therapy, such as low-energy to high-energy neutrons and photons generated during boron neutron capture therapy. These radiations may cause varying degrees of damage to normal human tissues. Therefore, in the field of radiation therapy, how to achieve effective treatment while reducing radiation contamination to the external environment, medical staff or normal tissues of patients is an extremely important issue. Radiation therapy equipment is usually installed in a space surrounded by shielding materials. The shielding wall formed by the shielding material cannot provide closed shielding where the components or elements pass through, which can easily cause radiation leakage. A shielding structure is installed where the components or elements pass through to enhance the shielding effect. The auxiliary parts between the enhanced shielding structure and the shielding wall are usually steel structures. When steel is irradiated by neutrons, it will produce radioactive isotopes with a long half-life, such as cobalt 60, forming secondary radiation, which has a negative impact on the environment and radiation safety.

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

In order to solve the above problems, the present invention provides a neutron capture therapy system, including an accelerator, a beam transmission unit, and a neutron beam generation unit. The accelerator accelerates charged particles to generate a charged particle beam. The beam transmission unit transmits the charged particle beam generated by the accelerator to the neutron beam generation unit. The neutron beam generation unit generates a neutron beam for treatment. The neutron capture therapy system also includes a space for accommodating the accelerator, the beam transmission unit, and the neutron beam generation unit. A shielding wall is provided at a portion where the beam transmission unit or the neutron beam generating unit passes through on the upstream side of the shielding wall in the beam transmission direction. The neutron capture therapy system further includes a mounting mechanism or a driving mechanism for the shielding body. The mounting mechanism is used to movably mount the shielding body on the upstream side of the shielding wall in the beam transmission direction. The driving mechanism is used to drive the shielding body to move. The driving mechanism can be manually driven or electrically driven. The shielding body can avoid or reduce the leakage of neutrons and other radiations caused by the shielding wall being passed by components or elements. The mounting mechanism of the shielding body is provided with a first neutron shielding structure or the driving mechanism is provided with a second neutron shielding structure to reduce the secondary radiation generated after the mounting mechanism or the driving mechanism is irradiated by neutrons.

As a preferred embodiment, the mounting mechanism includes a first connector that supports the shielding body, and the first neutron shielding structure shields the exposed portion of the first connector.

Furthermore, the mounting mechanism includes a guide rail and a roller, wherein the guide rail is fixed on the upstream side of the shielding wall in the beam transmission direction, and the roller is fixed on the shielding body, and the shielding body can slide along the guide rail through the roller.

Furthermore, the mounting mechanism includes a frame, the shielding body is a plate fixed to the frame, a connecting plate is fixed to the top of the frame, and the roller is fixed to the connecting plate through a first connecting member. Furthermore, the first connecting member passes through the connecting plate, the roller is mounted on one end of the first connecting member, and the first neutron shielding structure covers the part of the other end of the first connecting member protruding from the connecting plate, or covers the part of the first connecting member between the roller and the connecting plate, or covers the part of the first connecting member that overlaps with the connecting plate and is exposed, or covers the first connecting member and the connecting plate as a whole.

」形或周向封閉的。 As a preferred embodiment, the driving mechanism includes a fixed support and a second connecting member carrying the driving mechanism, the fixed support is fixedly mounted to the shielding wall through the second connecting member, and the second neutron shielding structure includes a baffle for shielding the second connecting member. Further, the baffle is fixed to the fixed support, shielding the second connecting member on the side facing upstream in the beam transmission direction, and can be L-shaped or "

"-shaped or circumferentially closed.

As a preferred embodiment, the driving mechanism includes a cylinder, the cylinder includes a cylinder body, and the second neutron shielding structure includes a collar covering the outer circumference of the cylinder body.

Furthermore, the cylinder body is fixed to the shielding wall, such as through a fixing bracket; the cylinder further includes a piston, one end of which extends into the cylinder body, and the other end of the piston is connected to the shielding body, such as fixedly connected to the shielding body through a connecting rod.

Furthermore, the driving mechanism further includes a transmission component connected to the piston, and the shielding body includes a first shielding part and a second shielding part, and the first shielding part and the second shielding part move in opposite directions under the drive of the cylinder and the transmission component.

Furthermore, the transmission member includes a sprocket and chains located on both sides of the sprocket, and the chains can move around the sprocket; the chains on both sides of the sprocket are respectively connected to the first shielding part and the second shielding part, such as the chains on both sides of the sprocket are respectively fixedly connected to the first and second frames that fix the first shielding part and the second shielding part, and the piston of the cylinder is connected to the first frame or the second frame, and the first shielding part and the second shielding part move in opposite directions under the drive of the piston and the chain.

As a preference, the material of the first and second neutron shielding structures is a boron-containing resin or a boron-containing glass fiber composite.

As a preferred embodiment, the material of the first shielding part and the second shielding part is a neutron shielding material, such as PE containing boron; the material of the first and second frames is a material whose products after neutron irradiation are non-radioactive or whose products after neutron irradiation have low radioactivity or whose radioactive isotopes produced after neutron irradiation have short half-life, such as aluminum alloy.

As a preferred embodiment, the first and second connecting members and the cylinder body are made of steel.

The neutron capture therapy system of the present invention can avoid or reduce the leakage of neutrons and other radiations caused by the shielding wall where the components or elements pass through. The mounting mechanism or driving mechanism of the shielding body includes a neutron shielding structure to avoid secondary radiation after the mounting mechanism or driving mechanism is irradiated by neutrons.

100: Neutron capture therapy system

10: Accelerator

101,101A,101B,101C: Irradiation room

102: Charged particle beam generation chamber

1021: Accelerator Room

1022: Beam transmission room

103: Partition wall

1031: Storage tank

1032: Slot

1033: Shielding plate

20: Beam transmission unit

21,24,25A,25B,25C: Transmission Department

22,23: Beam direction switch

26: Shielding cover

30,30A,30B,30C: Neutron beam generation unit

301: Heat dissipation layer

3011: Cooling channel

3012,3013: Cooling tube

302: Base layer

303: Action layer

304: Antioxidant layer

31: Beam shaping body

311:Reflector

312: Slow Body

313: Thermal neutron absorber

314: Radiation shield

315: beam exit

32: Collimator

40: Treatment table

50: Radiation shielding device

60: Support module

70: First shielding body

70A,70A’: Installation mechanism

70B: Driving mechanism

70C: Neutron shielding structure

703a: First connecting piece

704a:Connector plate

705a:Framework

705a1: First frame

705a2: Second frame

706a: chute

707a:Wheel

701b: Cylinder

702b: Connecting rod

703b:Chain

704b: Sprocket

705b:Connection block

706b: Buffer component

707b: Stop member

708b:Fixed bracket

709b: Second connecting piece

701c: Ring

702c: Cap cover

703c: Ring

703c’: Ring

704c: Baffle

704c’: baffle

705c: hood body

71: Receiving hole

72: First shielding part

721,731: Groove

73: Second shielding part

74,701a:Guide rails

75,702a:Roller

80: Second shielding body

90: The third shielding body

200: Patients

C: Transmission tube

D: Main shielding door

D’: Secondary shielding door

D1,D2,D3,D4,D5,D6,D7: Shielding door

L1, L2: Floor

L1,L2: Direction

L3,L4: Direction

M:Tumor cells

N: Neutron beam

P: Charged particle beam

S: Floor

T: Target

W: Concrete wall

W1: Shielding wall

W2: First partition shielding wall

W3: Second partition shielding wall

W4: The third partition shielding wall

W5: Inner shielding wall

Figure 1 is a schematic diagram of the structure of the neutron capture therapy system in the embodiment of the present invention; Figure 2 is a schematic diagram of the target material structure of the neutron capture therapy system in the embodiment of the present invention; Figure 3 is a schematic diagram of the layout of the neutron capture therapy system in the XY plane in the embodiment of the present invention; Figure 4 is a schematic diagram of the A-A section of Figure 3; Figure 5 is a schematic diagram of the installation of the beam shaping body support module of the neutron capture therapy system in the embodiment of the present invention; Figure 6 is a schematic diagram of the position of the neutron beam generation part of the neutron capture therapy system in the embodiment of the present invention passing through the shielding wall FIG. 7 is a schematic diagram of the shielding body of FIG. 6 in another state; FIG. 8 is a schematic diagram of the shielding body of another embodiment of the present invention, in which the neutron beam generating unit of the neutron capture therapy system passes through the shielding wall; FIG. 9 is a partially enlarged schematic diagram of another state of the mounting mechanism and driving mechanism of the shielding body of FIG. 8; FIG. 10 is a partially enlarged schematic diagram of the mounting mechanism of the shielding body of FIG. 8; and FIG. 11a to 11g are schematic diagrams of the neutron shielding structure of the mounting mechanism and driving mechanism of the shielding body of FIG. 8.

The following is a further detailed description of the embodiments of the present invention in conjunction with the drawings, so that those skilled in the art can refer to the text of the specification and implement it accordingly. Set the direction of the charged particle beam P emitted by the accelerator described later as the X-axis, the direction orthogonal to the direction of the charged particle beam P emitted by the accelerator as the Y-axis, and the direction perpendicular to the ground as the Z-axis as the XYZ coordinate system (refer to Figures 3 and 4), and use X, Y, and Z in the description of the positional relationship of each component.

Referring to FIG. 1 , the neutron capture therapy system in this embodiment is preferably a boron neutron capture therapy system 100. The boron neutron capture therapy system 100 is a device for cancer treatment using boron neutron capture therapy. Boron neutron capture therapy treats cancer by irradiating a patient 200 injected with boron (B-10) with a neutron beam N. After the patient 200 takes or injects a drug containing boron (B-10), the drug containing boron selectively accumulates in tumor cells M. Then, the drug containing boron (B-10) has a high capture cross section for thermal neutrons, and two heavily charged particles, ⁴ He and ⁷ Li, are generated by neutron capture and nuclear fission reaction of ¹⁰ B(n,α) ⁷ Li. The average energy of the two charged particles is about 2.33MeV, with high linear energy transfer (LET) and short range. The linear energy transfer and range of α particles are 150keV/μm and 8μm respectively, while those of ^7Li heavy-charged particles are 175keV/μm and 5μm. The total range of the two particles is approximately equivalent to the size of a cell. Therefore, the radiation damage caused to the organism can be limited to the cellular level, so that the purpose of locally killing tumor cells can be achieved without causing too much damage to normal tissues.

The boron neutron capture therapy system 100 includes an accelerator 10, a beam transmission unit 20, a neutron beam generation unit 30 and a treatment table 40. The accelerator 10 accelerates charged particles (such as protons, deuterons, etc.) to generate a charged particle beam P such as a proton beam; the beam transmission unit 20 transmits the charged particle beam P generated by the accelerator 10 to the neutron beam generation unit 30; the neutron beam generation unit 30 generates a therapeutic neutron beam N and irradiates the patient 200 on the treatment table 40.

The neutron beam generating unit 30 includes a target material T, a beam shaper 31, and a collimator 32. The charged particle beam P generated by the accelerator 10 is irradiated to the target material T through the beam transmission unit 20 and reacts with the target material T to generate neutrons. The generated neutrons pass through the beam shaper 31 and the collimator 32 in turn to form a therapeutic neutron beam N and irradiate the patient 200 on the treatment table 40. The target material T is preferably a metal target material. The appropriate nuclear reaction is selected according to the required neutron yield and energy, the energy and current of the accelerated charged particles that can be provided, the physical and chemical properties of the metal target material, and other characteristics. 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 of keV energy level, theoretically, if protons with energy just slightly higher than the threshold are used to bombard the metal lithium target, relatively low-energy neutrons can be produced, which can be used clinically without much slow processing. However, the cross-sections of lithium metal (Li) and benium metal (Be) targets with protons of the threshold energy are not high. In order to produce a sufficiently large neutron flux, protons with higher energy are usually selected to initiate nuclear reactions. The ideal target material should have high neutron yield, neutron energy distribution close to the epithermal neutron energy region (to be described in detail below), not too much strong penetrating radiation, safe, cheap, easy to operate and high temperature resistance, but in practice it is impossible to find a nuclear reaction that meets all the requirements. It is well known to those skilled in the art that the target material T can also be made of metal materials other than Li and Be, such as Ta or W and their alloys. The accelerator 10 can be a linear accelerator, a cyclotron accelerator, a synchrotron accelerator, or a synchrocyclotron accelerator.

The beam shaper 31 can adjust the beam quality of the neutron beam N generated by the interaction between the charged particle beam P and the target material T. The collimator 32 is used to converge the neutron beam N so that the neutron beam N has a higher targeting during the treatment process. The beam shaper 31 further includes a reflector 311, a retarder 312, a thermal neutron absorber 313, a radiation shield 314 and a beam outlet 315. The neutrons generated by the charged particle beam P interacting with the target material T have a wide energy spectrum. In addition to epithermal neutrons that meet the treatment needs, it is necessary to reduce the content of other types of neutrons and photons as much as possible to avoid causing harm to operators or patients. Therefore, the neutrons from the target material T need to pass through the retarder 312 to adjust the fast neutron energy (>40keV) to the epithermal neutron energy region (0.5eV-40keV) and reduce the thermal neutrons (<0.5eV) as much as possible. The retarder 312 is made of a material with a large cross section for fast neutron interaction and a small cross section for epithermal neutron interaction. In this embodiment, the retarder 312 is made of _D2O , _AlF3 , Fluental ^TM , CaF ₂ , Li ₂ CO ₃ , MgF ₂ and Al ₂ O ₃ ; the reflector 311 surrounds the retarder 312 and reflects the neutrons that pass through the retarder 312 to diffuse around back to the neutron beam N to improve the utilization rate of the neutrons. It is made of a material with strong neutron reflection ability. In this embodiment, the reflector 311 is made of at least one of Pb or Ni; there is a thermal neutron absorber 313 at the rear of the retarder 312, which is made of a material with a large cross-section for interacting with thermal neutrons. In this embodiment, the thermal neutron absorber 313 is made of Li-6. The thermal neutron absorber 313 is used to absorb the neutrons that pass through the retarder 312. Thermal neutrons are absorbed by the neutron beam N to reduce the content of thermal neutrons in the neutron beam N, so as to avoid excessive dose to shallow normal tissues during treatment. It can be understood that the thermal neutron absorber can also be integrated with the retarder, and the material of the retarder contains Li-6; the radiation shielding body 314 is used to shield the neutrons and photons leaked from the part outside the beam outlet 315. The material of the radiation shielding body 314 includes at least one of a photon shielding material and a neutron shielding material. In this embodiment, the material of the radiation shielding body 314 includes a photon shielding material lead (Pb) and a neutron shielding material polyethylene (PE). It is understood that the beam shaping body 31 may have other structures as long as the epithermal neutron beam required for treatment can be obtained. A radiation detection component (not shown) may also be provided in the beam shaping body 31 to detect various radiations in the neutron generation process. The collimator 32 is provided at the rear of the beam outlet 315. The epithermal neutron beam from the collimator 32 irradiates the patient 200. After passing through the shallow normal tissue, it is slowly converted into thermal neutrons to reach the tumor cells M. It is understood that the collimator 32 may also be eliminated or replaced by other structures. The neutron beam from the beam outlet 315 directly irradiates the patient 200. In this embodiment, a radiation shielding device 50 is further provided between the patient 200 and the beam outlet 315 to shield the radiation of the beam exiting the beam outlet 315 from irradiating the normal tissue of the patient. It is understandable that the radiation shielding device 50 may not be provided.

The target material T is arranged between the beam transmission part 20 and the beam shaping body 31. The beam transmission part 20 has a transmission tube C for accelerating or transmitting the charged particle beam P. In this embodiment, the transmission tube C extends into the beam shaping body 31 along the direction of the charged particle beam P, and passes through the reflector 311 and the retardant 312 in sequence. The target material T is arranged in the retardant 312 and is located at the end of the transmission tube C to obtain better neutron beam quality. It can be understood that the target material can have other arrangement methods, and can also be movable relative to the accelerator or the beam shaping body to facilitate target replacement or to make the charged particle beam and the target material act evenly. 2, the target material T includes a heat dissipation layer 301, a base layer 302 and an active layer 303. The active layer 303 interacts with the charged particle beam P to generate a neutron beam, and the base layer 302 supports the active layer 303. In this embodiment, the material of the active layer 303 is Li or its alloy, the charged particle beam P is a proton beam, and the target material T further includes an anti-oxidation layer 304 located on one side of the active layer 303 for preventing oxidation of the active layer. The charged particle beam P passes through the anti-oxidation layer 304, the active layer 303 and the base layer 302 in sequence along the incident direction. The material of the anti-oxidation layer 304 should be not easily corroded by the active layer and can reduce the loss of the incident proton beam and the heat generated by the proton beam, such as at least one of Al, Ti and its alloys or stainless steel. The heat dissipation layer 301 is made of a material with good thermal conductivity (such as at least one of Cu, Fe, and Al) or at least partially uses the same material as the base layer or is integrated. The heat dissipation layer can have a variety of structures, such as a flat plate, which is not described in detail in this embodiment. The heat dissipation layer 301 is provided with a cooling inlet IN (not shown), a cooling outlet OUT (not shown), and a cooling channel 3011 connecting the cooling inlet IN and the cooling outlet OUT. The cooling medium enters from the cooling inlet IN and exits from the cooling outlet OUT through the cooling channel 3011. In this embodiment, the first and second cooling tubes 3012 and 3013 are provided between the transmission tube C and the reflector 311 and the retarders 312. One end of the first and second cooling tubes 3012 and 3013 is connected to the cooling inlet IN and the cooling outlet OUT of the target T, respectively, and the other end is connected to an external cooling source. It can be understood that the first and second cooling tubes can also be provided in the beam shaping body in other ways, and can also be eliminated when the target is placed outside the beam shaping body. 3 and 4 , the boron neutron capture therapy system 100 is configured as a whole in the space of two floors L1 and L2. The boron neutron capture therapy system 100 also includes an irradiation room 101 (101A, 101B, 101C) and a charged particle beam generation room 102. The patient 200 on the treatment table 40 undergoes neutron beam N irradiation treatment in the irradiation room 101 (101A, 101B, 101C). The charged particle beam generation room 102 accommodates an accelerator 10 and at least a portion of the beam transmission unit 20. There may be one or more neutron beam generating units 30 to generate one or more therapeutic neutron beams N. The beam transmitting unit 20 may selectively transmit the charged particle beam P to one or more neutron beam generating units 30 or transmit the charged particle beam P to multiple neutron beam generating units 30 at the same time. Each neutron beam generating unit 30 corresponds to an irradiation chamber 101. In this embodiment, there are three neutron beam generating units and irradiation chambers, namely, neutron beam generating units 30A, 30B, 30C and irradiation chambers 101A, 101B, 101C. The beam transmission unit 20 includes: a first transmission unit 21, which is connected to the accelerator 10; a first and a second beam direction switcher 22, 23, which switches the traveling direction of the charged particle beam P; a second transmission unit 24, which is connected to the first and the second beam direction switcher 22, 23; a third, a fourth, and a fifth transmission unit 25A, 25B, 25C, which transmit the charged particle beam P from the first beam direction switch 22 or the second beam direction switch 23 to the neutron beam generation unit 30A, 30B, 30C, respectively, and the generated neutron beam N is then irradiated to the patients in the irradiation rooms 101A, 101B, 101C, respectively. The third transmission part 25A is connected to the first beam direction switch 22 and the neutron beam generating part 30A, the fourth transmission part 25B is connected to the second beam direction switch 23 and the neutron beam generating part 30B, and the fifth transmission part 25C is connected to the second beam direction switch 23 and the neutron beam generating part 30C. That is, the first transmission part 21 is branched into the second transmission part 24 and the third transmission part 25A in the first beam direction switch 22, and the second transmission part 24 is further branched into the fourth transmission part 25B and the fifth transmission part 25C in the second beam direction switch 23. The first and second transmission parts 21 and 24 transmit along the X-axis direction, the third transmission part 25A transmits along the Z-axis direction, the transmission directions of the fourth and fifth transmission parts 25B and 25C are in the XY plane and are in a "Y" shape with the transmission directions of the first and second transmission parts 21 and 24, the neutron beam generating parts 30A, 30B, 30C and the corresponding irradiation chambers 101A, 101B, 101C are respectively arranged along the transmission directions of the third, fourth, and fifth transmission parts 25A, 25B, 25C, and the direction of the generated neutron beam N is respectively the same as the transmission direction of the third, fourth, and fifth transmission parts 25A, 25B, 25C, so that the directions of the neutron beams generated by the neutron beam generating parts 30B and 30C are in the same plane, and the direction of the neutron beam generated by the neutron beam generating part 30A is perpendicular to the plane. This arrangement allows for efficient use of space, allowing for the simultaneous treatment of multiple patients without excessively extending the beam transmission line, resulting in minimal losses. It can be understood that the direction of the neutron beam N generated by the neutron beam generating section 30A (30B, 30C) and the transmission direction of the third (fourth, fifth) transmission section 25A (25B, 25C) can also be different; the transmission directions of the first and second transmission sections 21, 24 can also be different, and the second transmission section 24 can also be cancelled, with only one beam direction switch to branch the beam into two or more transmission sections; the transmission directions of the fourth and fifth transmission sections 25B, 25C and the transmission direction of the first transmission section 21 form a "Y" shape, which can also be a variation of the "Y", for example, the transmission direction of the fourth transmission section 25B or the fifth transmission section 25C is the same as the transmission direction of the first transmission section 21, and the transmission directions of the fourth and fifth transmission sections 25B, 25C and the transmission direction of the first transmission section 21 can also be different. Other shapes, such as "T" or arrow shape, as long as the transmission directions of the fourth and fifth transmission parts 25B and 25C form an angle greater than 0 degrees in the XY plane; the transmission directions of the fourth and fifth transmission parts 25B and 25C are not limited to the XY plane, and the transmission direction of the third transmission part 25A may not be along the Z axis, as long as the transmission directions of the fourth transmission part 25B, the fifth transmission part 25C and the first transmission part 21 are in the same plane (first plane), the transmission direction of the first transmission part 21 and the transmission direction of the third transmission part 25A are also in the same plane (second plane), and the first plane and the second plane are different; the third transmission part 25A, the neutron beam generation part 30A and the irradiation chamber 101A can also be eliminated, so that only the beam transmission in the XY plane is available.

The first and second beam direction switches 22 and 23 include a deflection electromagnet for deflecting the direction of the charged particle beam P and a switch electromagnet for controlling the direction of travel of the charged particle beam P. The boron neutron capture therapy system 100 may also include a beam collector (not shown) to perform output confirmation of the charged particle beam P before treatment. The first or second beam direction switch 22 and 23 can deviate the charged particle beam P from the regular orbit and guide it to the beam collector.

The first transmission part 21, the second transmission part 24, and the third, fourth, and fifth transmission parts 25A, 25B, and 25C are all constructed by a transmission tube C, and can be formed by connecting a plurality of sub-transmission parts. The transmission directions of the plurality of sub-transmission parts can be the same or different. For example, the beam transmission direction can be deflected by a deflection electromagnet. The transmission direction of the first, second, third, fourth, and fifth transmission parts 21, 24, 25A, 25B, and 25C can be any of the sub-transmission parts. The transmission direction of the transmission part, the first plane and the second plane formed above are planes formed between the sub-transmission parts directly connected to the beam direction switch; they can also include beam adjustment parts (not shown) for the charged particle beam P, respectively, and the beam adjustment parts include a horizontal type deflector and a horizontal vertical type deflector for adjusting the axis of the charged particle beam P, a quadrupole electromagnetic iron for suppressing the divergence of the charged particle beam P, and a four-way cutter for shaping the charged particle beam P. The third, fourth, and fifth transmission parts 25A, 25B, and 25C can include a current monitor (not shown) and a charged particle beam scanning part (not shown) as needed. The current monitor measures the current value (i.e., charge, irradiation dose rate) of the charged particle beam P irradiated to the target T in real time. The charged particle beam scanning unit scans the charged particle beam P and performs irradiation control of the charged particle beam P relative to the target T, such as controlling the irradiation position of the charged particle beam P relative to the target T.

The charged particle beam generation chamber 102 may include an accelerator chamber 1021 and a beam transmission chamber 1022. The accelerator chamber 1021 is two-story, and the accelerator 10 extends from L2 to L1. The beam transmission chamber 1022 is located at L2, and the first transmission unit 21 extends from the accelerator chamber 1021 to the beam transmission chamber 1022. The irradiation chambers 101B and 101C are located at L2, and the irradiation chamber 101A is located at L1. In this embodiment, L1 is below L2, that is, the floor of L2 is the ceiling of L1. It can be understood that the configuration may also be the opposite. The material of the floor (ceiling) S may be concrete or boron barite concrete with a thickness of more than 0.5 m. The irradiation chambers 101A, 101B, 101C and the beam transport chamber 1022 have a shielded space surrounded by a shielding wall W1. The shielding wall W1 may be a boron barite concrete wall with a thickness of more than 1 m and a density of 3 g/cc, including a first partition shielding wall W2 separating the beam transport chamber 1022 from the irradiation chambers 101B and 101C, a second partition shielding wall W3 separating the accelerator chamber 1021 from the beam transport chamber 1022 at L1, and a third partition shielding wall W4 separating the accelerator chamber 1021 from the irradiation chamber 101A at L2. The accelerator chamber 1021 is surrounded by a concrete wall W with a thickness of more than 1 m, the second partition shielding wall W3, and the third partition shielding wall W4. At least a portion of the neutron beam generating parts 30B and 30C are buried in the first partition shielding wall W2, and the fourth and fifth transmission parts 25B and 25C extend from the beam transmission chamber 1022 to the neutron beam generating parts 30B and 30C; the neutron beam generating part 30A is located in the irradiation chamber 101A, and the third transmission part 25A extends from the beam transmission chamber 1022 through the floor S to the irradiation chamber 101A. The irradiation rooms 101A, 101B, and 101C respectively have shielding doors D1, D2, and D3 for the treatment table 40 and the doctors to enter and exit. The accelerator room 1021 has shielding doors D4 and D5 at L1 and L2 respectively for entering and exiting the accelerator room 1021 to maintain the accelerator 10. The beam transmission room 1022 has a shielding door D6 for entering and exiting the beam transmission room 1022 from the accelerator room 1021 to maintain the beam transmission unit 20. The shielding door D6 is provided on the second partition shielding wall W3. The irradiation rooms 101A, 101B, and 101C also have an inner shielding wall W5 to form a maze-like passage from the shielding doors D1, D2, and D3 to the beam exit to prevent direct exposure to radiation when the shielding doors D1, D2, and D3 are accidentally opened. The inner shielding wall W5 can be set at different positions according to the different layouts of the irradiation rooms. A shielding door D7 inside the irradiation room can also be set between the inner shielding wall W5 and the shielding wall W1 or the third partition shielding wall W4 to form secondary protection during neutron beam irradiation therapy. The inner shielding wall W5 can be made of boron-containing barite concrete with a thickness of more than 0.5m and a density of 3g/c.c.; the shielding doors D1, D2, D3, D4, D5, D6, and D7 can be composed of two layers of independent main shielding doors D and secondary shielding doors D’, or only composed of main shielding doors D or secondary shielding doors D’, which can be determined according to actual circumstances. The main shielding door D can be boron-containing PE or barite concrete or lead with a thickness of more than 0.5m and a density of 6g/c.c. of the same material, and the secondary shielding door D’ can be boron-containing PE or barite concrete or lead with a thickness of more than 0.2m and a density of 6g/c.c. of the same material. In this embodiment, the shielding doors D1, D4, D5, and D6 are composed of a main shielding door D and a secondary shielding door D'. The shielding doors D1, D2, and D3 only include the main shielding door D, and the shielding door D7 only includes the secondary shielding door D'. The shielding walls and shielding doors form a shielding space to suppress the radiation from entering the irradiation room 101A, 101B, 101C and the beam transmission room 1022 from the outside and the radiation from the inside to the outside. In this embodiment, the second partition shielding wall W3 separating the accelerator chamber 1021 and the beam transmission chamber 1022 is set between the accelerator 10 and the first beam direction switch 22, that is, the first transmission part 21 passes through the second partition shielding wall W3. It can be understood that the second partition shielding wall W3 and the shielding door D6 can be cancelled or set at other positions, such as between the first and second beam direction switches 22 and 23 or between the second beam direction switch 23 and the neutron beam generating part 30B and 30C; or an additional partition shielding wall and shielding door are set between the second partition shielding wall W3 and the first partition shielding wall W2. In other words, a shielding wall is set between the neutron beam generating part and the accelerator to protect the operator from neutrons and other radiation leaked from the neutron beam generating part during the inspection and maintenance of the accelerator, and at the same time reduce the reaction of the accelerator to be activated by neutrons.

5, the beam shaping body 31 is supported by the support module 60 disposed in the partition wall 103 (first partition shielding wall W2), and a receiving groove 1031 for at least partially receiving the support module 60 is disposed on the side of the partition wall 103 close to the irradiation chamber 101, and a groove 1032 for the transmission tube of the accelerator to pass through is disposed on the side close to the charged particle beam generation chamber 102, so that the receiving groove 1031 and the groove 1032 pass through the partition wall in the transmission direction of the neutron beam N. In this embodiment, the wall surface of the partition wall 103 is a plane, and the transmission direction of the neutron beam N is perpendicular to the wall surface of the partition wall 103. The modular support structure allows the beam shaping body to be locally adjusted to meet the accuracy requirements, improve the beam quality and meet the assembly tolerance of the target. On a plane perpendicular to the transmission direction of the neutron beam N, the cross-sectional profile of the support module 60 is located between the cross-sectional profiles of the receiving groove 1031 and the groove 1032, thereby avoiding the occurrence of a through gap in the beam transmission direction, further reducing radiation, and facilitating the adjustment of the support module 60. In this embodiment, the support module 60 is a rectangular parallelepiped as a whole, and the cross-sectional profiles of the receiving groove 1031 and the groove 1032 perpendicular to the transmission direction of the neutron beam N are both "冂" shaped, and the side walls of the receiving groove 1031 and the groove 1032 are parallel to the transmission direction of the neutron beam N. A shielding plate 1033 is also provided on the side of the partition wall 103 close to the irradiation chamber 101, and the shielding plate 1033 can enhance the shielding effect of the partition wall, suppress the secondary radiation generated by the partition wall, and thus avoid radiation to the normal tissues of the patient. On a plane perpendicular to the transmission direction of the neutron beam N, the shielding plate 1033 can match the cross-sectional profile of the support module 60, thereby shielding the neutrons leaking from the support module and the partition wall. The shielding plate is a PE plate. It can be understood that a shielding plate can also be set on the side of the partition wall 103 close to the charged particle beam generation chamber 102 and the side of the support module 60 close to the irradiation chamber 101. The shielding plate can be made of other neutron or photon shielding materials such as lead, or a shielding plate may not be set.

The emission directions of neutrons generated by the interaction between the charged particle beam P and the target material T are almost uniformly distributed in space. At the same time, a large number of recoil neutrons will be generated during the process of "shaping" the neutrons by the beam shaper 31. These recoil neutrons are the key considerations in the radiation shielding design. In places where the shielding wall or floor is passed by components or elements, closed shielding cannot be achieved, which easily causes leakage of neutrons and other radiation. For example, in this embodiment, the neutron beam generating parts 30B and 30C pass through the first partition shielding wall W2, the first transmission part 21 passes through the second partition shielding wall W3, and the third transmission part 25A passes through the floor S. The first shielding body 70, the second shielding body 80, and the third shielding body 90 can be respectively set at the part where the neutron beam generating parts 30B and 30C, the first transmission part 21, and the third transmission part 25A pass through the first partition shielding wall W2, the second partition shielding wall W3, and the floor S on the upstream side of the beam transmission direction. The first shielding body 70 covers the ends of the neutron beam generating parts 30B and 30C facing the accelerator, and prevents the neutrons overflowing or reflected from the beam shaping bodies of the neutron beam generating parts 30B and 30C from entering the accelerator room 1021 and the beam transmission room 1022. The fourth and fifth transmission parts 25B and 25C pass through the first shielding body 70 to reach the target material T of the neutron beam generating parts 30B and 30C. The second shielding body 80 prevents the neutrons overflowing or reflected from the beam transmission part 20 from entering the accelerator room 1021. The first transmission part 21 passes through the second shielding body 80 and the second partition shielding wall W3 to reach the first beam direction switcher 22. The third shielding body 90 prevents the neutrons overflowing or reflected from the irradiation room 101A from entering the beam transmission room 1022. The third transmission part 25A passes through the third shielding body 90 and the floor S to reach the neutron beam generating part 30A. The materials of the first shield 70, the second shield 80 and the third shield 90 can be boron-containing PE or barite concrete or lead, and can also include other neutron shielding materials.

The first, second and third shielding bodies 70, 80 and 90 are described in detail below, taking the first shielding body 70 as an example. In one embodiment, the first shielding body 70 is movable, and is movably mounted on the upstream side of the first partition shielding wall W2 in the beam transmission direction (the side close to the charged particle beam generating chamber 102) through the mounting mechanism 70A, and has a first position and a second position. In the first position, the receiving hole 71 is formed for the fourth and fifth transmission parts 25B and 25C to pass through, and covers the ends of the neutron beam generating parts 30B and 30C facing the accelerator 10, shielding the reflected neutrons, limiting the high neutron dose area, protecting the accelerator components, reducing the radiation damage of the components, reducing the element activation of the accelerator components, and at the same time, when one irradiation room is in operation, protecting the other irradiation room to ensure that the radiation dose of the non-operating irradiation room is at a safe level; in the second position, the receiving hole 71 is opened, exposing the neutron beam generating parts 30B and 30C. The end of the accelerator 10 is formed with a hole 30C facing the accelerator 10, and an operating space is formed without removing the transmission tube C passing through the receiving hole 71. When the accelerator 10 is closed, the neutron beam generating parts 30B and 30C, such as the target material T, the beam shaping body 31, the radiation detection assembly arranged in the beam shaping body 31, or the first and second cooling tubes 3012 and 3013 can be replaced. It can also make room for the removal of some transmission tubes during replacement, or install, debug, and repair the beam transmission part 20 passing through the first partition shielding wall W2 and the first shielding body 70. The receiving hole can accommodate the transmission tube C, magnets, etc. of the fourth and fifth transmission parts 25B and 25C, and can also accommodate the first and second cooling tubes 3012 and 3013 or other functional components, which can facilitate movement and provide operating space without interfering with the non-movable components of the beam transmission part. The first shielding body 70 and the first separating shielding wall W2 can be in close contact to enhance the shielding effect, or there can be a gap between them. The shielding effect can be achieved by adjusting the size of the first shielding body 70.

As shown in FIGS. 6 and 7 , in this embodiment, the first shielding body 70 includes a first shielding portion 72 and a second shielding portion 73. The first shielding portion 72 and the second shielding portion 73 move to a first position along a first direction L1 and a second direction L2 close to the neutron beam generating portion 30B and 30C, respectively. The first shielding portion 72 and the second shielding portion 73 have a first groove 721 and a second groove 731, respectively. The first groove 721 and the second groove 731 jointly form the fourth and fifth transmission portions 2 at the first position. 5B, 25C pass through the receiving hole 71, and cover the end of the neutron beam generating part 30B, 30C facing the accelerator 10; the first shielding part 72 and the second shielding part 73 move to the second position along the third and fourth directions L3, L4 away from the neutron beam generating part 30B, 30C, respectively. In the second position, the receiving hole 71 is opened to expose the end of the neutron beam generating part 30B, 30C facing the accelerator 10, and the operating space is formed without removing the transmission tube C passing through the receiving hole 71. It can be understood that the first shielding body 70 can also include a third shielding part or be composed of more than three shielding parts.

In this embodiment, the first shielding part 72 and the second shielding part 73 are sliding, and the guide rail 74 and the roller 75 fixed on the first and second shielding parts 72 and 73 constitute the sliding assembly (mounting mechanism 70A) of the first shielding body 70. The roller 75 rolls along the guide rail 74 to drive the first and second shielding parts 72 and 73 to slide along the guide rail 74. The guide rail 74 is fixed on the side of the first partition shielding wall W2 facing the charged particle beam generation chamber 102 and the extension direction is parallel to the ground (XY plane), that is, the first and second shielding parts 72 and 73 are constructed as horizontal double-opening sliding doors. It can be understood that the mounting mechanism 70A can have other settings, or it can be moved by other means, such as rotation.

As shown in FIG8, in another embodiment, the mounting mechanism 70A' includes a guide rail 701a (74') and a roller 702a (75'), and the guide rail 701a is directly fixed to the first partition shielding wall W2 through expansion screws. In combination with FIG9 and FIG11b, the roller 702a is connected to the connecting plate 704a fixed to the first and second shielding parts 72 and 73 through a first connecting member 703a (such as bolts and nuts). Specifically, the roller 702a is rotatably arranged around its center axis at one end of the bolt (such as through a bearing), and the other end of the bolt passes through the connecting plate 704a and is tightened on both sides of the connecting plate 704a through nuts. It can be understood that the guide rail 701a and the roller 702a can also have other fixing methods. The mounting mechanism 70A' further includes a frame, which includes a first frame 705a1 and a second frame 705a2 for fixing the first and second shielding parts 72 and 73 (wherein the second frame has the same structure and function as the first frame, which is not shown in the figure). The first and second shielding parts 72 and 73 are both constructed of multiple plates, which are spliced and fixed to the first frame 705a1 and the second frame 705a2 of the first and second shielding parts 72 and 73, respectively. The connecting plate 704a is fixed to the top of the frame to form a hanging rail. In conjunction with Figure 10, a slide groove 706a can also be fixed at the bottom of the frame. The slide groove 706a cooperates with the wheel 707a fixed to the shielding wall W2 to form an auxiliary limit for the horizontal sliding of the first and second shielding parts 72 and 73 along the guide rail 701a, preventing the first and second shielding parts 72 and 73 and their first frame 705a1 and second frame 705a2 from turning over in a direction perpendicular to the shielding wall W2. The frame is made of aluminum alloy profiles, and the radioactive half-life of the product after neutron irradiation is short, which reduces the secondary radiation generated. The first and second shielding parts 72 and 73 are boron-containing PE plates. It can be understood that the frame can also use other materials whose products after neutron irradiation are not radioactive or whose products after neutron irradiation have low radioactive activity or whose radioactive isotopes produced after neutron irradiation have short half-life. The first and second shielding parts 72 and 73 can also use other neutron shielding materials.

The neutron capture therapy system 100 may further include a driving mechanism 70B of the first shielding body 70, wherein the driving mechanism 70B drives the movement of the first shielding body 70, and the driving mechanism 70B includes a cylinder 701b, a connecting rod 702b, a chain 703b, a sprocket 704b, and a connecting block 705b. The cylinder 701b is supplied with air through an air supply device (not shown) to drive the piston of the cylinder 701b to move. The piston of the cylinder 701b is connected to the first frame 705a1 of the first shielding part 72 through the connecting rod 702b, thereby driving the first shielding part 72 to move. Specifically, the piston moves in the horizontal direction, and one end of the piston of the cylinder 701b extends into the cylinder body of the cylinder 701b, and the other end is connected to the connecting rod 702b. The connecting rod 702b is fixed to the first frame 705a1 of the first shielding part 72 away from the first shielding part 72. The side of the second shielding part 73; the chain 703b is located on both sides of the sprocket 704b and is connected to the first frame 705a1 and the second frame 705a2 of the first and second shielding parts 72 and 73 respectively through the connecting block 705b. The movement of the first shielding part 72 drives the second shielding part 73 to move in the opposite direction through the chain 703b, thereby reaching the first position or the second position. Specifically, one end of the connecting block 705b is fixed to the top of the frame 705a, and the other end is engaged with the chain 703b through teeth. It can be understood that in this embodiment, the connecting rod 702b, the chain 703b, the sprocket 704b, and the connecting block 705b constitute the transmission component of the drive mechanism 70B, and the transmission component is connected to the piston of the cylinder 701b. It can be understood that the transmission component can also have other settings; a buffer component 706b can also be provided, and the first shielding part 72 is about to move to the end in a direction away from the second shielding part 73. When the first shielding part 72 is in the position of the first shielding part 73, the connecting rod 702b contacts the buffer member 706b to prevent impact caused by collision; a stop member 707b (such as a fixed screw) can also be provided, and the stop member 707b and the connecting rod 702b act to limit the maximum distance of the first shielding part 72 moving away from the second shielding part 73; there can also be other driving methods, such as driving the first or second shielding part to move by a motor. The driving mechanism 70B also includes a fixed bracket 708b, which is fixed to the shielding wall W2 through a second connecting member 709b (as shown in Figure 11d), and other parts of the driving mechanism 70B (such as the cylinder body of the cylinder 701b, the sprocket 704b, the buffer member 706b, and the stop member 707b) can be fixed on the fixed bracket 708b.

The neutron capture therapy system 100 can also control the operation of the driving mechanism 70B through a control mechanism (not shown) to control the movement of the first shield 70. The control mechanism can be set outside the charged particle beam generation chamber 102, such as in a control room (described below), to prevent the control mechanism from being activated by neutrons and becoming ineffective.

形，在框架705a上方包圍連接板704a和穿過連接板704a的第一連接件703a，可以理解，罩體705c還可以包括頂部，中子屏蔽結構所覆蓋的面積越大，對安裝機構在中子輻射後的二次輻射屏蔽效果越好。 The components of the mounting mechanism 70A, 70A' or the driving mechanism 70B can be made of materials whose products after neutron irradiation are non-radioactive or whose products after neutron irradiation have low radioactive activity or whose radioactive isotopes after neutron irradiation have short half-life, such as aluminum alloy. However, due to the requirements of mechanical performance, some components in this embodiment are still made of steel, such as the components that bear the driving force (such as the cylinder body of the cylinder 701b), the connecting parts that bear the first shielding body 70 (the first connecting parts 703a), and the connecting parts that bear the driving mechanism 70B (the second connecting parts 709b). After being irradiated by neutrons, steel will produce radioactive isotopes with long half-life, such as cobalt 60, and a neutron shielding structure 70C needs to be set to shield them, so as to reduce the secondary radiation generated after the mounting mechanism or the driving mechanism is irradiated by neutrons. As shown in FIG11a, a collar 701c is provided on the outer periphery of the cylinder body of the cylinder 701b. As shown in FIG11b, a cap 702c is provided on the outside of the first connecting member 703a, and the cap 702c covers the portion of the first connecting member 703a protruding from the connecting plate 704a at one end passing through the connecting plate 704a (the end of the nut and the bolt passing through the connecting plate 704a); the collar 703c may also be provided to cover other exposed portions of the first connecting member 703a, such as the portion where the bolt passes through the connecting plate 704a. The portion between the two side plates of the connecting plate 704a (the portion where the first connecting member overlaps with the connecting plate and is exposed), and the portion between the roller 702a and the connecting plate 704a. It can be understood that due to space limitations, the portion where the bolt passes through the connecting plate 704a and is located between the two side plates of the connecting plate 704a, as shown in FIG11c, can also be covered by a collar 703c' from the outside of the connecting plate 704a to cover the bolt. As shown in the Z-direction schematic diagram of FIG11d, without affecting the connection relationship of the mechanism, a cover body 705c can be integrally covered outside the connecting plate 704a to cover the connecting plate 704a and the first connecting member 703a passing through the connecting plate 704a as a whole. The cover body 705c can be

The cover 705c is shaped to surround the connecting plate 704a and the first connecting member 703a passing through the connecting plate 704a above the frame 705a. It can be understood that the cover body 705c can also include a top. The larger the area covered by the neutron shielding structure, the better the secondary radiation shielding effect of the installation mechanism after neutron radiation.

”形，在第二連接件709b的上側、下側和朝向射束傳輸方向上游的一側(靠近帶電粒子束生成室102的一側)對反衝中子進行遮擋。可以理解，擋板704c和704c’還可以包括側部以形成周向封閉，增強輻射屏蔽效果，如圖11g所示，擋板704c’還對第二連接件709b進行了側部包覆。 As shown in FIG. 11e, a baffle 704c is arranged outside the second connecting member 709b, and the baffle 704c is fixed on the fixing bracket 708b. In this embodiment, the baffle 704c is L-shaped, and shields the backwash neutrons at the lower side of the second connecting member 709b and the side facing the upstream of the beam transmission direction (the side close to the charged particle beam generation chamber 102). In another embodiment, as shown in FIG. 11f, the baffle 704c' is "

"-shaped, shielding the back-impact neutrons at the upper side, the lower side and the side facing upstream in the beam transmission direction (the side close to the charged particle beam generating chamber 102) of the second connecting piece 709b. It can be understood that the baffles 704c and 704c' can also include side portions to form a circumferential closure to enhance the radiation shielding effect. As shown in FIG. 11g, the baffle 704c' also covers the side of the second connecting piece 709b.

The material of the neutron shielding structure 70C may include boron-containing resin, boron-containing glass fiber composite material, etc. It can be understood that the form and position of the neutron shielding structure 70C can also be set according to specific needs.

The first and second beam direction switches 22 and 23 are respectively surrounded by a shielding cover 26 to prevent neutrons and other radiation from leaking from the beam direction switch. The material of the shielding cover 26 can be boron-containing PE or barite concrete or lead. It can be understood that the first and second beam direction switches 22 and 23 can also be surrounded by a shielding cover 26 as a whole; other parts of the beam transmission part, such as the vacuum tube, can also be surrounded by a shielding cover to prevent neutrons and other radiation from leaking from the beam transmission part.

The boron neutron capture therapy system 100 may also include a preparation room, a control room and other spaces for auxiliary treatment. Each irradiation room may be equipped with a preparation room for preparatory work such as fixing the patient to the treatment table, injecting boron medicine, and simulating the treatment plan before irradiation treatment. A connecting passage is set between the preparation room and the irradiation room. After the preparation work is completed, the patient is directly pushed into the irradiation room or automatically enters the irradiation room through the track controlled by the control mechanism. The preparation room and the connecting passage are also closed by a shielding wall, and the preparation room also has a shielding door. The control room is used to control the accelerator, beam transmission unit, treatment table, etc., to control and manage the entire irradiation process. The management personnel can also monitor multiple irradiation rooms at the same time in the control room.

It can be understood that the shielding wall (including the concrete wall W), shielding door, shielding body, and shielding cover in this embodiment can have other thicknesses or densities or be replaced with other materials.

Although the above describes the illustrative specific implementation of the present invention 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 implementation. For those skilled in the art, as long as the various changes are within the spirit and scope of the present invention defined and determined by the attached patent application, these changes are obvious and are within the scope of protection claimed by the present invention.

100: Neutron capture therapy system

10: Accelerator

20: Beam transmission unit

30: Neutron beam generation unit

3012,3013: Cooling tube

31: Beam shaping body

311:Reflector

312: Slow Body

313: Thermal neutron absorber

314: Radiation shield

315: beam exit

32: Collimator

40: Treatment table

50: Radiation shielding device

200: Patients

C: Transmission tube

M:Tumor cells

N: Neutron beam

P: Charged particle beam

T: Target

Claims (10)

A neutron capture therapy system includes an accelerator, a beam transmission unit, and a neutron beam generation unit. The accelerator accelerates charged particles to generate a charged particle beam. The beam transmission unit transmits the charged particle beam generated by the accelerator to the neutron beam generation unit. The neutron beam generation unit generates a therapeutic neutron beam. The neutron capture therapy system further includes a shielding wall that forms a space for accommodating the accelerator, the beam transmission unit, and the neutron beam generation unit. A shielding body is provided on the upstream side of the shielding wall in the beam transmission direction at a position where the beam transmission unit or the neutron beam generation unit passes through. The shielding body is movable and has a first position and a second position. At the first position, a receiving hole is formed for the beam transmission unit to pass through. At the second position, the receiving hole is open. A neutron capture therapy system as described in claim 1, wherein the neutron capture therapy system further comprises a charged particle beam generation chamber and an irradiation chamber, the charged particle beam generation chamber accommodates the accelerator and at least part of the beam transmission unit, the patient undergoes neutron beam irradiation therapy in the irradiation chamber, the shielding wall comprises a partition wall between the irradiation chamber and the charged particle beam generation chamber, at least a part of the neutron beam generation unit is embedded in the partition wall, in the first position, the end of the neutron beam generation unit facing the accelerator is covered, and in the second position, the end of the neutron beam generation unit facing the accelerator is at least partially exposed. The neutron capture therapy system as described in claim 2, wherein the beam transmission unit includes a first transmission unit connected to the accelerator, a beam switch for switching the traveling direction of the charged particle beam, and a second transmission unit for transmitting the charged particle beam to the neutron beam generating unit, the second transmission unit passes through the shielding body to reach the neutron beam generating unit, and the receiving hole receives the second transmission unit. The neutron capture therapy system as described in claim 2, wherein a receiving groove for at least partially receiving the neutron beam generating unit and a supporting module for supporting the neutron beam generating unit is provided on one side of the partition wall close to the irradiation chamber, and a groove for the beam transmission unit to pass through is provided on one side close to the charged particle beam generating chamber, the receiving groove and the groove pass through the partition wall in the neutron beam transmission direction, and on a plane perpendicular to the neutron beam transmission direction, the cross-sectional profile of the neutron beam generating unit and its supporting module is located between the cross-sectional profiles of the receiving groove and the groove. The neutron capture therapy system as described in claim 1, wherein the shielding body comprises a first shielding part and a second shielding part, the first shielding part and the second shielding part respectively move to the first position along the first and second directions close to the neutron beam generating part, the first shielding part and the second shielding part respectively have a first and a second groove, and the first and the second grooves jointly form the receiving hole at the first position. A neutron capture therapy system as described in claim 5, wherein the first shielding part and the second shielding part slide along a guide rail, and the guide rail is fixed on the upstream side of the shielding wall in the beam transmission direction and extends in a direction parallel to the ground. The neutron capture therapy system as described in claim 5, wherein the material of the first shielding part and the second shielding part is a neutron shielding material, and the neutron shielding material is boron-containing PE or barite concrete or lead. The neutron capture therapy system as described in claim 1, wherein the neutron capture therapy system further includes a mounting mechanism or a driving mechanism for a shielding body, wherein the mounting mechanism is used to movably mount the shielding body on the upstream side of the shielding wall in the beam transmission direction, and the driving mechanism is used to drive the shielding body to move. A neutron capture therapy system as described in claim 8, wherein the aforementioned mounting mechanism includes a guide rail and a roller, the guide rail is fixed to the upstream side of the aforementioned shielding wall in the beam transmission direction, the roller is fixed to the aforementioned shielding body, and the aforementioned shielding body moves along the guide rail through the roller. The neutron capture therapy system as described in claim 8, wherein the aforementioned driving mechanism includes a cylinder, the aforementioned cylinder includes a cylinder body and a piston, one end of the aforementioned piston extends into the cylinder body, and the other end is connected to the aforementioned shielding body.

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