Targets used in particle beam generators

Abstract

The present invention provides a target for use in a neutron capture therapy system and a particle beam generator, which can improve the heat dissipation performance of the target, reduce foaming, and extend the service life of the target. The neutron capture therapy system of the present invention includes a neutron generator and a beam shaper, the neutron generator includes an accelerator and a target, the charged particle beam accelerated by the accelerator acts on the target to generate a neutron beam, the target includes an action layer that acts on the charged particle beam to generate a neutron beam, a foaming suppression layer that suppresses foaming caused by the charged particle beam, a first heat dissipation layer and a second heat dissipation layer, the first heat dissipation layer directly and quickly conducts the amount of heat accumulated in the action layer to the second heat dissipation layer, and the second heat dissipation layer dissipates the amount of heat by a cooling medium.

Description

[Technical Field]

[0001] The present invention relates to targets for use in radiation irradiation systems, and more particularly to targets for use in particle beam generators. [Background technology]

[0002] With the development of atomic science, radiation therapy, such as cobalt-60, linear accelerators, and electron beams, has become one of the main means of cancer treatment. However, conventional photon or electron therapy kills tumor cells due to the limitations of the physical conditions of the radiation itself, while damaging many normal tissues in the beam path. In addition, tumor cells have different degrees of sensitivity to radiation, so conventional radiation therapy is not very effective in treating malignant tumors with high radiation resistance (e.g., glioblastoma multiforme and melanoma).

[0003] To reduce radiation damage to normal tissues surrounding tumors, the concept of targeted therapy in chemotherapy has been applied to radiotherapy. Furthermore, for tumor cells with high radiation resistance, radiation sources with high relative biological effectiveness (RBE), such as proton therapy, heavy ion therapy, and neutron capture therapy, are currently being actively developed. Among these, neutron capture therapy combines the above two concepts. For example, in boron neutron capture therapy, boron-containing drugs specifically collect in tumor cells, and, combined with highly precise neutron beam control, this provides a better cancer treatment option than conventional radiation.

[0004] In accelerator-based boron neutron capture therapy, a proton beam is accelerated by the accelerator to an energy sufficient to overcome the Coulomb repulsion between atomic nuclei in the target, causing a nuclear reaction with the target to generate neutrons. In the process of generating neutrons, the target is irradiated with an accelerated proton beam at a very high energy level, which causes a significant rise in temperature and makes the metal parts prone to foaming, thereby affecting the service life of the target.

[0005] Therefore, it is necessary to provide a new technical means to solve the above technical problems. Summary of the Invention

[0006] In order to solve the above problems, according to a first aspect of the present invention, a target used in a neutron beam generator includes an action layer that interacts with a charged particle beam to generate a neutron beam, a foaming suppression layer that is located behind the action layer along the incident direction of the charged particle beam and that can suppress foaming caused by the charged particle beam, a heat dissipation layer that conducts heat accumulated in the target to the outside, and a thermal conduction layer that conducts the heat in the action layer to the heat dissipation layer.

[0007] Preferably, the thermally conductive layer is disposed between the working layer and the expansion-inhibiting layer and connected to the heat dissipation layer. Since the expansion-inhibiting layer has poor heat dissipation performance and cannot effectively conduct the heat accumulated in the working layer to the heat dissipation layer, the thermally conductive layer is disposed to directly and quickly conduct the heat accumulated in the working layer to the heat dissipation layer, and the heat dissipation layer uses a cooling medium to discharge the heat, thereby lowering the target temperature, preventing deformation due to excessively high target temperature, and extending the service life of the target. Since heat is basically not conducted by the expansion-inhibiting layer, there is no need to consider the thermal conductivity of the expansion-inhibiting layer, and only the foaming prevention properties need to be considered.

[0008] Furthermore, the thermally conductive layer and the heat dissipation layer surround the expansion suppression layer, and an accommodation space for accommodating the expansion suppression layer is formed in the heat dissipation layer or the thermally conductive layer.

[0009] Furthermore, the storage space includes a bottom surface and a side wall connected to the bottom surface, and the expansion suppression layer has a top surface in contact with the bottom surface and an outer wall in contact with the side wall.

[0010] Preferably, the material of the working layer is Li, its compound or its alloy, the material of the heat dissipation layer and the heat conduction layer is Cu, its compound or its alloy, and the material of the foam suppression layer is Ta, its compound or its alloy.

[0011] Preferably, the target is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the action layer to the central axis is smaller than the maximum distance from the expansion suppression layer to the central axis, and the maximum distance from the expansion suppression layer to the central axis is smaller than the maximum distance from the heat dissipation layer to the central axis and the maximum distance from the thermal conduction layer to the central axis.

[0012] Preferably, the target further includes an anti-oxidation layer that prevents oxidation of the working layer and isolates the working layer from air, and the anti-oxidation layer, working layer, thermal conduction layer, foam suppression layer and heat dissipation layer are arranged in order along the incident direction of the charged particle beam.

[0013] Furthermore, the working layer, the heat conduction layer and the foaming inhibition layer are sequentially processed onto the heat dissipation layer in a film-forming manner, and the antioxidant layer is either processed onto the working layer in a film-forming manner or is a polymer film and processed onto the working layer by a film coating process.

[0014] Furthermore, the anti-oxidation layer is made of Al, Al2O3 or polyimide, and the anti-oxidation layer eliminates the need for special storage of the target and allows it to be exposed to air, which is very convenient, especially when installing and replacing the target. The anti-oxidation layer can also prevent by-products in the working layer from overflowing from the target, and it is also considered that the material of the anti-oxidation layer is not easily corroded by the working layer and can reduce the loss of the incident proton beam and the heat generated by the proton beam.

[0015] Furthermore, the polyimide has the following molecular structure: [ka]

[0016] According to a second aspect of the present invention, a target for use in a particle beam generator includes an operating layer for generating the particle beam, an expansion suppression layer for suppressing foaming in the operating layer during the generation of the particle beam, and first and second heat dissipation layers for conducting heat accumulated in the target to the outside, the expansion suppression layer being disposed between the first and second heat dissipation layers and conducting the heat in the operating layer to the second heat dissipation layer. Because the expansion suppression layer has poor heat dissipation performance and cannot effectively conduct the heat accumulated in the operating layer to the heat dissipation layer, the first heat dissipation layer is disposed to directly and quickly conduct the heat accumulated in the operating layer to the second heat dissipation layer, and the second heat dissipation layer uses a cooling medium to discharge the heat, thereby lowering the temperature of the target, preventing deformation due to excessive target temperature, and extending the service life of the target. Because heat is not essentially conducted by the expansion suppression layer, the thermal conductivity of the expansion suppression layer is not required, and only the foam prevention properties need to be considered.

[0017] Preferably, the first heat dissipation layer is placed between the working layer and the foaming suppression layer and connected to the second heat dissipation layer, thereby providing a large contact area with the working layer and enabling heat to be quickly conducted to the second heat dissipation layer.

[0018] Furthermore, the first heat dissipation layer and the second heat dissipation layer surround the expansion-inhibiting layer, and a storage space for storing the expansion-inhibiting layer is formed in the first heat dissipation layer or the second heat dissipation layer. Because heat is not basically conducted by the expansion-inhibiting layer, it is not necessary to consider the thermal conductivity of the expansion-inhibiting layer, and only the foam-inhibiting property needs to be considered.

[0019] Furthermore, the storage space includes a bottom surface and a side wall connected to the bottom surface, and the expansion suppression layer has a top surface in contact with the bottom surface and an outer wall in contact with the side wall.

[0020] Preferably, the target further includes an antioxidant layer for preventing oxidation of the working layer, and the antioxidant layer, working layer, first heat dissipation layer, foam suppression layer, and second heat dissipation layer are disposed in this order. The antioxidant layer eliminates the need for special storage of the target and allows it to be exposed to air, which is particularly convenient when installing and replacing the target. The antioxidant layer also prevents by-products in the working layer from spilling out of the target. The material of the antioxidant layer is also considered to be less susceptible to corrosion by the working layer and to reduce the loss of the incident proton beam and the heat generated by the proton beam.

[0021] Furthermore, the working layer, the first heat-dissipating layer and the foam-inhibiting layer are sequentially processed onto the second heat-dissipating layer in a film-forming manner, and the antioxidant layer is either processed onto the working layer in a film-forming manner or is a polymer film and processed onto the working layer by a film-coating process.

[0022] Furthermore, the target is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the action layer to the central axis is smaller than the maximum distance from the foaming suppression layer to the central axis and the maximum distance from the antioxidant layer to the central axis, and the maximum distance from the foaming suppression layer to the central axis is smaller than the maximum distance from the first heat dissipation layer to the central axis and the maximum distance from the second heat dissipation layer to the central axis.

[0023] Furthermore, the material of the action layer is Li, its compound or its alloy, the material of the first heat dissipation layer and the second heat dissipation layer is Cu, its compound or its alloy, the material of the foaming suppression layer is Ta, its compound or its alloy, and the material of the anti-oxidation layer is Al, Al2O3 or polyimide.

[0024] Furthermore, the polyimide has the following molecular structure: [ka]

[0025] According to a third aspect of the present invention, a target for use in a particle beam generator includes an active layer for generating the particle beam, an expansion suppression layer for suppressing expansion of the active layer during the particle beam generation process, and first and second heat dissipation layers for conducting heat accumulated in the target to the outside, the first and second heat dissipation layers being connected to each other and disposed between the active layer and the expansion suppression layer. Because the expansion suppression layer has poor heat dissipation performance and cannot effectively conduct the heat accumulated in the active layer to the heat dissipation layer, the first heat dissipation layer is disposed to directly and quickly conduct the heat accumulated in the active layer to the second heat dissipation layer, and the second heat dissipation layer uses a cooling medium to discharge the heat, thereby reducing the temperature of the target, preventing deformation due to excessive target temperature, and extending the service life of the target. The first heat dissipation layer has a large contact area with the active layer and can quickly conduct heat to the second heat dissipation layer.

[0026] Preferably, the first heat dissipation layer and the second heat dissipation layer surround the expansion-inhibiting layer, and a storage space for storing the expansion-inhibiting layer is formed in the first heat dissipation layer or the second heat dissipation layer. Because heat is not basically conducted by the expansion-inhibiting layer, it is not necessary to consider the thermal conductivity of the expansion-inhibiting layer, and only the foam-inhibiting property needs to be considered.

[0027] Preferably, the target further includes an antioxidant layer for preventing oxidation of the working layer, and the antioxidant layer, working layer, first heat dissipation layer, foam suppression layer, and second heat dissipation layer are disposed in this order. The antioxidant layer eliminates the need for special storage of the target and allows it to be exposed to air, which is particularly convenient when installing and replacing the target. The antioxidant layer also prevents by-products in the working layer from spilling out of the target. The material of the antioxidant layer is also considered to be less susceptible to corrosion by the working layer and to reduce the loss of the incident proton beam and the heat generated by the proton beam.

[0028] Furthermore, the working layer, the first heat-dissipating layer and the foam-inhibiting layer are sequentially processed onto the second heat-dissipating layer in a film-forming manner, and the antioxidant layer is either processed onto the working layer in a film-forming manner or is a polymer film and processed onto the working layer by a film-coating process.

[0029] Furthermore, the target is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the action layer to the central axis is smaller than the maximum distance from the foaming suppression layer to the central axis and the maximum distance from the antioxidant layer to the central axis, and the maximum distance from the foaming suppression layer to the central axis is smaller than the maximum distance from the first heat dissipation layer to the central axis and the maximum distance from the second heat dissipation layer to the central axis.

[0030] Furthermore, the material of the action layer is Li, its compound or its alloy, the material of the first heat dissipation layer and the second heat dissipation layer is Cu, its compound or its alloy, the material of the foaming suppression layer is Ta, its compound or its alloy, and the material of the anti-oxidation layer is Al, Al2O3 or polyimide.

[0031] Furthermore, the polyimide has the following molecular structure: [ka]

[0032] According to a fourth aspect of the present invention, a target used in a particle beam generator includes an anti-oxidation layer which is a polymer film, an action layer which reacts with an incident charged particle beam to generate a neutron beam, an expansion suppression layer which can suppress expansion of the action layer during the process of generating the particle beam, and a heat dissipation layer. The anti-oxidation layer isolates the action layer from air, so that the target does not need to be specially stored and can be exposed to air, which is very convenient, especially when installing and replacing the target. The anti-oxidation layer can also prevent by-products in the action layer from overflowing from the target.

[0033] Preferably, the material of the polymer film is a polyimide having the following molecular structure: [ka]

[0034] Preferably, the antioxidant layer is applied to the working layer by a film coating process, and the thickness of the antioxidant layer is greater than 5 nm.

[0035] Preferably, the target further includes a thermally conductive layer. Because the expansion-inhibiting layer has poor heat dissipation performance and cannot effectively conduct the heat accumulated in the working layer to the heat dissipation layer, the thermally conductive layer is installed to directly and quickly conduct the heat accumulated in the working layer to the heat dissipation layer, and the heat dissipation layer uses a cooling medium to discharge the heat, thereby lowering the temperature of the target, preventing deformation due to excessively high target temperature, and extending the service life of the target. The expansion-inhibiting layer is installed between the heat dissipation layer and the thermally conductive layer, and the thermally conductive layer is connected to the heat dissipation layer, and an accommodation space for accommodating the expansion-inhibiting layer is formed in the heat dissipation layer or the thermally conductive layer. Because heat is not essentially conducted by the expansion-inhibiting layer, it is not necessary to consider the thermal conductivity of the expansion-inhibiting layer, and only the foam-preventing properties need to be considered.

[0036] The heat conductive layer has a thickness of 5 μm to 50 μm, and the expansion suppression layer has a top surface in contact with the bottom surface and an outer wall in contact with the side wall.

[0037] Furthermore, the target is flat and has a center perpendicular to the surface of the plate. shaft It has a line and a center shaft In the same radial direction perpendicular to the line, the maximum distance from the working layer to the central axis is smaller than the maximum distance from the expansion suppression layer to the central axis, and the maximum distance from the expansion suppression layer to the central axis is smaller than the maximum distance from the thermal conduction layer to the central axis and the maximum distance from the heat dissipation layer to the central axis.

[0038] Furthermore, the working layer, the heat conduction layer and the foaming inhibiting layer are sequentially processed into the heat dissipation layer in a film-forming manner.

[0039] The working layer is made of Li, its compound, or its alloy, the thermal conduction layer and the heat dissipation layer are made of Cu, its compound, or its alloy, and the foaming suppression layer is made of Ta, its compound, or its alloy. The working layer has a thickness of 49 μm to 189 μm, sufficiently reacts with a proton beam with an energy of 2.2 MeV to 3 MeV, reduces contamination by gamma rays, and does not cause energy accumulation due to an excessive thickness that affects the heat dissipation performance of the target. The foaming suppression layer suppresses foaming caused by the charged particle beam and has a thickness of 5 μm to 50 μm, and quickly diffuses hydrogen generated in the target by the incident charged particle beam to reduce the concentration of hydrogen or release the hydrogen to the outside, effectively suppressing foaming caused by the incident charged particle beam, thereby avoiding or reducing deformation of the target due to foaming and extending the service life of the target.

[0040] According to a fifth aspect of the present invention, a substrate of a target used in a particle beam generating device includes an expansion suppression layer capable of suppressing expansion of the target during the process of generating the particle beam, and a first heat dissipation layer and a second heat dissipation layer for conducting heat accumulated in the target to the outside, wherein the expansion suppression layer is disposed between the first heat dissipation layer and the second heat dissipation layer, and the first heat dissipation layer is connected to the second heat dissipation layer.

[0041] Preferably, the first and second heat dissipation layers surround the expansion-inhibiting layer, and an accommodation space for accommodating the expansion-inhibiting layer is formed in the first or second heat dissipation layer. Further, the accommodation space includes a bottom surface and a sidewall connected to the bottom surface, and the expansion-inhibiting layer has a top surface in contact with the bottom surface and an outer wall in contact with the sidewall.

[0042] Preferably, the first heat-dissipating layer and the expansion-inhibiting layer are sequentially processed onto the second heat-dissipating layer in a film-forming manner.

[0043] Preferably, the substrate is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the expansion suppression layer to the central axis is smaller than the maximum distance from the first heat dissipation layer to the central axis and the maximum distance from the second heat dissipation layer to the central axis.

[0044] Preferably, the material of the first heat dissipation layer and the second heat dissipation layer is Cu, a compound thereof, or an alloy thereof, and the material of the expansion suppression layer is Ta, a compound thereof, or an alloy thereof.

[0045] A neutron capture therapy system according to a sixth aspect of the present invention includes a neutron generator and a beam shaper, the neutron generator including an accelerator and a target, a charged particle beam accelerated by the accelerator interacts with the target to generate a neutron beam, the beam shaper including a reflector, a moderator, a thermal neutron absorber, a radiation shield, and a beam outlet, the moderator moderating neutrons generated by the target to an epithermal neutron energy region, the reflector surrounding the moderator and guiding stray neutrons to the moderator to improve the intensity of the epithermal neutron beam, and the thermal neutron absorber preventing unnecessary radiation from reaching superficial normal tissue during treatment. The target absorbs thermal neutrons to avoid giving a dose to normal tissue in a non-irradiated area, and the radiation shield is installed around the beam exit and blocks escaping neutrons and photons to reduce the dose to normal tissue in a non-irradiated area. The target includes: an action layer that interacts with the charged particle beam to generate the neutron beam; an expansion suppression layer that is located behind the action layer along the incident direction of the charged particle beam and can suppress foaming caused by the charged particle beam; a heat dissipation layer that is located behind the expansion suppression layer along the incident direction of the charged particle beam and conducts heat accumulated in the target to the outside; and a thermal conduction layer that conducts the heat of the action layer to the heat dissipation layer. Since the heat dissipation performance of the foaming suppression layer is low and the heat accumulated in the working layer cannot be effectively conducted to the heat dissipation layer, a heat conduction layer is installed to directly and quickly conduct the heat accumulated in the working layer to the heat dissipation layer, and the heat is discharged by a cooling medium in the heat dissipation layer, thereby lowering the temperature of the target, preventing deformation due to excessively high target temperature, and extending the service life of the target.

[0046] Preferably, the thermal conduction layer is installed between the working layer and the foaming suppression layer and connected to the heat dissipation layer, so that the contact area with the working layer is large and heat can be quickly conducted to the heat dissipation layer.

[0047] Preferably, the heat dissipation layer and the heat conduction layer surround the expansion suppression layer, and the heat conduction layer is connected to the heat dissipation layer. Because heat is not generally conducted by the expansion suppression layer, it is not necessary to consider the thermal conductivity of the expansion suppression layer, and only the expansion prevention properties need to be considered. Furthermore, a storage space for storing the expansion suppression layer is formed in the heat dissipation layer or the heat conduction layer. Furthermore, the storage space includes a bottom surface and a sidewall connected to the bottom surface, and the expansion suppression layer has a top surface in contact with the bottom surface and an outer wall in contact with the sidewall.

[0048] Preferably, the foaming suppression layer is made of a material that suppresses foaming, for example, a material having a hydrogen diffusion coefficient of 10E-6 cm at 200°C. 2 / s or more, and the material of the foaming suppression layer contains at least one of Nb, Ta, Pd, V, alloys and compounds thereof, and the heat dissipation layer and heat conduction layer are made of a heat conduction material, and the material of the heat dissipation layer and heat conduction layer contains at least one of Cu, Fe, Al, alloys and compounds thereof.

[0049] Preferably, the target further includes an anti-oxidation layer for preventing oxidation of the working layer, which is located in front of the working layer along the incident direction of the charged particle beam. The anti-oxidation layer eliminates the need for special storage of the target and allows it to be exposed to air, which is very convenient, especially when installing and replacing the target. The anti-oxidation layer can also prevent by-products in the working layer from overflowing from the target. At the same time, it is considered that the material of the anti-oxidation layer is not easily corroded by the working layer and can reduce the loss of the incident proton beam and the heat generated by the proton beam. Furthermore, the material of the anti-oxidation layer includes at least one of Al, Ti, alloys and compounds thereof, and stainless steel.

[0050] Furthermore, the anti-oxidation layer, the working layer, the heat conduction layer, the foaming suppression layer and the heat dissipation layer are arranged in this order along the incident direction of the charged particle beam.

[0051] Furthermore, the working layer, the thermally conductive layer, and the foaming suppression layer are sequentially processed onto the heat dissipation layer in a film-forming manner, and the antioxidant layer is either processed onto the working layer in a film-forming manner or is a polymer film and processed onto the working layer by a film-coating process. Furthermore, the materials of the antioxidant layer, the working layer, the thermally conductive layer, and the foaming suppression layer are sequentially evaporated into gas in a vacuum environment and deposited onto the heat dissipation layer, thereby enabling precise control of the thickness of each target layer.

[0052] Furthermore, the target is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the action layer to the central axis is smaller than the maximum distance from the foaming suppression layer to the central axis and the maximum distance from the anti-oxidation layer to the central axis, and the maximum distance from the foaming suppression layer to the central axis is smaller than the maximum distance from the heat dissipation layer to the central axis and the maximum distance from the thermal conduction layer to the central axis.

[0053] Furthermore, the material of the working layer is Li, its compound or its alloy, the charged particle beam is a proton beam, the material of the heat dissipation layer and the heat conduction layer is Cu, its compound or its alloy, the material of the foaming suppression layer is Ta, its compound or its alloy, and the material of the anti-oxidation layer is Al, Al2O3 or polyimide.

[0054] Furthermore, the polyimide has the following molecular structure: [ka]

[0055] Furthermore, the proton beam has an energy of 2.2 MeV to 3 MeV, and can generate a high interaction cross section with the lithium target without generating too many fast neutrons, resulting in a higher quality beam. The interaction layer has a thickness of 49 μm to 189 μm, and can react sufficiently with protons, reducing contamination by gamma rays and preventing energy accumulation due to an excessive thickness from affecting the heat dissipation performance of the target. The foaming suppression layer has a thickness of 5 μm to 50 μm, and can rapidly diffuse hydrogen generated in the target by the incident charged particle beam, reducing the concentration of hydrogen or releasing the hydrogen to the outside, effectively suppressing foaming caused by the incident charged particle beam, thereby avoiding or reducing deformation of the target due to foaming and extending the service life of the target. The thickness of the oxidation prevention layer is greater than 5 nm, and the thickness of the thermal conduction layer is 5 μm to 50 μm. The service life of the target is 200 mA-h or more.

[0056] Preferably, the neutron capture therapy system further includes a treatment couch and a collimator, wherein the neutron beam generated by the neutron generator is irradiated onto a patient on the treatment couch through the beam shaper, and a radiation shielding device is installed between the patient and the beam outlet to block radiation of the beam exiting the beam outlet from reaching normal tissues of the patient, the collimator is installed after the beam outlet to collect the neutron beam, and a first cooling pipe and a second cooling pipe are installed within the beam shaper, the heat dissipation layer of the target has a cooling inlet, a cooling outlet, and a zigzag cooling passage installed between the cooling inlet and the cooling outlet, one end of the first cooling pipe and the second cooling pipe is connected to the cooling inlet and the cooling outlet of the target, respectively, and the other end is connected to an external cooling source, and the curved geometry of the zigzag cooling passage is a continuously curved smooth curve or curve segments or straight line segments connected end to end in sequence, and the continuously curved smooth curve is a sinusoidal function. The zigzag passage extends the flow path, increases the contact area between the heat-conducting wall surface and the cooling medium, and increases the heat dissipation surface. It also forms a secondary flow, improves the mixing effect, and improves the heat conduction capacity and heat dissipation effect, which helps to extend the service life of the target. The cooling passage can be formed using a continuously curved, smooth curve, such as a sinusoidal function, to further reduce the flow resistance due to the flow path.

[0057] Furthermore, a target is located within the beam shaper, the accelerator has an acceleration tube that accelerates the charged particle beam, the acceleration tube extends through the beam shaper along the direction of the charged particle beam and passes through the reflector and the decelerator in order, the target is installed within the decelerator and is located at an end of the acceleration tube, and the first and second cooling pipes are installed between the acceleration tube and the reflector and the decelerator.

[0058] A neutron capture therapy system according to a seventh aspect of the present invention includes a neutron generator and a beam shaper, the neutron generator including an accelerator and a target, a charged particle beam accelerated by the accelerator interacts with the target to generate a neutron beam, the beam shaper including a reflector, a moderator, a thermal neutron absorber, a radiation shield, and a beam outlet, the moderator moderating neutrons generated by the target to an epithermal neutron energy region, the reflector surrounding the moderator and guiding stray neutrons to the moderator to improve the intensity of the epithermal neutron beam, and the thermal neutron absorber preventing unnecessary radiation from reaching superficial normal tissue during treatment. The target includes an active layer that interacts with the charged particle beam to generate the neutron beam, an expansion suppression layer that suppresses expansion of the active layer during the neutron beam generation process, and a heat dissipation layer. The active layer has a thickness of 49 μm to 189 μm, can sufficiently react with the proton beam, reduces contamination by gamma rays, and is not too thick, causing energy accumulation and affecting the heat dissipation performance of the target.

[0059] Preferably, the thickness of the working layer is 97 μm.

[0060] Preferably, the target further includes a thermally conductive layer disposed between the working layer and the expansion suppression layer and connected to the heat dissipation layer for conducting heat from the working layer to the heat dissipation layer. Because the expansion suppression layer has poor heat dissipation performance and cannot effectively conduct heat accumulated in the working layer to the heat dissipation layer, the thermally conductive layer is provided to directly and quickly conduct the heat accumulated in the working layer to the heat dissipation layer, and the heat dissipation layer dissipates the heat using a cooling medium, thereby lowering the target temperature, preventing deformation due to excessive target temperature, and extending the target's service life. Furthermore, the thermally conductive layer has a thickness of 5 μm to 50 μm, and the expansion suppression layer has a thickness of 5 μm to 50 μm. The expansion suppression layer rapidly diffuses hydrogen generated in the target by the incident charged particle beam, reducing the hydrogen concentration or releasing the hydrogen to the outside, effectively suppressing foaming caused by the incident charged particle beam, thereby avoiding or reducing foaming-related deformation of the target and extending the target's service life.

[0061] Preferably, the material of the working layer is Li, its compound or its alloy, and the charged particle beam has an energy of 2.2 MeV to 3 MeV, which can generate a high cross section of interaction with the lithium target while not generating excessive fast neutrons, resulting in a higher quality beam.

[0062] Furthermore, the material of the heat dissipation layer and the heat conduction layer is Cu, a compound thereof, or an alloy thereof, and the material of the foaming suppression layer is Ta, a compound thereof, or an alloy thereof.

[0063] Furthermore, the working layer, the heat conduction layer and the foaming inhibiting layer are sequentially processed onto the heat dissipation layer in a film-forming manner.

[0064] Furthermore, the target is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the action layer to the central axis is smaller than the maximum distance from the expansion suppression layer to the central axis, and the maximum distance from the expansion suppression layer to the central axis is smaller than the maximum distance from the heat dissipation layer to the central axis and the maximum distance from the thermal conduction layer to the central axis.

[0065] Preferably, the target further comprises an antioxidant layer that isolates the working layer from the air and has a thickness of more than 5 nm. The antioxidant layer eliminates the need for special storage of the target and allows it to be exposed to air, which is particularly convenient when installing and replacing the target. The antioxidant layer can also prevent by-products in the working layer from overflowing from the target. It is also considered that the material of the antioxidant layer is not easily corroded by the working layer and can reduce the loss of the incident proton beam and the heat generated by the proton beam. The antioxidant layer is made of Al2O3 or polyimide and processed onto the working layer in a film-forming manner, or is a polymer film and processed onto the working layer by a film-coating process.

[0066] According to an eighth aspect of the present invention, a target used in a particle beam generator includes an anti-oxidation layer, a working layer, a foaming suppression layer, and a heat dissipation layer, arranged in this order along the incident direction of a charged particle beam. The working layer interacts with the charged particle beam to generate a neutron beam, has a thickness of 49 μm to 189 μm, can sufficiently react with protons, reduces contamination by gamma rays, and is not too thick to cause energy accumulation and affect the heat dissipation performance of the target. The anti-oxidation layer isolates the working layer from air and has a thickness of more than 5 nm. Due to the anti-oxidation layer, the target does not need to be specially stored and can be exposed to air, which is very convenient, especially when installing and replacing the target. The layer can further prevent by-products in the working layer from overflowing from the target, and the material of the anti-oxidation layer is not easily corroded by the working layer and can reduce the loss of the incident proton beam and the heat generated by the proton beam. The foaming suppression layer suppresses foaming caused by the charged particle beam and has a thickness of 5 μm to 50 μm. It quickly diffuses hydrogen generated in the target by the incident charged particle beam, reducing the concentration of hydrogen or releasing the hydrogen to the outside, effectively suppressing foaming caused by the incident charged particle beam, thereby avoiding or reducing deformation of the target due to foaming and extending the service life of the target.

[0067] Preferably, the charged particle beam has an energy of 2.2 MeV to 3 MeV, which can generate a high cross section of interaction with the lithium target, and does not generate excessive fast neutrons, resulting in a higher quality beam.

[0068] Preferably, the target further includes a thermally conductive layer having a thickness of 5 μm to 50 μm, which conducts the heat from the working layer to the heat dissipation layer. Because the expansion-inhibiting layer has poor heat dissipation performance and cannot effectively conduct the heat accumulated in the working layer to the heat dissipation layer, the thermally conductive layer is provided to directly and quickly conduct the heat accumulated in the working layer to the heat dissipation layer, and the heat dissipation layer uses a cooling medium to discharge the heat, thereby lowering the target temperature, preventing deformation due to excessive target temperature, and extending the service life of the target.

[0069] Furthermore, the expansion suppression layer is disposed between the heat dissipation layer and the heat conduction layer, the heat conduction layer is connected to the heat dissipation layer, and a space for accommodating the expansion suppression layer is formed in the heat dissipation layer or the heat conduction layer. Because heat is not basically conducted by the expansion suppression layer, it is not necessary to consider the thermal conductivity of the expansion suppression layer, and only the foam prevention property needs to be considered.

[0070] Furthermore, the material of the working layer is Li, its compound or its alloy, the material of the heat dissipation layer and the heat conduction layer is Cu, its compound or its alloy, the material of the foaming suppression layer is Ta, its compound or its alloy, and the anti-oxidation layer is made of Al2O3 or polyimide.

[0071] Furthermore, the working layer, the heat conduction layer and the foaming inhibition layer are sequentially processed onto the heat dissipation layer in a film-forming manner, and the antioxidant layer is either processed onto the working layer in a film-forming manner or is a polymer film and processed onto the working layer by a film coating process.

[0072] Furthermore, the target is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the action layer to the central axis is smaller than the maximum distance from the foaming suppression layer to the central axis and the maximum distance from the anti-oxidation layer to the central axis, and the maximum distance from the foaming suppression layer to the central axis is smaller than the maximum distance from the heat dissipation layer to the central axis and the maximum distance from the thermal conduction layer to the central axis.

[0073] A ninth aspect of the present invention provides a processing device for a target used in a particle beam generator, the target including an active layer for generating the particle beam, an expansion suppression layer for suppressing expansion of the active layer during the particle beam generation process, and a heat dissipation layer for conducting heat accumulated in the target to the outside, the processing device including a vacuum chamber, an exhaust device, an evaporation source, a support frame, and a heating device, the exhaust device exhausts air from the vacuum chamber to form a vacuum environment, the evaporation source sequentially evaporates materials of the expansion suppression layer and the active layer into gas in the vacuum chamber, the support frame is used to place the heat dissipation layer, and the heating device heats the heat dissipation layer so that the gas material is sequentially deposited on the surface of the heat dissipation layer facing the evaporation source. Using this processing device, the thickness of each layer of the target can be accurately controlled.

[0074] Preferably, the target further includes an anti-oxidation layer that prevents oxidation of the working layer, and the evaporation source evaporates the anti-oxidation layer into the gas after evaporating the working layer into the gas.

[0075] Preferably, the target further includes a thermally conductive layer that conducts heat from the working layer to the heat dissipation layer, and the evaporation source evaporates the foaming suppression layer into a gas, then evaporates the thermally conductive layer into a gas, and then evaporates the working layer into a gas. Because the foaming suppression layer has poor heat dissipation performance and cannot effectively conduct the heat accumulated in the working layer to the heat dissipation layer, the thermally conductive layer is installed to directly and quickly conduct the heat accumulated in the working layer to the heat dissipation layer, and the heat dissipation layer uses a cooling medium to dissipate the heat, thereby lowering the target temperature, preventing deformation due to excessive target temperature, and extending the service life of the target.

[0076] Furthermore, the processing device further includes a film thickness detection device for detecting the thickness of the working layer and the foaming suppression layer and controlling the gas deposition rate.

[0077] A tenth aspect of the present invention provides a method for processing a target for use in a particle beam generator, the target including a working layer for generating the particle beam, an expansion suppression layer for suppressing foaming of the working layer during the particle beam generation process, a heat dissipation layer for conducting heat accumulated in the target to the outside, and a thermally conductive layer for conducting the heat from the working layer to the heat dissipation layer, the processing method including sequentially processing the expansion suppression layer, the thermally conductive layer, and the working layer by forming a film on the heat dissipation layer. Because the expansion suppression layer has poor heat dissipation performance and cannot effectively conduct the heat accumulated in the working layer to the heat dissipation layer, the thermally conductive layer is provided to directly and quickly conduct the heat accumulated in the working layer to the heat dissipation layer, and the heat dissipation layer uses a cooling medium to dissipate the heat, thereby reducing the temperature of the target, preventing deformation due to excessive target temperature, and extending the service life of the target. The processing method also allows for accurate control of the thickness of each layer of the target.

[0078] Preferably, the target further includes an antioxidant layer that prevents oxidation of the working layer, and the processing method includes coating a film-like antioxidant layer on the working layer or processing the antioxidant layer on the working layer in a film-forming manner.

[0079] Preferably, the film is formed by physical vapor deposition, sputtering, thermal welding or atomic layer deposition.

[0080] An eleventh aspect of the present invention provides a method for processing a target used in a neutron beam generator, wherein the target includes an action layer that interacts with a charged particle beam to generate a neutron beam, an anti-oxidation layer that is located in front of the action layer along the incident direction of the charged particle beam and prevents oxidation of the action layer, an expansion suppression layer that is located behind the action layer along the incident direction of the charged particle beam and can suppress expansion caused by the charged particle beam, and a heat dissipation layer that is located behind the expansion suppression layer along the incident direction of the charged particle beam and conducts heat accumulated in the target to the outside, and the anti-oxidation layer and the action layer are processed by different methods.

[0081] Preferably, the target further includes a heat conduction layer for conducting heat from the working layer to the heat dissipation layer, and the expansion suppression layer, heat conduction layer, and working layer are sequentially processed into the heat dissipation layer in a film-forming manner. Furthermore, the materials of the expansion suppression layer, heat conduction layer, and working layer are sequentially evaporated into gas in a vacuum environment and deposited on the heat dissipation layer, thereby enabling precise control of the thickness of each layer of the target.

[0082] Preferably, the anti-oxidation layer is a polymer film, which is processed into the working layer by a film coating process, and the use of a polymer film makes it easy to assemble and low cost.

[0083] In the target used in the neutron capture therapy system and particle beam generator of the present invention, a first heat dissipation layer is installed to directly and quickly conduct the heat accumulated in the working layer to the second heat dissipation layer, and the second heat dissipation layer uses a cooling medium to dissipate the heat, thereby lowering the temperature of the target, preventing deformation due to excessively high target temperature, and extending the service life of the target. [Brief explanation of the drawings]

[0084] [Figure 1] 1 is a schematic diagram of a neutron capture therapy system in accordance with an embodiment of the present invention. [Figure 2] 1 is a schematic diagram of a target according to an embodiment of the present invention. [Figure 3] FIG. 3 is an exploded view of the target in FIG. 2. [Figure 4] FIG. 3 is a schematic diagram of a first example of a heat dissipation layer of the target in FIG. 2. [Figure 5] FIG. 5 is a schematic diagram of a first plate of the heat dissipation layer in FIG. [Figure 6] FIG. 3 is a schematic diagram of a second embodiment of the heat dissipation layer of the target in FIG. 2. [Figure 7] FIG. 7 is a schematic diagram of a first plate of the heat dissipation layer in FIG. 6. [Figure 8] 1 is a schematic diagram of a target processing device according to an embodiment of the present invention. [Figure 9] 1 is a flowchart of a target processing method according to an embodiment of the present invention. [Figure 10] 10 shows simulated neutron yields from bombardment of lithium targets of different thicknesses with 2.2 MeV protons in an embodiment of the present invention. [Figure 11] 10 shows simulated neutron yields from bombardment of lithium targets of different thicknesses with 2.5 MeV protons in an embodiment of the present invention. [Figure 12] 10 shows simulated neutron yields from bombardment of lithium targets of different thicknesses with 3 MeV protons in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0085] The embodiments of the present invention will be described in more detail below with reference to the drawings, so that those skilled in the art can implement the invention by referring to the specification.

[0086] As shown in Fig. 1, the neutron capture therapy system in this embodiment is preferably a boron neutron capture therapy system 100, and includes a neutron generator 10, a beam shaper 20, a collimator 30, and a treatment table 40. The neutron generator 10 includes an accelerator 11 and a target T. The accelerator 11 accelerates charged particles (e.g., protons, deuterium nuclei, etc.) to generate a charged particle beam C such as a proton beam. The charged particle beam C is irradiated onto the target T and interacts with the target T to generate a neutron beam N. The target T is preferably a metal target. An appropriate nuclear reaction is selected depending on the required neutron yield and energy, the energy and current magnitude of the accelerated charged particles that can be provided, the physical and chemical properties of the metal target, etc., and commonly considered nuclear reactions include: 7 Li(p,n) 7 Be and 9 Be(p,n) 9B, and both of these reactions are endothermic. These two nuclear reactions have energy thresholds of 1.881 MeV and 2.055 MeV, respectively. Therefore, the ideal neutron source for boron neutron capture therapy is epithermal neutrons at the keV energy level. In theory, bombarding a metallic lithium target with protons slightly above the threshold energy can generate relatively low-energy neutrons, making them clinically usable without requiring significant moderation. However, the interaction cross-section between lithium (Li) and beryllium (Be) targets and protons at the threshold energy is not high, so to generate sufficient neutron flux, relatively high-energy protons are generally used to initiate nuclear reactions. An ideal target would have a high neutron yield, an energy distribution of the generated neutrons close to the epithermal neutron energy range (described in detail below), little generation of highly penetrating radiation, and be safe, inexpensive, easy to operate, and resistant to high temperatures. However, in practice, it is impossible to find a nuclear reaction that meets all of these requirements. As known to those skilled in the art, the target T may be made of alloys, compounds, or other materials of Li, Be, for example, Ta or W and their alloys, compounds, etc. The accelerator 11 may be a linear accelerator, a cyclotron, a synchrotron, or a synchrocyclotron.

[0087] The neutron beam N generated by the neutron generator 10 is sequentially irradiated onto a patient 200 on a treatment couch 40 through a beam shaper 20 and a collimator 30. The beam shaper 20 can adjust the beam quality of the neutron beam N generated by the neutron generator 10, and the collimator 30 collects the neutron beam N, so that the neutron beam N has high targetability during the treatment process.The beam shaper 20 further includes a reflector 21, a moderator 22, a thermal neutron absorber 23, a radiation shield 24, and a beam outlet 25. Since the energy spectrum of the neutrons generated by the neutron generator 10 is wide, it is necessary to reduce the content of other types of neutrons and photons as much as possible other than epithermal neutrons that meet the treatment needs to avoid causing damage to the operator or patient. Therefore, the neutrons emitted from the neutron generator 10 are passed through the moderator 22 to reduce the energy of fast neutrons (>40 keV). ) must be adjusted to the epithermal neutron energy region (0.5 eV to 40 keV), the moderator 22 is manufactured from a material that has a large cross section of interaction with fast neutrons and a small cross section of interaction with epithermal neutrons. In this embodiment, the moderator 22 is manufactured from at least one of D2O, AlF3, Fluental™, CaF2, Li2CO3, MgF2, and Al2O3, and the reflector 21 surrounds the moderator 22 and reflects neutrons that have passed through the moderator 22 and diffused to the surroundings into a neutron beam N to form a neutral beam. The reflector 21 is made of a material with high neutron reflectivity and improves the utilization rate of neutrons. In this embodiment, the reflector 21 is made of at least one of Pb and Ni. The moderator 22 has a thermal neutron (<0.5 eV) absorber 23 at the rear and is made of a material with a large cross section for interacting with thermal neutrons. In this embodiment, the thermal neutron absorber 23 is made of Li-6. The thermal neutron absorber 23 absorbs the thermal neutrons that have passed through the moderator 22, reducing the content of thermal neutrons in the neutron beam N and preventing unnecessary doses from being delivered to superficial normal tissues during treatment. As can be understood, the thermal neutron absorber may be integrated with the moderator, and the material of the moderator may include Li-6, and the radiation shielding body 24 is installed surrounding the beam outlet 25 to block neutrons and photons leaking from portions other than the beam outlet 25, and the material of the radiation shielding body 24 includes at least one of a photon shielding material and a neutron shielding material, and in this embodiment, the material of the radiation shielding body 24 includes lead (Pb) as a photon shielding material and polyethylene (PE) as a neutron shielding material. As can be understood, the beam shaper 20 may have other structures as long as it obtains an epithermal neutron beam required for treatment.The collimator 30 is installed behind the beam outlet 25, and the epithermal neutron beam emitted from the collimator 30 is irradiated onto the patient 200, passes through superficial normal tissue, and is then slowed down to thermal neutrons before reaching the tumor cells M; as can be understood, the collimator 30 may be removed or may have another structure, and the neutron beam is emitted from the beam outlet 25 and directly irradiated onto the patient 200. In this embodiment, a radiation shielding device 50 is further installed between the patient 200 and the beam outlet 25 to block radiation of the beam emitted from the beam outlet 25 to the patient's normal tissue; as can be understood, the radiation shielding device 50 may not be installed.

[0088] After patient 200 takes or is injected with a boron (B-10)-containing drug, the boron-containing drug is selectively collected in tumor cells M. The boron (B-10)-containing drug then utilizes its high thermal neutron capture cross section to generate two heavy charged particles, 4He and 7Li, through neutron capture and fission reactions with 10B(n,α)7Li. The two charged particles have an average energy of approximately 2.33 MeV and are characterized by high linear energy transfer (LET) and short range. The linear energy transfer and range of the α particle are 150 keV / μm and 8 μm, respectively, while the linear energy transfer and range of the 7Li heavy charged particle are 175 keV / μm and 5 μm. The total range of the two particles is approximately the size of a single cell. This limits radiation damage to the living body at the cellular level, achieving the goal of locally killing tumor cells without causing excessive damage to normal tissues.

[0089] The structure of the target T will be described in detail below with reference to FIGS.

[0090] The target T is installed between the accelerator 11 and the beam shaper 20. The accelerator 11 has an accelerating tube 111 that accelerates the charged particle beam C. In this embodiment, the accelerating tube 111 extends into the beam shaper 20 along the direction of the charged particle beam C and passes through the reflector 21 and the decelerator 22 in order. The target T is installed in the decelerator 22 and located at the end of the accelerating tube 111 to obtain a high-quality neutron beam.

[0091] The target T includes an active layer 12, a foaming suppression layer 13, a (first) heat dissipation layer 14, and a (second) heat conduction layer 15. The active layer 12 interacts with the charged particle beam C to generate a neutron beam, and in the process of generating neutrons, the target is irradiated with the accelerated charged particle beam C at a very high energy level, which causes foaming and a temperature rise in the target, thereby reducing the service life of the target. The expansion suppression layer 13 is located behind the working layer 12 in the direction of incidence of the charged particle beam C. It rapidly diffuses hydrogen generated in the target T by the incident charged particle beam C, reducing the concentration of hydrogen or releasing the hydrogen to the outside, effectively suppressing foaming caused by the incident charged particle beam C, thereby avoiding or reducing deformation of the target T due to foaming and extending the service life of the target. The expansion suppression layer 13 is made of a material that suppresses foaming, such as a material with a hydrogen diffusion coefficient of 10E-6 cm2 / s or more at 200°C. In one embodiment, the material of the expansion suppression layer 13 includes at least one of Nb, Ta, Pd, V, and alloys and compounds thereof. The heat dissipation layer 14 is located behind the expansion suppression layer 13 in the direction of incidence of the charged particle beam C. It conducts heat accumulated in the target and dissipates it through a cooling medium, thereby lowering the target temperature, preventing deformation due to excessive target temperature, and extending the service life of the target. Since the heat dissipation performance of the foaming suppression layer 13 is low, the heat accumulated in the working layer 12 cannot be effectively conducted to the heat dissipation layer 14. Therefore, the heat conduction layer 15 is provided to directly and quickly conduct the heat accumulated in the working layer 12 to the heat dissipation layer 14. The heat dissipation layer 14 and the heat conduction layer 15 are made of a thermally conductive material, and in one embodiment, the material of the heat dissipation layer 14 and the heat conduction layer 15 includes at least one of Cu, Fe, Al, alloys and compounds thereof.The thermally conductive layer 15 is placed between the working layer 12 and the expansion-inhibiting layer 13 and is connected to the heat dissipation layer 14; that is, the expansion-inhibiting layer 13 is placed between the heat dissipation layer 14 and the thermally conductive layer 15, which are connected to each other. With this arrangement, the thermally conductive layer 15 has a large contact area with the working layer 12 and can quickly conduct heat to the heat dissipation layer 14. Since heat is basically not conducted by the expansion-inhibiting layer 13, there is no need to consider the thermal conductivity of the expansion-inhibiting layer 13; only the anti-foaming properties need to be considered. As shown in FIG. 3, in this embodiment, the heat dissipation layer 14 and the heat conduction layer 15 surround the expansion suppression layer 13, and the heat conduction layer 15 forms an accommodating space 151 for accommodating the expansion suppression layer 13, the accommodating space 151 including a bottom surface 1511 and a side wall 1512 connected to the bottom surface 1511, and the expansion suppression layer 13 has a top surface 131 in contact with the bottom surface 1511 and an outer wall 132 in contact with the side wall 1512. As can be understood, the accommodating space may be formed by the heat dissipation layer, or may be formed by both the heat conduction layer and the heat dissipation layer. The target T may further include an anti-oxidation layer 16 for preventing oxidation of the working layer 12. The anti-oxidation layer 16 is located in front of the working layer 12 along the incident direction of the charged particle beam C. The anti-oxidation layer 16 and the thermal conductive layer 15 seal the working layer 12, i.e., isolate the working layer 12 from the air, so that the target T does not need to be specially stored and can be exposed to the air, which is very convenient especially when installing and replacing the target and greatly reduces costs. The anti-oxidation layer 16 can also prevent by-products (e.g., 8Be) in the working layer 12 from overflowing from the target T. Regarding the material of the anti-oxidation layer 16, In this case, it is considered that the working layer is resistant to corrosion and can reduce the loss of the incident proton beam and the heat generated by the proton beam at the same time, and it includes, for example, at least one of Al, Ti, alloys and compounds thereof, or stainless steel. In one embodiment, Al2O3 is used, which has a higher oxidation resistance after pre-oxidation, and the radioactive products produced after Al is activated by neutrons have a shorter half-life, reducing secondary radiation. In another embodiment, the oxidation prevention layer 16 is a polymer film, for example a polyimide (PI) film, and polyimide has the following molecular structure: [ka]

[0092] Polyimide has high temperature resistance, high insulation performance, excellent mechanical properties, and high radiation resistance. Its thermal decomposition temperature reaches over 400 degrees Celsius, and it can effectively shield high-energy neutrons, reducing radiation damage to normal tissues in deep-seated tumors. Furthermore, the polymer film can be processed into the working layer 12 by a film coating process (such as hot pressing or gluing), making it easy to assemble and inexpensive. It can be seen that an antioxidant layer is not required.

[0093] In one embodiment, a proton beam is bombarded with a lithium target to generate neutrons. The proton beam passes through the oxidation prevention layer 16, the working layer 12, the thermal conduction layer 15, the foaming suppression layer 13, and the heat dissipation layer 14 in the direction of incidence. The proton beam has an energy of 2.2 MeV to 3 MeV, which can generate a high interaction cross section with the lithium target without generating excessive fast neutrons, resulting in a higher quality beam. The working layer 12 has a thickness of 49 μm to 189 μm, which can react sufficiently with the protons, reducing gamma ray contamination and preventing energy accumulation due to excessive thickness, which would affect the heat dissipation performance of the target.

[0094] Using simulation software, proton beams with energies of 2.2 MeV, 2.5 MeV, and 3 MeV were simulated to bombard lithium targets of different thicknesses, and the neutron yields for different lithium target thicknesses were obtained. As shown in Figures 10 to 12, the neutron yield was highest when the proton beam energy was 2.2 MeV and the corresponding target active layer thickness was 49 μm; the neutron yield was highest when the proton beam energy was 2.5 MeV and the corresponding target active layer thickness was 97 μm; and the neutron yield was highest when the proton beam energy was 3 MeV and the corresponding target active layer thickness was 189 μm.

[0095] In this embodiment, when the proton beam energy is 2.5 MeV and the target working layer 12 has a thickness of 97 μm, the neutron beam required for irradiation can be obtained without the neutron yield being too low.

[0096] Ta generates radioactive products after being activated by neutrons, and the foaming suppression layer 13 should be as thin as possible to absorb all remaining proton beams. The foaming suppression layer 13 may have a thickness of 5 μm to 50 μm. In order to reduce the energy loss of the proton beam, the anti-oxidation layer 16 should be as thin as possible, and may have a thickness greater than 5 nm. The thermal conduction layer 15 uses ultra-high purity Cu and has a thickness of 5 μm to 50 μm to quickly conduct heat to the heat dissipation layer 14. The target's service life is 200 mA-h or more.

[0097] The entire target T is flat and has a central axis A perpendicular to the plate surface. As can be understood, the above thickness is the thickness of each layer of the target T along the central axis A of the target T, and the edges of each layer of the target T may have different thicknesses depending on structural needs.

[0098] The heat dissipation layer 14 may have multiple structures, as long as the thickness of the heat dissipation layer 14 meets the needs of the cooling structure. In the first embodiment of the heat dissipation layer shown in Figures 4 and 5, the heat dissipation layer 14 is plate-shaped and includes a first plate 141 and a second plate 142. The first plate 141 has a first side 1411 facing the working layer 12 and a second side 1412 opposite the first side 1411. A cooling passage P is formed on the second side 1412 for the flow of a cooling medium. The second plate 142 is closely attached to the second side 1412 of the first plate 141. As can be seen, the cooling passage P may be installed on the side of the second plate 142 facing the first plate 141. The cooling passage P has a zigzag shape, and the zigzag cooling passage P includes a plurality of parallel zigzag sub-passages P1, i.e., a plurality of zigzag walls W are arranged in parallel, and zigzag grooves S (i.e., parallel zigzag sub-passages P1) are formed between adjacent walls W. The curved geometry of the parallel zigzag sub-passages P1 is a sinusoidal function as follows:

number

[0099] As can be appreciated, the cooling passage P may have other zigzag shapes, such as a continuously curved, smooth curve or a series of end-to-end curved or straight segments. The zigzag passage extends the flow path, increases the contact area between the heat-conducting wall surface and the coolant, and increases the heat dissipation surface. It also forms secondary flows, improves the stirring effect, and improves the heat conduction capacity and heat dissipation effect, thereby helping to extend the service life of the target. The cooling passage P may also have a continuously curved, smooth curve, such as a sinusoidal function, which can further reduce the flow resistance of the flow path. The zigzag cooling passage P may also be arranged in other arrangements.

[0100] The heat dissipation layer 14 further has a cooling inlet IN and a cooling outlet OUT, and a cooling passage P communicates with the cooling inlet IN and the cooling outlet OUT, and the cooling medium enters from the cooling inlet IN, passes through the cooling passage P, and then exits from the cooling outlet OUT. The target T is irradiated with an accelerated proton beam at a high energy level, causing the temperature to rise and generate heat, and the thermal conduction layer and the heat dissipation layer cool the target T by conducting the heat to the outside and dissipating the heat by the cooling medium flowing through the cooling passage. There are three cooling inlets IN and three cooling outlets OUT, which are symmetrically arranged at both ends of the cooling passage P on the first plate 141 and extend from the first side 1411 to the second side 1412. The second side 1412 further has an inlet groove S1 and an outlet groove S2, which are connected to the cooling inlets IN, the cooling outlets OUT, and each of the parallel zigzag sub-passages P1, respectively, so that the cooling medium entering through the cooling inlets IN enters each of the parallel zigzag sub-passages P1 through the inlet grooves S1 and then passes through the outlet grooves S2 and exits through the cooling outlets OUT. It should be understood that the cooling inlets IN and cooling outlets OUT may be of other numbers or types, and may be arranged together on the second plate, or may be arranged on the first plate and the second plate, respectively. A circumferential wall W1 is further installed around the cooling inlet IN and the cooling outlet OUT. The second plate 142 is in intimate contact with the surface of the circumferential wall W1 facing the second plate 142, forming a cavity between the first plate 141 and the second plate 142. The cooling medium entering through the cooling inlet IN can only exit through the cooling outlet OUT. The contact surface between the second plate 142 and the first plate 141 is flat. The height of the zigzag wall W and the height of the circumferential wall W1 are the same. It is understood that a stepped surface or other structure may be used. In this case, the heights of the zigzag wall W and the circumferential wall W1 may be different. Each parallel zigzag sub-passage P1 may be independent of the others. The flow direction D of the cooling medium in adjacent parallel zigzag sub-passages P1 (the overall flow direction of the cooling medium in the cooling passage) may be different, further improving heat dissipation efficiency. The inlet groove S1 and the outlet groove S2 may be arranged in other arrangements, for example, the cooling medium flows through each of the parallel zigzag sub-passages P1 in turn.In this embodiment, the first and second plates are both made of Cu, which has high heat dissipation performance and low cost. The number and size of the grooves S forming the cooling passages P are determined according to the actual size of the target. The cross-sections of the grooves may be various shapes, such as rectangular, circular, polygonal, elliptical, etc., and different cross-sections may have different shapes.

[0101] The first plate 141 and the second plate 142 are both fixed to the inside of the moderator 22 or to the end of the accelerating structure 111 by connecting members such as bolts or screws or other fixing structures such as welding. Alternatively, the first plate 141 and the second plate 142 are first connected and one of them is fixed to the inside of the moderator 22 or to the end of the accelerating structure 111. As can be understood, the heat dissipation layer 14 may be fixed or attached by other detachable connections to make it easier to replace the target. The heat dissipation layer 14 may further include a support member (not shown), and the first plate 141 and / or the second plate 142 may be fixed by the support member, and the cooling inlet IN and the cooling outlet OUT may be installed on the support member. In this embodiment, a first cooling pipe D1 and a second cooling pipe D2 are installed between the accelerating structure 111 and the reflector 21 and the moderator 22. One end of the first cooling pipe D1 and the second cooling pipe D2 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. The cooling medium may be deionized water, which has extremely low conductivity to prevent leakage current from occurring in a high voltage environment and interference with the generation of the neutron beam, and as can be appreciated, the first and second cooling pipes may also be installed within the beam shaper in other ways, or may even be removed if the target is located outside the beam shaper.

[0102] 6 and 7, a second embodiment of the heat dissipation layer will be described below, focusing on differences from the first embodiment. In the second embodiment of the heat dissipation layer, the zigzag cooling passage P' includes multiple spiral zigzag sub-passages P1', i.e., one or more zigzag walls W' spirally extend around the same center, each wall W' forms multiple layers in the radial direction, and the layers formed by each wall W' are alternately arranged in the radial direction, forming a groove S' (i.e., a spiral zigzag sub-passage P1') between adjacent layers. The locus function of the spiral zigzag sub-passage P1' is given by:

number

[0103] The cooling inlet IN' is located at the center of the second plate 142' and penetrates the center of each spiral zigzag sub-passage P1'. The four cooling outlets OUT' are located evenly around the periphery of the cooling passage P' in the first plate 141' and extend from the first side 1411' to the second side 1412'; however, other installation methods may be used. The center of the cooling passage P', i.e., the center of each spiral zigzag sub-passage P1', is formed as an inlet groove S1'. An outlet groove S2' is further formed on the second side 1412' of the first plate 141'. The outlet groove S2' communicates with the cooling outlets OUT' and each spiral zigzag sub-passage P1'. The cooling medium entering through the cooling inlet IN' enters each spiral zigzag sub-passage P1' from the center of the cooling passage P' and then exits through the outlet groove S2' at the cooling outlet OUT'. A circumferential wall W1' is installed around the cooling outlet OUT', and the second plate 142' is in close contact with the surface of the circumferential wall W1' facing the second plate 142'. A receiving cavity is formed between the first plate 141' and the second plate 142', so that the cooling medium entering through the cooling inlet IN' can only exit through the cooling outlet OUT'. The contact surface between the second plate 142' and the first plate 141' is flat, and the height of the zigzag wall W' is the same as the height of the circumferential wall W1'. It is understood that a stepped surface or other structure may be used, in which case the height of the zigzag wall W' may differ from the height of the circumferential wall W1'. Each spiral zigzag sub-passage P1' may be independent of the others. The flow direction of the cooling medium in adjacent spiral zigzag sub-passages P1' may be different, further improving heat dissipation efficiency. A protrusion 1413′ may be further provided at the center of the first plate 141′, which rectifies the flow and increases the heat conduction area to reduce the temperature of the central hot spot. The protrusion 1413′ may have a height greater than the height of the wall W′ and the circumferential wall W1′ and extend to the cooling inlet IN′ of the second plate. The shape of the protrusion 1413′ may be a solid cone, a hollow cone, a sheet, etc.

[0104] To achieve the above target structure, the other layers (antioxidation layer 16, working layer 12, thermal conduction layer 15, and foaming suppression layer 13) of target T can be processed into heat dissipation layer 14 by a film-forming method, such as PVD (Physical Vapor Deposition), sputtering, thermal welding, atomic layer deposition, etc. As shown in FIG. 8, the manufacturing process of target T includes the following steps S10 to S50.

[0105] In step S10, a heat dissipation layer 14 (made of a copper plate) is placed, and the maximum distance from the heat dissipation layer 14 to the central axis A of the target T is R1; In S20, the expansion-inhibiting layer 13 (Ta) is processed by a method of forming a film on the surface of the heat dissipation layer 14 by sputtering or the like, and the maximum distance from the expansion-inhibiting layer 13 to the central axis A is R2, and R2 is made smaller than R1, and it is necessary to shield the area of ​​the heat dissipation layer 14 where the film (expansion-inhibiting layer 13) does not need to be formed. For example, a metal plate is used to shield the section from the surface of the heat dissipation layer 14 to the central axis A, where the distance is R2 to R1. In step S30, the thermally conductive layer 15 (Cu) is processed by forming a film on the surface of the foaming suppression layer 13 by sputtering or the like, and the maximum distance from the thermally conductive layer 15 to the central axis A is R3, which is greater than R2. That is, before performing step S32, the shielding metal plate is removed in step S31. In S40, the working layer 12 (Li) is processed on the surface of the thermal conduction layer 15 by a method such as thermal welding or PVD to form a film, and the maximum distance from the working layer 12 to the central axis A is R4. R4 is made smaller than R3, and it is necessary to shield the area on the surface of the workpiece obtained in step S32 where no film (working layer 12) needs to be formed. For example, a metal plate is used to shield the section from the surface of the workpiece obtained in step S32 to the central axis A, where the distance is R4-R3. In this embodiment, by making R4 smaller than R2, the foaming suppression layer can completely absorb the remaining protons. In S50, an anti-oxidation layer 16 (Al2O3) is processed on the surface of the working layer 12 by a method such as atomic layer deposition to form a film, and the maximum distance from the anti-oxidation layer 16 to the central axis A is R5, which is greater than R4; that is, the shielding metal plate is removed in step S33 before performing step S34.

[0106] In this example, R5 and R3 are equal to R1, but may have other settings as can be appreciated.

[0107] If the antioxidant layer 16 is a polymer film (e.g., a PI film), step S50 may be to process the antioxidant layer 16 of the polymer film product onto the working layer 12 through a film coating process such as hot pressing or an adhesive process, in which a water-free silicone pressure-sensitive adhesive can be used, which does not react with the metal layer, is easy to assemble, and is low cost, or to apply a liquid polymer film material to the working layer 12 and then harden it (this may be considered as processing in a film-forming manner), for example, by spin coating, which is more uniform.

[0108] In one embodiment, for the target T, the materials for each layer (anti-oxidation layer 16, working layer 12, thermally conductive layer 15, and foaming suppression layer 13) are sequentially converted into gas in a vacuum environment and then deposited (PVD) on the heat dissipation layer 14. As shown in FIG. 9 , in this embodiment, the processing apparatus 300 for the target T includes a vacuum chamber 310, an exhaust device 320, an evaporation source 330, a support frame 340, and a heating device 350. The exhaust device 320 evacuates the vacuum chamber 310 to form a vacuum environment. The evaporation source 330 sequentially evaporates the materials for each layer into gas in the vacuum chamber 310. In this embodiment, the evaporation source 330 uses electron beam or ion beam evaporation and is installed at the bottom of the vacuum chamber. A support frame 340 is used to place the heat dissipation layer 14. In this embodiment, the support frame 340 is installed on top of the vacuum chamber 310. After the heating device 350 heats the heat dissipation layer 14, gas material is deposited on the surface of the heat dissipation layer 14 facing the evaporation source 330. The processing apparatus 300 further includes a film thickness detection device 360 ​​for detecting the thickness of the material of each layer and controlling the gas deposition rate.

[0109] Using the above processing equipment and process, the thickness of each layer of the target can be precisely controlled. The support frame 340 can also be a rotating structure to which multiple heat dissipation layers are fixed and processed in sequence, improving processing efficiency and allowing multiple targets to be processed simultaneously. It will be appreciated that the processing equipment 300 can also be configured in other ways.

[0110] The target of this embodiment has high anti-foaming and heat dissipation performance due to its structure and processing process, and has a service life of 400 mA-h or more. It can be understood that the processing apparatus and processing method of this embodiment can be used for targets that do not have an anti-oxidation layer or a thermally conductive layer, and the target T can be manufactured using other manufacturing methods.

[0111] In this embodiment, the target T is disk-shaped. It is understood that the target T may also be rectangular or flat, have other solid shapes, and be movable relative to the accelerator or beam shaper to facilitate target replacement or to allow the particle beam to uniformly act on the target. The foam suppression layer 13, the heat dissipation layer 14, and the thermally conductive layer 15 may further constitute the base material T1 of the target T, and different target Ts may be formed by processing different working layers 12 thereon. The target T may further include a support (not shown) for supporting or mounting the target. The support may be used to mount at least a portion of the first cooling pipe D1 and the second cooling pipe D2. The support may be made of an aluminum alloy material, since the radioactive products produced by Al after activation by neutrons have a short half-life and reduce secondary radiation.

[0112] As can be appreciated, the target of the present invention can be further applied to other neutron generators in medical and non-medical fields, and the target materials can also be differentiated according to different nuclear reactions, so long as the generation of neutrons is based on a nuclear reaction between a particle beam and the target, and can be further applied to other particle beam generators.

[0113] The above describes exemplary specific embodiments of the present invention to facilitate understanding of the present invention by those skilled in the art. However, it is clear that the present invention is not limited to the scope of the specific embodiments. Various changes will be apparent to those skilled in the art, provided that they are within the spirit and scope of the present invention as defined and determined by the appended claims, and all of these changes are within the scope of the claims of the present invention.

Claims

1. The device includes an active layer that interacts with an incident charged particle beam to generate a neutron beam, a foaming suppression layer that is located behind the active layer along the incident direction of the charged particle beam and that can suppress foaming of the active layer during the process of generating the particle beam, a thermal conduction layer that conducts heat accumulated in the active layer to a heat dissipation layer, and the heat dissipation layer that dissipates the heat, the heat conduction layer is located between the working layer and the foaming suppression layer, the thermal conduction layer includes a first surface located opposite to the working layer and a second surface located opposite to the first surface, and is directly connected to the heat dissipation layer at an outer edge side of the second surface; a housing portion for housing the foaming suppression layer is formed in the thermal conduction layer or the heat dissipation layer, The storage portion includes a bottom surface and a side wall connected to the bottom surface, and the expansion suppression layer has a top surface in contact with the bottom surface and an outer wall in contact with the side wall.

2. A target for use in a particle beam generating device.

2. The target of claim 1 , wherein the thermally conductive layer and the heat dissipation layer surround the foaming suppression layer.

3. 2. The target according to claim 1, wherein the material of the working layer is Li, a compound thereof, or an alloy thereof.

4. 4. The target according to claim 3, wherein the energy of the charged particle beam is 2.2 MeV to 3 MeV, and the thickness of the working layer is 49 μm to 189 μm.

5. 2. The target according to claim 1, wherein the material of the expansion suppression layer contains at least one of Nb, Ta, Pd, V, alloys and compounds thereof.

6. 2. The target according to claim 1, wherein the material of the heat conduction layer and the heat dissipation layer includes at least one of Cu, Fe, Al, alloys and compounds thereof.

7. 2. The target of claim 1, further comprising an anti-oxidation layer that prevents oxidation of the working layer, wherein the anti-oxidation layer, working layer, thermal conduction layer, foam suppression layer, and heat dissipation layer are arranged in order along the incident direction of the charged particle beam.

8. The target according to claim 7, wherein the target is flat and has a central axis perpendicular to the plate surface, and in the same radial direction perpendicular to the central axis, the maximum distance from the action layer to the central axis is smaller than the maximum distance from the foaming suppression layer to the central axis and the maximum distance from the antioxidant layer to the central axis, and the maximum distance from the foaming suppression layer to the central axis is smaller than the maximum distance from the thermal conduction layer to the central axis and the maximum distance from the heat dissipation layer to the central axis.

9. The target of claim 7, wherein the foaming suppression layer has a thickness of 5 μm to 50 μm, the thermal conduction layer and the heat dissipation layer have a thickness of 5 μm to 50 μm, and the antioxidant layer has a thickness greater than 5 nm.

10. 8. The target according to claim 7, wherein the material of the oxidation prevention layer includes at least one of Al, Ti, alloys and compounds thereof, and stainless steel.

11. The target of claim 10 , wherein the anti-oxidation layer, the working layer, the thermally conductive layer, and the foaming inhibiting layer are sequentially processed onto the heat dissipation layer in a film-forming manner.

12. 8. The target of claim 7, wherein the anti-oxidation layer is a polymer film and is processed onto the working layer by a film coating process.

13. 13. The target of claim 12, wherein the polymer film is a polyimide having the following molecular structure: 【Chemistry 1】

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