WO2019029483A1 - 中子捕获治疗系统及用于粒子线产生装置的靶材 - Google Patents

中子捕获治疗系统及用于粒子线产生装置的靶材 Download PDF

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Publication number
WO2019029483A1
WO2019029483A1 PCT/CN2018/098985 CN2018098985W WO2019029483A1 WO 2019029483 A1 WO2019029483 A1 WO 2019029483A1 CN 2018098985 W CN2018098985 W CN 2018098985W WO 2019029483 A1 WO2019029483 A1 WO 2019029483A1
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Prior art keywords
cooling
target
neutron
plate
meandering
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PCT/CN2018/098985
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English (en)
French (fr)
Inventor
蔡炅彣
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南京中硼联康医疗科技有限公司
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Priority claimed from CN201710670326.9A external-priority patent/CN109381802A/zh
Priority claimed from CN201720988337.7U external-priority patent/CN207856090U/zh
Application filed by 南京中硼联康医疗科技有限公司 filed Critical 南京中硼联康医疗科技有限公司
Publication of WO2019029483A1 publication Critical patent/WO2019029483A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K5/00—Irradiation devices
    • G21K5/04—Irradiation devices with beam-forming means
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H3/00—Production or acceleration of neutral particle beams, e.g. molecular or atomic beams
    • H05H3/06—Generating neutron beams
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H6/00—Targets for producing nuclear reactions
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K7/00—Constructional details common to different types of electric apparatus
    • H05K7/20—Modifications to facilitate cooling, ventilating, or heating

Definitions

  • One aspect of the invention relates to a radiation illumination system, and more particularly to a neutron capture treatment system; another aspect of the invention relates to a target for a radiation illumination system, and more particularly to a particle line generating device Target.
  • neutron capture therapy combines the above two concepts, such as boron neutron capture therapy, by the specific agglomeration of boron-containing drugs in tumor cells, combined with precise neutron beam regulation, providing better radiation than traditional radiation. Cancer treatment options.
  • the accelerator boron neutron capture treatment accelerates the proton beam by an accelerator, and the proton beam accelerates to an energy sufficient to overcome the coulomb repulsion of the target nucleus, and reacts with the target to generate neutrons, thus generating
  • the target is irradiated by an accelerated proton beam of very high energy level, the temperature of the target will rise sharply, and the metal part of the target will easily foam, thereby affecting the service life of the target.
  • an aspect of the present invention provides a neutron capture treatment system including a neutron production device and a beam shaping body, the neutron production device including an accelerator and a target, and the accelerator accelerates generation of charged particles A line interacts with the target to produce a neutron beam, the beam shaping body comprising a reflector, a retarding body, a thermal neutron absorber, a radiation shield, and a beam outlet, the slowing body being from the target
  • the neutrons generated by the material are decelerated to an epithermal neutron energy region, the reflector surrounding the retarding body and guiding the offset neutrons back to the retarding body to increase the intensity of the epithermal neutron beam
  • the thermal neutron absorber is used to absorb thermal neutrons to avoid excessive doses with shallow normal tissue during treatment, the radiation shield being disposed around the beam exit at the rear of the reflector for shielding leakage Neutrons and photons to reduce the normal tissue dose in the non-irradiated area, the target comprising an active layer,
  • the meandering channel extends the flow path, which increases the contact area between the heat transfer wall and the cooling medium to increase the heat dissipation surface, and simultaneously forms a secondary flow, increases the mixing effect, improves the heat transfer capacity and the heat dissipation effect, and helps to extend the target. life.
  • the neutron capture treatment system further comprises a treatment table and a collimator, the neutron line generated by the neutron production device illuminating the patient on the treatment table by the beam shaping body,
  • a radiation shielding device is disposed between the patient and the beam outlet to shield radiation from the beam exiting the beam exit to the patient's normal tissue, the collimator being disposed at the rear of the beam outlet to concentrate the neutron line
  • the first and second cooling tubes are disposed in the beam shaping body, the target has a cooling inlet and a cooling outlet, and the cooling passage is disposed between the cooling inlet and the cooling outlet, the first and second cooling One end of the tube is respectively connected to the cooling inlet and the cooling outlet of the target, and the other end is connected to an external cooling source, and the curved geometry of the meandering cooling passage is a continuous curved smooth curve or a curved section or a straight line connected end to end.
  • the smooth curve of the continuous curve is a sine wave function.
  • the target is located in the beam shaping body
  • the accelerator has an accelerating tube that accelerates the charged particle beam
  • the accelerating tube extends into the beam shaping body in the direction of the charged particle beam and sequentially passes through the a reflector and a retarding body
  • the target is disposed in the retarding body and located at an end of the accelerating tube
  • the first and second cooling tubes are disposed at the accelerating tube and the reflector and the retarding body between.
  • Another aspect of the present invention provides a target for a particle beam generating device, the target comprising an active layer, a susceptor layer, and a heat dissipation layer, the active layer for generating the particle line, the pedestal
  • the layer supports the active layer
  • the heat dissipation layer includes a meandering cooling passage.
  • the meandering channel extends the flow path, which increases the contact area between the heat transfer wall and the cooling medium to increase the heat dissipation surface, and simultaneously forms a secondary flow, increases the mixing effect, improves the heat transfer capacity and the heat dissipation effect, and helps to extend the target. life.
  • the curved geometry of the meandering cooling channel is a continuous curved smooth curve or a curved segment or a straight line segment connected end to end, the continuous curved smooth curve being a sine wave function.
  • the cooling channel uses a continuous curved smooth curve, such as a sine wave function, which further reduces the flow resistance caused by the flow path.
  • the meandering cooling passage comprises a plurality of sub-parallel meandering passages formed by parallel rows of a plurality of meandering walls or a plurality of sub-spiral meandering passages formed by spirally expanding one or more meandering walls, at least
  • the flow directions of the cooling medium in the two adjacent sub-parallel tortuous channels or sub-spin-fold channels are different.
  • the flow direction of the cooling medium in the adjacent sub-parallel meandering channel or the sub-screw zigzag channel is different, further increasing the heat dissipation efficiency.
  • the bending geometry of the sub-parallel tortuous channel is a sine wave function:
  • phase angle, x is the coordinate of the flow direction of the cooling medium
  • k is the amplitude
  • T is the period.
  • the trajectory function of the sub-screw zigzag channel is:
  • Rin is the center radius
  • R_out is the outer radius
  • ⁇ is the polar coordinate angle
  • K is the amplitude
  • T is the period.
  • the heat dissipation layer includes a first plate having a first side facing the active layer and a second side opposite the first side, the meandering shape A cooling passage is formed on the second side or on a side of the second plate opposite the first plate.
  • the heat dissipation layer includes a support, the first plate and/or the second plate are fixed by the support member, the heat dissipation layer has a cooling inlet and a cooling outlet, and the cooling inlet and the cooling outlet are disposed at the Support
  • the heat dissipation layer has a cooling inlet that communicates with the cooling inlet and the cooling outlet, and a cooling outlet that is disposed on one of the first plate and the second plate Or respectively disposed on the first board and the second board.
  • the material of the first plate and/or the second plate is Ta or Ta-W alloy or Cu, and the zigzag cooling passage has a cross-sectional shape of a rectangle, a circle, a polygon or an ellipse.
  • the heat dissipation layer has an inlet groove that communicates with the cooling inlet and the meandering cooling passage, and an outlet groove that communicates with the cooling outlet and the meandering cooling passage.
  • a peripheral wall is further disposed at a periphery of the cooling inlet and/or the cooling outlet, the second plate being in close contact with the surface of the circumferential wall facing the second plate, forming a cavity between the first plate and the second plate The cooling medium entering from the cooling inlet can only exit through the cooling outlet.
  • the surface of the second plate in contact with the first plate is a plane, and the height of the meandering wall is the same as the height of the circumferential wall.
  • FIG. 1 is a schematic diagram of a neutron capture treatment system in accordance with an embodiment of the present invention
  • FIG. 2 is a schematic view of a target in an embodiment of the present invention.
  • FIG. 3 is a schematic view of a first embodiment of a heat dissipation layer of the target of FIG. 2;
  • FIG. 4 is a schematic view of a first plate of the heat dissipation layer of FIG. 3;
  • Figure 5 is a schematic view of a second embodiment of the heat dissipation layer of the target of Figure 2;
  • FIG. 6 is a schematic view of the first plate of the heat dissipation layer of FIG. 5.
  • the neutron capture treatment system of the present embodiment is preferably a boron neutron capture treatment system 100, including a neutron production device 10, a beam shaping body 20, a collimator 30, and a treatment table 40.
  • the neutron generating device 10 includes an accelerator 11 and a target T, and the accelerator 11 accelerates charged particles (such as protons, helium nuclei, etc.) to generate a charged particle beam C such as a proton beam, and the charged particle beam C is irradiated to the target T and
  • the target T acts to produce a neutron beam (neutron beam) N, and the target T is preferably a metal target.
  • the appropriate nuclear reaction is selected.
  • the nuclear reaction is often discussed as 7 Li(p,n) 7 Be and 9 Be(p,n) 9 B, both of which are endothermic reactions.
  • the energy thresholds of the two nuclear reactions are 1.881 MeV and 2.055 MeV, respectively. Since the ideal neutron source for boron neutron capture therapy is the superheated neutron of the keV energy level, theoretically, if proton bombardment with energy only slightly higher than the threshold is used.
  • Metallic lithium target which can produce relatively low-energy neutrons, can be used in clinical practice without too much slow processing.
  • the target T may also be made of a metal material other than Li, Be, such as Ta or W and alloys thereof.
  • the accelerator 11 may be a linear accelerator, a cyclotron, a synchrotron, or a synchrocyclotron.
  • the neutron beam N generated by the neutron generating device 10 is sequentially irradiated to the patient 200 on the treatment table 40 by the beam shaping body 20 and the collimator 30.
  • the beam shaping body 20 is capable of adjusting the beam quality of the neutron beam N generated by the neutron generating device 10, and the collimator 30 is used to concentrate the neutron beam N so that the neutron beam N has a higher process during the treatment. Targeting.
  • the beam shaping body 20 further includes a reflector 21, a retarding body 22, a thermal neutron absorber 23, a radiation shield 24, and a beam outlet 25.
  • the neutron generated by the neutron generating device 10 has a wide spectrum of energy, except for the super
  • thermal neutrons need to reduce other types of neutrons and photons as much as possible to avoid injury to the operator or patient, so the neutrons coming out of the neutron generating device 10 need to pass through the retarding body 22
  • the fast neutron energy is adjusted to the superheated neutron energy region, and the retarding body 22 is made of a material having a large cross section with fast neutron action and a small thermal neutron action cross section.
  • the retarding body 22 is composed of D 2 .
  • At least one of O, AlF 3 , Fluental, CaF 2 , Li 2 CO 3 , MgF 2 , and Al 2 O 3 is formed; the reflector 21 surrounds the retarding body 22 and diffuses through the retarding body 22 to the periphery. The neutron is reflected back to the neutron beam N to improve the utilization of the neutron, and is made of a material having strong neutron reflection capability.
  • the reflector 21 is made of at least one of Pb or Ni;
  • the thermal neutron absorber 23 is made of Li-6, and the thermal neutron absorber 23 is used to absorb the thermal neutrons passing through the retarding body 22 to reduce the thermal neutrons in the neutron beam N.
  • the content avoids excessive doses with shallow normal tissue during treatment;
  • the radiation shield 24 is disposed around the beam outlet 25 at the rear of the reflector for shielding neutrons and photons leaking from outside the beam outlet 25, radiation
  • the material of the shielding body 24 includes at least one of a photonic shielding material and a neutron shielding material.
  • the material of the radiation shielding body 24 includes a photonic shielding material lead (Pb) and a neutron shielding material polyethylene (PE).
  • the beam shaping body 20 can have other configurations as long as the epithermal neutron beam required for treatment can be obtained.
  • the collimator 30 is disposed at the rear of the beam outlet 25, and the epithermal neutron beam emerging from the collimator 30 is irradiated to the patient 200, and is slowly heated to a thermal neutron to reach the tumor cell M through the shallow normal tissue.
  • the collimator 30 can also be eliminated or replaced by other structures that illuminate the patient 200 directly from the beam exit 25.
  • a radiation shielding device 50 is disposed between the patient 200 and the beam outlet 25 to shield the radiation from the beam outlet 25 to the normal tissue of the patient. It is understood that the radiation shielding device 50 may not be provided. .
  • the boron-containing drug selectively accumulates in the tumor cell M, and then uses the boron-containing (B-10) drug to have a high capturing cross-section characteristic of the thermal neutron.
  • Two heavy-charged particles, 4 He and 7 Li, are generated by 10 B(n, ⁇ ) 7 Li neutron capture and nuclear splitting reaction.
  • the average energy of the two charged particles is about 2.33 MeV, which has high linear transfer (LET) and short range characteristics.
  • the linear energy transfer and range of ⁇ short particles are 150 keV/ ⁇ m and 8 ⁇ m, respectively, while the 7 Li heavy particles It is 175keV/ ⁇ m, 5 ⁇ m.
  • the total range of the two particles is about one cell size. Therefore, the radiation damage caused by the organism can be limited to the cell level, and it can reach the locality without causing too much damage to the normal tissue. The purpose of killing tumor cells.
  • the target T is disposed between the accelerator 11 and the beam shaping body 20, and the accelerator 11 has an accelerating tube 111 for accelerating the charged particle beam C.
  • the accelerating tube 111 is incident on the charged particle beam C.
  • the body 20 passes through the reflector 21 and the retarding body 22 in sequence, and the target T is disposed in the retarding body 22 and located at the end of the accelerating tube 111 to obtain better neutron beam quality.
  • the target T includes a heat dissipation layer 12, a susceptor layer 13 and an active layer 14, and the active layer 14 acts on the charged particle beam C to generate a neutron line, and the susceptor layer 13 supports the active layer 14.
  • the heat dissipation layer 12 is made of a heat conductive material (such as a material having good thermal conductivity such as Cu, Fe, Al, etc.) or a material capable of both heat conduction and foaming inhibition;
  • the base layer 13 is made of a material that inhibits foaming;
  • the material or the material capable of both thermally and inhibiting foaming includes at least one of Fe, Ta or V.
  • the material of the active layer 14 is Li or its alloy
  • the charged particle beam C is a proton line
  • the target T further includes an anti-oxidation layer 15 on the side of the active layer 14 for preventing oxidation of the active layer, the pedestal layer. 13 can simultaneously suppress foaming caused by incident proton rays, and the charged particle beam C sequentially passes through the oxidation resistant layer 15, the active layer 14, and the susceptor layer 13 in the incident direction.
  • the material of the oxidation resistant layer 15 is considered to be less susceptible to corrosion by the active layer and can reduce the loss of the incident proton beam and the heat generation caused by the proton beam, such as at least one of Al, Ti and its alloys or stainless steel.
  • the anti-oxidation layer 15 is a material capable of undergoing nuclear reaction with protons at the same time, and can further increase the neutron yield while performing the above-mentioned functions.
  • the anti-oxidation layer is simultaneously a part of the active layer, such as Be.
  • the energy of the incident proton beam is higher than the energy threshold of the nuclear reaction with Li and Be, respectively producing two different nuclear reactions, 7 Li(p,n) 7 Be and 9 Be(p,n) 9 B;
  • Be has a high melting point and good thermal conductivity, and its melting point is 1287 ° C, thermal conductivity is 201 W / (m K), and high temperature resistance relative to Li (melting point of 181 ° C, thermal conductivity: 71 W / (m K))
  • the heat dissipation performance has great advantages, further increasing the life of the target, and its reaction threshold with the proton generating (p, n) nuclear reaction is about 2.055 MeV, most of the accelerator neutron source using proton beam, the energy is Above the reaction threshold, the target is also the best choice for lithium targets.
  • the neutron yield is improved due to the presence of Be compared to the antioxidant layer using other materials such as Al.
  • the proton beam energy is 2.5 MeV-5 MeV, which can generate a high effective cross section with the lithium target, and does not generate excessive fast neutrons, and obtains better beam quality;
  • the thickness of the active layer 14 is 80 ⁇ m-240 ⁇ m, fully reacts with protons, and does not cause excessive energy deposition, affecting the heat dissipation performance of the target; while achieving the above effects while ensuring low manufacturing cost, the thickness of the anti-oxidation layer 15 is 5 ⁇ m-25 ⁇ m .
  • Monte Carlo software was used to simulate the proton beams of 2.5MeV, 3MeV, 3.5MeV, 4MeV, 4.5MeV and 5MeV respectively.
  • the proton beam was injected into the anti-oxidation layer 15 in the direction perpendicular to the surface of the target T.
  • Layer 14 (Li) and pedestal layer 13 (Ta, which will be described later in detail) the material of the oxidation resistant layer 15 is compared with Be, and the thickness of the oxidation resistant layer 15 is 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, respectively.
  • the thickness of the active layer 14 is 80 ⁇ m, 120 ⁇ m, 160 ⁇ m, 200 ⁇ m, 240 ⁇ m, respectively.
  • the thickness of the pedestal layer 12 has little effect on the neutron yield, which can be adjusted according to the actual situation, and the obtained neutron yield (ie, each proton generated)
  • the number of sub-numbers) is shown in Table 1 and Table 2.
  • the calculation results of the neutron yield increase ratio of Be as the lithium target anti-oxidation layer relative to Al are shown in Table 3. From the results, it is known that when Be is used as the anti-oxidation layer material, the neutron yield is significantly improved relative to Al.
  • the neutron yield available was 7.31E-05n/proton-5.61E-04n/proton.
  • the pedestal layer 13 When the pedestal layer 13 is made of Ta, it has a certain heat dissipation effect and can reduce foaming, inhibit inelastic scattering of protons and Li to release ⁇ , and prevent excess protons from passing through the target; in this embodiment, the pedestal layer
  • the material of 13 is a Ta-W alloy, which can obviously improve the low strength of pure tantalum and poor heat conductivity while maintaining the excellent performance of the above Ta, so that the heat generated by the nuclear reaction of the active layer 14 can be conducted out in time by the pedestal layer.
  • the weight percentage of W in the Ta-W alloy is 2.5%-20% to ensure the foaming property of the susceptor layer, and the pedestal layer has higher strength and thermal conductivity, further extending the service life of the target.
  • Ta-W alloys such as Ta-2.5 wt% W, Ta-5.0 wt% W, Ta-7.5 wt% W, Ta-10 wt% W, Ta-12 wt% W, Ta- are used for powder metallurgy, forging, pressing, and the like.
  • 20 wt% W or the like) is formed into a plate-like susceptor layer 13 having a proton line energy of 1.881 MeV-10 MeV and a pedestal layer having a thickness of at least 50 ⁇ m to sufficiently absorb excess protons.
  • the heat sink layer can have a variety of configurations, such as a heat pipe.
  • the heat dissipation layer 12 is plate-shaped, including a first plate 121 and a second plate 122, the first plate 121 having a first side 1211 facing the active layer 14. And a second side 1212 opposite to the first side 1211, the cooling channel P for the circulation of the cooling medium is formed on the second side 1212, and the second plate 122 is in close contact with the second side 1212 of the first plate 121. It can be understood that the cooling channel P may also be disposed on the side of the second plate 122 opposite the first plate 121.
  • the cooling passage P has a meandering shape, and the meandering cooling passage P includes a plurality of sub-parallel meandering passages P1, that is, a plurality of meandering walls W are arranged in parallel, and a zigzag groove S is formed between the adjacent walls W (ie, the sub-parallel Zigzag channel P1).
  • the bending geometry of the sub-parallel tortuous channel P1 is a sine wave function:
  • phase angle, x is the coordinate of the cooling medium flow direction (described in detail below), k is the amplitude, and T is the period.
  • the cooling passage P can also be other zigzag shapes, such as a smooth curve of continuous bending or a curved section or a straight section connected end to end.
  • the meandering passage extends the circulation path and can increase the contact between the heat transfer wall and the cooling medium. The area thus increases the heat dissipation surface, while forming a secondary flow, increasing the mixing effect, improving the heat transfer capacity and the heat dissipation effect, and contributing to prolonging the life of the target.
  • the cooling channel P adopts a continuous curved smooth curve, such as a sine wave function, which can further reduce the flow resistance caused by the flow path.
  • the meandering cooling passage P can also have other arrangements.
  • the heat dissipation layer 12 further has a cooling inlet IN that communicates with the cooling inlet IN and a cooling outlet OUT, and a cooling passage P that enters from the cooling inlet IN, passes through the cooling passage P, and then exits from the cooling outlet OUT.
  • the target T is heated by an accelerated proton beam irradiation temperature of a high energy level, and the susceptor layer and the heat dissipation layer conduct heat, and carry out heat by a cooling medium circulating in the cooling passage, thereby cooling the target T.
  • cooling inlets IN and cooling outlets OUT There are three cooling inlets IN and cooling outlets OUT, symmetrically disposed on both ends of the cooling passage P on the first plate 121, and extending in the direction of the first side 1211 to the second side 1212, on the second side 1212
  • An inlet tank S1 and an outlet tank S2 are also formed.
  • the inlet tank S1 and the outlet tank S2 communicate with the cooling inlet IN, the cooling outlet OUT and the respective sub-parallel meandering passages P1, respectively, so that the cooling medium entering from the cooling inlet IN enters from the inlet tank S1.
  • Each of the sub-parallel meandering passages P1 exits the cooling outlet OUT through the outlet slot S2.
  • cooling inlet IN and the cooling outlet OUT may be in other numbers or other forms, and may be simultaneously disposed on the second plate or separately on the first plate and the second plate.
  • a peripheral wall W1 is further disposed at a periphery of the cooling inlet IN and the cooling outlet OUT, and the second plate 122 is in close contact with the surface of the circumferential wall W1 facing the second plate 122, and a cavity is formed between the first plate 121 and the second plate 122 so that the cooling is performed.
  • the cooling medium entering the inlet IN can only pass through the cooling outlet OUT, the surface of the second plate 122 contacting the first plate 121 is a plane, and the height of the meandering wall W is the same as the height of the circumferential wall W1; it can be understood that it can also be a step In the face or other configuration, the height of the meandering wall W and the height of the circumferential wall W1 may be different at this time as long as the respective sub-parallel meandering passages P1 are independent of each other.
  • the cooling medium flow direction D (the flow direction of the entire cooling medium in the cooling passage) in the adjacent sub-parallel meandering passages P1 may also be different, further increasing the heat dissipation efficiency.
  • the inlet groove S1 and the outlet groove S2 may have other arrangements, such as causing the cooling medium to sequentially flow through the respective sub-parallel tortuous passages P1.
  • the materials of the first plate and the second plate are both Cu, which has better heat dissipation performance and lower cost.
  • the number and size of the grooves S forming the cooling passage P are determined according to the size of the actual target, and the cross-sectional shape of the grooves may also be various, such as rectangular, circular, polygonal, elliptical, etc., and different cross sections may also have different shape.
  • the first plate 121 and the second plate 122 are fixed together into the retarding body 22 or the end of the accelerating tube 111 by a connecting member such as a bolt or a screw or other fixing structure such as welding, or the first plate 121 and the second plate 122.
  • a connecting member such as a bolt or a screw or other fixing structure such as welding
  • the first plate 121 and the second plate 122 are fixed to the retarding body 22 or the end of the accelerating tube 111.
  • the heat dissipation layer can also be fixed or installed by other detachable connections for easy replacement of the target material; the heat dissipation layer 12 can also have a support member (not shown), the first plate 121 and/or the second plate 122.
  • the cooling inlet IN and the cooling outlet OUT can also be arranged on the support by fixing by means of a support.
  • the first and second cooling pipes D1 and D2 are disposed between the accelerating tube 111 and the reflector 21 and the retarding body 22, and one ends of the first and second cooling pipes D1 and D2 are respectively cooled to the cooling inlet of the target T. IN is connected to the cooling outlet OUT and the other end is connected to an external cooling source. It can be understood that the first and second cooling tubes can also be disposed in the beam shaping body in other ways, and can also be eliminated when the target is placed outside the beam shaping body.
  • the meandering cooling passage P' comprises a plurality of sub-spiral meandering passages P1', i.e., spirally unfolded around the same center by one or more meandering walls W', each wall W A plurality of layers are formed in the radial direction, and the layers formed by the respective walls W' are alternately arranged in the radial direction, and the grooves S' (i.e., the sub-helical meandering passages P1') are formed between the adjacent layers.
  • the trajectory function of the sub-helical meandering channel P1' is:
  • R in is the center radius
  • R out is the outer radius
  • ⁇ is the polar coordinate angle
  • K is the amplitude
  • T is the period.
  • the cooling inlet IN' is disposed at the center of the second plate 122', penetrates the center of each of the sub-screw-folding passages P1', and has four cooling outlets OUT', and is circumferentially disposed on the first plate 121' on the cooling passage P'.
  • the periphery extends in the direction from the first side 1211' to the second side 1212', it being understood that other arrangements are possible.
  • the center of the cooling passage P' that is, the center of each sub-screw-shaped passage P1', as the inlet groove S1', is formed with an outlet groove S2' on the second side 1212' of the first plate 121', and the outlet groove S2' is connected.
  • the cooling outlet OUT' and each of the sub-screw-folding passages P1' are such that the cooling medium entering from the cooling inlet IN' enters each of the sub-screw-folding passages P1' from the center of the cooling passage P', and then exits the cooling outlet OUT' through the outlet groove S2'. Go out.
  • a peripheral wall W1' is disposed around the periphery of the cooling outlet OUT', and the second plate 122' is in close contact with the surface of the circumferential wall W1' facing the second plate 122', forming a cavity between the first plate 121' and the second plate 122', so that a cavity is formed
  • the cooling medium entering from the cooling inlet IN' can only exit through the cooling outlet OUT', the surface of the second plate 122' in contact with the first plate 121' is flat, and the height of the meandering wall W' is the same as the height of the circumferential wall W1'.
  • a protrusion 1213' may also be disposed at the center of the first plate 121' for rectifying and increasing the heat transfer area, and reducing the central hot spot temperature.
  • the height of the protrusion 1213' may be higher than the height of the wall W' and the circumferential wall W1' and protrude into the cooling inlet IN' of the second plate; the shape of the protrusion 1213' may be a solid cone, a hollow cone, a sheet Wait.
  • the manufacturing process of the target T is as follows:
  • S1 pouring liquid lithium metal or an alloy thereof onto the pedestal layer 13 to form the active layer 14, and may also be treated by evaporation or sputtering, and an extremely thin adhesion layer 16 may be disposed between the pedestal layer and the active layer.
  • the material of the adhesion layer 16 includes at least one of Cu, Al, Mg or Zn, and the same can be treated by evaporation or sputtering to improve the adhesion between the pedestal layer and the active layer;
  • the oxidation resistant layer 15 is simultaneously subjected to HIP treatment or by other processes to close the susceptor layer 13 to form a cavity and/or to surround the active layer 14.
  • the anti-oxidation layer 15 and the pedestal layer 13 may be subjected to HIP treatment or the susceptor layer 13 may be closed to form a cavity by another process, and then the liquid lithium metal or An alloy is poured into the cavity to form an active layer 14.
  • the heat dissipation layer may also be at least partially made of the same material or integral structure as the base layer.
  • the first plate made of Ta or Ta-W alloy serves as the heat dissipation layer 12 and the base layer 13 at the same time.
  • step S2 can be eliminated, and the active layer 14 can be connected to the first plate by a process such as casting, evaporation or sputtering.
  • the target T is generally in the shape of a circular plate; it can be understood that the target T can also be a rectangular plate shape; the target T can also be other solid shapes; the target T can also be a relative accelerator or a beam shaping body. Movable to facilitate target change or even particle line and target.
  • a liquid material liquid metal can also be used for the active layer 14.
  • the target of the present invention can also be applied to other neutron production devices in the medical and non-medical fields, as long as the generation of the neutron is based on the nuclear reaction between the particle beam and the target, the material of the target is also based on different nuclear reactions. The difference can also be applied to other particle line generating devices.

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Abstract

本发明提供一种中子捕获治疗系统及用于粒子线产生装置的靶材，能提升靶材的散热性能，减少起泡，增加靶材寿命。本发明的中子捕获治疗系统，包括中子产生装置和射束整形体，中子产生装置包括加速器和靶材，加速器加速产生的带电粒子线与靶材作用产生中子线，靶材包括作用层、基座层和散热层，作用层与带电粒子线作用产生中子线，基座层支撑作用层，散热层包括曲折状的冷却通道。

Description

中子捕获治疗系统及用于粒子线产生装置的靶材 技术领域
本发明一方面涉及一种辐射线照射系统，尤其涉及一种中子捕获治疗系统；本发明另一方面涉及一种用于辐射线照射系统的靶材，尤其涉及一种用于粒子线产生装置的靶材。
背景技术
随着原子科学的发展，例如钴六十、直线加速器、电子射束等放射线治疗已成为癌症治疗的主要手段之一。然而传统光子或电子治疗受到放射线本身物理条件的限制，在杀死肿瘤细胞的同时，也会对射束途径上大量的正常组织造成伤害；另外由于肿瘤细胞对放射线敏感程度的不同，传统放射治疗对于较具抗辐射性的恶性肿瘤(如：多行性胶质母细胞瘤(glioblastoma multiforme)、黑色素细胞瘤(melanoma))的治疗成效往往不佳。
为了减少肿瘤周边正常组织的辐射伤害，化学治疗(chemotherapy)中的标靶治疗概念便被应用于放射线治疗中；而针对高抗辐射性的肿瘤细胞，目前也积极发展具有高相对生物效应(relative biological effectiveness,RBE)的辐射源，如质子治疗、重粒子治疗、中子捕获治疗等。其中，中子捕获治疗便是结合上述两种概念，如硼中子捕获治疗，借由含硼药物在肿瘤细胞的特异性集聚，配合精准的中子射束调控，提供比传统放射线更好的癌症治疗选择。
在加速器硼中子捕获治疗中，加速器硼中子捕获治疗通过加速器将质子束加速，质子束加速至足以克服靶材原子核库伦斥力的能量，与靶材发生核反应以产生中子，因此在产生中子的过程中靶材会受到非常高能量等级的加速质子束的照射，靶材的温度会大幅上升，同时靶材的金属部分容易起泡，从而影响靶材的使用寿命。
因此，有必要提出一种新的技术方案以解决上述问题。
发明内容
为了解决上述问题，本发明一方面提供了一种中子捕获治疗系统，包括中子产生装置和射束整形体，所述中子产生装置包括加速器和靶材，所述加速器加速产生的带电粒子线与所述靶材作用产生中子线，所述射束整形体包括反射体、缓速体、热中子吸收体、辐射屏蔽体和射束出口，所述缓速体将自所述靶材产生的中子减速至超热中子能区，所述反射体包围所述缓速体并将偏离的中子导回至所述缓速体以提高超热中子射束强度，所述热中子吸收体用于吸收热中子以避免治疗时与浅层正常组织造成过多剂量，所述辐射屏蔽体围绕所述射束出口设置在所述反射体后部用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量，所述 靶材包括作用层、基座层和散热层，所述作用层与带电粒子线作用产生中子线，所述基座层支撑所述作用层，所述散热层包括曲折状的冷却通道。曲折状的通道延长了流通路径，能够增加传热壁面与冷却介质的接触面积从而增加散热表面，同时形成二次流，增加搅混效应，提升传热能力和散热效果，有助于延长靶材的寿命。
作为一种优选地，中子捕获治疗系统还包括治疗台和准直器，所述中子产生装置产生的中子线通过所述射束整形体照射向所述治疗台上的患者，所述患者和射束出口之间设置辐射屏蔽装置以屏蔽从所述射束出口出来的射束对患者正常组织的辐射，所述准直器设置在所述射束出口后部以汇聚中子线，所述射束整形体内设置第一、第二冷却管，所述靶材具有冷却进口、冷却出口，所述冷却通道设置在所述冷却进口和冷却出口之间，所述第一、第二冷却管的一端分别与所述靶材的冷却进口和冷却出口连接，另一端连接到外部冷却源，所述曲折状的冷却通道的弯曲几何为连续弯曲的平滑曲线或依次首尾相连的曲线段或直线段，所述连续弯曲的平滑曲线为弦波函数。
进一步地，靶材位于所述射束整形体内，所述加速器具有对带电粒子线进行加速的加速管，所述加速管沿带电粒子线方向伸入所述射束整形体并依次穿过所述反射体和缓速体，所述靶材设置在所述缓速体内并位于所述加速管端部，所述第一、第二冷却管设置在所述加速管与所述反射体和缓速体之间。
本发明另一方面提供了一种用于粒子线产生装置的靶材，所述靶材包括作用层、基座层和散热层，所述作用层用于产生所述粒子线，所述基座层支撑所述作用层，所述散热层包括曲折状的冷却通道。曲折状的通道延长了流通路径，能够增加传热壁面与冷却介质的接触面积从而增加散热表面，同时形成二次流，增加搅混效应，提升传热能力和散热效果，有助于延长靶材的寿命。
作为一种优选地，曲折状的冷却通道的弯曲几何为连续弯曲的平滑曲线或依次首尾相连的曲线段或直线段,所述连续弯曲的平滑曲线为弦波函数。冷却通道采用连续弯曲的平滑曲线，如弦波函数，能进一步减少流动路径造成的流动阻力。
作为另一种优选地，曲折状的冷却通道包括多个曲折状的壁平行排列形成的多个子平行曲折通道或一个或多个曲折状的壁以螺旋线展开形成的多个子螺旋曲折通道，至少2个相邻的所述子平行曲折通道或子螺旋曲折通道中的冷却介质流通方向不同。相邻的子平行曲折通道或子螺旋曲折通道中的冷却介质流通方向不同，进一步增加散热效率。
进一步地，子平行曲折通道的弯曲几何为弦波函数：
Figure PCTCN2018098985-appb-000001
其中，
Figure PCTCN2018098985-appb-000002
为相位角、x为冷却介质流通方向的坐标、k为振幅、T为周期。
子螺旋曲折通道的轨迹函数为：
Figure PCTCN2018098985-appb-000003
其中，Rin为中心半径、R_out为外半径、θ为极坐标角度、K为振幅、T为周期。
作为另一种优选地，散热层包括第一板和第二板，所述第一板具有面向所述作用层的第一侧和与所述第一侧相对的第二侧，所述曲折状的冷却通道形成在所述第二侧上或所述第二板上与所述第一板相对的一侧上。
进一步地，散热层包括支撑件，所述第一板和/或第二板通过所述支撑件进行固定，所述散热层具有冷却进口和冷却出口，所述冷却进口和冷却出口设置在所述支撑件上
进一步地，散热层具有冷却进口和冷却出口，所述曲折状的冷却通道连通所述冷却进口和冷却出口，所述冷却进口和冷却出口均设置在所述第一板和第二板之一上，或分别设置在所述第一板和第二板上。第一板和/或第二板的材料为Ta或Ta-W合金或Cu，所述曲折状的冷却通道的横截面形状为矩形、圆形、多边形或椭圆形。
更进一步地，散热层具有进口槽和出口槽，所述进口槽连通所述冷却进口和所述曲折状的冷却通道，所述出口槽连通所述冷却出口和所述曲折状的冷却通道。冷却进口和/或冷却出口外围还设置有周向壁，所述第二板与所述周向壁面向所述第二板的表面紧密接触，在所述第一板和第二板之间形成容腔，使得从所述冷却进口进入的冷却介质只能通过所述冷却出口出去。
更进一步地，第二板与第一板接触的面为平面，所述曲折状的壁的高度和所述周向壁的高度相同。
附图说明
图1为本发明实施例中的中子捕获治疗系统示意图；
图2为本发明实施例中的靶材的示意图；
图3为图2中的靶材的散热层的第一实施例的示意图；
图4为图3中的散热层的第一板的示意图；
图5为图2中的靶材的散热层的第二实施例的示意图；
图6为图5中的散热层的第一板的示意图。
具体实施方式
下面结合附图对本发明的实施例做进一步的详细说明，以令本领域技术人员参照说明书文字能够据以实施。
如图1，本实施例中的中子捕获治疗系统优选为硼中子捕获治疗系统100，包括中子产生装置10、射束整形体20、准直器30和治疗台40。中子产生装置10包括加速器11和靶材T，加速器11对带电粒子(如质子、氘核等)进行加速，产生如质子线的带电粒子线C，带电粒子线C照射到靶材T并与靶材T作用产生中子线(中子束)N，靶材T优选为金属靶材。依据所需的中子产率与能量、可提供的加速带电粒子能量与电流大小、金属靶材的物化性等特性来挑选合适的核反应，常被讨论的核反应有 7Li(p,n) 7Be及 9Be(p,n) 9B，这两种反应皆为吸热反应。两种核反应的能量阀值分别为1.881MeV和2.055MeV，由于硼中子捕获治疗的理想中子源为keV能量等级的超热中子，理论上若使用能量仅稍高于阀值的质子轰击金属锂靶材，可产生相对低能的中子，不需太多的缓速处理便可用于临床，然而锂金属(Li)和铍金属(Be)两种靶材与阀值能量的质子作用截面不高，为产生足够大的中子通量，通常选用较高能量的质子来引发核反应。理想的靶材应具备高中子产率、产生的中子能量分布接近超热中子能区(将在下文详细描述)、无太多强穿辐射产生、安全便宜易于操作且耐高温等特性，但实际上并无法找到符合所有要求的核反应。本领域技术人员熟知的，靶材T也可以由Li、Be之外的金属材料制成，例如由Ta或W及其合金等形成。加速器11可以是直线加速器、回旋加速器、同步加速器、同步回旋加速器。
中子产生装置10产生的中子束N依次通过射束整形体20和准直器30照射向治疗台40上的患者200。射束整形体20能够调整中子产生装置10产生的中子束N的射束品质，准直器30用以汇聚中子束N，使中子束N在进行治疗的过程中具有较高的靶向性。射束整形体20进一步包括反射体21、缓速体22、热中子吸收体23、辐射屏蔽体24和射束出口25，中子产生装置10生成的中子由于能谱很广，除了超热中子满足治疗需要以外，需要尽可能的减少其他种类的中子及光子含量以避免对操作人员或患者造成伤害，因此从中子产生装置10出来的中子需要经过缓速体22将其中的快中子能量调整到超热中子能区，缓速体22由与快中子作用截面大、超热中子作用截面小的材料制成，本实施例中，缓速体22由D 2O、AlF 3、Fluental、CaF 2、Li 2CO 3、MgF 2和Al 2O 3中的至少一种制成；反射体21包围缓速体22，并将穿过缓速体22向四周扩散的中子反射回中子射束N以提高中子的利用率，由具有中子反射能力强的材料制成，本实施例中，反射体21由Pb或Ni中的至少一种制成；缓速体22后部有一个热中子吸收体23，由与热中子作用截面大的材料制成，本实施例中，热中子吸收体23由Li-6制成，热中子吸收体23用于吸收穿过缓速体22的热中子以减少中子束N中热中子的含量，避免治疗时与浅层正常组织造成过多剂量；辐射屏蔽体24围绕射束出口25设置在反射体后部，用于屏蔽从射束出 口25以外部分渗漏的中子和光子，辐射屏蔽体24的材料包括光子屏蔽材料和中子屏蔽材料中的至少一种，本实施例中，辐射屏蔽体24的材料包括光子屏蔽材料铅(Pb)和中子屏蔽材料聚乙烯(PE)。可以理解，射束整形体20还可以有其他的构造，只要能够获得治疗所需超热中子束即可。准直器30设置在射束出口25后部，从准直器30出来的超热中子束向患者200照射，经浅层正常组织后被缓速为热中子到达肿瘤细胞M，可以理解，准直器30也可以取消或由其他结构代替，中子束从射束出口25出来直接向患者200照射。本实施例中，患者200和射束出口25之间还设置了辐射屏蔽装置50，屏蔽从射束出口25出来的射束对患者正常组织的辐射，可以理解，也可以不设置辐射屏蔽装置50。
患者200服用或注射含硼(B-10)药物后，含硼药物选择性地聚集在肿瘤细胞M中，然后利用含硼(B-10)药物对热中子具有高捕获截面的特性，借由 10B(n,α) 7Li中子捕获及核分裂反应产生 4He和 7Li两个重荷电粒子。两荷电粒子的平均能量约为2.33MeV，具有高线性转移(Linear Energy Transfer,LET)、短射程特征，α短粒子的线性能量转移与射程分别为150keV/μm、8μm，而 7Li重荷粒子则为175keV/μm、5μm，两粒子的总射程约相当于一个细胞大小，因此对于生物体造成的辐射伤害能局限在细胞层级，便能在不对正常组织造成太大伤害的前提下，达到局部杀死肿瘤细胞的目的。
下面结合图2对靶材T的结构做详细的说明。
靶材T设置在加速器11和射束整形体20之间，加速器11具有对带电粒子线C进行加速的加速管111，本实施例中，加速管111沿带电粒子线C方向伸入射束整形体20，并依次穿过反射体21和缓速体22，靶材T设置在缓速体22内并位于加速管111的端部，以得到较好的中子射束品质。
靶材T包括散热层12、基座层13和作用层14，作用层14与带电粒子线C作用产生中子线，基座层13支撑作用层14。散热层12由导热材料(如Cu、Fe、Al等导热性能好的材料)或既能导热又能抑制发泡的材料制成；基座层13由抑制发泡的材料制成；抑制发泡的材料或既能导热又能抑制发泡的材料包括Fe、Ta或V中的至少一种。本实施例中，作用层14的材料为Li或其合金，带电粒子线C为质子线，靶材T还包括位于作用层14一侧用于防止作用层氧化的抗氧化层15，基座层13能同时抑制由入射质子线引起的发泡，带电粒子线C沿入射方向依次穿过抗氧化层15、作用层14和基座层13。抗氧化层15的材料同时考虑不易被作用层腐蚀且能够减小入射质子束的损耗及质子束导致的发热，如包括Al、Ti及其合金或者不锈钢中的至少一种。本实施例中，抗氧化层15为同时能够与质子发生核反应的材料，起到上述作用的同时能进一步地增加中子产率，此时，抗氧化层同时为作用层 的一部分，如采用Be或其合金，入射质子束的能量高于与Li和Be发生核反应的能量阀值，分别产生两种不同的核反应， 7Li(p,n) 7Be及 9Be(p,n) 9B；另外，Be具有高熔点及良好的导热特性，其熔点为1287℃，热传导率为201W/(m K)，相对于Li(熔点为181℃，热传导率为71W/(m K))的耐高温及散热性能具有极大优势，进一步增加了靶材的寿命，并且其与质子发生(p,n)核反应的反应阀值约为2.055MeV，多数采用质子射束的加速器中子源，其能量皆高于该反应阀值，而铍靶亦是锂靶以外的最佳选择。与采用其他材料，如Al，的抗氧化层相比，由于Be的存在，中子产率得到了提高。本实施例中，质子线能量为2.5MeV-5MeV，能够与锂靶产生较高的作用截面，同时不会产生过多的快中子，获得较好的射束品质；作用层14的厚度为80μm-240μm，与质子能发生充分的反应，也不会过厚造成能量沉积，影响靶材散热性能；在达到上述效果的同时保证较低的制造成本，抗氧化层15的厚度为5μm-25μm。在对比试验中，采用蒙地卡罗软件分别仿真2.5MeV、3MeV、3.5MeV、4MeV、4.5MeV、5MeV的质子束由垂直于靶材T的作用表面的方向依次射入抗氧化层15、作用层14(Li)及基座层13(Ta，将在后文详述)，抗氧化层15的材料以Al与Be进行对比，抗氧化层15厚度分别为5μm、10μm、15μm、20μm、25μm，作用层14厚度分别为80μm、120μm、160μm、200μm、240μm，基座层12厚度对中子产率几乎没有影响可视实际情况调整，得到的中子产率(即每个质子产生的中子个数)结果如表1、表2所示。使用Be作为锂靶抗氧化层相对于Al的中子产率提升比例计算结果如表3所示，由结果知，使用Be作为抗氧化层材料时，中子产率相对于Al有明显提升，可以获得的中子产率为7.31E-05n/proton-5.61E-04n/proton。
表1、使用Al作为锂靶抗氧化层的中子产率(n/proton).E为入射质子线能量
Figure PCTCN2018098985-appb-000004
Figure PCTCN2018098985-appb-000005
表2、使用Be作为锂靶抗氧化层的中子产率(n/proton).E为入射质子线能量
Figure PCTCN2018098985-appb-000006
Figure PCTCN2018098985-appb-000007
Figure PCTCN2018098985-appb-000008
表3、使用Be作为锂靶抗氧化层相对于Al的中子产率提升比例.E为入射质子线能量
Figure PCTCN2018098985-appb-000009
Figure PCTCN2018098985-appb-000010
基座层13采用Ta制成时，具有一定的散热效果同时能够减少起泡，抑制质子与Li发生非弹性散射而释放γ，及阻止多余的质子通过靶材；本实施例中，基座层13的材料为Ta-W合金，在保持上述Ta的优良性能的同时能明显地改善纯钽强度低、热传导性差的劣势，使得作用层14发生核反应产生的热量能由基座层及时传导出去。Ta-W合金中W的重量百分比为2.5％-20％，以保证基座层抑制发泡的特性，同时基座层具有更高的强度和热传导性，进一步延长靶材使用寿命。采用粉末冶金、锻造、压制等将Ta-W合金(如Ta-2.5wt％W、Ta-5.0wt％W、Ta-7.5wt％W、Ta-10wt％W、Ta-12wt％W、Ta-20wt％W等)制成板状的基座层13，在质子线能量为1.881MeV-10MeV，基座层的厚度至少为50μm，以充分吸收多余的质子。
散热层可以有多种构造，如为热管。在图3和图4示出的散热层的第一实施例中，散热层12为板状，包括第一板121和第二板122，第一板121具有面向作用层14的第一侧1211和与第一侧1211相对的第二侧1212，第二侧1212上形成供冷却介质流通的冷却通道P，第二板122与第一板121的第二侧1212紧密接触，可以理解，冷却通道P也可以设置在第二板122上与第一板121相对的一侧上。冷却通道P为曲折状，曲折状的冷却通道P包括多个子平行曲折通道P1，即由多个曲折状的壁W平行排列，相邻的壁W之间形成曲折状的槽S(即子平行曲折通道P1)。子平行曲折通道P1的弯曲几何为弦波函数：
Figure PCTCN2018098985-appb-000011
其中，
Figure PCTCN2018098985-appb-000012
为相位角、x为冷却介质流通方向(下文详述)的坐标、k为振幅、T为周期。
可以理解，冷却通道P还可以为其他的曲折形状，如连续弯曲的平滑曲线或依次首尾相连的曲线段或直线段，曲折状的通道延长了流通路径，能够增加传热壁面与冷却介质的接触面积从而增加散热表面，同时形成二次流，增加搅混效应，提升传热能力和散热效果，有助于延长靶材的寿命。冷却通道P采用连续弯曲的平滑曲线，如弦波函数，能进一步减少流动路径造成的流动阻力。曲折状的冷却通道P也可以有其他的排布方式。
散热层12还具有冷却进口IN和冷却出口OUT，冷却通道P连通冷却进口IN和冷却出口OUT，冷却介质从冷却进口IN进入，通过冷却通道P，然后从冷却出口OUT出来。靶材T受到高能量等级的加速质子束照射温度升高发热，基座层和散热层将热量导出，并通过流通在冷却通道内的冷却介质将热量带出，从而对靶材T进行冷却。冷却进口IN和冷却出口OUT各有3个，对称设置在第一板121上冷却通道P的两端，并在第一侧1211到第二侧1212的方向上延伸贯通，在第二侧1212上还形成有进口槽S1和出口槽S2，进口槽S1、出口槽S2分别连通冷却进口IN、冷却出口OUT和各个子平行曲折通道P1，使得从冷却进口IN进入的冷却介质从进口槽S1分别进入各个子平行曲折通道P1，再经过出口槽S2从冷却出口OUT出去。可以理解，冷却进口IN和冷却出口OUT可以为其他的个数或其他的形式，还可以同时设置在第二板上或分别设置在第一板上和第二板上。冷却进口IN和冷却出口OUT外围还设置有周向壁W1，第二板122与周向壁W1面向第二板122的表面紧密接触，在第一板121和第二板122之间形成容腔，使得从冷却进口IN进入的冷却介质只能通过冷却出口OUT出去，第二板122与第一板121接触的面为平面，曲折状的壁W的高度和周向壁W1的高度相同；可以理解，也可以为阶梯面或其他构造，此时曲折状的壁W的高度和周向壁W1的高度可能不同，只要使得各个子平行曲折通道P1之间是相互独立的即可。相邻的子平行曲折通道P1中的冷却介质流通方向D(冷却通道中冷却介质整体的流通方向)也可以不同，进一步增加散热效率。进口槽S1和出口槽S2可以有其他的设置方式，如使得冷却介质依次流经各个子平行曲折通道P1。本实施例中，第一板和第二板的材料都为Cu，具有较好的散热性能且成本较低。形成冷却通道P的槽S的个数及大小根据实际靶的尺寸决定，槽的横截面形状也可以是多样的，如矩形、圆形、多边形、椭圆形等，不同的横截面还可以具有不同的形状。
第一板121和第二板122一起通过螺栓或螺钉等连接件或其他固定结构，如焊接等，固定到缓速体22内或加速管111端部，或者第一板121和第二板122先连接再将其中之一固定到 缓速体22内或加速管111端部。可以理解，散热层还可以采用其他可拆卸的连接进行固定或安装，便于更换靶材；散热层12还可以具有支撑件(图中未示出)，第一板121和/或第二板122通过支撑件进行固定，冷却进口IN和冷却出口OUT也可以设置在支撑件上。本实施例中，加速管111与反射体21和缓速体22之间设置第一、第二冷却管D1、D2，第一、第二冷却管D1、D2的一端分别与靶材T的冷却进口IN和冷却出口OUT连接，另一端连接到外部冷却源。可以理解，第一、第二冷却管还可以以其他方式设置在射束整形体内，当靶材置于射束整形体之外时，还可以取消。
如图5和图6，为散热层的第二实施例，下面仅描述与第一实施例不同的地方。在散热层的第二实施例中，曲折状的冷却通道P′包括多个子螺旋曲折通道P1′，即由一个或多个曲折状的壁W′围绕同一中心以螺旋线展开，每个壁W′在径向上形成很多层，各个壁W′形成的层在径向上交互排列，相邻的层之间形成槽S′(即子螺旋曲折通道P1′)。子螺旋曲折通道P1′的轨迹函数为：
Figure PCTCN2018098985-appb-000013
其中，R in为中心半径、R out为外半径、θ为极坐标角度、K为振幅、T为周期。
冷却进口IN′设置在第二板122′的中心，与各子螺旋曲折通道P1′的中心贯通，冷却出口OUT′有4个，周向平均设置在第一板121′上冷却通道P′的外围，在第一侧1211′到第二侧1212′的方向上延伸贯通，可以理解，还可以有其他的设置方式。冷却通道P′的中心，即各子螺旋曲折通道P1′的中心，作为进口槽S1′，在第一板121′的第二侧1212′上还形成有出口槽S2′，出口槽S2′连通冷却出口OUT′和各个子螺旋曲折通道P1′，使得从冷却进口IN′进入的冷却介质从冷却通道P′中心分别进入各个子螺旋曲折通道P1′，再经过出口槽S2′从冷却出口OUT′出去。冷却出口OUT′外围设置有周向壁W1′，第二板122′与周向壁W1′面向第二板122′的表面紧密接触，在第一板121′和第二板122′之间形成容腔，使得从冷却进口IN′进入的冷却介质只能通过冷却出口OUT′出去，第二板122′与第一板121′接触的面为平面，曲折状的壁W′的高度和周向壁W1′的高度相同；可以理解，也可以为阶梯面或其他构造，此时曲折状的壁W′的高度和周向壁W1′的高度可能不同，只要使得各个子螺旋曲折通道P1′之间是相互独立的即可。相邻的子螺旋曲折通道P1′中的冷却介质流通方向也可以不同，进一步增加散热效率。第一板121′的中心处还可以设置有突出部1213′，用于整流和增加传热面积，降低中心热点温度。突出部1213′的高度可以高于壁W′和周向壁W1′的高度，并伸入第二板上的冷却进口IN′；突出部1213′的形状可以为实心锥体、空心锥体、片状等。
本实施例中，靶材T的制造工艺如下：
S1：将液态的锂金属或其合金浇注到基座层13上形成作用层14，也可以采用蒸镀或溅射等处理，基座层和作用层之间还可以设置极薄的附着层16，附着层16的材料包括Cu、Al、Mg或Zn中的至少一种，同样可采用蒸镀或溅射等处理，提高基座层与作用层的附着性；
S2：将基座层13与散热层12进行HIP(Hot Isostatic Pressing：热等静压)处理或其他工艺进行连接；
S3：抗氧化层15同时进行HIP处理或通过其他工艺将基座层13封闭形成一个容腔和/或将作用层14包围。
上述步骤S1、S2、S3不分先后，如可以先将抗氧化层15与基座层13进行HIP处理或通过其他工艺将基座层13封闭形成一个容腔，再将液态的锂金属或其合金浇注到该容腔内形成作用层14。散热层也可以至少部分与基座层采用相同的材料或一体构造，如采用Ta或Ta-W合金制成的第一板同时作为散热层12和基座层13，此时第二板可以采用与第一板相同的材料或仍然采用Cu制成，步骤S2可以取消，作用层14通过浇注、蒸镀或溅射等工艺与第一板连接即可。
本实施例中，靶材T整体呈圆板状；可以理解，靶材T还可以为矩形板状；靶材T也可以为其他固体形状；靶材T还可以相对加速器或射束整形体是可运动的，以方便换靶或使粒子线与靶材均匀作用。作用层14也可以使用液状物(液体金属)。
可以理解，本发明的靶还可以应用于其他医疗和非医疗领域的中子产生装置，只要其中子的产生是基于粒子线与靶材的核反应，则靶材的材料也基于不同的核反应有所区别；还可以应用于其他粒子线产生装置。
尽管上面对本发明说明性的具体实施方式进行了描述，以便于本技术领域的技术人员理解本发明，但应该清楚，本发明不限于具体实施方式的范围，对本技术领域的普通技术人员来讲，只要各种变化在所附的权利要求限定和确定的本发明的精神和范围内，这些变化是显而易见的，都在本发明要求保护的范围之内。

Claims (15)

  1. 一种中子捕获治疗系统，其特征在于，所述中子捕获治疗系统包括中子产生装置和射束整形体，所述中子产生装置包括加速器和靶材，所述加速器加速产生的带电粒子线与所述靶材作用产生中子线，所述射束整形体包括反射体、缓速体、热中子吸收体、辐射屏蔽体和射束出口，所述缓速体将自所述靶材产生的中子减速至超热中子能区，所述反射体包围所述缓速体并将偏离的中子导回至所述缓速体以提高超热中子射束强度，所述热中子吸收体用于吸收热中子以避免治疗时与浅层正常组织造成过多剂量，所述辐射屏蔽体围绕所述射束出口设置在所述反射体后部用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量，所述靶材包括作用层、基座层和散热层，所述作用层与带电粒子线作用产生中子线，所述基座层支撑所述作用层，所述散热层包括曲折状的冷却通道。
  2. 如权利要求1所述的中子捕获治疗系统，其特征在于，所述中子捕获治疗系统还包括治疗台和准直器，所述中子产生装置产生的中子线通过所述射束整形体照射向所述治疗台上的患者，所述患者和射束出口之间设置辐射屏蔽装置以屏蔽从所述射束出口出来的射束对患者正常组织的辐射，所述准直器设置在所述射束出口后部以汇聚中子线，所述射束整形体内设置第一、第二冷却管，所述靶材具有冷却进口、冷却出口，所述冷却通道设置在所述冷却进口和冷却出口之间，所述第一、第二冷却管的一端分别与所述靶材的冷却进口和冷却出口连接，另一端连接到外部冷却源，所述曲折状的冷却通道的弯曲几何为连续弯曲的平滑曲线或依次首尾相连的曲线段或直线段，所述连续弯曲的平滑曲线为弦波函数。
  3. 如权利要求2所述的中子捕获治疗系统，其特征在于，所述靶材位于所述射束整形体内，所述加速器具有对带电粒子线进行加速的加速管，所述加速管沿带电粒子线方向伸入所述射束整形体并依次穿过所述反射体和缓速体，所述靶材设置在所述缓速体内并位于所述加速管端部，所述第一、第二冷却管设置在所述加速管与所述反射体和缓速体之间。
  4. 一种用于粒子线产生装置的靶材，其特征在于，所述靶材包括作用层、基座层和散热层，所述作用层用于产生所述粒子线，所述基座层支撑所述作用层，所述散热层包括曲折状的冷却通道。
  5. 如权利要求4所述的用于粒子线产生装置的靶材，其特征在于，所述曲折状 的冷却通道的弯曲几何为连续弯曲的平滑曲线或依次首尾相连的曲线段或直线段,所述连续弯曲的平滑曲线为弦波函数。
  6. 如权利要求4所述的用于粒子线产生装置的靶材，其特征在于，所述曲折状的冷却通道包括多个曲折状的壁平行排列形成的多个子平行曲折通道或一个或多个曲折状的壁以螺旋线展开形成的多个子螺旋曲折通道，至少2个相邻的所述子平行曲折通道或子螺旋曲折通道中的冷却介质流通方向不同。
  7. 如权利要求4所述的用于粒子线产生装置的靶材，其特征在于，所述散热层包括第一板和第二板，所述第一板具有面向所述作用层的第一侧和与所述第一侧相对的第二侧，所述曲折状的冷却通道形成在所述第二侧上或所述第二板上与所述第一板相对的一侧上。
  8. 如权利要求7所述的用于粒子线产生装置的靶材，其特征在于，所述散热层具有冷却进口和冷却出口，所述曲折状的冷却通道连通所述冷却进口和冷却出口，所述冷却进口和冷却出口均设置在所述第一板和第二板之一上，或分别设置在所述第一板和第二板上。
  9. 如权利要求7所述的用于粒子线产生装置的靶材，其特征在于，所述第一板和/或第二板的材料为Ta或Ta-W合金或Cu，所述曲折状的冷却通道的横截面形状为矩形、圆形、多边形或椭圆形。
  10. 如权利要求8所述的用于粒子线产生装置的靶材，其特征在于，所述冷却进口和/或冷却出口外围还设置有周向壁，所述第二板与所述周向壁面向所述第二板的表面紧密接触，在所述第一板和第二板之间形成容腔，使得从所述冷却进口进入的冷却介质只能通过所述冷却出口出去。
  11. 如权利要求6所述的用于粒子线产生装置的靶材，其特征在于，所述子平行曲折通道的弯曲几何为弦波函数：
    Figure PCTCN2018098985-appb-100001
    其中，
    Figure PCTCN2018098985-appb-100002
    为相位角、x为冷却介质流通方向的坐标、k为振幅、T为周期。
  12. 如权利要求6所述的用于粒子线产生装置的靶材，其特征在于，所述子螺旋曲折通道的轨迹函数为：
    Figure PCTCN2018098985-appb-100003
    其中，R in为中心半径、R _out为外半径、θ为极坐标角度、K为振幅、T为 周期。
  13. 如权利要求7所述的用于粒子线产生装置的靶材，其特征在于，所述散热层包括支撑件，所述第一板和/或第二板通过所述支撑件进行固定，所述散热层具有冷却进口和冷却出口，所述冷却进口和冷却出口设置在所述支撑件上。
  14. 如权利要求8所述的用于粒子线产生装置的靶材，其特征在于，所述散热层具有进口槽和出口槽，所述进口槽连通所述冷却进口和所述曲折状的冷却通道，所述出口槽连通所述冷却出口和所述曲折状的冷却通道。
  15. 如权利要求10所述的用于粒子线产生装置的靶材，其特征在于，所述第二板与第一板接触的面为平面，所述曲折状的壁的高度和所述周向壁的高度相同。
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