Collimator and neutron capture treatment system

Abstract

The utility model relates to a neutron capture therapy system. The neutron capture therapy system comprises a beam shaping body and a collimator, the beam shaping body comprises a target material, a beam inlet and a beam outlet which are arranged in the beam shaping body, the target material and a charged particle beam incident from the beam inlet are subjected to nuclear reaction to generate neutrons, the neutrons form neutron beams, the neutron beams are emitted from the beam outlet and define a neutron beam axis, and the collimator is arranged at the beam outlet; the collimator comprises a collimation body and a replacement part, the collimation body, the replacement part and the beam outlet are communicated, and at least part of the replacement part can be installed in the beam shaping body and can be detached from the collimation body. Compared with the beam shaping body and the collimating body, the replacement part of the collimator can be replaced, so that different beam shaping bodies can be adapted by selecting or replacing the replacement part meeting the requirement, the irradiation requirements of different treatment parts can be met, and the beam quality can be effectively ensured.

Description

Technical Field

[0001] The present application relates to the field of neutron therapy, and in particular to a collimator and a neutron capture therapy system. Background Art

[0002] The description in this section merely provides background information related to the disclosure of the present application and does not constitute prior art.

[0003] With the development of atomic science, neutron capture therapy (e.g., boron neutron capture therapy (BNCT)) has become a new cancer treatment method due to its precise targeting characteristics and high relative biological effect. The treatment process is: first, a boron-containing compound with specific adsorption ability to tumors is injected into the patient's body; then, after the tumor is 10 After the B atoms are gathered, an epithermal / thermal neutron beam is used to irradiate the tumor. The neutrons are then absorbed by the tumor. 10 After B is captured, a nuclear reaction occurs, and the alpha particles released by the reaction and 7 Li particles are very damaging to cells, and their total range is within the range of one cell, so they can locally kill tumor cells without destroying normal cells.

[0004] The neutron capture therapy system may include an accelerator and a beam shaping system, wherein the beam shaping system may include a beam shaping body and a target material disposed in the beam shaping body. When the accelerator accelerates the charged particle beam to a speed sufficient to overcome the Coulomb repulsion of the atomic nuclei of the target material, the charged particle beam undergoes a nuclear reaction with the target material to generate neutrons, and the neutrons are suitable for treatment after being adjusted by the energy spectrum of the beam shaping body (BSA).

[0005] Generally, the neutron capture therapy system may also include a collimator disposed downstream of the moderator along the direction of beam movement, so as to collimate the neutron beam and reduce exposure to neutrons and photons outside the treatment range. At present, the collimators used in neutron capture therapy systems generally adopt two structures. The first collimator is a cylindrical structure with a truncated cone-shaped hole in the center, which is not easy to disassemble and is mostly a fixed configuration; the second collimator is based on the first collimator, and an externally extended fixed configuration collimation structure is used to meet the collimation requirements.

[0006] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0007] The present application creatively discovered that the collimator structure in the prior art is generally a fixed configuration. When the structure changes inside the beam shaper, the originally adapted collimator and beam shaper are no longer adapted. Especially for different treatment parts or different treatment populations, the treatment dose per unit time may change accordingly, and the structure of the beam shaper needs to be adjusted accordingly to meet different neutron beam intensity requirements.

[0008] For example, when the length of the moderator changes, the collimator that was originally attached to or adjacent to the moderator is no longer applicable. For example, when the length of the moderator increases, the moderator and the collimator cannot be installed. Therefore, a certain gap is usually reserved between the moderator and the collimator to avoid this situation. When the length of the moderator decreases, the gap between the moderator and the collimator will increase, or even increase further. Moreover, after many tests and studies, it has been shown that this gap between the moderator and the collimator is not conducive to the output neutron beam during actual use.

[0009] Therefore, for different beam shapers, especially for the needs of different treatment apertures corresponding to different treatment parts, how to make the collimator adapt to different beam shapers while ensuring the quality of the neutron beam is a technical problem that needs to be solved urgently.

[0010] In order to achieve the above-mentioned purpose, the present invention provides a neutron capture therapy system on one hand, which includes a beam shaper and a collimator; the beam shaper includes a target material, a beam inlet and a beam outlet arranged in the beam shaper, the target material undergoes a nuclear reaction with a charged particle beam incident from the beam inlet to produce neutrons, the neutrons form a neutron beam, the neutron beam is emitted from the beam outlet and defines a neutron beam axis, and the collimator is arranged at the beam outlet; the collimator includes a collimating body and a replacement part, the collimating body, the replacement part and the beam outlet are connected and arranged, and at least part of the replacement part can be installed in the beam shaper and can be separated from the collimating body and the beam shaper respectively.

[0011] Further, the replacement part has a first end and a second end opposite to each other along the axis direction of the neutron beam, the first end of the replacement part is adjacent to or in close contact with the collimating body, the second end of the replacement part is located inside the beam shaping body, and the interior of the beam shaping body has a wall surface adjacent to or in close contact with the second end of the replacement part.

[0012] Furthermore, the replacement part has a first end and a second end opposite to each other along the neutron beam axis direction, the first end of the replacement part can be separated from the collimation body, and the second end of the replacement part is fitted with the inside of the beam shaping body.

[0013] Furthermore, at least part of the replacement part is made of any one or more of lead, molybdenum, bismuth, graphite or Teflon.

[0014] Furthermore, an inner surface of the replacement portion is inclined from the beam entrance toward the collimating body to form a cone with a gradually decreasing diameter.

[0015] Furthermore, the collimating body includes a reflecting unit and a shielding unit wrapped around the reflecting unit, and an inner surface of the reflecting unit is coplanar with an inner surface of the replacement part.

[0016] Furthermore, the neutron capture therapy system further comprises a moderator, and along the axial direction of the neutron beam, the replacement portion has a preset length adapted to the distance formed between the collimating body and the moderator.

[0017] Further, the replacement part is an integrated structure, or,

[0018] The replacement part includes at least two replacement units, and at least two of the replacement units are detachable.

[0019] Furthermore, along the neutron beam axis direction, at least two replacement units have different lengths.

[0020] Another aspect of the present invention provides a collimator, including a collimator body and a replacement part, wherein the collimator body has a first end and a second end opposite to each other, the first end of the collimator body has a collimation outlet, the replacement part can be detached from the second end of the collimator body, and the collimator body is connected to the replacement part.

[0021] Further, the replacement portion extends in a direction away from the collimation outlet.

[0022] Furthermore, at least part of the replacement part is made of any one or more of lead, molybdenum, bismuth, graphite or Teflon.

[0023] Furthermore, the inner surface of the replacement portion is inclined along the direction of the collimated outlet to form a cone with a gradually decreasing diameter.

[0024] Furthermore, the collimating body includes a reflecting unit and a shielding unit wrapped around the reflecting unit, and an inner surface of the reflecting unit is coplanar with an inner surface of the replacement part.

[0025] Furthermore, the replacement part is of an integrated structure, or the replacement part includes at least two replacement units, and at least two of the replacement units are detachable.

[0026] Furthermore, along the collimated outlet direction, the lengths of at least two replacement units are different.

[0027] By means of the above technical solution, the replacement part of the collimator in the present application is replaceable compared to the beam shaper and the collimator body. Therefore, different beam shapers can be adapted by selecting or replacing the replacement part that meets the requirements, thereby not only being able to meet the irradiation requirements of different treatment parts, but also being able to effectively ensure the beam quality.

[0028] With reference to the following description and accompanying drawings, the specific embodiments of the present application are disclosed in detail, indicating the way in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not therefore limited in scope. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present application include many changes, modifications and equivalents.

[0029] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0030] It should be emphasized that the term “include / comprising” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are for explanation purposes only and are not intended to limit the scope of the present application in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes and are used to help understand the present application. They do not specifically limit the shapes and proportional dimensions of the components of the present application. Under the guidance of the present application, those skilled in the art can select various possible shapes and proportional dimensions to implement the present application according to specific circumstances. In the drawings:

[0032] Figure 1 A schematic diagram of the overall structure of a neutron capture therapy system provided in one embodiment of the present invention.

[0033] Figure 2 A schematic structural diagram of a neutron capture therapy system provided in one embodiment of the present invention.

[0034] Figure 3 A schematic structural diagram of a collimator provided in one embodiment of the present invention.

[0035] Figure 4 A partially enlarged schematic diagram of a neutron capture therapy system provided in one embodiment of the present invention.

[0036] Figure 5 A partially enlarged schematic diagram of a neutron capture therapy system provided in another embodiment of the present invention.

[0037] Figure 6It is a schematic structural diagram of an optional replacement part of the present invention.

[0038] Figure 7 It is a schematic structural diagram of another optional replacement part of the present invention.

[0039] Figure 8 This is a schematic structural diagram of yet another optional replacement part of the present invention.

[0040] Fig. 9 A schematic structural diagram of a neutron capture therapy system provided in another embodiment of the present invention.

[0041] Fig.10 A schematic structural diagram of a neutron capture therapy system provided in yet another embodiment of the present invention.

[0042] The figure markings of the above drawings are: 1, beam shaping body; 11, target material; 12, beam entrance; 13, beam exit; 14, moderator; 15, main body; 151, reflector; 1511, first channel; 1512, first conical surface; 1513, second conical surface; 152, shielding body; 1521, second channel; 16, thermal neutron absorber; 2, collimator; 21, collimating body; 211, reflecting unit; 212, shielding unit; 2121, neutron shielding layer; 2122, photon shielding layer; 213, supporting structure; 215, collimating exit; 22, replacement part; 221, through hole; 222, replacement unit; X, neutron beam axis. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0044] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0046] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0047] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and to distinguish similar objects. There is no order of precedence between the two, and they cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the inclusive meaning of "plurality" is two or more.

[0048] Neutron capture therapy has been increasingly used in recent years as an effective means of treating cancer, among which boron neutron capture therapy is the most common. Neutrons for boron neutron capture therapy can be supplied by nuclear reactors or accelerators. The embodiments of the present application take accelerator boron neutron capture therapy as an example. The basic components of accelerator boron neutron capture therapy usually include an accelerator for accelerating charged particles (such as protons, deuterons, etc.), a neutron capture therapy system, wherein the neutron capture therapy system includes a target material and a beam shaper, wherein the accelerated charged particles interact with the target material to produce neutrons, and the appropriate nuclear reaction is selected based on the required neutron yield and energy, the energy and current of the accelerated charged particles that can be provided, the physical and chemical properties of the target material and other characteristics. The nuclear reactions that are often discussed are: 7 Li(p,n) 7 Be and 9 Be(p,n) 9 B. Both reactions are endothermic reactions.

[0049] The ideal target material should have high neutron yield, neutron energy distribution close to the epithermal neutron energy region (described in detail below), no strong penetrating radiation, safe, cheap, easy to operate, and high temperature resistance. However, it is actually impossible to find a nuclear reaction that meets all the requirements. In the embodiment of the present application, a target material made of lithium metal is used. However, it is well known to those skilled in the art that the target material can also be made of other metal materials besides the metal materials mentioned above.

[0050] Regardless of whether the neutron source of BNC therapy comes from a nuclear reactor or a nuclear reaction between charged particles in an accelerator and a target material, a mixed radiation field is generated, that is, the beam contains neutrons and photons ranging from low energy to high energy. For BNC therapy of deep tumors, the more radiation content there is except for epithermal neutrons, the greater the proportion of non-selective dose deposition in normal tissues. Therefore, these radiations that will cause unnecessary doses should be reduced as much as possible.

[0051] The International Atomic Energy Agency (IAEA) has given five recommendations for air beam quality factors for neutron sources used in clinical boron neutron capture therapy. These five recommendations can be used to compare the advantages and disadvantages of different neutron sources and serve as a reference for selecting neutron production methods and designing beam shapers. The five recommendations are as follows:

[0052] Epithermal neutron flux>1x 10 9 n / cm 2 s

[0053] Fast neutron contamination <2x 10 -13 Gy-cm 2 / n

[0054] Photon contamination<2x 10 -13 Gy-cm 2 / n

[0055] thermal to epithermal neutron flux ratio<0.05epithermal neutron current to flux ratio>0.7

[0056] Note: The epithermal neutron energy range is between 0.5eV and 10keV, the thermal neutron energy range is less than 0.5eV, and the fast neutron energy range is greater than 10keV.

[0057] 1. Epithermal neutron beam flux:

[0058] The neutron beam flux and the concentration of boron-containing drugs in the tumor jointly determine the clinical treatment time. If the concentration of boron-containing drugs in the tumor is high enough, the requirement for neutron beam flux can be reduced; conversely, if the concentration of boron-containing drugs in the tumor is low, high-flux epithermal neutrons are required to give the tumor a sufficient dose. The IAEA requirement for epithermal neutron beam flux is more than 10 epithermal neutrons per square centimeter per second. 9For current boron-containing drugs, neutron beams at this flux can roughly control the treatment time to within one hour. In addition to the advantages of patient positioning and comfort, the short treatment time can also more effectively utilize the limited residence time of boron-containing drugs in the tumor.

[0059] 2. Fast neutron contamination:

[0060] Since fast neutrons can cause unnecessary normal tissue doses, they are considered contamination. The dose is positively correlated with the neutron energy, so the content of fast neutrons should be minimized in neutron beam design. Fast neutron contamination is defined as the fast neutron dose associated with a unit epithermal neutron flux. The IAEA recommends that fast neutron contamination be less than 2x 10 -13 Gy-cm 2 / n.

[0061] 3. Photon pollution (gamma ray pollution):

[0062] Gamma rays are highly penetrating radiation and will non-selectively cause dose deposition in all tissues along the beam path. Therefore, reducing the gamma ray content is also a necessary requirement for neutron beam design. Gamma ray contamination is defined as the gamma ray dose associated with a unit epithermal neutron flux. The IAEA recommends that gamma ray contamination be less than 2x 10 -13 Gy-cm 2 / n.

[0063] 4. Ratio of thermal neutron to epithermal neutron flux:

[0064] Since thermal neutrons decay quickly and have poor penetration, most of their energy is deposited in the skin tissue after entering the human body. In addition to epidermal tumors such as melanocytoma, which require thermal neutrons as the neutron source for boron neutron capture therapy, the thermal neutron content should be reduced for deep tumors such as brain tumors. The IAEA recommends that the ratio of thermal neutrons to epithermal neutrons be less than 0.05.

[0065] 5. Neutron current and flux ratio:

[0066] The ratio of neutron current to flux represents the directionality of the beam. The larger the ratio, the better the forward direction of the neutron beam. A highly forward-directed neutron beam can reduce the dose to surrounding normal tissues caused by neutron divergence, and also increase the treatment depth and positioning flexibility. The IAEA recommends that the ratio of neutron current to flux be greater than 0.7.

[0067] 1. Effective treatment depth:

[0068] The depth at which the tumor dose is equal to the maximum dose of normal tissue. After this depth, the dose received by tumor cells is less than the maximum dose of normal tissue, which means that the advantage of boron neutron capture is lost. This parameter represents the penetration ability of neutron beams. The greater the effective treatment depth, the deeper the depth of the tumor that can be treated. The unit is cm.

[0069] 2. Effective treatment depth dose rate:

[0070] That is, the tumor dose rate at the effective treatment depth is equal to the maximum dose rate of normal tissue. Because the total dose received by normal tissue is a factor that affects the total dose that can be given to the tumor, the parameter affects the length of treatment time. The larger the effective treatment depth dose rate, the shorter the irradiation time required to give a certain dose to the tumor. The unit is cGy / mA-min.

[0071] 3. Effective therapeutic dose ratio:

[0072] The ratio of the average dose received by the tumor and normal tissue from the brain surface to the effective treatment depth is called the effective treatment dose ratio. The average dose can be calculated by integrating the dose-depth curve. The larger the effective treatment dose ratio, the better the treatment effect of the neutron beam.

[0073] In order to provide a comparative basis for the design of the beam shaper, in addition to the five IAEA-recommended beam quality factors in air and the above three parameters, the following parameters for evaluating the performance of neutron beam dose are also used in the embodiments of the present application:

[0074] 1. Irradiation time ≤ 30 min (the proton current used by the accelerator is 10 mA)

[0075] 2. 30.0RBE-Gy can treat a depth of ≥7cm

[0076] 3. Maximum tumor dose ≥ 60.0 RBE-Gy

[0077] 4. Maximum dose to normal brain tissue ≤ 12.5 RBE-Gy

[0078] 5. Maximum skin dose ≤ 11.0 RBE-Gy

[0079] Note: RBE (Relative Biological Effectiveness) is the relative biological effect. Since photons and neutrons have different biological effects, the dose items above are multiplied by the relative biological effects of different tissues to obtain the equivalent dose.

[0080] Reference Figure 1 and Figure 2As shown, the embodiment of the present application discloses a neutron capture therapy system, which may include a beam shaper 1 and a collimator 2. The beam shaper 1 may include a main body 15, a target 11 and a moderator 14 disposed in the main body 15, a beam inlet 12 and a beam outlet 13. The main body 15 may include a reflector 151 wrapped outside the moderator 14 and a radiation shield 152 disposed in the beam shaper 1. The target 11 may be adjacent to the moderator 14. The target 11 undergoes a nuclear reaction with a proton beam incident from the beam inlet 12 to generate neutrons and form a neutron beam, which defines a main axis. The moderator 14 decelerates the neutrons generated from the target 11 to the epithermal neutron energy zone, and the reflector 151 guides the neutrons that deviate from the main axis back to the main axis to converge the epithermal neutrons. The radiation shield 152 is used to shield leaked neutrons and photons to reduce the normal tissue dose in the non-irradiated area. The neutron beam axis X may be understood as the overall or general direction of movement of the proton beam from the target 11 to the moderator 14 to generate neutrons, and then continuing along the main axis toward the beam outlet 13 .

[0081] The moderator 14 has a first side ( Figure 1 middle right side) and the second side ( Figure 1 The beam inlet 12 and the target 11 are arranged on the first side of the moderator 14. The collimator 2 is arranged on the second side of the target 11. Figure 2As shown, the collimator 2 includes a collimating body 21 and a replacement part 22. The collimating body 21 can be detachably connected to the beam shaping body 1. For example, the detachable connection can be achieved by fasteners, quick-clamp structures, connecting rods, lock buckles, concave-convex buckles and other structures. The replacement part 22 can be installed in the beam shaping body 1 and can be separated from the beam shaping body 1 and the collimating body 21 respectively. It can be understood that the replacement part 22 can be separated from the beam shaping body 1, indicating that in an optional embodiment, there can be a connection relationship between the replacement part 22 and the beam shaping body 1, but if necessary, the replacement part 22 and the beam shaping body 1 can also be separated, disengaged or separated after disassembly; or, in another optional embodiment, the replacement part 22 and the beam shaping body 1 have no direct connection relationship, but are abutted between the beam shaping body 1 and the collimating body 21 through a gap between the two, and the replacement part 22 and the beam shaping body 1 can be separated, disengaged or separated by manual or machine methods. The fact that the replacement part 22 can be separated from the collimating body 21 indicates that, in an optional embodiment, there may be a connection relationship between the replacement part 22 and the collimating body 21, but, if necessary, the replacement part 22 and the collimating body 21 may be separated, detached or moved away from each other after disassembly, or, in another optional embodiment, the replacement part 22 and the collimating body 21 have no direct connection relationship, but are abutted between the collimating body 21 and the beam shaping body 1 through a gap between the two, and the replacement part 22 and the collimating body 21 may be moved away, detached or separated by manual or machine means.

[0082] In other words, the replacement part 22 has at least two states. In the installed state, the replacement part 22 is installed inside the beam shaping body 1. In the separated state, the replacement part 22 can be separated from the beam shaping body and the collimating body 21.

[0083] When the replacement part 22 is installed inside the beam shaping body 1 and the collimating body 21 is installed to the beam shaping body 1, the replacement part 22 is located between the moderator 14 and the collimating body 21 along the neutron beam axis X direction. In other words, the moderator 14, the replacement part 22, and the collimating body 21 are arranged along the neutron beam axis X direction ( Figure 1 The replacement part 22 also has a through hole 221. The through hole 221 penetrates the replacement part 22 along the neutron beam axis X direction, thereby connecting the beam outlet 13 and the collimating body 21, so that the epithermal neutrons generated by the beam shaping body 1 are collimated by the collimating body 21 and then emitted outward.

[0084] Since the replacement part 22 is replaceable, the replacement part 22 that meets the requirements can be selected or replaced according to the requirements of the output beam energy range of the beam shaper, that is, the replacement part 22 that meets the requirements can be selected or replaced according to the actual parameters of the collimator body 21 and the beam shaper 1 (for example, the thickness of the moderator 14, whether the thermal neutron absorber 16 (described in detail below) is installed, the thickness of the thermal neutron absorber 16, etc.). It can be understood that the length of the replacement part 22 that meets the requirements along the neutron beam axis X direction must be less than or equal to the distance between the moderator 14 and the collimator body 21 along the neutron beam axis X direction to avoid interference with the beam shaper 1 or the collimator body 21. Furthermore, the replacement part 22 can utilize the gap space between the moderator 14 and the collimator body 21 along the neutron beam axis X direction, that is, shorten the distance between the moderator 14 and the collimator 2 along the neutron beam axis X direction, and can reflect neutrons deviating from the neutron beam back to the neutron beam to a certain extent, thereby improving the intensity of the neutron beam.

[0085] The replacement part 22 has a first end ( Figure 1 middle right end) and the second end ( Figure 1 In the installed state, in order to minimize the distance between the moderator 14 and the collimator 2 along the neutron beam axis X direction, a replacement part 22 with a more suitable length and shape can be selected, so that the first end of the replacement part 22 can be as close to or fit to the second side of the moderator 14 as possible. In addition, in order to minimize the distance between the second end of the replacement part 22 and the collimating body 21, a replacement part 22 with a more suitable length and shape can be selected, so that the second end of the replacement part 22 can be as close to or fit to the collimating body 21 as possible.

[0086] For example, the original moderator 14 has a length of 30 cm along the X direction of the neutron beam axis. At this time, the distance between the moderator 14 and the collimator body 21 along the X direction of the neutron beam axis is 8 cm. At this time, a replacement part 22 with a length of 8 cm can be selected. The length of the moderator 14 along the X direction of the neutron beam axis is adjusted to 28 cm. At this time, the distance between the moderator 14 and the collimator body 21 along the X direction of the neutron beam axis is adjusted to 10 cm. At this time, a replacement part 22 with a length of 10 cm can be selected. The length of the moderator 14 along the X direction of the neutron beam axis is adjusted to 32 cm. At this time, the distance between the moderator 14 and the collimator body 21 along the X direction of the neutron beam axis is adjusted to 6 cm. At this time, a replacement part 22 with a length of 6 cm can be selected. In summary, the neutron capture therapy system, especially the collimator 2 part, is easy to install and has strong replaceability. It can meet the needs of different beam shaping bodies 1 (especially the moderator 14) while ensuring the neutron beam intensity.

[0087] In an ideal state, the first end and the second end of the replacement part 22 are respectively fitted with the moderator 14 and the collimation body 21, but considering the assembly accuracy or the actual situation, the first end and the second end of the replacement part 22 can be as close to the moderator 14 and the collimation body 21 as possible (that is, the first end of the replacement part 22 is at a certain distance from the moderator 14, and / or the second end of the replacement part 22 is at a certain distance from the collimation body 21), or, in order to make the first end and the second end of the replacement part 22 close to the moderator 14 or the collimation body 21, respectively, a corresponding assembly structure is adopted.

[0088] In order to further improve the collimation effect of the collimator 2 , the replacement part 22 can be made of any one or more materials with good reflective effect, such as lead, molybdenum, bismuth, graphite or Teflon.

[0089] In order to further illustrate the influence of the replacement part 22 on the neutron beam, the present embodiment also tests the comparison of neutron beam parameters at different lengths along the neutron beam axis X direction and without the replacement part 22, wherein the neutron source is a neutron beam slowed down by the beam shaper 1, located on the upstream side of the replacement part 22, and the neutron direction is cosine distribution. The results are shown in Table 1. The epithermal neutron flux Φ with the replacement part 22 is ep_有 Compared with the epithermal neutron flux Φ without the replacement part 22 ep_无 The ratio is greater than 1, and the ratio increases with the increase of the length of the replacement part 22. Therefore, the neutron beam intensity can be improved by providing the replacement part 22, and the benefit increases with the increase of the length of the replacement part 22.

[0090] Table 1 Comparison of neutron beam parameters at different lengths without and with the replacement portion 22

[0091]

[0092] In an optional embodiment, the replacement part 22 can be detachably connected to the collimation body 21. After the replacement part 22 is installed to the collimation body 21, the replacement part 22 and the collimation body 21 are simultaneously installed on the beam shaping body 1. Continuing with the previous embodiment, in order to match the length of the moderator 14 along the neutron beam axis X direction of 30 cm, and the distance between the moderator 14 and the collimation body 21 along the neutron beam axis X direction of 8 cm, a replacement part 22 with a length of 8 cm can be selected first, and then the replacement part 22 with a length of 8 cm can be detachably connected to the collimation body 21 through fasteners, quick clamping structures, connecting rods, lock buckles, concave-convex buckles and other structures, and then, the collimation body 21 with the replacement part 22 installed can be detachably connected to the beam shaping body 1 through fasteners, quick clamping structures, connecting rods, lock buckles, concave-convex buckles and other structures. When the collimating body 21 with the replacement part 22 installed thereon is installed on the beam shaping body 1 , the replacement part 22 extends into the interior of the beam shaping body 1 until it is in contact with or close to the second side of the moderator 14 .

[0093] In an optional embodiment, the replacement part 22 can be detachably connected to the beam shaping body 1. Before the collimator body 21 is installed on the beam shaping body 1, the replacement part 22 is first installed on the beam shaping body 1. Continuing with the previous embodiment, in order to match the length of the moderator 14 along the neutron beam axis X direction of 32 cm and the distance between the moderator 14 and the collimator body 21 along the neutron beam axis X direction of 6 cm, a replacement part 22 with a length of 6 cm can be first selected, and then the replacement part 22 with a length of 6 cm can be detachably connected to the beam shaping body 1 through fasteners, quick clamping structures, connecting rods, locks, concave-convex buckles and other structures, and then the collimator body 21 can be detachably connected to the beam shaping body 1 through fasteners, quick clamping structures, connecting rods, locks, concave-convex buckles and other structures. In the process of installing the replacement part 22 to the beam shaping body 1, the replacement part 22 extends into the interior of the beam shaping body 1 until it is in contact with or close to the second side of the moderator 14. After the collimating body 21 is mounted on the beam shaping body 1 , the collimating body 21 is in contact with or adjacent to the second end of the replacement part 22 .

[0094] In an optional embodiment, the replacement part 22 can be transitionally matched with the beam shaping body 1 by embedding or the like. Before the collimating body 21 is installed in the beam shaping body 1, the replacement part 22 is first placed (i.e. installed) in the beam shaping body 1. Continuing with the previous embodiment, in order to match the length of the moderator 14 along the neutron beam axis X direction of 28, and the distance between the moderator 14 and the collimating body 21 along the neutron beam axis X direction of 10 cm, a replacement part 22 with a length of 10 cm can be first selected, and then the replacement part 22 with a length of 10 cm is placed in the beam shaping body 1 by embedding or the like, and then the collimating body 21 is detachably connected to the beam shaping body 1 by fasteners, quick clamp structures, connecting rods, lock buckles, concave-convex buckles and other structures. In the process of placing the replacement part 22 in the beam shaping body 1, the replacement part 22 extends into the beam shaping body 1 until it is in contact with or close to the second side of the moderator 14. After the collimating body 21 is mounted on the beam shaping body 1 , the collimating body 21 is in contact with or adjacent to the second end of the replacement part 22 .

[0095] In summary, the neutron capture therapy system in the present application can be assembled and replaced with matching replacement parts according to treatment requirements, so it has strong replaceability.

[0096] The following Figure 1 and 2 As an example, an embodiment of the present application is specifically described. Figure 1 and 2 As shown, the neutron capture therapy system includes a beam shaper 1 and a collimator 2. The neutron capture therapy system includes a main body 15, a moderator 14, a target 11 and a beam inlet 12. The main body 15 includes a reflector 151 and a shield 152 arranged along the neutron beam axis X direction. That is, the shield 152 is located on the downstream side of the reflector 151 along the neutron beam axis X direction ( Figure 2 The reflector 151 has a first channel 1511, and the shielding body 152 has a second channel 1521. The first channel 1511 and the second channel 1521 are connected and penetrate the main body 15, so as to provide beam movement. Generally, the moderator 14 can be arranged in the first channel 1511 of the reflector 151, so as to be wrapped by the reflector 151. It can be understood that the inner side wall of the reflector 151 used to form the first channel 1511 is adapted to the outer peripheral wall of the moderator 14. In this embodiment, the first channel 1511 of the reflector 151 can be annular. The outer peripheral wall of the moderator 14 can have an annular shape adapted to the first channel 1511.

[0097] The moderator 14 has an upstream side ( Figure 2 middle right side) and downstream side ( Figure 2The beam inlet 12 and the target 11 are both arranged on the upstream side of the moderator 14. When the replacement part 22 is installed in the beam shaping body 1 (reflector 151), the replacement part 22 is located on the downstream side of the moderator 14. In addition, the upstream end of the replacement part 22 is adjacent to or in contact with the downstream side of the moderator 14.

[0098] Combination Figure 2 and Figure 3 As shown, in order to facilitate the installation of the collimating body 21, generally, the second channel 1521 of the shielding body 152 is larger than the first channel 1511 of the reflector 151, so that a portion of the downstream end surface of the reflector 151 is exposed. The collimating body 21 can be connected to the exposed portion of the downstream end surface of the reflector 151 by fastening bolts or other fasteners. In this embodiment, the collimating body 21 may include a reflecting unit 211 and a shielding unit 212 wrapped around the outside of the reflecting unit 211. The inner surface of the reflecting unit 211 is along the neutron beam axis X direction ( Figure 1 The reflecting unit 211 is used to reflect the neutrons deviating from the neutron beam back to the neutron beam to increase the neutron beam intensity and play a collimating role. A material with a larger neutron elastic scattering cross section can be used. For example, the reflecting unit 211 can be made of any one or more materials of lead, molybdenum, bismuth, graphite or Teflon. The shielding unit 212 may include a neutron shielding layer 2121 and a photon shielding layer 2122 wrapped outside the neutron shielding layer 2121. Neutron absorbing materials are added to the shielding material in the neutron shielding layer 2121 to prevent neutron leakage, and the shielding material has a reflective effect and can increase the neutron beam intensity, wherein the material of the neutron shielding layer 2121 includes but is not limited to polyethylene (PE). The photon shielding layer 2122 is used to shield the photons in the beam and reduce photon pollution, wherein the material of the photon shielding layer 2122 includes but is not limited to lead (Pb).

[0099] The collimating body 21 may further include a support structure 213, which is used to fix the remaining components of the collimating body 21 for easy disassembly. Specifically, the support structure 213 is wrapped around the outside of the shielding unit 212, and is fixed to the reflecting unit 211 and the shielding unit 212 through a pressing block. Generally, the support structure 213 may also include a first support portion and a second support portion, wherein the first support portion and the shielding body 152 are adapted to form the inner side wall of the second channel 1521, and the second support portion is in contact with the downstream side wall of the shielding body 152.

[0100] In order to verify the performance superiority of multilayer materials over single-layer or double-layer materials, this example compares Figure 2 or Figure 3The neutron beam performance of the collimator 2 of multilayer material (including reflection unit 211, neutron shielding layer 2121 and photon shielding layer 2122), the collimator of double-layer material (including neutron shielding layer 2121 made of boron-containing polyethylene (PE) material or boron-containing polyethylene material or lithium-containing polyethylene material and photon shielding layer 2122 made of lead), and the collimator of single-layer material (including neutron shielding layer 2121 made of boron-containing polyethylene (PE) material) are shown in the figure. The neutron source is the neutron beam slowed down by beam shaper 1, located at the entrance of collimator 2, and the neutron direction is cosine distribution. The evaluation parameter is epithermal neutron flux Φ ep (n·cm -2 ·s -1 ), neutron flux with energy between 0.5eV-10keV at the beam exit of collimator 2; fast neutron contamination D f / Φ ep (Gy cm 2 ), fast neutron dose per unit epithermal neutron flux at the beam exit of collimator 2; photon contamination D γ / Φ ep (Gy cm 2 ), the gamma-ray dose per unit of epithermal neutron flux at the beam exit of collimator 2. All calculation results are based on the Φ of the multilayer material. ep Normalized as a benchmark.

[0101] The comparison of neutron beam parameters of the collimator 2 composed of the above three different materials is shown in Table 2. For epithermal neutron flux, the epithermal neutron flux of the multilayer material is significantly higher than that of the combination of the double-layer material (containing boron PE and lead) and the single-layer material (containing boron PE), and the performance of the double-layer material (containing boron PE and lead) and the single-layer material (containing boron PE) is equivalent; for fast neutron contamination, the performance of the three is equivalent; for photon contamination, the multilayer material combination is significantly lower than the other two, and the difference is nearly 8-10 times. Therefore, the combination of multilayer materials can increase the epithermal neutron flux, reduce beam radiation contamination, and is more suitable for actual needs.

[0102] Table 2 Comparison of neutron beam parameters of collimator 2 with different composition materials

[0103] Beam evaluation parameters Present Embodiment (Multilayer Material) Double layer material Single layer material <![CDATA[Normalized Φ ep > 1 0.767 0.769 <![CDATA[Normalized D f / Φ ep > 1 1.008 0.974 <![CDATA[Normalized D γ / Φ ep > 1 7.868 9.997

[0104] In this embodiment, the replacement part 22 can also be detachably connected to the collimation body 21 by means of fasteners, adhesives, etc. In order to further improve the focusing effect of the replacement part 22 on neutrons. The inner surface of the replacement part 22 is inclined from the beam inlet 12 to the collimation body 21 to form a cone with a gradually decreasing diameter. Of course, in other optional embodiments, the inner surface of the replacement part 22 can also be set to a circular, stepped, arc-shaped, etc. as needed. Generally, the outer surface of the replacement part 22 is adapted to the inner side wall of the reflector 151 for forming the first channel 1511, that is, a circular surface. Of course, in other optional embodiments, the outer surface of the replacement part 22 can also be square, elliptical, etc., as long as part or all of the replacement part 22 can be placed in the reflector 151.

[0105] In this embodiment, the upstream side of the reflective unit 211 has a first wall surface located in the first channel 1511 of the reflector 151. The replacement part 22 can be detachably connected to the first wall surface of the reflective unit 211 by means of fasteners, adhesives, etc. Preferably, the inner surface of the reflective unit 211 is coplanar with the inner surface of the replacement part 22. The material of the replacement part 22 is the same as that of the reflective unit 211. In this way, the collimation effect of the collimator 2 on thermal neutrons / epitothermal neutrons can be made more stable.

[0106] Reference Figure 4 As shown, the inner surface of the reflective unit 211 and the inner surface of the replacement part 22 may also form an angle other than 0° or 180°. Figure 5 As shown, the inner surface of the reflective unit 211 may also be stepped. Of course, in other optional implementations, the inner surface of the reflective unit 211 may also be set to other shapes as needed.

[0107] In this embodiment, the replacement part 22 can be an integrated structure. Of course, in other optional embodiments, refer to Figure 6As shown, the replacement part 22 may also include at least two replacement units 222 as required. The at least two replacement units 222 are detachably connected by fasteners or adhesives. Preferably, at least two replacement units 222 are arranged along the neutron beam axis X direction. The length of each replacement unit 222 may be the same. For example, the length of each replacement unit 222 may be 1 cm. When a replacement part 22 length of 6 cm is required, 6 replacement units 222 are required. When a replacement part 22 length of 8 cm is required, 8 replacement units 222 are required. Alternatively, the length of the replacement unit 222 may be designed to be different lengths, so as to meet the needs of superposition. For example, the length of each replacement unit 222 may be set to 1 cm, 2 cm, 5 cm, etc. When a replacement part 22 length of 6 cm is required, two replacement units 222 with lengths of 1 cm and 5 cm may be selected. When a replacement part 22 length of 8 cm is required, three replacement units 222 with lengths of 1 cm, 2 cm and 5 cm may be selected.

[0108] Reference Figure 6 As shown, the inner surfaces of the replacement unit 222 can be coplanar. Figure 7 As shown, the inner surfaces of the replacement units 222 may form an angle other than 0° or 180°. Figure 8 As shown, the inner surfaces of the replacement units 222 may not be coplanar, but may be stepped. Of course, in other optional embodiments, the inner surfaces of the replacement units 222 may also be configured in other shapes as required.

[0109] Reference Fig. 9As shown, in another optional embodiment, the first channel 1511 of the reflector 151 includes a first conical surface 1512 and a second conical surface 1513 arranged along the neutron beam axis X direction. The first conical surface 1512 is inclined along the neutron beam axis X direction to form a conical surface with a gradually increasing diameter. The second conical surface 1513 is inclined along the neutron beam axis X direction to form a conical surface with a gradually decreasing diameter. Correspondingly, the moderator 14 has a first end and a second end corresponding to the neutron beam axis X direction. The outer wall surface of the first end of the moderator 14 is inclined along the neutron beam axis X direction to form a conical surface with a gradually increasing diameter, and the outer wall surface of the first end of the moderator 14 is adapted to the first conical surface 1512. The outer wall surface of the second end of the moderator 14 is inclined along the neutron beam axis X direction to form a conical surface with a gradually decreasing diameter. The outer wall surface of the second end of the moderator 14 is adapted to the second conical surface 1513. In this embodiment, the outer wall surface of the replacement part 22 is inclined along the neutron beam axis X direction to form a tapered surface with a gradually decreasing diameter. In addition, the outer wall surface of the replacement part 22 matches the second tapered surface 1513 of the reflector 151, so that the replacement part 22 can be embedded in the reflector 151. As mentioned above, before the collimating body 21 is installed in the beam shaping body 1, the replacement part 22 is first embedded in the beam shaping body 1.

[0110] In some structures of the beam shaping body 1, due to structural limitations, the upstream end of the replacement part 22 can only be attached to or close to the inner wall surface of the beam shaping body 1 without interference, so as to be as close to the moderator 14 as possible. Fig.10 As shown, for example, in an optional embodiment, the downstream side of the moderator 14 ( Fig.10 A thermal neutron absorber 16 adjacent to the moderator 14 may also be provided (on the left side in the middle). The thermal neutron absorber 16 is used to absorb thermal neutrons to avoid excessive dose to shallow normal tissue during treatment. When the replacement part 22 is installed in the beam shaping body 1, the upstream end of the replacement part 22 may be close to or fit the thermal neutron absorber 16, so as to be as close to the moderator 14 as possible to adapt to the different lengths of the moderator 14 required for different beam energy requirements. For another example, in an optional embodiment, a portion of the reflector 151 not only wraps around the circumference of the moderator 14, but also a portion of the reflector 151 also wraps around the downstream side of the moderator 14 ( Fig.10 When the replacement part 22 is installed in the beam shaping body 1, the upstream end of the replacement part 22 can be close to or fit with the downstream side of the moderator 14 wrapped by the reflector 151, so as to be as close to the moderator 14 as possible to adapt to the length of the moderator 14.

[0111] On the other hand, refer to Figure 3As shown, the present application also includes a collimator 2, including a collimating body 21 and a replacement part 22, wherein the first end of the collimating body 21 has a collimating outlet 215. The replacement part 22 can be separated from the second end of the collimating body 21.

[0112] In an optional embodiment, the replacement part 22 and the second end of the collimation body 21 may be connected to each other. However, if necessary, the replacement part 22 and the second end of the collimation body 21 may be separated, disengaged or moved away from each other after being disassembled.

[0113] In another optional embodiment, the replacement part 22 and the collimating body 21 are not directly connected, but the replacement part 22 and the collimating body 21 can be separated, disengaged or separated manually or by machine. The collimating body 21 and the replacement part 22 are connected.

[0114] In other words, the replacement part 22 has at least two states. In the split state, the replacement part 22 can be detached, separated or away from the collimating body 21, so that the replacement part 22 can be selected and / or replaced as needed. After the replacement part 22 is selected, the replacement part 22 can be installed, so that the replacement part 22 is switched to the installation state. In the installation state, the replacement part 22 is close to or attached to the second end of the collimating body 21. The through hole 221 of the replacement part 22 is connected to the collimating outlet 215. The replacement part 22 and the collimating body 21 can be in a state of being installed together to the beam shaping body 1 or have been installed together to the beam shaping body 1, or can also be in a state of having been installed to the beam shaping body 1 separately. At this time, thermal neutrons / epitothermal neutrons can leave the collimating outlet 215 through the through hole 221 of the replacement part 22 after being collimated by the replacement part 22 and the collimating body 21. When the replacement part 22 needs to be replaced, the replacement part 22 can be removed from the collimating body 21 and / or the beam shaping body 1 , so that the replacement part 22 to be replaced is switched to a split state to facilitate replacement with a new replacement part 22 .

[0115] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the foregoing claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed application subject matter.

Claims

1. A neutron capture therapy system, characterized in that: The neutron capture therapy system comprises a beam shaper and a collimator; the beam shaper comprises a target material, a beam inlet and a beam outlet arranged in the beam shaper, the target material undergoes a nuclear reaction with a charged particle beam incident from the beam inlet to generate neutrons, the neutrons form a neutron beam, the neutron beam is emitted from the beam outlet and defines a neutron beam axis, and the collimator is arranged at the beam outlet; The collimator comprises a collimating body and a replacement part, wherein the collimating body, the replacement part and the beam outlet are connected and arranged, and at least part of the replacement part can be installed inside the beam shaping body and can be separated from the collimating body and the beam shaping body respectively.

2. The neutron capture therapy system according to claim 1, characterized in that: The replacement part has a first end and a second end opposite to each other along the axis direction of the neutron beam, the first end of the replacement part is adjacent to or in close contact with the collimating body, the second end of the replacement part is located inside the beam shaping body, and the interior of the beam shaping body has a wall surface adjacent to or in close contact with the second end of the replacement part.

3. The neutron capture therapy system according to claim 1, characterized in that: The replacement part has a first end and a second end opposite to each other along the neutron beam axis direction. The first end of the replacement part can be separated from the collimation body, and the second end of the replacement part is fitted with the inside of the beam shaping body.

4. The neutron capture therapy system according to claim 1, characterized in that: At least part of the replacement part is made of any one of lead, molybdenum, bismuth, graphite or Teflon.

5. The neutron capture therapy system according to claim 1, characterized in that: The inner surface of the replacement portion is inclined from the beam entrance toward the collimating body to form a cone surface with a gradually decreasing diameter.

6. The neutron capture therapy system according to claim 5, characterized in that: The collimating body comprises a reflecting unit and a shielding unit wrapped outside the reflecting unit, and the inner surface of the reflecting unit is coplanar with the inner surface of the replacement part.

7. The neutron capture therapy system according to claim 1, characterized in that: The neutron capture therapy system further includes a moderator, and along the axial direction of the neutron beam, the replacement portion has a preset length adapted to the distance formed between the collimating body and the moderator.

8. The neutron capture therapy system according to claim 1, characterized in that: The replacement part is of one-piece construction, or, The replacement part includes at least two replacement units, and at least two of the replacement units are detachable.

9. The neutron capture therapy system according to claim 8, characterized in that: Along the neutron beam axis direction, at least two of the replacement units have different lengths.

10. A collimator, characterized in that: It comprises a collimating body and a replacement part, wherein the collimating body has a first end and a second end opposite to each other, the first end of the collimating body has a collimating outlet, the replacement part can be detached from the second end of the collimating body, and the collimating body is connected to the replacement part.

11. The collimator according to claim 10, characterized in that: The replacement part is of one-piece construction, or, The replacement part includes at least two replacement units, and at least two of the replacement units are detachable.

12. The collimator according to claim 11, characterized in that Along the collimated outlet direction, the lengths of at least two replacement units are different.

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