CN118267642A - Neutron capture therapy system - Google Patents

Abstract

The application provides a neutron capture treatment system, which comprises a beam shaping body, a vacuum tube and at least one cooling device, wherein the vacuum tube is arranged in the beam shaping body, the beam shaping body comprises a beam inlet, a containing cavity for containing the vacuum tube, a retarder adjacent to the end part of the containing cavity, a reflector surrounding the retarder, a radiation shield and a beam outlet, the radiation shield and the beam outlet are arranged in the beam shaping body, the end part of the vacuum tube is provided with a target, the cooling device is used for cooling the target, the target and a charged particle beam incident from the beam inlet are subjected to nuclear reaction to generate neutrons, the retarder decelerates neutrons generated from the target to an epithermal neutron energy region, the reflector guides deflected neutrons back to the retarder to improve the epithermal neutron beam intensity, and at least one containing pipeline for containing the cooling device is also arranged in the beam shaping body, and a filler is filled between the cooling device and the inner wall of the containing pipeline.

Description

Neutron capture therapy system

Technical Field

The invention relates to a radioactive ray irradiation system, in particular to a neutron capture treatment system.

Background

With the development of atomic science, radiation therapy such as cobalt sixty, linac, electron beam, etc. has become one of the main means for cancer therapy. However, the traditional photon or electron treatment is limited by the physical condition of the radioactive rays, and a large amount of normal tissues on the beam path can be damaged while killing tumor cells; in addition, due to the different sensitivity of tumor cells to radiation, traditional radiotherapy often has poor therapeutic effects on malignant tumors with relatively high radiation resistance (such as glioblastoma multiforme (glioblastoma multiforme) and melanoma (melanoma)).

In order to reduce radiation damage to normal tissue surrounding a tumor, the concept of target treatment in chemotherapy (chemotherapy) is applied to radiotherapy; for tumor cells with high radiation resistance, radiation sources with high relative biological effects (relative biological effectiveness, RBE) such as proton therapy, heavy particle therapy, neutron capture therapy, etc. are also actively developed. The neutron capture treatment combines the two concepts, such as boron neutron capture treatment, and provides better cancer treatment selection than the traditional radioactive rays by means of the specific aggregation of boron-containing medicaments in tumor cells and the accurate neutron beam regulation.

In an accelerator neutron capture treatment system, a charged particle beam is accelerated by an accelerator, the charged particle beam is accelerated to energy sufficient to overcome coulomb repulsion of a target atomic nucleus in a beam shaping body, and nuclear reaction occurs to the target to generate neutrons, so that the target is irradiated by the accelerated charged particle beam with high power in the neutron generation process, and the temperature of the target is greatly increased, thereby influencing the service life of the target.

A neutron capture therapeutic system with a cooling device generally comprises a tubular second cooling part for inputting a cooling medium, a tubular third cooling part for outputting the cooling medium, and a first cooling part connected between the second cooling part and the third cooling part and in direct contact with a target material for cooling the target material. In this configuration, the tubular second and third cooling sections are exposed to air, and some neutrons generated on the target will scatter from the surroundings of the second and third cooling sections through the air to the outside of the beam shaping body, thereby reducing the yield of effective neutrons, and neutrons scattered to the outside of the beam shaping body will have an effect on the instruments within the neutron capture treatment system and possibly cause radiation leakage, reducing the lifetime of the neutron capture treatment system and presenting radiation safety hazards.

Disclosure of Invention

To solve the above problems, one embodiment of the present application provides a neutron capture therapy system, which includes a beam shaping body, a vacuum tube disposed in the beam shaping body, and at least one cooling device, wherein the beam shaping body includes a beam inlet, a receiving cavity for receiving the vacuum tube, a retarder adjacent to an end of the receiving cavity, a reflector surrounding the retarder, a thermal neutron absorber adjacent to the retarder, a radiation shield and a beam outlet disposed in the beam shaping body, the end of the vacuum tube is provided with a target material, the cooling device is used for cooling the target material, the target material reacts with a charged particle beam incident from the beam inlet to generate neutrons, the neutrons form a neutron beam, the neutron beam defines a neutron beam axis, the retarder decelerates neutrons generated from the target material to an epithermal neutron energy region, the reflector guides the deviated neutrons back to the retarder to increase the epithermal neutron beam intensity, the thermal neutron absorber is used for absorbing thermal neutrons to avoid excessive doses caused by shallow normal tissues during therapy, the radiation shield is used for shielding neutrons and photons to reduce normal tissue doses of the nonirradiated regions, the beam shaping body is further provided with at least one receiving cooling device, and a filling pipe is disposed between the inner wall of the receiving device and the receiving device.

Compared with the prior art, the technical scheme recorded in the embodiment has the following beneficial effects: and filling a filler between the cooling device and the inner wall of the accommodating pipeline, so that the service life of the neutron capture treatment device is prolonged, the neutron leakage is prevented, and the neutron beam intensity is enhanced.

Preferably, the filler is aluminum alloy or lead alloy, and compared with the technical scheme that the filler is not filled between the cooling device and the inner wall of the containing pipeline, the method can effectively improve the epithermal neutron yield, reduce the fast neutron pollution and shorten the irradiation time.

Further, the receiving duct is located outside the inner wall of the receiving chamber.

Preferably, the cooling device comprises a first cooling part for cooling the target material, a second cooling part and a third cooling part which are positioned at two sides of the first cooling part and respectively communicated with the first cooling part; the first cooling part is arranged in the first accommodating pipeline, the second cooling part is arranged in the second accommodating pipeline, the third cooling part is arranged in the third accommodating pipeline, and the filler is filled between the inner walls of the second cooling part and the second accommodating pipeline and between the inner walls of the third cooling part and the third accommodating pipeline.

Further, the second and third cooling portions are tubular structures, and the second and third accommodation ducts are provided as circular-cross-section ducts extending in a direction parallel to the neutron beam axis.

Preferably, the first cooling part is positioned at the end part of the vacuum tube and is contacted with the target plane, and the second cooling part and the third cooling part extend along the direction parallel to the axis of the neutron beam and are respectively positioned at the upper side and the lower side of the vacuum tube to form a 匚 type structure with the first cooling part; the second and third accommodating pipelines extend along the direction parallel to the axis of the neutron beam and are respectively positioned at the upper side and the lower side of the vacuum tube to form a 匚 -type structure with the first accommodating pipeline.

Preferably, the first cooling part is positioned at the end part of the vacuum tube and is in contact with the target plane, and an included angle between the second cooling part and the third cooling part and the neutron beam axis is more than 0 degrees and less than or equal to 180 degrees; the included angle between the axes of the neutron beams in the second accommodating pipeline and the third accommodating pipeline is more than 0 degrees and less than or equal to 180 degrees.

Preferably, the second cooling portion inputs the cooling medium to the first cooling portion, and the third cooling portion outputs the cooling medium in the first cooling portion.

Further, the reflector protrudes out of the retarder at two sides of the axis of the neutron beam, the vacuum tube comprises an extension section surrounded by the reflector and an embedded section extending from the extension section to be embedded into the retarder, and the target is arranged at the end part of the embedded section.

Preferably, the speed bump is arranged to comprise at least one cone.

The "cone" or "cone" in the embodiments of the present application refers to a structure in which the overall trend of the outer contour gradually decreases from one side to the other side along the direction of the drawing, and one of the outer contours may be a line segment, such as a corresponding contour line of a cone, or may be an arc, such as a corresponding contour line of a sphere, and the entire surface of the outer contour may be smoothly transitioned, or may be non-smoothly transitioned, such as a surface of a cone or sphere having a plurality of protrusions and grooves formed thereon.

Drawings

FIG. 1 is a schematic diagram of a neutron capture therapy system in accordance with a first embodiment of the present application, wherein the second and third cooling sections of the cooling device are parallel to the neutron beam axis;

FIG. 2 is a cross-sectional view of a neutron capture treatment system along the axis of the neutron beam of FIG. 1 in accordance with a first embodiment of the application;

FIG. 3 is a schematic diagram of a neutron capture treatment system in accordance with a first embodiment of the application, wherein the gap between the vacuum tube and the beam shaping body is not filled with filler;

FIG. 4 is an enlarged schematic view of a portion of a cooling device of a neutron capture therapy system according to a first embodiment of the present application;

FIG. 5 is a schematic diagram of a neutron capture therapy system in accordance with a second embodiment of the application, wherein the second and third cooling sections of the cooling device are perpendicular to the neutron beam axis;

FIG. 6 is a schematic diagram of a neutron capture treatment system in accordance with a third embodiment of the application, wherein the second and third cooling sections of the cooling device are angled more than 90 degrees from the neutron beam axis;

FIG. 7 is a schematic diagram of a target structure in a neutron capture therapy system according to an embodiment of the present application.

Detailed Description

Neutron capture therapy has been increasingly used in recent years as an effective means of treating cancer, where it is most common to supply neutrons from a boron neutron capture therapy to a nuclear reactor or accelerator. Taking accelerator boron neutron capture therapy as an example, the basic components of accelerator boron neutron capture therapy generally include an accelerator for accelerating charged particles (e.g., protons, deuterons, etc.), a neutron production and heat removal system, and a beam shaping body. The accelerating charged particles and the metal neutron generating part act to generate neutrons, and proper nuclear reactions are selected according to the required neutron yield and energy, available accelerating charged particle energy and current, physicochemical properties of the metal neutron generating part and the like. The nuclear reactions often discussed are ⁷Li(p,n)⁷ Be and ⁹Be(p,n)⁹ B, both of which are endothermic, with energy thresholds of 1.881MeV and 2.055MeV, respectively. Because the ideal neutron source for boron neutron capture treatment is epithermal neutrons with a keV energy level, theoretically, if protons with energy only slightly higher than a threshold are used to bombard a metallic lithium neutron generating part, relatively low-energy neutrons can Be generated, and the neutron capturing treatment can Be used clinically without too much retarding treatment, however, the proton action cross section of the two neutron generating parts of lithium metal (Li) and beryllium metal (Be) and the threshold energy is not high, and in order to generate enough neutron flux, protons with higher energy are generally selected to initiate nuclear reaction.

The ideal target should have high neutron yield, a neutron energy distribution close to that of the epithermal neutron energy region (described in detail below), no too much intense penetrating radiation, safety, low cost, easy operation, and high temperature resistance, but practically no nuclear reaction meeting all the requirements can be found. In the embodiment of the application, a target made of lithium metal is adopted. However, it is well known to those skilled in the art that the material of the target may be made of other metallic materials than those mentioned above.

The requirements for the heat removal system vary depending on the chosen nuclear reaction, e.g., ⁷Li(p,n)⁷ Be is higher than ⁹Be(p,n)⁹ B due to the poor melting point and thermal conductivity of the metal target (lithium metal). The nuclear reaction of ⁷Li(p,n)⁷ Be was used in the examples of the present application. Therefore, the temperature of the target irradiated by the high-energy-level accelerated charged particle beam is inevitably greatly increased, and the service life of the target is affected.

Regardless of whether the neutron source of the boron neutron capture treatment is from the nuclear reaction of charged particles of a nuclear reactor or an accelerator with a target, a mixed radiation field is generated, i.e. the beam contains neutrons and photons with low energy to high energy. For boron neutron capture treatment of deep tumors, the more radiation content, except for epithermal neutrons, the greater the proportion of non-selective dose deposition of normal tissue, and therefore the less radiation that will cause unnecessary doses. In addition to the air beam quality factor, in order to better understand the dose distribution of neutrons in the human body, the embodiments of the present application use a human head tissue prosthesis for dose calculation, and use the prosthesis beam quality factor as a design reference for neutron beams, as will be described in detail below.

The international atomic energy organization (IAEA) gives five air beam quality factor suggestions for neutron sources for clinical boron neutron capture treatment, and the five suggestions can be used for comparing the advantages and disadvantages of different neutron sources and serve as reference bases for selecting neutron generation paths and designing beam shaping bodies. These five suggestions are as follows:

Epithermal neutron beam flux EPITHERMAL NEUTRON FLUX >1x 10 ⁹n/cm² s

Fast neutron contamination Fast neutron contamination <2x 10 ^-13Gy-cm²/n

Photon pollution Photon contamination <2x 10 ^-13Gy-cm²/n

The ratio thermal to epithermal neutron flux ratio of thermal neutron to epithermal neutron flux is less than 0.05

Neutron current to flux ratio EPITHERMAL NEUTRON CURRENT TO FLUX RATIO >0.7

Note that: the epithermal neutron energy region is between 0.5eV and 40keV, the thermal neutron energy region is less than 0.5eV, and the fast neutron energy region is more than 40keV.

1. Epithermal neutron beam flux:

The neutron beam flux and the boron-containing drug concentration in the tumor together determine the clinical treatment time. If the concentration of the boron-containing medicament in the tumor is high enough, the requirement on the neutron beam flux can be reduced; conversely, if the boron-containing drug concentration in the tumor is low, a high flux epithermal neutron is required to administer a sufficient dose to the tumor. IAEA the requirement for the flux of the epithermal neutron beam is that the number of epithermal neutrons per second per square centimeter is more than 10 ⁹, the neutron beam under the flux can generally control the treatment time within one hour for the current boron-containing medicament, and the short treatment time has advantages of positioning and comfort for patients and can effectively utilize the limited residence time of the boron-containing medicament in tumors.

2. Fast neutron contamination:

since fast neutrons cause unnecessary normal tissue doses, which are positively correlated with neutron energy, as a matter of pollution, the fast neutron content should be minimized in the neutron beam design. Fast neutron contamination is defined as the fast neutron dose accompanied by a unit epithermal neutron flux, and IAEA is recommended for fast neutron contamination to be less than 2x 10 ^-13Gy-cm²/n.

3. Photon pollution (gamma ray pollution):

Gamma rays belong to the intense penetrating radiation and can cause non-selective dose deposition of all tissues on a beam path, so that the reduction of gamma ray content is also an essential requirement for neutron beam design, gamma ray pollution is defined as the gamma ray dose accompanied by unit epithermal neutron flux, and the proposal of IAEA on gamma ray pollution is smaller than 2x 10 ^-13Gy-cm²/n.

4. Ratio of thermal neutron to epithermal neutron flux:

Because of high thermal neutron attenuation speed and poor penetrating capacity, most of energy is deposited on skin tissues after entering a human body, and thermal neutrons are required to be used as neutron sources for boron neutron capture treatment for superficial tumors such as melanoma and the like, so that the thermal neutron content is required to be reduced for deep tumors such as brain tumors and the like. IAEA the ratio of thermal neutron to epithermal neutron flux was recommended to be less than 0.05.

5. Neutron current to flux ratio:

The ratio of neutron current to flux represents the directionality of the beam, the larger the ratio is, the better the frontage of the neutron beam is, the high frontage neutron beam can reduce the surrounding normal tissue dose caused by neutron divergence, and the treatable depth and the posture setting elasticity are improved. IAEA neutron current to flux ratios of greater than 0.7 are suggested.

In order to solve the target cooling problem and obtain better neutron beam quality, referring to fig. 1-4, a neutron capture treatment system 1 is provided, and the neutron capture treatment system 1 includes a beam shaping body 10, a cooling device 20 disposed in the beam shaping body 10, and a vacuum tube 30.

As shown in fig. 1 and 2, the beam shaper 10 comprises a beam inlet 11, a receiving chamber 12 for receiving a vacuum tube 30, a receiving duct 13 for receiving a cooling device 20, a retarder 14 adjacent to an end of the receiving chamber 12, a reflector 15 surrounding the retarder 14, a thermal neutron absorber 16 adjacent to the retarder 14, a radiation shield 17 arranged within the beam shaper 10, and a beam outlet 18. The end of the evacuated tube 30 is provided with a target 31, the target 31 undergoing nuclear reaction with a charged particle beam incident from the beam inlet 11 and passing through the evacuated tube 30 to produce neutrons, the neutrons forming a neutron beam, the neutron beam exiting from the beam outlet 18 and defining a neutron beam axis X substantially coincident with the central axis of the evacuated tube 30. The moderator 14 moderates neutrons generated from the target 31 to the epithermal neutron energy region and the reflector 15 directs neutrons offset from the neutron beam axis X back to the moderator 14 to increase the epithermal neutron beam intensity. The reflector 15 projects beyond the retarder 14 on both sides of the neutron beam axis X. The thermal neutron absorber 16 is used to absorb thermal neutrons to avoid overdosing with shallow normal tissue during treatment. The radiation shield 17 serves to shield the leaking neutrons and photons to reduce the normal tissue dose in the non-irradiated region.

Accelerator neutron capture therapy systems accelerate a charged particle beam, as a preferred embodiment, from lithium metal, with the charged particle beam accelerated to an energy sufficient to overcome the coulomb repulsion of the target nuclei, and react with the target 31 to produce neutrons, ⁷Li(p,n)⁷ Be nuclei, with the beam shaper 10 slowing down neutrons to the epithermal neutron energy region and reducing thermal and fast neutron content. The retarder 14 is made of a material having a large fast neutron action cross section and a small epithermal neutron action cross section, the reflector 15 is made of a material having a strong neutron reflection capability, and the thermal neutron absorber 16 is made of a material having a large thermal neutron action cross section. As a preferred embodiment, the retarder 14 is made of at least one of D ₂O、AlF₃、Fluental^TM、CaF₂、Li₂CO₃、MgF₂ and Al ₂O₃, the reflector 15 is made of at least one of Pb or Ni, and the thermal neutron absorber 16 is made of ⁶ Li.

As shown in fig. 1, the retarder 14 is provided in a structure having at least one cone for increasing the epithermal neutron flux. In this embodiment the speed bump 14 consists of two cones. The retarder 14 has a first end 141, a second end 142 and a third end 143 between the first end 141 and the second end 142. The first, second and third ends 141, 142, 143 are circular in cross-section, and the diameters of the first and second ends 141, 142 are smaller than the diameter of the third end 143. A first taper 146 is formed between the first end 141 and the third end 143, and a second taper 148 is formed between the third end 143 and the second end 142. In the embodiment of the application, the cone or cone structure of the retarder refers to a structure that the overall trend of the outline of the retarder gradually becomes smaller from one side to the other side along the direction of the neutron beam axis X, one outline of the outline can be a line segment, such as a corresponding outline of the cone, or an arc, such as a corresponding outline of the sphere, and the whole surface of the outline can be in smooth transition or non-smooth transition, such as a plurality of bulges and grooves formed on the surface of the cone or sphere.

The radiation shield 17 includes a photon shield 171 and a neutron shield 172, and as a preferred embodiment, the radiation shield 17 includes a photon shield 171 made of lead (Pb) and a neutron shield 172 made of Polyethylene (PE).

The accommodating cavity 12 is a cylindrical cavity surrounded by the reflector 15 and the first cone 146 of the retarder 14. The accommodating chamber 12 includes a reflector accommodating chamber 121 surrounded by the reflector 15, and a retarder accommodating chamber 122 extending from the reflector accommodating chamber 121 and surrounded by the retarder 14.

The containment duct 13 comprises second and third containment ducts 132, 133 extending in the direction of the neutron beam axis X and located on both sides of the containment chamber 12 and arranged 180 ° apart, and a first containment duct 131 arranged in a plane perpendicular to the neutron beam axis X and located between the target 31 and the retarder 14. The second and third accommodation ducts 132, 133 extend beyond the accommodation chamber 12 in the direction of the neutron beam axis X and communicate with the first accommodation duct 131, respectively. That is, the first accommodating duct 131 is located at the end of the accommodating cavity 12 and between the target 31 and the retarder 14, and the second accommodating duct 132 and the third accommodating duct 133 are located at two sides of the accommodating cavity 12 and are respectively communicated with the first accommodating duct 131, so that the entire accommodating duct 30 is in a '匚' structure. As shown in connection with fig. 3, the second and third receiving ducts 132, 133 comprise second and third reflector receiving ducts 1321, 1331, respectively, located outside the reflector receiving cavity 121, and second and third retarder receiving ducts 1322, 1332, respectively, extending from the second and third reflector receiving ducts 1321, 1331, respectively, located outside the retarder receiving cavity 122. In the present embodiment, the second and third accommodating ducts 132, 133 extend in the direction of the neutron beam axis X and are parallel to the neutron beam axis X, i.e., the angle between the second and third accommodating ducts 132, 133 and the neutron beam axis X is 0 °.

In the present embodiment, the second and third receiving ducts 132, 133 are in communication with the receiving chamber 12, i.e. the outer surface portions of the vacuum tube 30 received in the receiving chamber 12 are exposed in the second and third receiving ducts 132, 133, and in other embodiments, the second and third receiving ducts 132, 133 may not be in communication with the receiving chamber 12, i.e. the second and third receiving ducts 132, 133 are separated from the receiving chamber 12 by the reflector 15 and the retarder 14. In summary, the second and third receiving ducts 132, 133 are located outside the inner wall of the receiving chamber 12. In the embodiment of the present application, the second and third receiving pipes 132 and 133 are provided as circular arc-shaped pipes extending in the axial direction of the vacuum pipe 30, and in other embodiments, square, triangular or other polygonal pipes may be used instead. In the embodiment of the present application, the second and third receiving ducts 132, 133 are two receiving ducts which are spaced apart from each other in the circumferential direction of the receiving chamber 12, and in other embodiments, the second and third receiving ducts 132, 133 communicate in the circumferential direction of the receiving chamber 12, that is, are replaced by one receiving duct which surrounds the receiving chamber 12.

The vacuum tube 30 comprises an extension 32 surrounded by the reflector 15 and an embedded section 34 extending from the extension 32 into the retarder 14, i.e. the extension 32 is accommodated in the reflector accommodating chamber 121 and the embedded section 34 is accommodated in the retarder accommodating chamber 122. The target 31 is provided at the end of the embedded section 34 of the vacuum tube 30. In the present embodiment, the vacuum tube 30 is partially embedded in the retarder 14, so that the cooling device 20 can cool the target 31 in the vacuum tube 30 embedded in the segment while ensuring that the beam shaping body 10 obtains better neutron beam quality.

As shown in fig. 7, the target 31 includes a lithium target layer 311 and an oxidation-resistant layer 312 located at one side of the lithium target layer 311 for preventing oxidation of the lithium target layer 311. The antioxidation layer 312 of the target 31 is made of Al or stainless steel.

As shown in fig. 4, the cooling device 20 includes a first cooling portion 21 arranged in a vertical direction and located in front of the target 31 for cooling the target 31, a second cooling portion 22 and a third cooling portion 23 extending in a direction of the neutron beam axis X and located on both sides of the vacuum tube 30 and parallel to the neutron beam axis X, and the first cooling portion 21 is connected between the second and third cooling portions 22, 23. The first cooling portion 21 is accommodated in a first accommodation duct 131 arranged in a direction perpendicular to the neutron beam axis X, and the second and third cooling portions 22, 23 are accommodated in second and third accommodation ducts 132, 133 arranged in the direction of the neutron beam axis X, respectively. The second cooling unit 22 inputs the cooling medium to the first cooling unit 21, and the third cooling unit 23 outputs the cooling medium in the first cooling unit 21. The first cooling part 21 is located between the target 31 and the retarder 14, one side of the first cooling part 21 is in direct contact with the target 31 and the other side is in contact with the retarder 14. The second cooling part 22 and the third cooling part 23 comprise a first and a second cooling section 221, 231 located outside the reflector housing cavity 121 and a third and a fourth cooling section 222, 232 extending from the first and the second cooling section 221, 231 and located outside the retarder housing cavity 122, respectively. The third and fourth cooling sections 222 and 232 communicate with the first cooling portion 21, respectively. That is, the first cooling part 21 is located at the end of the insertion section 121 of the vacuum tube 30 at one side of the target 31 and is in direct contact with the target 31, and the second and third cooling parts 22 and 23 are respectively located at the upper and lower sides of the vacuum tube 30 accommodated in the accommodating chamber 12 and are respectively communicated with the first cooling part 21, so that the entire cooling device 20 is provided in a '匚' type structure. In this embodiment, the first cooling portion 21 is in planar contact with the target 31, the second cooling portion 22 and the third cooling portion 23 are both tubular structures made of copper, and the second cooling portion 22 and the third cooling portion 23 extend in the direction of the neutron beam axis X and are parallel to the neutron beam axis X, that is, the included angle between the second cooling portion 22 and the third cooling portion 23 and the neutron beam axis X is 0 °.

The first cooling portion 21 includes a first contact portion 211, a second contact portion 212, and a cooling groove 213 between the first contact portion 211 and the second contact portion 212 through which a cooling medium passes. The first contact portion 211 is in direct contact with the target 31, and the second contact portion 212 may be in direct contact with the retarder 14 or may be in indirect contact with the retarder through air. The cooling tank 213 has an input tank 214 communicating with the second cooling portion 22 and an output tank 215 communicating with the third cooling portion 23. The first contact portion 211 is made of a heat conductive material. The upper edge of the input groove 214 is located above the upper edge of the second cooling part 22, and the lower edge of the output groove 215 is located below the lower edge of the third cooling part 23. The advantage of this arrangement is that the cooling device 20 can more smoothly input cooling water into the cooling tank 213 and cool the target 31 in time, and the heated cooling water can be smoothly output from the cooling tank 213, and at the same time, the water pressure of the cooling water in the cooling tank 213 can be reduced to a certain extent.

The first contact portion 211 is made of a heat conductive material (such as a material having good heat conductive properties such as Cu, fe, al, etc.) or a material capable of both heat conduction and foaming inhibition, and the second contact portion 212 is made of a material capable of foaming inhibition, either of Fe, ta, or V. The target 31 is heated by the accelerated irradiation temperature rise of the high energy level, and the first contact portion 211 extracts heat and brings the heat out by the cooling medium flowing through the cooling tank 213, thereby cooling the target 31. In the present embodiment, the cooling medium is water.

In the present embodiment, the angles between the second and third accommodation pipes 132, 133 and the second and third cooling portions 22, 23 and the neutron beam axis X are 0 °. In other embodiments, the angles between the second and third accommodating ducts 132, 133 and the second and third cooling portions 22, 23 and the neutron beam axis X may be any angle greater than 0 ° and less than or equal to 180 °, for example, as shown in fig. 6, the angles between the second and third accommodating ducts 132', 133' and the second and third cooling portions 22', 23' and the neutron beam axis X ' are 90 °, for example, as shown in fig. 7, and the angles between the second and third accommodating ducts 132", 133" and the second and third cooling portions 22", 23" and the neutron beam axis X "are 135 °.

As shown in fig. 5, a schematic diagram of a neutron capture treatment system 1 'according to a second embodiment of the present application is disclosed, wherein the second cooling portion 22' and the third cooling portion 23 'of the cooling device 20' are perpendicular to the neutron beam axis X ', i.e. the cooling device 20' is configured in an "I" type structure to cool the target 31 'in the embedded vacuum tube 30'. The first cooling portion 21 'of the "I" type cooling device 20' is identical to the first cooling portion 21 of the 匚 type cooling device 20 in arrangement, except that the second cooling portion 22 'and the third cooling portion 23' of the "I" type cooling device 20 'are located in the same plane perpendicular to the neutron beam axis X' as the first cooling portion 21', and the second cooling portion 22' and the third cooling portion 23 penetrate out of the retarder 14 'along the direction perpendicular to the neutron beam axis X, respectively, i.e. the included angle between the second cooling portion 22' and the third cooling portion 23 'and the neutron beam axis X' is 90 °, so that the entire cooling device is rectangular in arrangement, i.e. the above-mentioned "I" type structure.

With continued reference to fig. 5, the accommodating duct 30' is also configured in an "I" shape, and the first accommodating duct 131' of the "I" shape accommodating duct 30' is configured identically to the first accommodating duct 131 of the 匚 -shape cooling duct 30, except that the second accommodating duct 132' and the third accommodating duct 133' of the "I" shape accommodating duct 30' are located in the same plane perpendicular to the neutron beam axis X ' as the first accommodating duct 131', and the second accommodating duct 132' and the third accommodating duct 133' are respectively penetrated out of the retarder 14' in a direction perpendicular to the neutron beam axis X ', i.e., an included angle between the second and third accommodating ducts 132', 133' and the neutron beam axis X ' is 90 °, so that the entire accommodating duct is configured in a rectangular shape, i.e., the "I" shape structure described above.

As shown in fig. 6, a schematic diagram of a neutron capture treatment system 1 "according to a third embodiment of the present application is disclosed, wherein the angles between the second cooling portion 22" and the third cooling portion 23 "of the cooling device 20" and the neutron beam axis X "are greater than 90 °, and the first cooling portion 21" of the cooling device 20 "is identical to the first cooling portion 21 of the 匚 -type cooling device 20, except that the angles between the second cooling portion 22" and the third cooling portion 23 "of the cooling device 20" and the neutron beam axis X "are 135 °. The first containment duct 131 'of the containment duct 30 "is identical to the first containment duct 131 of the 匚 -type containment duct 30, except that the second containment duct 132" and the third containment duct 133 "of the containment duct 30" are angled at 135 ° to the neutron beam axis X'.

Referring to fig. 1, 3, 5 and 6, the second and third cooling units 22 and 23;22', 23';22", 23" and second and third containment ducts 132, 133, respectively; 132', 133';132", 133" having a gap between the inner walls, the gap having a filler 40 therein; 40';40", filler 40;40';40 "is a substance capable of absorbing or reflecting neutrons, such as a lead alloy or an aluminum alloy. A filler 40;40';40 "can reflect neutrons reflected or scattered into the gap into the retarder 14 or reflector 15, thereby increasing the yield of epithermal neutrons and reducing the time the irradiated body needs to be irradiated. On the other hand, the leakage of neutrons to the outside of the beam shaping body 10 is avoided, the adverse effect is caused on the instrument of the neutron capture treatment system, and the radiation safety is improved. In the embodiment of the application, the content of lead in the lead alloy is more than or equal to 85 percent, and the content of aluminum in the aluminum alloy is more than or equal to 85 percent.

In order to compare the effect on the yield of epithermal neutrons, the amount of fast neutron contamination and the irradiation time when the filler 40 is air or lead alloy or aluminum alloy, respectively, a detailed comparison is set forth in tables one through three.

Wherein, the first table shows the productivity (n/cm ² mA) of epithermal neutrons when the filler is air, aluminum alloy and lead alloy respectively under the aperture of different accommodating cavities:

Table one: yield of epithermal neutrons (n/cm ² mA)

Accommodation cavity aperture (CM)

16CM

18CM

20CM

22CM

24CM

26CM

Air-conditioner

8.20E+07

7.82E+07

7.38E+07

6.97E+07

6.56E+07

6.22E+07

Aluminum alloy

8.74E+07

8.58E+07

8.40E+07

8.23E+07

8.07E+07

7.88E+07

Lead alloy

8.94E+07

8.88E+07

8.79E+07

8.69E+07

8.63E+07

8.53E+07

Table two shows the fast neutron pollution (Gy-cm 2/n) for air, aluminum alloy, lead alloy for each filler at different cell pore diameters:

And (II) table: fast neutron pollution (Gy-cm ²/n)

Accommodation cavity aperture (CM)

16CM

18CM

20CM

22CM

24CM

26CM

Air-conditioner

7.01E-13

7.51E-13

8.23E-13

8.95E-13

9.80E-13

1.06E-12

Aluminum alloy

6.54E-13

6.83E-13

7.17E-13

7.54E-13

7.90E-13

8.37E-13

Lead alloy

6.56E-13

6.83E-13

7.18E-13

7.52E-13

7.87E-13

8.29E-13

Table three shows the irradiation time (minutes) required for the irradiated body when the filler is air, aluminum alloy, lead alloy, respectively, at the aperture of the different accommodation chambers:

TABLE III time required for irradiation of the object (Min)

Accommodation cavity aperture (CM)	16CM	18CM	20CM	22CM	24CM	26CM
							Air-conditioner	30.86	31.16	32.29	32.66	33.42	34.12
Aluminum alloy	29.65	29.07	30.46	29.42	29.22	29.39
							Lead alloy	28.94	28.00	28.37	27.76	27.91	28.04

It can be seen from tables one to three that when the aperture of the accommodating chamber is the same, the productivity of epithermal neutrons is higher and the amount of fast neutron pollution and the required irradiation time are less when filling the lead alloy or aluminum alloy than when filling air.

The neutron capture therapy system of the present disclosure is not limited to the above embodiments and the structures shown in the drawings. For example, the retarder may be provided as a cylinder, the cooling means may be provided in several, and the receiving conduit correspondingly has several etc. Obvious changes, substitutions, or modifications to the materials, shapes, and positions of the components therein are made on the basis of the present application, and are within the scope of the present application as claimed.

Claims (10)

1. A neutron capture therapy system, characterized by: the neutron capture treatment system comprises a beam shaping body, a vacuum tube and at least one cooling device, wherein the vacuum tube is arranged in the beam shaping body, the beam shaping body comprises a beam inlet, a containing cavity for containing the vacuum tube, a retarder and a beam outlet, a target is arranged at the end part of the vacuum tube, the cooling device is used for cooling the target, the target and a charged particle beam incident from the beam inlet undergo nuclear reaction to generate neutrons, the neutrons form a neutron beam, the neutron beam is emitted from the beam outlet and defines a neutron beam axis, at least one containing pipeline for containing the cooling device is further arranged in the beam shaping body, and a filler is filled between the cooling device and the inner wall of the containing pipeline.

2. The neutron capture therapy system of claim 1, wherein: the filler is lead alloy or aluminum alloy.

3. The neutron capture therapy system of claim 1, wherein: the receiving duct is located outside the inner wall of the receiving chamber.

4. The neutron capture therapy system of claim 1, wherein: the cooling device comprises a first cooling part for cooling the target, a second cooling part and a third cooling part which are positioned at two sides of the first cooling part and are respectively communicated with the first cooling part; the first cooling part is arranged in the first accommodating pipeline, the second cooling part is arranged in the second accommodating pipeline, the third cooling part is arranged in the third accommodating pipeline, and the filler is filled between the inner walls of the second cooling part and the second accommodating pipeline and between the inner walls of the third cooling part and the third accommodating pipeline.

5. The neutron capture therapy system of claim 4, wherein: the second and third cooling parts are tubular structures, and the second and third accommodating pipelines are arranged as pipelines with circular cross sections extending along the direction parallel to the axis of the neutron beam.

6. The neutron capture therapy system of claim 4, wherein: the first cooling part is positioned at the end part of the vacuum tube and is in plane contact with the target, and the second cooling part and the third cooling part extend along the direction parallel to the axis of the neutron beam and are respectively positioned at the upper side and the lower side of the vacuum tube to form a 匚 type structure with the first cooling part; the second and third accommodating pipelines extend along the direction parallel to the axis of the neutron beam and are respectively positioned at the upper side and the lower side of the vacuum tube to form a 匚 -type structure with the first accommodating pipeline.

7. The neutron capture therapy system of claim 4, wherein: the first cooling part is positioned at the end part of the vacuum tube and is contacted with the target plane, and an included angle between the second cooling part and the third cooling part and the neutron beam axis is more than 0 degrees and less than or equal to 180 degrees; the included angle between the second and third containing pipelines and the axis of the neutron beam is more than 0 degrees and less than or equal to 180 degrees.

8. The neutron capture therapy system of claim 4, wherein: the second cooling unit inputs a cooling medium to the first cooling unit, and the third cooling unit outputs the cooling medium in the first cooling unit.

9. The neutron capture therapy system of claim 1, wherein: the reflector protrudes out of the retarder at two sides of the axis of the neutron beam, the vacuum tube comprises an extension section surrounded by the reflector and an embedded section extending from the extension section to be embedded into the retarder, and the target is arranged at the end part of the embedded section.

10. The neutron capture therapy system of claim 1, wherein: the retarder is arranged to comprise at least one cone.