Neutron capture therapy system

Abstract

Radiation risks to workers may be high. [Solution] A neutron capture therapy system (100) includes an accelerator (200) for generating a charged particle beam (P), a neutron generator (10) that reacts with the charged particle beam (P) to generate a neutron beam (N), and a beam shaper (20). The beam shaper (20) includes a housing (21), a moderator (22), a reflector (23), a thermal neutron absorber (24), a radiation shield (25), and a beam outlet (26). The housing (21) is provided with a vacuum tube (30) connected to the accelerator (200). The vacuum tube (30) transfers the charged particle beam (P) accelerated by the accelerator (200) to the neutron generator, which can react with the charged particle beam (P) to generate neutrons. The neutron generator (10) moves between a first position and a second position. At the first position, the neutron generator (10) can react with the charged particle beam (P) to generate neutrons. At the second position, the neutron generator (10) detaches from the beam shaper (20).

Description

[Technical Field]

[0001] This invention relates to a radiotherapy system, and more particularly to a neutron capture therapy system. [Background technology]

[0002] With the advancement of atomic science, radiotherapy using cobalt-60, linear accelerators, and electron beams has already become one of the main methods of cancer treatment. However, conventional photon or electron therapy, while killing tumor cells due to the physical limitations of the radiation itself, also damages numerous normal tissues along the beam path. Furthermore, different tumor cells have varying degrees of sensitivity to radiation, and conventional radiotherapy is ineffective against highly radiation-resistant malignant tumors (e.g., glioblastoma multiforme, melanoma).

[0003] To mitigate radiation damage to surrounding normal tissues, targeted therapies in chemotherapy are being used in radiotherapy. Furthermore, for highly radiation-resistant tumor cells, radiation sources with high relative biological effectiveness (RBE) are currently being actively developed (e.g., proton therapy, heavy ion therapy, neutron capture therapy). Neutron capture therapy combines these two concepts. For example, in boron neutron capture therapy, boron-containing drugs specifically accumulate in tumor cells, and combined with highly precise control of the neutron beam, it provides a better cancer treatment option compared to conventional radiation therapy. [Overview of the project] [Problems that the invention aims to solve]

[0004] In accelerator neutron capture therapy systems, a charged particle beam is accelerated by an accelerator to an energy level that can overcome the nuclear force of the target, and then reacts with the neutron generator to produce neutrons. If the neutron generator is irradiated with a high-power accelerated charged particle beam during the neutron generation process, its temperature rises significantly, affecting its lifespan and necessitating its replacement. However, a neutron generator irradiated with a high-energy accelerated charged particle beam inevitably contains a large amount of radiation, and therefore there is always a risk of radiation exposure when replacing the neutron generator. [Means for solving the problem]

[0005] To provide a neutron capture therapy system that reduces the risk of radiation, one embodiment of the present application provides a neutron capture therapy system comprising an accelerator for generating a charged particle beam, a neutron generator for reacting with the charged particle beam to generate a neutron beam, and a beam shaping body, wherein the beam shaping body comprises a housing, a decelerator adjacent to the neutron generator, a reflector surrounding the decelerator, a thermal neutron absorber adjacent to the decelerator, a radiation shield installed within the beam shaping body, and a beam outlet, wherein the housing is provided with a vacuum tube connected to the accelerator, the neutron generator is provided at the end of the vacuum tube, and the vacuum tube reacts with the charged particles accelerated by the accelerator to generate neutrons. The neutron generator is transferred to a neutron generator, which generates neutrons by causing a nuclear reaction with the charged particle beam. These neutrons form a neutron beam, which is then limited to a single main axis. The decelerator slows the neutrons generated from the neutron generator to the epithermal neutron energy region. The reflector returns the diverted neutrons to the decelerator to improve the intensity of the epithermal neutron beam. Radiation shielding is used to shield leaked neutrons and photons to reduce the dose to normal tissue in the unirradiated area. The neutron generator moves between a first and second position. In the first position, the neutron generator can react with the charged particle beam to generate neutrons. In the second position, the neutron generator detaches from the beam shaping body. This grounding allows for easy and rapid target replacement simply by moving the neutron generator and detaching it from the beam shaping body. In some measures, robotic hands or remote control can be employed to avoid exposure of workers to radiation.

[0006] Preferably, the change in the overall length of the vacuum tube provides a space for the neutron generator to move from a first position to a second position, and at the second position, the neutron generator moves together with the vacuum tube, exits the housing, and detaches from the beam shaping body.

[0007] Furthermore, the vacuum tube includes at least a first vacuum tube section connected to the accelerator, a second vacuum tube section housed in the beam shaping housing and containing a neutron generator, and a third vacuum tube section connecting the first and second vacuum tube sections. The third vacuum tube section is detachable, thereby shortening the overall length of the vacuum tube and providing space for the neutron generator to move out of the housing. In the second position, the neutron generator moves together with the second vacuum tube section, exits the housing, and detaches from the beam shaping body. Furthermore, to facilitate the movement of the neutron generator and its exit from the housing, a filler material is packed between the outer circumference of the vacuum tube and the inner wall of the housing.

[0008] Furthermore, the filler is a material capable of absorbing neutrons or a material capable of reflecting neutrons. Furthermore, the neutron capture therapy system includes a cooling device located within the housing to cool the neutron generator, with a packing material filling the outer circumference of the vacuum tube and the inner wall of the housing to enclose the cooling device, and in the second position, the cooling device and packing material detach from the housing together with the neutron generator.

[0009] Preferably, the cooling device includes a first cooling section located at the end of the vacuum tube and in contact with the neutron generation section in a planar manner, and a second cooling section and a third cooling section located on either side of the first cooling section and communicating with the first cooling section, wherein the second and third cooling sections extend along a direction parallel to the neutron beam axis and form a U-shaped structure with the first cooling section on the upper and lower sides of the vacuum tube, respectively.

[0010] Preferably, the neutron capture therapy system includes a first shield and a second shield adjacent to the decelerator and covering the outer circumference of the housing, as movable space for the neutron generator to detach from the housing together with the vacuum tube, wherein the second shield can move away from the vacuum tube relative to the first shield, and the vacuum tube includes at least a first vacuum tube section housed in the housing and containing the neutron generator, and a second vacuum tube section connecting the first vacuum tube section to the accelerator, wherein the first vacuum tube section can detach from the second vacuum tube section, and when the first vacuum tube section detaches from the second vacuum tube section and the second shield moves to a position where it can detach from the housing of the first vacuum tube section, the neutron generator detaches from the beam shaping body together with the first vacuum tube section. In other words, the movement of the second shield provides space for the vacuum tube to move, and the detachment of the first vacuum tube section from the second vacuum tube section causes the neutron generator to detach from the beam shaping body together with the first vacuum tube section. Furthermore, to reduce worker contact with the neutron generator and improve radiation safety, the neutron capture therapy system also includes a containment device located vertically below the vacuum tube. After the neutron generator moves outside the containment device, it falls into the containment device, which is made of shielding material.

[0011] Furthermore, the storage device includes a bottom and four sides connected to the bottom, the bottom and the four sides connecting to form a storage space with an opening, the storage device is further provided with two rotating parts that shield the opening, one end of each rotating part connected to one of the sides and the other end being able to rotate relative to the side into the storage space, in its natural state the two rotating parts shield the top of the storage device from above the storage space; in the action of an external force the rotating parts rotate into the storage space and are housed there; when the external force is removed the rotating parts return to their natural state.

[0012] To provide a neutron capture therapy system that reduces the risk of radiation, another embodiment of the present application provides a neutron capture therapy system comprising an accelerator for generating an electric particle beam, a neutron generator for reacting with the charged particle beam to generate a neutron beam, and a beam shaping body, wherein the beam shaping body comprises a housing, a decelerator adjacent to the neutron generator, a reflector surrounding the decelerator, a thermal neutron absorber adjacent to the decelerator, radiation shielding installed within the beam shaping body, a shielding device adjacent to the beam shaping body and a beam outlet, wherein the housing is provided with a vacuum tube in contact with the accelerator, the neutron generator is provided at the end of the vacuum tube, the vacuum tube transfers charged particles accelerated by the accelerator to the neutron generator, the neutron generator reacts with the charged particle beam to generate neutrons, and the neutrons are neutrons A beam is formed, the neutron beam is limited to a single main axis, the decelerator slows the neutrons generated from the neutron generator to the epithermal neutron energy region, the reflector returns the diverted neutrons to the decelerator to improve the intensity of the epithermal neutron beam, the radiation shielding is used to shield leaked neutrons and photons to reduce the dose to normal tissue in the non-irradiated area, the neutron generator moves between a first position and a second position, in the first position the neutron generator can react with a charged particle beam to generate neutrons, in the second position the neutron generator detaches from the beam shaping body, and the beam shaping body and the shielding device are kept shielded at all times during the process of the neutron generator moving from the first position to the second position, thereby preventing radiation leaking from the neutron generator from irradiating workers.

[0013] When the neutron generator is located within the beam shaping body, radiation shielding within the beam shaping body can shield against radiation leaking from the neutron generator, thus preventing radiation exposure to workers; however, after the neutron generator has detached from the beam shaping body, radiation shielding is no longer sufficient to protect it. In this case, a shielding device is used to shield the neutron generator, ensuring that it remains shielded throughout its movement from the first position to the second position, thereby preventing radiation leaking from the neutron generator from irradiating workers.

[0014] Preferably, the vacuum tube includes at least a first vacuum tube portion connected to the accelerator, a second vacuum tube portion housed in the housing portion of the beam shaper and storing the neutron generation portion, and a third vacuum tube portion connecting the first vacuum tube portion and the second vacuum tube portion. By being able to remove the third vacuum tube portion, a space is provided for the neutron generation portion to move out of the housing portion. In the second position, the neutron generation portion can move together with the second vacuum tube portion out of the housing portion and fall off from the beam shaper.

[0015] Furthermore, the shielding device includes a bottom wall and a first side wall and a second side wall that are connected to the bottom wall and installed opposite to each other. The bottom wall and the two side walls form a U-shaped structure having a first opening, a second opening, and a third opening. The first opening is adjacent to the first vacuum tube portion, the second opening is adjacent to the second vacuum tube portion, and the third vacuum tube portion penetrates through the third opening. In this application, preferably, the third vacuum tube portion is removed after installing the shielding device outside the vacuum tube. However, during actual operation, the shielding device may be installed after first removing the third vacuum tube portion.

[0016] Furthermore, the shielding device further includes a ceiling installed opposite to the bottom wall, the bottom wall, a third side wall and a fourth side wall connected to the ceiling. The third side wall and the fourth side wall are installed opposite to each other. The bottom wall, the ceiling and the four side walls form a shielding space. So that the shielding device has a U-shaped structure, the ceiling can rotate away from the shielding space around the second side wall or the fourth side wall, and the first side wall and the third side wall can each rotate away from the shielding space around the bottom wall. When the shielding device is located between the first vacuum tube portion and the second vacuum tube portion, the shielding device has a U-shaped structure; when the neutron generation portion is located in the shielding device together with the second vacuum tube portion, the shielding device forms a shielding space to shield the neutron generation portion.

[0017] Furthermore, in order for the neutron generation unit to move out of the accommodating portion, a filler is filled between the outer periphery of the vacuum tube and the inner wall of the accommodating portion. The neutron capture therapy system further includes a cooling device located within the accommodating portion for cooling the neutron generation unit. The filler is filled between the outer periphery of the vacuum tube and the inner wall of the accommodating portion to wrap the cooling device. When the neutron generation unit moves into the shielding device, the cooling device and the filler move into the shielding device together with the neutron generation unit.

[0018] Furthermore, the filler is a material that can absorb neutrons or a material that can reflect neutrons. Furthermore, the neutron capture therapy system further includes a cooling device located within the accommodating portion for cooling the neutron generation unit. The filler is filled between the outer periphery of the vacuum tube and the inner wall of the accommodating portion to wrap the cooling device.

[0019] Preferably, the cooling device includes a first cooling portion located at an end of the vacuum tube and in a plane in contact with the neutron generation unit, and second and third cooling portions located on both sides of the first cooling portion and communicating with the first cooling portion respectively. The second and third cooling portions extend along a direction parallel to the neutron beam axis and are located on the upper and lower sides of the vacuum tube respectively, so that the first cooling portion forms a U-shaped structure.

[0020] Furthermore, in order for an operator to reduce contact with the neutron generation unit and improve radiation safety, the neutron capture therapy system further has a storage device located vertically below the vacuum tube. After the neutron generation unit moves outside the accommodating portion, it falls into the storage device, and the storage device is made of a shielding material.

[0021] Furthermore, the storage device includes a bottom and four sides connected to the bottom, the bottom and the four sides connecting to form a storage space with an opening, the storage device is further provided with two rotating parts that shield the opening, one end of each rotating part connected to one of the sides and the other end being able to rotate into the storage space relative to the connected side, in its natural state the two rotating parts shield the top of the storage device from above the storage space; in the action of an external force the rotating parts rotate into the storage space and are housed there; when the external force is removed the rotating parts return to their natural state. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic diagram of a first embodiment of the neutron capture therapy system of the present invention, in which the neutron generator is located in a first position. [Figure 2] This is a cross-sectional view of the cooling device in Figure 1, taken along a direction perpendicular to the neutron beam irradiation direction. [Figure 3] This is a partial cross-sectional view of the neutron capture therapy system along the direction perpendicular to the neutron beam irradiation direction in Figure 1. [Figure 4] Figure 1 is a schematic diagram showing the third vacuum tube section of the vacuum tube removed. [Figure 5] This is a schematic diagram showing the second vacuum tube section and the neutron generator section after the third vacuum tube section in Figure 4 has been removed and moved out of the housing, i.e., the neutron generator section is in the second position. [Figure 6] This is a schematic diagram of a second embodiment of the neutron capture therapy system of the present invention, wherein a shielding device is installed between the first vacuum tube section and the second vacuum tube section. [Figure 7] This is a schematic diagram showing the relocation of the second vacuum tube section and neutron generation section in Figure 6 into the shielding device. [Figure 8] This is a schematic diagram showing the second vacuum tube section and neutron generator section in Figure 6 with the shielding device that houses them removed. [Figure 9] This is a three-dimensional schematic diagram of the shielding device shown in Figure 6. [Figure 10]Figure 9 is a schematic diagram of another embodiment of the shielding device shown. [Figure 11] Figure 10 is a schematic three-dimensional view of the shielding device. [Figure 12] This is a schematic diagram of a third embodiment of the neutron capture therapy system described in this application. [Figure 13] Figure 12 is a schematic diagram showing that the second shielding section moves away from the neutron generator relative to the first shielding section. [Figure 14] This is a partial cross-sectional view of the neutron capture therapy system along the direction perpendicular to the neutron beam irradiation direction in Figure 12. [Figure 15] This is a partial cross-sectional view of the neutron capture therapy system along the direction perpendicular to the neutron beam irradiation direction in Figure 13. [Figure 16] Figure 14 is a schematic diagram showing the first vacuum tube section and neutron generator section after the second shielding section has moved out of their respective housing spaces. [Figure 17] This is a partial cross-sectional view of the neutron capture therapy system along a method perpendicular to the direction of neutron beam irradiation in Figure 16. [Figure 18] Figure 15 is a schematic diagram of the storage device in its natural state. [Figure 19] Figure 18 is a schematic diagram of the storage device subjected to external forces. [Modes for carrying out the invention]

[0023] Neutron capture therapy has seen increasing application in recent years as an effective means of treating cancer, with boron neutron capture therapy becoming the most common. Neutrons used in boron neutron capture therapy can be supplied by a nuclear reactor or accelerator. Embodiments of the present invention take accelerator-based boron neutron capture therapy as an example. The basic module of accelerator-based boron neutron capture therapy generally includes an accelerator used to accelerate charged particles (protons, deuterium nuclei, etc.), a target, a thermal removal system, and a beam shaping assembly. Neutrons are generated by the interaction of the accelerated charged particles with a metal target, and an appropriate nuclear reaction is selected based on the required neutron yield and energy, the energy and current of the available accelerated charged particles, and the physical and chemical properties of the metal target. Well-considered nuclear reactions are 7 Li(p, n) 7 Be and 9 Be(p, n) 9 Both are endothermic reactions with energy thresholds of 1.881 MeV and 2.055 MeV, respectively. The ideal neutron source for boron neutron capture therapy is epithermal neutrons at the keV energy level. Theoretically, a relatively low-energy neutron can be generated by impacting a lithium target with protons slightly above the threshold energy, allowing for clinical application without requiring much moderation. However, since the two targets, lithium (Li) and beryllium (Be), do not have a large surface area for interaction with threshold-energy protons, nuclear reactions are generally induced with relatively high-energy protons to ensure a sufficient neutron flux.

[0024] Ideal targets require characteristics such as a high neutron yield, an energy distribution of the generated neutrons close to the epithermal neutron energy region (to be described in detail later), not generating too much strongly penetrating radiation, being safe, simple, and easy to operate, and having high heat resistance. However, since no nuclear reaction that actually meets all the requirements has been found, a lithium target is adopted in the embodiments of the present invention. However, as is well known to those skilled in this field, other metal materials other than the above metal materials can be adopted as the target material.

[0025] The requirements of the heat removal system vary depending on the selected nuclear reaction. For example, 7 Li(p, n) 7 In the case of Be, due to the low melting point and low thermal conductivity of the metal target (lithium), the requirements of the heat removal system are 9 Be(p, n) 9 more stringent than those of B. In the embodiments of the present invention, 7 Li(p, n) 7 the nuclear reaction of Be is adopted.

[0026] The neutron source for boron neutron capture therapy is based on the nuclear reaction between charged particles from a nuclear reactor or an accelerator and a target, and all that is generated is a mixed radiation field. That is, the beam contains neutrons and photons from low energy to high energy. Regarding boron neutron capture therapy for deep tumors, the higher the content of radiation other than epithermal neutrons, the greater the proportion of non-selective dose deposition in normal tissues. Therefore, it is necessary to reduce the radiation that causes these unnecessary doses as much as possible. In addition to the quality factors of the air beam, in order to further understand the dose distribution in the human body by neutrons, the embodiments of the present invention calculate the dose using an artificial organ of human head tissue and use the quality factors of the beam in the artificial organ as a reference for neutron beam design. This will be described in detail later.

[0027] The International Atomic Energy Agency (IAEA) has issued five proposals regarding the quality elements of air beams for neutron sources used in clinical boron neutron capture therapy. These five proposals can be used to compare the advantages and disadvantages of different neutrons, and as a reference when selecting neutron generation pathways and designing beam shaping assemblies. The five proposals are as follows:

[0028] ·Epithermal neutron flux > 1 x 10 9 n / cm 2 s • Fast neutron contamination < 2 x 10⁻⁶ -13 Gy-cm 2 / n • Photon contamination < 2 x 10⁻⁶ -13 Gy-cm 2 / n • Ratio of thermal to epithermal neutron flux < 0.05 • Epithermal neutron current to flux ratio > 0.7 Note: The epithermal neutron energy range is 0.5 eV to 40 keV, the thermal neutron energy range is less than 0.5 eV, and the fast neutron energy range is greater than 40 keV.

[0029] 1. Epithermal neutron flux: The duration of clinical treatment is determined by the neutron flux and the concentration of the boron-containing drug in the tumor. If the concentration of the boron-containing drug in the tumor is sufficiently high, the requirement for neutron flux can be reduced. Conversely, if the concentration of the boron-containing drug in the tumor is low, it is necessary to deliver a sufficient dose to the tumor with high-flux epithermal neutrons. The IAEA proposes that for epithermal neutron flux, 10⁶ epithermal neutrons per square centimeter per second is required. 9We are looking for more than one unit. For existing boron-containing drugs, this flux of neutron beam can reduce treatment time to approximately one hour. Shorter treatment times can contribute to improved positioning and comfort, as well as the effective utilization of the limited residence time of boron-containing drugs in tumors.

[0030] 2. Fast neutron contamination: Fast neutrons are considered contamination because they cause unnecessary doses to normal tissue. Since there is a positive correlation between this dose and neutron energy, it is necessary to reduce the fast neutron content as much as possible in the design of neutron beams. Fast neutron contamination is defined as the dose of fast neutrons associated with a unit epithermal neutron flux. The IAEA defines fast neutron contamination as 2 x 10⁻¹⁶ -13 Gy-cm 2 It is recommended to make it smaller than / n.

[0031] 3. Photon contamination (gamma ray contamination): Gamma rays belong to the category of highly penetrating radiation and cause dose deposition in all tissues in the beam path non-selectively; therefore, reducing the gamma ray content is also a requirement in neutron beam design. Gamma ray contamination is defined as the dose of gamma rays associated with a unit epithermal neutron flux. The IAEA defines gamma ray contamination as 2 x 10⁻¹⁶ -13 Gy-cm 2 It is recommended to make it smaller than / n.

[0032] 4. Ratio of thermal neutron flux to epithermal neutron flux: Thermal neutrons have a fast decay rate and weak penetrating power, and when they enter the human body, most of their energy is deposited in the skin tissue. Therefore, except when using thermal neutrons as a neutron source for boron neutron capture therapy for skin tumors such as melanoma, it is necessary to reduce the thermal neutron content in cases of deep tumors such as brain tumors. The IAEA recommends that the ratio of thermal neutron flux to epithermal neutron flux be less than 0.05.

[0033] 5. Ratio of neutron flow to flux: The ratio of neutron flow to flux indicates the directionality of the beam. A larger ratio results in stronger forward beam directionality. A neutron beam with strong forward directionality can reduce the dose to surrounding healthy tissue due to neutron divergence, and improve the flexibility of therapeutic depth and positioning orientation. The IAEA recommends a neutron flow to flux ratio greater than 0.7.

[0034] To solve the problem of replacing neutron generators and, at the same time, to minimize worker contact with radiation, this application provides a type of neutron capture therapy system. Since the primary radiation to the target replacement is from the radiation generated by a nuclear reaction after the charged particle beam irradiates the neutron generator, this application describes the removal of the neutron generator after the nuclear reaction has occurred, and does not describe the installation of a new neutron generator.

[0035] As shown in Figure 1, the neutron capture therapy system 100 includes an accelerator 200 for generating a charged particle beam, a neutron generator 10 for generating a neutron beam N in reaction with the charged particle beam P, and a beam shaping body 20. The beam shaping body 20 includes a housing 21, a decelerator 22 adjacent to the neutron generator, a reflector 23 surrounding the decelerator 22, a thermal neutron absorber 24 adjacent to the decelerator 22, and radiation shielding 25 and a beam outlet 26 installed within the beam shaping body 20. The housing 21 houses a vacuum tube 30 connected to the accelerator 200, and the neutron generator 10 is located at the end of the vacuum tube 30 and adjacent to the decelerator 22. The vacuum tube 30 transfers the charged particles P, which have been accelerated by the accelerator 200, to the neutron generator 10, and the accelerator 200 accelerates the charged particles P to an energy that can overcome the target's nuclear force and then transfers them to the neutron generator 12 and 7 Li(p, n) 7A Be nuclear reaction is initiated to generate neutrons, which form a neutron beam N, and this neutron beam N limits a single main axis I. The decelerator 22 decelerates the neutrons generated from the neutron generator 10 to the epithermal neutron energy region. The reflector 23 returns the diverted neutrons to the decelerator 22, improving the intensity of the epithermal neutron beam. The thermal neutron absorber 24 is used to absorb thermal neutrons and avoid excessive doses to shallow normal tissue during treatment. The radiation shield 25 is used to shield leaked neutrons and photons and reduce the normal tissue dose in non-irradiated areas.

[0036] Referring to Figure 2, the neutron capture therapy system 100 further includes a cooling device 40 that cools the neutron generator 10 to improve the service life of the neutron generator. The cooling device 40 includes a first cooling section 41 located at the end of the vacuum tube 30 and in contact with the neutron generation section 10 in a planar manner, and a second cooling section 42 and a third cooling section 43 located on either side of the first cooling section 41 and communicating with the first cooling section 41, respectively. There is a gap between the outer circumference of the vacuum tube 30 and the inner wall of the housing section 21, and the second cooling section 42 and the third cooling section 43 extend within the gap along a direction parallel to the neutron beam axis I, and are located on the upper and lower sides of the vacuum tube 30, respectively, forming a U-shaped structure with the first cooling section 41. While the cooling device 40 cools the neutron generation section 10 at the end of the vacuum tube 30, the beam shaping body 20 fits a portion of the vacuum tube 30 into the decelerator 22 (not shown) in order to obtain good neutron beam quality. The second cooling section 242 introduces a coolant into the first cooling section 41, and the third cooling section 43 leads out the coolant from the first cooling section 41. The first cooling unit 41 is positioned between the neutron generation unit 10 and the decelerator 22, with one side of the first cooling unit 41 in direct surface contact with the neutron generation unit 31 and the other side in contact with the decelerator 14.

[0037] The first cooling section 41 includes a first contact section 411, a second contact section 412, and a cooling groove 413 located between the first contact section 411 and the second contact section 412 through which a coolant passes. The first contact section 411 is in direct contact with the neutron generator 10, and the second contact section 412 may be in direct contact with the moderator 22 or indirectly in contact with it through air. The cooling groove 413 has an introduction groove 414 communicating with the second cooling section 42 and an exit groove 415 communicating with the third cooling section 43. The first contact section 411 is made of a thermally conductive material. The first contact section 411 is made of a thermally conductive material (e.g., a material with good thermal conductivity such as Cu, Fe, or Al) or a material that combines thermal conductivity and foam suppression, and the second contact section 412 is made of a foam suppression material, and the foam suppression material or the material that combines thermal conductivity and foam suppression may be made of Fe, Ta, or V. The neutron generation unit 10 is subjected to high-energy accelerated irradiation, causing its temperature to rise and generating heat. The first contact unit 411 extracts the heat, and the refrigerant circulating in the cooling groove 413 removes the heat, thereby cooling the neutron generation unit 10. In this embodiment, the refrigerant is water.

[0038] Referring to Figures 1 and 5, Figure 1 is a schematic diagram of the neutron generator when it is in the first position, and Figure 5 is a schematic diagram of the neutron generator when it is in the second position. The neutron generator 10 moves between the first and second positions. In the first position, the neutron generator 10 reacts with the charged particle beam to generate neutrons, and in the second position, the neutron generator 10 detaches from the beam shaping body 20.

[0039] Referring to Figure 3, there is a gap between the housing 21 and the outer wall of the vacuum tube 30, and the gap is filled with a packing material 50. The packing material 50 covers the outer wall of the vacuum tube 30 and the cooling device 40. The packing material 50 is a material such as a lead alloy or an aluminum alloy that can absorb or reflect neutrons. In the embodiments of this application, the lead content of the lead alloy is 85% or more, and the aluminum content of the aluminum alloy is 85% or more. The packing material 50 increases the yield of epithermal neutrons by reflecting neutrons that have been reflected or scattered into the gap back into the decelerator 22 or reflector 23, thereby reducing the irradiation time required for the irradiated object, while also preventing neutrons from leaking outside the beam shaping body 20 and adversely affecting the equipment of the neutron capture therapy system, thereby improving radiation safety. Then, when the neutron generator 10 moves to the outside of the housing 21, the cooling device 40 and the packing material 50 move out of the housing 21 together with the neutron generator 10, and thus detach from the beam shaping body 20.

[0040] As a first embodiment, referring to Figures 1, 4, and 5, the vacuum tube 30 includes a first vacuum tube section 31 connected to the accelerator 200, a second vacuum tube section 32 housed in a housing section 21, and a third vacuum tube section 33 connecting the first vacuum tube section 31 and the second vacuum tube section 32. One end of the second vacuum tube section 32 is adjacent to the decelerator 22, and the other end extends from the housing section 21 and connects to the third vacuum tube section 33. The neutron generator 10 is provided at the end of the second vacuum tube section 32 and adjacent to the decelerator 22. By removing the third vacuum tube section 33 from the first vacuum tube section 31 and the second vacuum tube section 32, the overall length of the vacuum tube 30 can be shortened, providing space for the neutron generator 10 to move out of the housing section 21 along the opposite direction of irradiation by the neutron beam N. After the third vacuum tube section 33 is removed from between the first vacuum tube section 31 and the second vacuum tube section 32, the second vacuum tube section 32 moves along the opposite direction to the neutron beam N irradiation, exits the housing section 21, and detaches from the beam shaping body 20.

[0041] In this embodiment, the vacuum tube 30 can be detached from the beam shaping body 20 because three Vacuum tube section 33 After removing the first two Vacuum tube section 32This is because there is space for the neutron generator to move along the opposite direction of the neutron beam N irradiation and exit the housing section 21; in other words, by changing the overall length of the vacuum tube 30, space is secured for the neutron generator 10 to escape. Another embodiment of changing the overall length of the vacuum tube is to install the vacuum tube in a manner that allows it to contract along the direction of the neutron beam irradiation (a portion of the vacuum tube located outside the beam shaping body is installed in an expandable and contractible corrugated tube, and when the corrugated tube is compressed, the overall length of the vacuum tube is shortened, and the neutron generator moves along the vacuum tube along the opposite direction of the neutron beam irradiation and exits the beam shaping body). Here, the detailed invention is omitted.

[0042] Figures 6 to 8 are schematic diagrams of a second embodiment of the neutron capture therapy system of the present invention, wherein the neutron capture therapy system 100 further includes a shielding device 60 in order to reduce the safety risk of radiation to workers.

[0043] Referring to Figure 9, the shielding device 60 includes a bottom wall 61, a ceiling 62 installed opposite the bottom wall 61, and a first side wall 63, a second side wall 64, a third side wall 65, and a fourth side wall 66 connecting the bottom wall 61 and the ceiling 62. The first side wall 63 is installed opposite the third side wall 65, and the second side wall 64 is installed opposite the fourth side wall 66, and the bottom wall 61, the ceiling 62, and the four side walls are connected to form a shielding space 67. The ceiling 62 can rotate around the second side wall 64 or the fourth side wall 66 in a direction away from or towards the shielding space 67, and the first side wall 63 and the third side wall 65 can each rotate around the bottom wall 61 in a direction away from or towards the shielding space 67. The rotation of the ceiling 62, the first side wall 63, and the third side wall 65 is Ceiling 62 This is achieved by a rotating member 68 attached to the first side wall 63 and the third side wall 65. When the ceiling 62, the first side wall 63 and the third side wall 65 rotate around the rotating member 68 in a direction away from the shielding space 67, the shielding device 60 takes on a U-shaped structure, so that the worker can see two Vacuum tube section 32 This is convenient for moving the beam shaping body 20 outside and moving the neutron generating unit 10 within the shielding space 67.

[0044] Of course, as another embodiment of the shielding device 60 described above (see Figures 10 and 11), the shielding device 60 shown may include only a bottom wall 61 and two side walls (64, 66) connected to and facing the bottom wall 61. The bottom wall 61 and the two side walls have a first opening 631, a second opening 651, and a third opening 621 facing the bottom wall 61, that is, the bottom wall 61 and the two side walls form a U-shaped structure, and the U-shaped structure has a shielding space 67. The first opening 631 is adjacent to the first vacuum tube section 31, the second opening 651 is adjacent to the second vacuum tube section 32, and the third vacuum tube section penetrates the third opening, two opening 651 This is used by the worker to move the second vacuum tube section 31 into the shielding space 67. In this embodiment of the application, the shielding device 60 is provided on the outer circumference of the vacuum tube 30, and when it is necessary to replace the neutron generator, the third vacuum tube section is removed, the worker moves the second vacuum tube section 32, and the neutron generator 10, filling section 50, and cooling device 40 all move together with the second vacuum tube section 3 and are housed in the shielding space 67 of the shielding device 60. Then the shielding device 60 is removed from the first vacuum tube section 31, and then the ceiling 60, first side wall 63, and third side wall 65 are rotated respectively to cover the shielding space 67, thereby completely shielding from radiation within the shielding space 67. The shielding device 60 shields the radiation remaining in the neutron generator 10 after the nuclear reaction has occurred, thereby reducing the safety risk of radiation to the worker. Of course, in the actual operation process, after removing the third vacuum tube section 33, a shielding device 60 may be installed between the first vacuum tube section 31 and the second vacuum tube section 32.

[0045] The shielding device 60 may be installed by connecting (contacting) the first aperture 631 to the first vacuum tube section 31, and by connecting (contacting) the second aperture 651 to the second vacuum tube section 32 (beam shaping body 20), or by supporting it on the outer circumference of the vacuum tube 30 by installing an additional structure.

[0046] Since the worker stands beside the beam shaping body to replace the neutron generator, the bottom and side walls of the shielding unit can shield the radiation remaining in the neutron generator when the worker moves the second vacuum tube unit. After the neutron generator unit moves into the shielding space together with the second vacuum tube unit, the ceiling, first side wall, and third side wall are rotated so that the shielding space is completely enclosed by the shielding material, further reducing the risk of radiation to the worker. Of course, the U-shaped shielding device 60 can also sufficiently shield the worker from radiation that could potentially reach them, thus reducing the risk of radiation to the worker.

[0047] Figures 12-17 are schematic diagrams of a third embodiment of the neutron capture therapy system of the present invention. The neutron capture therapy system 100' further includes a shielding section adjacent to the decelerator 22, the shielding section covering the outer circumference of the housing section 21. The shielding section includes a first shielding section 71 and a second shielding section 72, the second shielding section 72 being able to move away from the vacuum tube 30 relative to the first shielding section 71, causing the neutron generator 10 to fall out of the housing section 2. The vacuum tube 30 includes at least a first vacuum tube section 31' connected to the accelerator 200 and a second vacuum tube section 32' connected to the first vacuum tube section 31' and housed in the housing section 21. The first vacuum tube section 31' detaches from the second vacuum tube section 32', and the second shielding section 72 moves away from the neutron generator 10, two Vacuum tube section 32’ When the neutron generator 10 is able to fall out of the housing section 21, it moves together with the second vacuum tube section 32' and exits the housing section 21, detaching from the beam shaping body 20. The filling section and cooling device also detach from the beam shaping body 20 together with the neutron generator 10.

[0048] To reduce the safety risk of radiation to workers, the neutron capture therapy system may further include a shielding device 60 in Embodiment Two, or a containment device 80 located below the vacuum tube 30, the neutron generator 10 falling from the containment unit 21 into the containment device 80, and the containment device 80 is made of shielding material.

[0049] Referring to Figures 18-19, the storage device 80 includes a bottom 81, a top 82 positioned opposite the bottom 81, and four side sections 83 connected to the bottom 81 and top 82, the bottom 81, top 82, and four side sections 83 connecting to form a storage device 80 having a storage space 84. The top 82 of the storage device 80 is further provided with an opening, and the opening shield has two opposing rotating parts 85, one end of each rotating part 85 connected to the top 82, and the other end of each rotating part 85 being able to rotate into the storage space 84 relative to the top. In its natural state, the two rotating parts 85 are positioned above the storage space 84 and shield the opening; due to the action of an external force, the rotating parts 85 rotate into the storage space 84 and are housed in the storage space 84; when the external force is removed, the rotating parts 85 return to their natural state. The movement of the rotating part 85 is achieved by installing a shaft member on the top part 82, causing the rotating part 85 to move into the storage space 84 around the shaft member (not shown), or by covering the opening above the storage space 84. A detailed explanation is omitted here.

[0050] Of course, the first and second embodiments may also be equipped with the storage device of the third embodiment to further reduce the probability of workers coming into direct contact with radiation. The neutron capture therapy system accelerates a charged particle beam P by an accelerator, and in a preferred embodiment, the neutron generator 31 is made of lithium metal and accelerates the charged particle beam to an energy that can overcome the nuclear force of the target, and the neutron generator 12 and 7 Li(p, n) 7 A Be nuclear reaction is generated to produce neutrons, and the beam shaping body 20 slows the neutrons to the epithermal neutron energy region, reducing the content of thermal neutrons and fast neutrons. As shown in Figure 3, the neutron generation unit 10 includes a lithium target layer 101 and an oxidation prevention layer 102 located on the lithium target layer 10 side to prevent oxidation of the lithium target layer 101. The oxidation prevention layer 102 of the neutron generation unit 10 is made of Al or stainless steel.

[0051] The decelerator 22 is made of a material with a large fast neutron cross-section and a small epithermal neutron cross-section, the reflector 23 is made of a material with strong neutron reflection capability, and the thermal neutron absorber 24 is made of a material with a large thermal neutron cross-section. In preferred embodiments, the decelerator 22 is made of D2O, AlF3, and Fluental TM The reflector 23 is made from at least one of CaF2, Li2CO3, MgF2, and Al2O3, the reflector 23 is made from at least one of Pb or Ni, and the thermal neutron absorber 24 is 6 It is manufactured using lithium.

[0052] The radiation shielding 25 includes photon shielding 251 and neutron shielding 252, preferably including photon shielding 251 made of lead (Pb) and neutron shielding 252 made of polyethylene (PE). In the description of this application, the same part number is used to indicate the same component.

[0053] The neutron capture therapy system disclosed in this application is not limited to the structure shown in the above-described embodiments and drawings. For example, the moderator may be installed in a cylindrical shape, multiple cooling devices may be installed, or there may be multiple corresponding storage pipes. Any obvious modifications, substitutions, or changes made to the material, shape, and position of the components therein on the basis of this application are within the scope of this disclosure.

Claims

1. A neutron capture therapy system, the neutron capture therapy system includes an accelerator for generating a charged particle beam, a neutron generator for generating a neutron beam in reaction with the charged particle beam, and a beam shaping body, the beam shaping body includes a housing section, a decelerator adjacent to the neutron generator, a reflector surrounding the decelerator, a thermal neutron absorber adjacent to the decelerator, a radiation shield installed within the beam shaping body, and a beam outlet, the housing section is provided with a vacuum tube connected to the accelerator, the neutron generator is provided at the end of the vacuum tube, the vacuum tube transfers charged particles accelerated by the accelerator to the neutron generator, and the neutron generator causes a nuclear reaction with the charged particle beam. Neutrons are generated, the neutrons form a neutron beam, the neutron beam is limited to a single main axis, the decelerator slows the neutrons generated from the neutron generator to the epithermal neutron energy region, the reflector returns the diverted neutrons to the decelerator to improve the intensity of the epithermal neutron beam, the radiation shielding is used to shield leaked neutrons and photons to reduce the dose to normal tissue in the unirradiated area, the neutron generator moves between a first position and a second position, in the first position the neutron generator can react with a charged particle beam to generate neutrons, the second position is the position where the neutron generator is separated from the beam shaping body and moved outside the housing portion of the beam shaping body, The neutron capture therapy system further includes a shielding device adjacent to the beam shaping body, the shielding device being positioned outside and around the vacuum tube, the shielding device including at least a bottom wall, a second side wall connected to the bottom wall and a fourth side wall, the second side wall and the fourth side wall being positioned opposite each other, The bottom wall, the second side wall, and the fourth side wall form a first opening, a second opening opposite the first opening, and a third opening opposite the bottom wall. The bottom wall, the second side wall, and the fourth side wall form a U-shaped structure, and the U-shaped structure has a shielding space. The vacuum tube includes at least a first vacuum tube section connected to the accelerator, a second vacuum tube section housed in the housing section and containing the neutron generator, and a third vacuum tube section connecting the first vacuum tube section and the second vacuum tube section. The first opening is adjacent to the first vacuum tube section, the second opening is adjacent to the second vacuum tube section, and the third vacuum tube section is configured to be removed from the first and second vacuum tube sections through the third opening. After the third vacuum tube section is removed from the first and second vacuum tube sections, the second vacuum tube section and the neutron generation section are configured to move through the second aperture into the shielding space in the direction opposite to the irradiation direction of the neutron beam. A neutron capture therapy system characterized by the following features.

2. The neutron capture therapy system according to claim 1, characterized in that the neutron generating unit moves from a first position to a second position by changing the overall length of the vacuum tube.

3. The neutron capture therapy system according to claim 2, characterized in that the neutron generation unit exits the housing unit by shortening the overall length of the vacuum tube.

4. The neutron capture therapy system according to claim 3, characterized in that the third vacuum tube section is removed to shorten the overall length of the vacuum tube, thereby providing space for the neutron generator to move out of the housing section, and in the second position, the neutron generator, together with the second vacuum tube section, moves out of the housing section and separates from the beam shaping body.

5. The neutron capture therapy system according to claim 1, characterized in that a filler is filled between the outer circumference of the vacuum tube and the inner wall of the housing, and the filler is a material capable of absorbing neutrons or a material capable of reflecting neutrons.

6. The neutron capture therapy system according to claim 5, further comprising a cooling device located within a housing for cooling a neutron generator, wherein the packing material is filled between the outer circumference of the vacuum tube and the inner wall of the housing to enclose the cooling device, and in the second position, the cooling device and the packing material together with the neutron generator exit the housing and separate from the beam shaping body.

7. The neutron capture therapy system according to claim 1, characterized in that when the neutron generation unit is in the first position, the first aperture is adjacent to the first vacuum tube unit, the second aperture is adjacent to the second vacuum tube unit, and the third vacuum tube unit is located inside the shielding device.

8. The neutron capture therapy system according to claim 7, characterized in that when the neutron generator is in the first position, the third vacuum tube is located inside the shielding device, the first vacuum tube and the second vacuum tube are located outside the shielding device, the first aperture is adjacent to the first vacuum tube, the second aperture is adjacent to the second vacuum tube, and when the third vacuum tube is removed from between the first and second vacuum tubes, and the neutron generator moves from the first position to the second position, the neutron generator moves from the beam shaping housing through the second aperture to inside the shielding device, following the second vacuum tube.

9. The neutron capture therapy system according to claim 8, further comprising a first side wall and a third side wall, wherein the first side wall and the third side wall are installed facing each other, the bottom wall, ceiling and four side walls form a shielding space, the ceiling can rotate away from the shielding space around the second side wall or the fourth side wall, and the first side wall and the third side wall can each rotate away from the shielding space around the bottom wall.

10. The neutron capture therapy system according to claim 9, characterized in that when the neutron generator is in the first position, the shielding device is located outside the first vacuum tube section and the second vacuum tube section, and after the neutron generator moves to the second position, it is covered by the bottom wall, ceiling, first side wall, second side wall, third side wall and fourth side wall of the shielding device, so that the neutron generator is located inside the shielding device together with the second vacuum tube section, and the shielding space formed by the bottom wall, ceiling, first side wall, second side wall, third side wall and fourth side wall of the shielding device shields the neutron generator.

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