Adjustable beam shaping device

Abstract

The utility model provides an adjustable beam shaping device, which comprises a reflector with an accommodating cavity, and a moderated core body is filled in the accommodating cavity. The spare core body is arranged in the containing cavity and axially abuts against the moderated core body, and the spare core body is provided with a connecting hole for a proton beam channel to penetrate through. According to the adjustable beam shaping device, the neutron energy and flux of the output end of the beam shaping device can be adjusted; therefore, the applicability of the beam shaping device for boron neutron capture therapy to different tumor cells is enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of boron neutron capture therapy, in particular to an adjustable beam shaping device. Background Art

[0002] The principle of Boron Neutron Capture Therapy (BNCT) is to use the nuclear reaction that occurs in tumor cells to destroy tumor cells. 10 Compound B is introduced into the patient's body. Since this compound has a strong affinity with tumor cells, it quickly accumulates in tumor cells after entering the body, and is rarely distributed in other normal tissues. Then, a neutron beam is used to irradiate the tumor site, so that the neutrons interact with the accumulated neutrons in the tumor cells. 10 B undergoes a nuclear reaction, 10 B captures a neutron to form an unstable compound nucleus 11 B, 11 B then spontaneously splits into an alpha particle with a kinetic energy of 1.78 MeV and a 7 Li recoil nucleus (reaction cross section 6.3%); or an alpha particle with a kinetic energy of 1.47 MeV and a 7 Li recoils the nucleus and emits a photon with an energy of 0.48 MeV (reaction cross section is 93.7%). 11 B spontaneously splits into alpha particles and 7 Li recoils the nucleus, and the reaction equation is as follows:

[0003] 10 B+n th → 11 B→ 7 Li(1.01MeV)+4He(1.78MeV)6.3%

[0004] 10 B+n th → 11 B→ 7 Li(0.84MeV)+4He(1.47MeV)+γ(0.48MeV)93.7%

[0005] The reaction products of this process are alpha particles and 7 Li recoil nuclei have the characteristics of high linear energy transfer (LET) and low oxygen enhancement ratio, which can kill tumor cells with high selectivity and intensity while minimizing damage to surrounding normal tissues.

[0006] In fact, neutrons produced by accelerator neutron sources or reactor neutron sources cannot be used directly to treat patients, especially accelerator-based neutron source boron neutron capture therapy (AB-BNCT), which generally uses the reaction of protons with lithium or beryllium to produce neutrons. The emitted neutrons have high energy and can easily penetrate the human body directly, and cannot achieve the expected therapeutic effect. Therefore, after the neutron beam is obtained through the neutron source target, the neutron beam needs to be slowed down and aligned by a beam shaping assembly (BSA) until it meets the treatment standards before it can be used to irradiate the patient.

[0007] The current design standards of existing beam shaping systems mainly refer to the IAEA-TECDOC-1223 document issued by the International Atomic Energy Agency in 2001 and the "Advances in Boron Neutron Capture Therapy" published in 2023. Both documents recommend the use of neutrons in the energy range of 0.5keV to 10keV as epithermal neutrons. However, some scholars believe that neutrons slightly higher than 10keV can also be used to treat deep tumors, such as 16keV and below.

[0008] A Chinese invention patent with publication number CN115120893A discloses a boron neutron capture therapy beam shaping device, comprising: a particle beam channel portion, a beam shaping portion, an activation suppression portion, a beam shielding portion and a beam extraction portion; the beam shaping portion is used to shape the initial neutron source generated by the target material to obtain an epithermal neutron beam that meets the IAEA indicators and can be used for neutron capture therapy.

[0009] However, the main function of the retarder included in the beam shaping section in the above-mentioned prior art is to reduce the high-energy neutron beam to an epithermal neutron beam for effective treatment, so as to effectively treat brain glioma, melanoma and recurrent tumors of the head and neck, etc., but there is a technical defect that it is difficult to shape the initial neutron source to obtain a low-energy neutron beam, so that superficial tumors cannot be treated, which limits the applicability of the boron neutron capture therapy beam shaping device to different tumor cells. Utility Model Content

[0010] The purpose of the utility model is to provide an adjustable beam shaping device, an assembly method and an application, which are used to solve the many defects of beam shaping devices in the prior art, especially to achieve the selection of low-energy neutron beams or high-energy neutron beams for treatment of different tumors, thereby improving the applicability to different tumor cells.

[0011] To achieve the above-mentioned purpose, in a first aspect, the utility model provides an adjustable beam shaping device, comprising: a reflector having an accommodating cavity, an axial portion of a proton beam channel penetrating the reflector, a target material being arranged in the proton beam channel, and a moderator core arranged in the accommodating cavity; a collimator being axially embedded in one end of the reflector away from the proton beam channel; the moderator core being located at one end of the proton beam channel extending into the reflector; the moderator core being composed of a plurality of base cores and a plurality of adjustment cores to slow down a high-energy neutron beam into a neutron beam energy range of lower energy, or the moderator core being composed of a plurality of base cores to slow down a high-energy neutron beam into an epithermal neutron energy range.

[0012] According to the utility model, in some schemes, the moderator core is composed of a total of 2 or 3 base cores and adjustment cores to slow down the high-energy neutron beam into a lower-energy neutron beam energy range, and the total thickness of the base core and the adjustment core is 21-33 cm or 22-33 cm.

[0013] According to the utility model, in some schemes, the moderation core is composed of a base core and an adjustment core; the thickness of the base core is 20-27 cm, and the thickness of the adjustment core is 1-6 cm.

[0014] According to the utility model, in some schemes, the moderation core is composed of one base core and two adjustment cores; the thickness of the base core is 20-27 cm, the total thickness of the two adjustment cores is 2-6 cm, and the minimum thickness of a single adjustment core is 1 cm.

[0015] According to the utility model, in some schemes, the moderation core is composed of two base cores and one adjustment core; the thickness of the adjustment core is 1-6 cm; the total thickness of the two base cores is 21-27 cm, among which there is at least one base core with a thickness of 20 cm, and the thickness of the other base core is 1-7 cm.

[0016] According to the utility model, in some schemes, the moderator core is composed of no more than four base cores to slow down the high-energy neutron beam to the epithermal neutron energy range, wherein there is at least one base core with a thickness of 20 cm, and the thickness of the other three base cores is at least 1 cm, and the total thickness of the four base cores is 23-33 cm.

[0017] According to the utility model, in some schemes, the base core and the adjustment core are sequentially arranged in the accommodating cavity along the extension direction of the proton beam channel, and the base core and the adjustment core are axially abutted against each other.

[0018] According to the utility model, in some schemes, the base core material is magnesium fluoride, and the adjustment core material is polyethylene or magnesium fluoride or a combination of polyethylene and magnesium fluoride.

[0019] According to the utility model, in some schemes, the collimator is constructed with a conical hole that gradually shrinks along the axial direction; the inner diameter of the expansion portion formed at one end of the conical hole close to the slowing core is 28-38 cm, the inner diameter of the opening portion formed at one end of the conical hole opposite to the expansion portion is 10-24 cm, and the axial length of the conical hole is 10 or 14 cm.

[0020] According to the utility model, in some schemes, the collimator is constructed with a cylindrical through hole that penetrates axially; the inner diameter of the through hole is 10-24 cm, and the axial length of the through hole is 10 or 14 cm.

[0021] According to the utility model, in some schemes, the adjustable beam shaping device also includes: a filtering unit formed between the moderator core and the collimator, a telescopic tube formed in the proton beam channel to configure the target material, a cooling unit circumferentially arranged around the target material to cool the target material, and a driving unit for driving the telescopic tube to extend and retract axially to drive the target material to be close to the moderator core.

[0022] According to the present invention, in some solutions, the filter unit is configured as a thermal neutron filter and / or a gamma ray filter.

[0023] According to the utility model, in some schemes, the reflector includes: a side reflector circumferentially arranged around the moderator core and the filter unit, a back reflector axially pressed against the side reflector, the accommodating cavity is formed by the side reflector and the back reflector, and a spare core arranged in the accommodating cavity and axially pressing against the moderator core; the back reflector and the spare core are axially sleeved on the outside of the proton beam channel in sequence.

[0024] In a second aspect, the utility model provides an assembly method of an adjustable beam shaping device as disclosed in any of the above utility model inventions, comprising the following steps:

[0025] Step S1, according to different neutron capture therapy requirements, neutron beams with different energy ranges need to be drawn, and a plurality of base cores and a plurality of adjustment cores, or a plurality of base cores, made of different materials are correspondingly selected;

[0026] Step S2, arranging and combining a plurality of base cores and a plurality of adjustment cores side by side to form a moderator core, or arranging and combining a plurality of base cores in rows to form a moderator core;

[0027] Step S3, placing the spare core, the moderator core, the filter unit and the collimator into the side reflector in sequence along the axial direction, and placing the spare core close to the moderator core, and then connecting the back reflector to the side of the side reflector close to the spare core;

[0028] Step S4, the proton beam channel is axially passed through the back reflector and the spare core in sequence, and then the driving unit drives the telescopic tube to axially extend and retract in the proton beam channel to drive the target material to be close to the moderator core, so as to finally form an adjustable beam shaping device.

[0029] In a third aspect, the utility model provides an adjustable beam shaping device as disclosed in any of the above utility model creations, and the adjustable beam shaping device is applied to an accelerator boron neutron capture experimental device.

[0030] The adjustable beam shaping device, assembly method and application of the utility model have the following beneficial technical effects: a high-current charged particle beam generated by a charged particle linear accelerator (not shown) passes through a proton beam channel to bombard a target material and is consumed to become a high-energy neutron beam, and then interacts with the high-energy neutron beam through a moderator core, so that the high-energy neutron beam loses part of its energy and is slowed down to a lower energy neutron beam energy range to obtain a lower energy neutron beam, thereby enabling effective treatment of superficial tumors; or it is slowed down to an epithermal neutron energy range to obtain an epithermal neutron beam, thereby enabling effective treatment of brain gliomas, melanomas and recurrent head and neck tumors, etc., thereby achieving more accurate neutron treatment for different tumor cases and improving applicability to different tumor cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural diagram of the adjustable beam shaping device provided in the present application, wherein the moderator core is composed of multiple base cores.

[0032] Figure 2 This is a structural diagram of the adjustable beam shaping device provided in the present application, wherein the moderator core is composed of multiple base cores, and the accommodating cavity is filled with a number of spare cores.

[0033] Figure 3 This is a structural diagram of the adjustable beam shaping device provided in the present application, wherein the moderator core is composed of a base core and a plurality of adjustment cores, and the accommodating cavity is filled with a plurality of spare cores.

[0034] Figure 4 for Figure 3 The energy spectrum of the outgoing neutron beam using a moderator core with a total thickness of 24 cm.

[0035] Figure 5 for Figure 4Dose rate distribution diagram of the emitted neutron beam in the soft tissue phantom, where Tumor is tumor tissue and Normal is normal tissue;

[0036] Figure 6 for Figure 1 or Figure 2 The energy spectrum of the outgoing neutron beam using a moderating core with a total thickness of 20-32 cm;

[0037] Figure 7 for Figure 6 Dose rate distribution diagram of the emitted neutron beam in the soft tissue phantom, where Tumor is tumor tissue and Normal is normal tissue;

[0038] Figure 8 A flow chart of an assembly method of the adjustable beam shaping device provided in the present application. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the technical solution of the present disclosure clearer, the technical solution of the embodiment of the present disclosure will be clearly and completely described in combination with the drawings of the specific embodiments of the present disclosure. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0040] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the utility model belongs. The words "first", "second" and similar words used in the patent application specification and claims of the utility model do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Inside", "outside", "upper", "lower", "far", "near", "front", "back" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. The drawings in this disclosure are not strictly drawn according to the actual scale, and the specific size and quantity of each structure can be determined according to actual needs. The drawings described in this disclosure are only schematic diagrams of the structure.

[0041] It should be noted that in all embodiments of the present invention, the epithermal neutron beam mentioned in the present invention is an epithermal neutron energy range between 0.5eV and 10keV with an average energy greater than 1keV and less than 10keV, and the lower energy neutron beam mentioned in the present invention is a neutron beam energy range with an average energy lower than 1keV.

[0042] Please refer to Figures 1 to 8 The utility model provides an adjustable beam shaping device, an assembly method and a specific implementation method of application.

[0043] In the existing linear accelerator driven boron neutron capture therapy system, the neutron irradiation method is to accelerate the charged particle beam through the linear accelerator, the charged particle beam is accelerated to an energy sufficient to overcome the Coulomb repulsion of the target material nuclei, bombard the target material, and generate a high-energy neutron beam through a nuclear reaction. The high-energy neutron beam is shaped and slowed down by a specific beam shaping device to obtain an epithermal neutron beam. Finally, the neutron beam is concentrated and converged through a collimator to irradiate the target area of ​​the human body. Compared with the prior art, the adjustable beam shaping device 100 provided in this embodiment can provide accurate neutron therapy for different tumor cases. For example, by adopting a plurality of base cores 41 and a plurality of adjustment cores 42 as Figure 3 The moderator core 40 shown in the figure can be used to slow down the high-energy neutron beam to a lower-energy neutron beam energy range to obtain a lower-energy neutron beam, thereby effectively treating superficial tumors; or by using a plurality of base cores 41 as shown in the figure. Figure 1 or Figure 2 The moderator core 40 shown is used to slow down the high-energy neutron beam to the epithermal neutron energy range to obtain an epithermal neutron beam, thereby being able to effectively treat brain gliomas, melanomas, and recurrent head and neck tumors, etc., and improving the applicability to different tumor cells.

[0044] like Figures 1 to 7 As shown, the adjustable beam shaping device 100 comprises: a reflector 10 having a receiving cavity 11, an axial direction (ie, Figure 1A proton beam channel 20 (in the direction indicated by the central axis W) partially penetrates the reflector 10, and a target material 30 and a moderator core 40 arranged in the accommodating cavity 11 are arranged in the proton beam channel 20; a collimator 50 is axially embedded in one end of the reflector 10 away from the proton beam channel 20; the moderator core 40 is located at one end of the proton beam channel 20 extending into the reflector 10; the moderator core 40 is composed of a plurality of base cores 41 and a plurality of adjustment cores 42 to slow down a high-energy neutron beam into a neutron beam energy range with lower energy, or the moderator core 40 is composed of a plurality of base cores 41 to slow down a high-energy neutron beam into an epithermal neutron energy range. The high-current charged particle beam generated by the charged particle linear accelerator (not shown) passes through the proton beam channel 20 to bombard the target material 30 and is consumed to become a high-energy neutron beam, and then interacts with the high-energy neutron beam through the moderation core 40, so that the high-energy neutron beam loses part of its energy and is moderated to a lower energy neutron beam energy range to obtain a lower energy neutron beam; or it is moderated to an epithermal neutron energy range to obtain an epithermal neutron beam, which can be collimated by the collimator 50 and used for the emitted neutron beam to increase the neutron flux. In actual use, by using a plurality of base cores 41 and a plurality of adjustment cores 42, as shown in FIG. Figure 3 The moderator core 40 shown in FIG. 4 can be used to slow down the high-energy neutron beam to a lower-energy neutron beam energy range to obtain a lower-energy neutron beam, thereby achieving effective treatment of superficial tumors; and, the moderator core 40 can also be used to form a plurality of base cores 41 as shown in FIG. Figure 1 or Figure 2 The moderator core 40 shown is used to slow down the high-energy neutron beam to the epithermal neutron energy range to obtain an epithermal neutron beam, thereby being able to effectively treat brain glioma, melanoma, and recurrent head and neck tumors, etc. This can provide more accurate neutron therapy for different tumor cases and improve the applicability to different tumor cells.

[0045] It should be noted that the material of the target 30 can be a lithium target or a beryllium target, etc., and a high-energy neutron beam is generated by bombarding the lithium target or the beryllium target with a common high-current particle beam. The material of the reflector 10 is preferably lead (Pb). In addition, the charged particle linear accelerator (not shown) can also be an electrostatic linear accelerator, a cyclotron linear accelerator, a synchrotron linear accelerator, a cyclotron + synchrotron linear accelerator, a linear accelerator, a laser-driven linear accelerator, etc.

[0046] It should be noted that the material of the substrate core 41 can be a mixture of one or more of magnesium fluoride, aluminum fluoride, calcium fluoride and aluminum, and the material of the substrate core 41 is preferably magnesium fluoride (MgF 2); the core body 42 material can be adjusted to be a mixture of one or more of magnesium fluoride, polyethylene, polytetrafluoroethylene, beryllium oxide, heavy water and water, and the core body 42 material is preferably adjusted to be polyethylene (PE).

[0047] like Figure 3 As shown, when a neutron beam with lower energy is required, specifically, the moderator core 40 is composed of a total of 2 or 3 base cores 41 and an adjustment core 42, so as to slow down the high-energy neutron beam into a neutron beam energy range with lower energy, and the total thickness of the base core 41 and the adjustment core 42 is 21-33 cm or 22-33 cm. The base core 41 is preferably made of magnesium fluoride, and the adjustment core 42 is preferably made of polyethylene.

[0048] like Figure 4 As shown, curve 1 "24MF" means that the moderator core 40 is composed of one, two or three substrate cores 41 with a total thickness of 24 cm; curve 2 "4PE+20MF" means that the moderator core 40 is composed of an adjustment core 42 and a substrate core 41 sequentially arranged in the accommodating cavity 11 along the extension direction of the proton beam channel 20, a substrate core 41 with a thickness of 20 cm and one or two adjustment cores 42 with a total thickness of 4 cm; curve 3 "20MF+4PE" means that the moderator core 40 is composed of a substrate core 41 and an adjustment core 42 sequentially arranged in the accommodating cavity 11 along the extension direction of the proton beam channel 20, a substrate core 41 with a thickness of 20 cm and one or two adjustment cores 42 with a total thickness of 4 cm; combining these three curves and Figure 4 As shown, when the thickness is the same (i.e., 24 cm), using the adjustment core 42 to replace the base core 41 of part of the thickness can significantly reduce the high-energy neutron component, and the base core 41 and the adjustment core 42 sequentially arranged in the accommodating cavity 11 along the extension direction of the proton beam channel 20 have a better effect of reducing the high-energy neutron component. Therefore, preferably, the moderator core 40 is composed of a plurality of base cores 41 and a plurality of adjustment cores 42 to improve the effect of the moderator core 40 in reducing the high-energy neutron component. And the base core 41 and the adjustment core 42 are sequentially arranged in the accommodating cavity 11 along the extension direction of the proton beam channel 20, and the base core 41 and the adjustment core 42 are axially abutted.

[0049] After a strong charged particle beam passes through the proton beam channel 20 and bombards the target material 30 to form a high-energy neutron beam, the high-energy neutron beam first enters the base core 41 made of magnesium fluoride. Magnesium fluoride can slow down the high-energy neutron beam to about 10 keV energy, so that the neutron energy passing through the base core 41 is high-energy neutrons of about 10 keV or medium-energy neutrons below 10 keV, thereby reducing the high-energy neutrons above 10 keV incident on the adjustment core 42. After that, neutrons at about 10 keV or below 10 keV are incident on the adjustment core 42. The adjustment core 42 made of polyethylene can quickly slow down neutrons at about 10 keV or below 10 keV and slow them down to a lower energy neutron beam energy range, so that the collimator 50 emits a lower energy neutron beam, thereby achieving effective treatment of superficial tumors.

[0050] Furthermore, if Figure 3 and Figure 5 As shown, the filter unit 60 is formed between the moderator core 40 and the collimator 50, and the filter unit 60 is configured as a thermal neutron filter 61 and / or a gamma ray filter 62. The material of the thermal neutron filter 61 is preferably lithium fluoride (LiF), and the material of the gamma ray filter 62 is preferably lead (Pb).

[0051] The dose rate distribution of neutron beam in soft tissue phantom is as follows: Figure 5 As shown, Tumor is tumor tissue, Nomal is normal tissue, and the normal tissue tolerates 12.5Gy equivalent photon dose and the tumor lethal dose is 30Gy. Curve 1 "Tumor_22MF,0.3LIF,0.3Pb" means that the moderator core 40 is composed of two substrate cores 41 with a total thickness of 22cm, and the filter unit 60 is configured as a thermal neutron filter 61 with a thickness of 0.3cm and a gamma ray filter 62 with a thickness of 0.3cm; Curve 2 "Tumor_22MF,0.6Pb" means that the moderator core 40 is composed of two substrate cores 41 with a total thickness of 22cm, and the filter unit 60 is configured as a thermal neutron filter 61 with a thickness of 0.3cm and a gamma ray filter 62 with a thickness of 0.3cm. 0 is configured as one or two gamma-ray filters 62 with a total thickness of 0.6 cm; when the moderating core 40 is composed of two base cores 41 with a total thickness of 22 cm, the thermal neutron filter 61 is removed and replaced by a gamma-ray filter 62 with the same thickness, that is, when curve 1 changes to curve 2, the peak value of the dose rate curve of curve 1 changes from a depth of 2.20 cm to 1.95 cm, and the peak value increases by 6%. Therefore, the above two changes are beneficial to the treatment of shallow tumors.

[0052] Furthermore, if Figure 5As shown, curve 3 "Tumor_20MF,2PE,0.6Pb" means that the moderator core 40 is composed of two substrate cores 41 with a total thickness of 20 cm and one or two adjustment cores 42 with a total thickness of 2 cm, and the filter unit 60 is configured as two components or one γ-ray filter 62 with a total thickness of 0.6 cm, and the peak of the dose rate curve is at a depth of 0.85 cm; curve 4 "Tumor_20MF,4PE,0.6Pb" means that the moderator core 40 is composed of two substrate cores 41 with a total thickness of 20 cm and one or two adjustment cores 42 with a total thickness of 4 cm, and the filter unit 60 is configured as two components or one The γ-ray filter 62 with a total thickness of 0.6 cm, the peak of the dose rate curve is at a depth of 0.35 cm; Curve 5 "Tumor20MF,6PE,0.6Pb" means that the moderation core 40 is composed of two base cores 41 with a total thickness of 20 cm and one or two adjustment cores 42 with a total thickness of 6 cm, and the filter unit 60 is configured as two or one γ-ray filter 62 with a total thickness of 0.6 cm, and the peak of the dose rate curve is at a depth of 0.25 cm; these 5 curves show that when the thickness of the adjustment core 42 is 6 cm or less, tumor treatment can be completed within the range of the dose that normal tissue can withstand (i.e. 12.5 Gy). It can be seen that the combination of the base core 41 and the adjustment core 42 can adjust the depth of the peak of the dose rate curve.

[0053] Moreover, in this embodiment, experiments conducted by R&D personnel have proved that the total thickness of the base core 41 and the adjustment core 42 is 21-33 cm or 22-33 cm, and the moderator core 40 is composed of a total of 2 or 3 base cores 41 and adjustment cores 42, wherein there is at least one base core 41 preferably with a thickness of 20 cm, and an adjustment core 42 with a thickness of 1-6 cm, so as to achieve the best effect.

[0054] When a neutron beam with lower energy is required, the moderator core 40 may be composed of the following embodiments: the moderator core 40 may be composed of a base core 41 and an adjustment core 42, and the thickness of the base core 41 is 20-27 cm, and the thickness of the adjustment core 42 is 1-6 cm; or, the moderator core 40 may be composed of a base core 41 and two adjustment cores 42, and the thickness of the base core 41 is 20-27 cm, the total thickness of the two adjustment cores 42 is 2-6 cm, and the minimum thickness of a single adjustment core 42 is 1 cm; or, the moderator core 40 may be composed of two base cores 41 and one adjustment core 42, and the thickness of the adjustment core 42 is 1-6 cm, the total thickness of the two base cores 41 is 21-27 cm, the thickness of one base core 41 is 20 cm, and the thickness of the other base core 41 is 1-7 cm.

[0055] like Figure 1 and Figure 2 As shown, when an epithermal neutron beam is required, specifically, the moderator core 40 is composed of no more than four base cores 41 to moderate the high-energy neutron beam into an epithermal neutron energy range, wherein at least one base core 41 has a thickness of 20 cm, and the thickness of the other three base cores 41 is at least 1 cm. The total thickness of the four base cores 41 is 23-33 cm, and the base cores 41 are axially supported against each other. The base core 41 is made of magnesium fluoride (MgF 2 ), the filter unit 60 is formed between the moderator core 40 and the collimator 50, and the filter unit 60 is configured as a thermal neutron filter 61 and a gamma ray filter 62. The material of the thermal neutron filter 61 is preferably lithium fluoride (LiF), and the material of the gamma ray filter 62 is preferably lead (Pb).

[0056] Furthermore, if Figure 6 and Figure 7 As shown, Tumor is tumor tissue, Nomal is normal tissue, and the normal tissue tolerates an equivalent photon dose of 12.5Gy, and the tumor lethal dose is 30Gy. Curve 1 "20MF" means that the slowing core 40 is composed of a substrate core 41 with a thickness of 20cm; Curve 2 "24MF" means that the slowing core 40 is composed of a substrate core 41 with a total thickness of 24cm and no more than four; Curve 3 "28MF" means that the slowing core 40 is composed of a substrate core 41 with a total thickness of 28cm and no more than four; Curve 4 "32MF" means that the slowing core 40 is composed of a substrate core 41 with a total thickness of 32cm and no more than four; Combining these four curves and Figure 6 and Figure 7 As shown, by using a moderator core 40 composed of one or no more than four substrate cores 41 with a thickness of 20-32 cm, the peak position of the emitted neutron energy spectrum can be reduced from 16 keV to 1 keV.

[0057] In this embodiment, the researchers calculated that when a moderating core 40 consisting of no more than four substrate cores 41 with a total thickness of 20-28 cm is used, the neutron beam treatment depth gradually increases from 4.8 cm to 5.6 cm; when a moderating core 40 consisting of no more than four substrate cores 41 with a total thickness of 28-32 cm is used, the treatment depth remains unchanged at 5.6 cm. There is at least one substrate core 41 with a thickness of 20 cm, and the thickness of the other three substrate cores 41 is at least 1 cm.

[0058] When it is necessary to obtain an epithermal neutron beam, the moderator core 40 may be composed of the following embodiments: the moderator core 40 is composed of a base core 41 with a thickness of 20 cm; or, the moderator core 40 is composed of two axially abutting base cores 41, one of which has a thickness of 20 cm, and the other has a thickness of 1-13 cm; or, the moderator core 40 is composed of three axially abutting base cores 41, one of which has a thickness of 20 cm, and the other two have a total thickness of 2-13 cm; or, the moderator core 40 is composed of four axially abutting base cores 41, one of which has a thickness of 20 cm, and the other three have a total thickness of 3-13 cm.

[0059] like Figures 1 to 3 As shown, the adjustable beam shaping device 100 further includes: a filter unit 60 formed between the moderator core 40 and the collimator 50, a telescopic tube 70 formed in the proton beam channel 20 to arrange the target 30, a cooling unit (not shown) circumferentially arranged around the target 30 to cool the target 30, and a driving unit (not shown) driving the telescopic tube 70 to extend and retract axially to drive the target 30 to be close to the moderator core 40. The reflector 10 includes: a side reflector 12 circumferentially arranged around the moderator core 40 and the filter unit 60, a back reflector 13 axially abutting against the side reflector 10, an accommodating cavity 11 formed by the side reflector 12 and the back reflector 13, and a spare core 101 arranged in the accommodating cavity 11 and axially abutting against the moderator core 40; the back reflector 13 and the spare core 101 are axially sleeved on the outside of the proton beam channel 20 in sequence. Preferably, the material of the spare core 101 is lead (Pb).

[0060] In the above process of obtaining a neutron beam or epithermal neutron beam with a lower energy, the moderator core 40 is composed of a plurality of base cores 41 and a plurality of adjustment cores 42, or the moderator core 40 is composed of a plurality of base cores 41. When the total thickness of the plurality of base cores 41 and the plurality of adjustment cores 42 or the total thickness of the plurality of base cores 41 is less than the axial length of the accommodating cavity 11, the plurality of spare cores 101 can be filled between the base core 41 and the target 30 to make the base core 41 and the adjustment core 42 axially abut against each other, or to make the plurality of base cores 41 axially abut against each other. In addition, the back reflector 13 and the spare core 101 are constructed with a connecting hole (not shown) for the proton beam channel 20 to pass through, so that the proton beam channel 20 can axially extend into the connecting hole, so that the driving unit can drive the telescopic tube 70 to extend and retract axially to drive the target 30 to be close to the moderator core 40.

[0061] In this embodiment, preferably, the collimator 50 is constructed with a tapered hole 51 that gradually decreases in the axial direction; the inner diameter of the expansion portion 511 formed at one end of the tapered hole 51 close to the moderation core 40 is 28-38 cm, the inner diameter of the opening portion 512 formed at one end of the tapered hole 51 opposite to the expansion portion 511 is 10-24 cm, and the axial length of the tapered hole 51 is 10 or 14 cm. Preferably, the material of the collimator 50 is composed of a mixture of polyethylene and lithium fluoride to achieve moderation and absorption of neutrons. The inner diameters of the expansion portion 511 and the opening portion 512 can be set according to the specific tumor conditions, and different inner diameters of the expansion portion 511 and the opening portion 512 are used for different tumor patients. The smaller the inner diameter of the opening 512 and the larger the inner diameter of the expansion portion 511, the more neutron flux can be enhanced; the larger the inner diameter of the opening 512 and the smaller the inner diameter of the expansion portion 511, the less neutron leakage can be achieved to prevent damage to normal tissue.

[0062] For example, in some embodiments, the collimator 50 is constructed with a cylindrical through hole (not shown) that runs axially; the inner diameter of the through hole is 10-24 cm, and the axial length of the through hole is 10 or 14 cm. The inner diameter of the through hole can be set according to the specific tumor situation, and different inner diameters are used for different tumor patients.

[0063] Combination Figures 1 to 8 As shown, the utility model also provides an assembly method of an adjustable beam shaping device, comprising the following steps:

[0064] Step S1: According to different neutron capture therapy requirements, neutron beams of different energy ranges need to be drawn out, and a plurality of substrate cores 41 and a plurality of adjustment cores 42, or a plurality of substrate cores 41, made of different materials are selected accordingly; when neutron capture therapy is required for superficial tumors, the total number of substrate cores 41 and adjustment cores 42 selected accordingly is 2 or 3, and the total thickness of the substrate cores 41 and the adjustment cores 42 is 21-33 cm or 22-33 cm, wherein at least one substrate core 41 preferably has a thickness of 20 cm, and one substrate core 41 preferably has a thickness of 20 cm. An adjustment core 42 with a thickness of 1-6 cm, and the material of the base core 41 is preferably magnesium fluoride, and the material of the adjustment core 42 is preferably polyethylene; or when neutron capture therapy is required for brain glioma, melanoma, head and neck recurrent tumors, etc., no more than four corresponding base cores 41 are selected, and the total thickness of the four base cores 41 is 23-33 cm, among which there is at least one base core 41 with a thickness of 20 cm, and the thickness of the other three base cores 41 is at least 1 cm, and the material of the base core 41 is preferably magnesium fluoride;

[0065] Step S2, arranging a plurality of base cores 41 and a plurality of adjustment cores 42 side by side to form a moderator core 40, or arranging a plurality of base cores 41 in a row to form a moderator core 40; a total of 2 or 3 base cores 41 and adjustment cores 42 are sequentially arranged in the accommodating cavity 11 along the extending direction of the proton beam channel 20 to form the moderator core 40; or no more than four base cores 41 form the moderator core 40;

[0066] Step S3, placing the spare core 101, the moderator core 40, the filter unit 60 and the collimator 50 in the side reflector 12 in sequence along the axial direction, and making the spare core 101 close to the moderator core 40, and then connecting the back reflector 13 to the side of the side reflector 12 close to the spare core 101;

[0067] Step S4, the proton beam channel 20 is axially penetrated through the back reflector 13 and the spare core 101 in sequence, and then the telescopic tube 70 is driven by a driving unit (not shown) to axially telescope in the proton beam channel 20 to drive the target material 30 to be close to the moderator core 40, so as to finally form an adjustable beam shaping device 100.

[0068] Based on the technical solution of an adjustable beam shaping device 100 disclosed in the above embodiment, the adjustable beam shaping device 100 is applied to an accelerator boron neutron capture experiment device (BNCT) (not shown), so that the accelerator boron neutron capture experiment device (BNCT) equipped with the adjustable beam shaping device 100 can select the configuration of the moderation core 40 for different tumor cases, for example, by adopting a plurality of base cores 41 and a plurality of adjustment cores 42 as shown in FIG. Figure 3 The moderator core 40 shown in the figure can be used to slow down the high-energy neutron beam to a lower-energy neutron beam energy range to obtain a lower-energy neutron beam, thereby effectively treating superficial tumors; or by using a plurality of base cores 41 as shown in the figure. Figure 1 or Figure 2 The moderator core 40 shown is used to slow down the high-energy neutron beam to the epithermal neutron energy range to obtain an epithermal neutron beam, thereby being able to effectively treat brain gliomas, melanomas, and recurrent head and neck tumors, etc., and improving the applicability to different tumor cells.

[0069] In summary, the utility model provides a moderator with adjustable thickness to achieve precise treatment of a variety of different tumors; at the same time, it provides a spare core with a connection hole. When this moderator is used in a beam shaping device, the target material can be deeply inserted into the accommodating cavity and arranged close to the moderator, so that there is no need to fill the accommodating cavity with the moderator to achieve the effect of thinning the overall thickness of the moderator, thereby adjusting the neutron energy and flux at the output end of the beam shaping device.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. An adjustable beam shaping device, characterized in that: It comprises a reflector with a receiving cavity filled with a moderator core; and a spare core arranged in the receiving cavity and axially abutting against the moderator core, wherein the spare core is provided with a connecting hole for a proton beam passage to pass through.

2. The adjustable beam shaping device according to claim 1, characterized in that: The moderator core includes a plurality of substrate cores.

3. The adjustable beam shaping device according to claim 2, characterized in that: The moderator core also includes a plurality of adjustment cores axially supported against the base core.

4. The adjustable beam shaping device according to claim 1, characterized in that: The adjustable beam shaping device is connected with a proton beam channel with a target material at the end; the proton beam channel extends into the accommodating cavity, passes through the connecting hole of the spare core body, and abuts against the moderator core body.

5. The adjustable beam shaping device according to claim 4, characterized in that: The distance that the proton beam channel extends into the accommodating cavity is adjustable, and the number of the spare cores is adapted to the distance that the proton beam channel extends into the accommodating cavity so as to fill the cavity around the proton beam channel.

6. The adjustable beam shaping device according to claim 4, characterized in that: A telescopic tube is formed in the proton beam channel.

7. The adjustable beam shaping device according to claim 1, characterized in that: A collimator is axially embedded in one end of the reflector away from the proton beam channel; the collimator is detachably connected to the reflector.

8. The adjustable beam shaping device according to claim 3, characterized in that: The total thickness of the base core and the adjustment core is 21 to 33 cm or 22 to 33 cm.

9. The adjustable beam shaping device according to claim 2, characterized in that: The thickness of the plurality of substrate cores is 20-27 cm.

10. The adjustable beam shaping device according to claim 3, characterized in that: The thickness of the plurality of adjustment cores is 1-6 mm.

11. The adjustable beam shaping device according to claim 3, characterized in that: The moderation core is composed of one base core and two adjustment cores.

12. The adjustable beam shaping device according to claim 3, characterized in that: The moderation core is composed of two base cores and one adjustment core; The thickness of the adjusting core is 1 to 6 cm; The total thickness of the two base cores is 21-27 cm, wherein at least one base core has a thickness of 20 cm, and the thickness of the other base core is 1-7 cm.

13. The adjustable beam shaping device according to claim 3, characterized in that: The moderator core is composed of no more than four base cores to slow down the high-energy neutron beam to the epithermal neutron energy range, wherein there is at least one base core with a thickness of 20 cm, and the thickness of the other three base cores is at least 1 cm, and the total thickness of the four base cores is 23 to 33 cm.

14. The adjustable beam shaping device according to claim 7, characterized in that: The collimator is constructed with a tapered hole that gradually shrinks along the axial direction; the inner diameter of the expansion portion formed at one end of the tapered hole close to the moderation core is 28 to 38 cm, the inner diameter of the opening portion formed at one end of the tapered hole opposite to the expansion portion is 10 to 24 cm, and the axial length of the tapered hole is 10 cm or 14 cm.

15. The adjustable beam shaping device according to claim 7, characterized in that: The collimator is constructed with a cylindrical through hole that penetrates along the axial direction; the inner diameter of the through hole is 10 to 24 cm, and the axial length of the through hole is 10 cm or 14 cm.

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