CN106512233B - Beam-shaping body for neutron capture treatment - Google Patents

Beam-shaping body for neutron capture treatment Download PDF

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CN106512233B
CN106512233B CN201510579928.4A CN201510579928A CN106512233B CN 106512233 B CN106512233 B CN 106512233B CN 201510579928 A CN201510579928 A CN 201510579928A CN 106512233 B CN106512233 B CN 106512233B
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neutron
powder
slow
target
sintering
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CN106512233A (en
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刘渊豪
陈韦霖
李珮仪
张敏娟
徐文玉
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Neuboron Medtech Ltd
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Neuboron Medtech Ltd
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Priority to CN201811467047.3A priority Critical patent/CN109568812B/en
Application filed by Neuboron Medtech Ltd filed Critical Neuboron Medtech Ltd
Priority to CN201811294328.3A priority patent/CN109589503A/en
Priority to CN201811294323.0A priority patent/CN109568808A/en
Priority to CN201510579928.4A priority patent/CN106512233B/en
Priority to CN201811294634.7A priority patent/CN109568809B/en
Priority to EP16789264.5A priority patent/EP3254729B1/en
Priority to CN201680022431.5A priority patent/CN107921273B/en
Priority to EP19184558.5A priority patent/EP3570294B1/en
Priority to JP2017557373A priority patent/JP6843766B2/en
Priority to RU2017142120A priority patent/RU2682972C1/en
Priority to PCT/CN2016/079568 priority patent/WO2016177270A1/en
Publication of CN106512233A publication Critical patent/CN106512233A/en
Priority to US15/704,495 priority patent/US10328286B2/en
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Priority to US16/401,328 priority patent/US10617893B2/en
Priority to US16/727,216 priority patent/US20200188695A1/en
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Abstract

A kind of beam-shaping body for neutron capture treatment, including beam entrance, target, the slow body for being adjacent to target, slow external reflector, the thermal neutron absorber adjacent with slow body, setting are enclosed in the intracorporal radiation shield of beam-shaping and beam outlet, nuclear reaction occurs for target to generate neutron with the proton beam from beam entrance incidence, neutron forms the neutron beam for limiting a main shaft, slow body is by from the neutron degradation that target generates to epithermal neutron energy area, and the material of slow body is by containing MgF2With occupy MgF2Weight percent be that 0.1-5% containing6LiF is mixed, block is become by powder or powder compact by powder sintering process through powder sintered equipment, the neutron that reflector will deviate from main shaft leads back to main shaft to improve epithermal neutron intensity of beam, thermal neutron absorber caused multi-dose for absorbing thermal neutron with shallow-layer normal tissue when treatment, radiation shield is used to shield neutron and the photon of leakage to reduce the normal tissue dose in non-irradiated area.

Description

Beam-shaping body for neutron capture treatment
Technical field
The present invention relates to a kind of beam-shaping body more particularly to a kind of beam-shaping bodies for neutron capture treatment.
Background technique
As the radiation cures such as the development of atomics, such as cobalt 60, linear accelerator, electron beam have become cancer One of the main means of disease treatment.However conventional photonic or electronic therapy are limited by radioactive ray physical condition itself, are being killed While dead tumour cell, normal tissue a large amount of in beam approach can also be damaged；Additionally, due to tumour cell to putting The difference of radiation-sensitive degree, traditional radiation therapy is for relatively having the malignant tumour of radiation resistance (such as: multirow glioblast Tumor (glioblastoma multiforme), melanocytoma (melanoma)) treatment effect it is often bad.
Target therapy in order to reduce the radiation injury of tumour surrounding normal tissue, in chemotherapy (chemotherapy) Concept is just applied in radiation cure；And it is directed to the tumour cell of radiation resistance, also actively development has high phase at present To the radiation source of biological effect (relative biological effectiveness, RBE), such as proton therapeutic, heavy particle Treatment, neutron capture treatment etc..Wherein, neutron capture treatment is to combine above two concept, if boron neutron capture is treated, is borrowed Specificity by boracic drug in tumour cell is gathered, and accurately neutron beam regulates and controls for cooperation, provides more preferable than conventional radiation Treatment of cancer selection.
Boron neutron capture treatment (Boron Neutron Capture Therapy, BNCT) be using boracic (10B) drug There is the characteristic of high capture cross section to thermal neutron, by10B(n,α) 7Li neutron capture and nuclear fission reaction generate4He and7Li two A heavy burden charged particle.Referring to Figures 1 and 2, which respectively show boron neutron capture reaction schematic diagram and10B(n,α) 7Li neutron Nuclear equation formula is captured, the average energy of two charged particles is about 2.33MeV, and there is High Linear to shift (Linear Energy Transfer, LET), short range feature, the linear energy transfer of α particle and range are respectively 150 keV/ μm, 8 μm, and7Li Heavy burden particle is then 175 keV/ μm, 5 μm, and the integrated range of two particle is approximately equivalent to a cell size, therefore for organism Caused by radiation injury can be confined to cell level, be gathered in tumour cell when boracic drug selectivity, arrange in pairs or groups it is appropriate Neutron penetrates source, just can achieve the purpose that tumour cell is killed in part under the premise of normal tissue does not cause too major injury.
Because the effect of boron neutron capture treatment depends on tumour cell position boracic drug concentration and thermal neutron quantity, therefore again Referred to as binary radioactive ray treatment of cancer (binary cancer therapy)；It follows that in addition to the exploitation of boracic drug, Neutron penetrates source flux and the improvement of quality occupies key player in the research that boron neutron capture is treated.
Summary of the invention
In order to improve the flux and quality that neutron penetrates source, one aspect of the present invention provides a kind of for neutron capture treatment Beam-shaping body comprising beam entrance, target, the slow body for being adjacent to target, be enclosed in slow external reflector, with The adjacent thermal neutron absorber of slow body, setting are exported in the intracorporal radiation shield of beam-shaping and beam, target with from beam Nuclear reaction occurs for the proton beam of entrance incidence to generate neutron, and neutron forms neutron beam, and neutron beam limits a main shaft, delays Fast body is by from the neutron degradation that target generates to epithermal neutron energy area, and the material of slow body is by containing PbF4、Al2O3、AlF3、 CaF2Or MgF2One of or multiple mixed materials and occupy containing PbF4、Al2O3、AlF3、 CaF2Or MgF2One of or The weight percent of multiple mixed materials is containing for 0.1-5%6The material of Li element is mixed, wherein the material of slow body Block is become by powder or powder compact by powder sintering process through powder sintered equipment, the neutron that reflector will deviate from main shaft is led Main shaft is returned to improve epithermal neutron intensity of beam, thermal neutron absorber is for absorbing thermal neutron to avoid normal with shallow-layer when treating Tissue caused multi-dose, and radiation shield is used to shield neutron and the photon of leakage to reduce the normal tissue agent in non-irradiated area Amount.
Beam-shaping body is further used for the treatment of accelerator boron neutron capture, and the treatment of accelerator boron neutron capture passes through acceleration Proton beam acceleration, target are made of metal by device, and proton beam accelerates to the energy for being enough to overcome target atom core coulomb repulsion, with Nuclear reaction occurs for target to generate neutron, beam-shaping physical efficiency by neutron slowly to epithermal neutron energy area, and reduce thermal neutron and Fast neutron content, epithermal neutron energy area hanker subzone less than 0.5eV, fast-neutron range is greater than between 0.5eV to 40keV 40keV, reflector with the strong material of neutron reflection ability by being made, and thermal neutron absorber is by big with thermal neutron action section Material is made.
Preferably reflector is made of at least one of Pb or Ni as a kind of, thermal neutron absorber by6Li is made, Air duct is equipped between thermal neutron absorber and beam outlet, radiation shield includes that the photon made of Pb shields and by PE system At neutron shield.
In order to effectively slow down to neutron beam, on the one hand, preferably as one kind, slow body is arranged to two phases Opposite direction adjoins each other cone-shaped.
Further, cone-shaped includes first diameter, second diameter and third diameter, and first diameter length is 1cm- 20cm, second diameter length are 30cm-100cm, and third diameter length is 1cm-50cm, and the density of the material of slow body is theory The 80%-100% of density.
Still further, clearance channel is set between slow body and reflector to improve epithermal neutron flux, slow body Material is by containing MgF2Powder and occupy MgF2Powder weight is 0.1-5%'s6LiF powder is mixed.
On the other hand, powder sintered equipment is hot-press sintering equipment or discharging plasma sintering equipment, powder sintering process For hot-pressing sintering technique or discharge plasma sintering process.
Preferably, hot-press sintering equipment includes heating furnace, is placed in the pressurizing device in heating furnace, mold, is packed into mold Powder or powder compact and for control hot-press sintering equipment normal work control device, hot-pressing sintering technique include it is as follows Step: mold is filled with suitable powder or powder compact；Hot pressing furnace is opened with preset pressure and temperature parameter；Mobile pressurization dress Set in mold powder or powder compact pressurization；Control device controls hot-press sintering equipment in the case of normal work；It is logical Electricity is blocking to be sintered.
Preferably as another kind, discharging plasma sintering equipment includes first electrode, second electrode, is placed in first electrode Conductive die between second electrode, the impulse current generator that pulse current is provided to mold, with for pressurization plus The pressurizing device of casting die and control device for controlling pulse current transmitter and pressurizing device, first electrode and second electrode At least one of can move, at least one of first electrode and second electrode are connected to pressurize with pressurizing device The powder being placed in mold；Discharge plasma sintering process includes the following steps: suitable powder filling mold；Mobile second Electrode pressurizes to the powder in mold；Impulse current generator is opened by control device to generate conductive die conduction Plasma, powder particle surface are activated and generate heat；It is sintered blocking.
Discharging plasma sintering equipment further comprises the displacement measurement system for measuring the displacement of pressurizing device, is used for The atmosphere control system for controlling atmosphere in mold, for cooling water-cooling system, for measuring in discharging plasma sintering equipment Temperature temperature measuring device, discharge plasma sintering process further comprises following steps: control device command displacement survey For amount system to ensure that displacement measurement system works normally, control device controls atmosphere control system to ensure that atmosphere is just in mold Often in the case of work, control device controls water-cooling system to ensure that water-cooling system works normally, and control device controls temperature and surveys Device is measured to ensure the temperature in discharging plasma sintering equipment in the case of normal work.
" cylinder " described in the embodiment of the present invention or " bar shape " refer to along diagram direction side to the other side its A wherein contour line for the structure that the overall trend of outer profile is basically unchanged, outer profile can be line segment, such as cylindrical shape Corresponding contour line is also possible to the biggish circular arc close to line segment of curvature, such as the corresponding wheel of the biggish sphere body shape of curvature The whole surface of profile, outer profile can be rounding off, be also possible to non-rounding off, such as in cylindrical shape or curvature Many protrusions and groove are done in the surface of biggish sphere body shape.
" cone " described in the embodiment of the present invention or " cone-shaped " refer to along diagram direction side to the other side its A wherein contour line for the gradually smaller structure of the overall trend of outer profile, outer profile can be line segment, such as cone shape Corresponding contour line, is also possible to circular arc, and such as the corresponding contour line of sphere body shape, the whole surface of outer profile can be round and smooth Transition, it is also possible to non-rounding off, has such as done many protrusions and groove on the surface of cone shape or sphere body shape.
Detailed description of the invention
Fig. 1 is boron neutron capture reaction schematic diagram.
Fig. 2 is10B(n,α) 7Li neutron capture nuclear equation formula.
Fig. 3 is the floor map of the beam-shaping body for neutron capture treatment in first embodiment of the invention, In, clearance channel is provided between slow body and reflector.
Fig. 4 is the floor map of the beam-shaping body for neutron capture treatment in second embodiment of the invention, In, slow body is arranged to bicone, and the clearance channel position in first embodiment is filled with slow body material.
Fig. 5 is the floor map of the beam-shaping body for neutron capture treatment in third embodiment of the invention, In, slow body is arranged to bicone, and the clearance channel position in first embodiment is filled with reflector material.
Fig. 6 is the neutron yield rate figure of neutron energy and the double differential of neutron angle.
Fig. 7 is the floor map of the beam-shaping body for neutron capture treatment in fourth embodiment of the invention, In, slow body is arranged to cylinder.
Fig. 8 is the floor map of the beam-shaping body for neutron capture treatment in fifth embodiment of the invention, In, slow body is arranged to cylinder+cone.
Fig. 9 is the preparation facilities schematic diagram of the slow body material of the present invention in one embodiment, wherein preparation dress It is set to discharging plasma sintering equipment.
Figure 10 is the preparation facilities schematic diagram of the slow body material of the present invention in one embodiment, wherein the preparation Device is hot-press sintering equipment.
Specific embodiment
Neutron capture treatment as a kind of effective treating cancer means in recent years using gradually increasing, wherein with boron Neutron capture treatment is most commonly seen, and the neutron of supply boron neutron capture treatment can be supplied by nuclear reactor or accelerator.This hair By taking the treatment of accelerator boron neutron capture as an example, the basic module of accelerator boron neutron capture treatment generally includes to use bright embodiment In the accelerator, target and hot removal system and beam-shaping body that are accelerated to charged particle (such as proton, deuteron), wherein Accelerate charged particle and metal targets effect to generate neutron, is charged according to required neutron yield rate and energy, available acceleration The characteristics such as the materialization of particle energy and size of current, metal targets select suitable nuclear reaction, the nuclear reaction being often discussed Have7Li(p,n)7Be and9Be(p,n)9B, both reactions are all the endothermic reaction.The energy threshold of two kinds of nuclear reactions is respectively 1.881MeV and 2.055MeV, it is theoretical due to the epithermal neutron that the ideal neutron source of boron neutron capture treatment is keV energy grade If the upper proton bombardment lithium metal target for being only slightly taller than threshold values using energy can produce the neutron of opposite low energy, be not necessary to too many Slow processing can be used for clinic, however the proton-effect of two kinds of targets of lithium metal (Li) and beryllium metal (Be) and threshold values energy is cut Face is not high, to generate sufficiently large neutron flux, the proton of higher-energy is usually selected to cause nuclear reaction.
Ideal target should have high neutron yield rate, the neutron energy of generation is distributed (will be under close to epithermal neutron energy area Text detailed description), without wear by force too much radiation generate, the characteristics such as cheap easily operated and high temperature resistant of safety, but actually and can not It finds and meets required nuclear reaction, using target made of lithium metal in the embodiment of the present invention.But art technology Known to personnel, the material of target can also be made of other metal materials other than the above-mentioned metal material talked about.
Requirement for hot removal system is then different according to the nuclear reaction of selection, such as7Li(p,n)7Be is because of metal targets (lithium Metal) fusing point and thermal conductivity coefficient it is poor, requirement to hot removal system just compared with9Be(p,n)9B high.It is adopted in the embodiment of the present invention With7Li(p,n)7The nuclear reaction of Be.
No matter boron neutron capture treatment nuclear reaction of the neutron source from nuclear reactor or accelerator charged particle and target, What is generated is all mixed radiation field, i.e., beam contains neutron, photon of the low energy to high energy；The boron neutron of deep tumor is caught Treatment is obtained, other than epithermal neutron, remaining radiation content is more, causes the ratio of the non-selective dosage deposition of normal tissue It is bigger, therefore these radiation that will cause unnecessary dosage should reduce as far as possible.In addition to air beam quality factor, in knowing more about Son in human body caused by dosage be distributed, carry out Rapid Dose Calculation using human body head tissue prosthese in the embodiment of the present invention, and With prosthese beam quality factor as the design reference of neutron beam, will be described in more detail below.
International Atomic Energy Agency (IAEA) is directed to the neutron source of clinical boron neutron capture treatment, penetrates given five air Beam quality factor suggestion, this five suggestions can be used for the superiority and inferiority of the different neutron sources of comparison, and be provided with as select neutron generate way Reference frame when diameter, design beam-shaping body.This five suggestion difference are as follows:
Epithermal neutron beam flux Epithermal neutron flux > 1 x 109 n/cm2s
Fast neutron pollutes Fast neutron contamination < 2 x 10-13 Gy-cm2/n
Photon contamination Photon contamination < 2 x 10-13 Gy-cm2/n
Thermal and epithermal neutron flux ratio thermal to epithermal neutron flux ratio < 0.05
Middle electron current and ratio > 0.7 flux ratio epithermal neutron current to flux
Note: subzone is hankered less than 0.5eV, fast-neutron range is greater than between 0.5eV to 40keV in epithermal neutron energy area 40keV。
1, epithermal neutron beam flux:
Boracic drug concentration has codetermined the clinical treatment time in neutron beam flux and tumour.If tumour boracic drug The enough height of concentration, the requirement for neutron beam flux can reduce；Conversely, needing high pass if boracic drug concentration is low in tumour Epithermal neutron is measured to give tumour enough dosage.Requirement of the IAEA for epithermal neutron beam flux is per second every square centimeter Epithermal neutron number be greater than 109, the neutron beam under this flux can substantially control treatment for current boracic drug Time, short treatment time, can also relatively effective use boracic medicine other than advantageous to patient's positioning and comfort level in one hour Object limited residence time in tumour.
2, fast neutron pollutes:
Since fast neutron will cause unnecessary normal tissue dose, regard as pollution, this dosage size and neutron Energy is positively correlated, therefore should reduce the content of fast neutron to the greatest extent in neutron beam design.Fast neutron pollution definition is unit The adjoint fast neutron dosage of epithermal neutron flux, IAEA are less than 2 x 10 to the suggestion that fast neutron pollutes-13 Gy-cm2/n。
3, photon contamination (gamma-ray contamination):
Gamma-rays, which belongs to, wears radiation by force, can non-selectively cause the organized dosage deposition of institute on course of the beam, therefore Reduce gamma-rays content be also neutron beam design exclusive requirement, gamma-ray contamination define for unit epithermal neutron flux it is adjoint Gamma-rays dosage, IAEA are less than 2 x 10 to the suggestion of gamma-ray contamination-13 Gy-cm2/n。
4, thermal and epithermal neutron flux ratio:
Since thermal neutron decay speed is fast, penetration capacity is poor, into human body after most of energy be deposited on skin histology, remove It is swollen for deep layers such as brain tumors outside the neutron source that the Several Epidermal Tumors such as melanocytoma need to use thermal neutron to treat as boron neutron capture Tumor should reduce thermal neutron content.IAEA is less than 0.05 to thermal and epithermal neutron flux ratio suggestion.
5, middle electron current and flux ratio:
Middle electron current and flux ratio represent the directionality of beam, and tropism is good before the bigger expression neutron beam of ratio, high The neutron beam of preceding tropism can reduce because neutron diverging caused by normal surrounding tissue dosage, in addition also improve can treat depth and Put pose gesture elasticity.IAEA centering electron current and flux ratio suggestion are greater than 0.7.
The dosage in tissue is obtained using prosthese to be distributed, and according to the dose versus depth curve of normal tissue and tumour, pushes away false Body beam quality factor.Following three parameter can be used for carrying out the comparison of different neutron beam treatment benefits.
1, effective therapeutic depth:
Depth of the tumor dose equal to normal tissue maximum dose, the position after this depth, what tumour cell obtained Dosage is less than normal tissue maximum dose, that is, loses the advantage of boron neutron capture.What this parameter represented neutron beam penetrates energy Power, effective therapeutic depth is bigger to indicate that medicable tumor depth is deeper, unit cm.
2, effective therapeutic depth dosage rate:
That is the tumor dose rate of effective therapeutic depth is also equal to the maximum dose rate of normal tissue.Because normal tissue receives Accumulated dose is the factor for influencing to give tumour accumulated dose size, therefore parameter influences the length for the treatment of time, and effectively treatment is deep Irradiation time needed for tumour doses are given in the bigger expression of degree dosage rate is shorter, unit cGy/mA-min.
3, dose therapeutically effective ratio:
From brain surface to effective therapeutic depth, tumour and the received mean dose ratio of normal tissue, referred to as effectively Therapeutic dose ratio；The calculating of mean dose can be integrated to obtain by dose versus depth curve.Dose therapeutically effective ratio is bigger, represents The treatment benefit of the neutron beam is better.
Compare foundation to there is beam-shaping body in design, in addition to five IAEA suggest air in beam quality because Three plain and above-mentioned parameters also utilize in the embodiment of the present invention following for assessing the ginseng of neutron beam dosage performance superiority and inferiority Number:
1, the proton current that irradiation time≤30min(accelerator uses is 10mA)
2,30.0RBE-Gy can treat depth >=7cm
3, tumour maximum dose >=60.0RBE-Gy
4, normal cerebral tissue's maximum dose≤12.5RBE-Gy
5, skin maximum dose≤11.0RBE-Gy
Note: RBE(Relative Biological Effectiveness) it is relative biological effect, due to photon, neutron The biological effect that will cause is different, thus dosage item as above be multiplied by respectively the relative biological effect of different tissues in the hope of etc. Imitate dosage.
In order to improve the flux and quality that neutron penetrates source, the embodiment of the present invention is for penetrating for neutron capture treatment The improvement that beam shaping body proposes is preferably as one kind for the beam-shaping body for the treatment of accelerator boron neutron capture Improvement.As shown in figure 3, the beam-shaping body 10 for neutron capture treatment in first embodiment of the invention comprising penetrate Beam entrance 11, target 12, adjacent and target 12 slow body 13, the reflector 14 and slow body 13 being enclosed in outside slow body 13 Adjacent thermal neutron absorber 15, the radiation shield 16 being arranged in beam-shaping body 10 and beam outlet 17, target 12 with from Nuclear reaction occurs for the incident proton beam of beam entrance 11 to generate neutron, and neutron forms neutron beam, and neutron beam limits one Major axis X, by from the neutron degradation that target 12 generates to epithermal neutron energy area, reflector 14 will deviate from major axis X slow body 13 Son leads back to major axis X to improve epithermal neutron intensity of beam, and clearance channel 18 is arranged between slow body 13 and reflector 14 to improve Epithermal neutron flux caused multi-agent with shallow-layer normal tissue when thermal neutron absorber 15 is for absorbing thermal neutron to avoid treatment Amount, radiation shield 16 are used to shield neutron and the photon of leakage to reduce the normal tissue dose in non-irradiated area.
The treatment of accelerator boron neutron capture passes through accelerator by proton beam acceleration, as a kind of preferred embodiment, target 12 It is made of lithium metal, proton beam accelerates to the energy for being enough to overcome target atom core coulomb repulsion, occurs with target 127Li(p, n)7Be nuclear reaction is to generate neutron.Beam-shaping body 10 can be by neutron slowly to epithermal neutron energy area, and reduces thermal neutron and fast Neutron content, slow body 13 is made of the material big with fast neutron action section, epithermal neutron action section is small, as one kind Preferred embodiment, slow body 13 is by D2O、AlF3、FluentalTM、CaF2、Li2CO3 、MgF2And Al2O3At least one of system At.Reflector 14 with the strong material of neutron reflection ability by being made, and as a kind of preferred embodiment, reflector 14 is by Pb or Ni At least one of be made.Thermal neutron absorber 15 is made of the material big with thermal neutron action section, as a kind of preferred reality Apply example, thermal neutron absorber 15 by6Li is made, and is equipped with air duct 19 between thermal neutron absorber 15 and beam outlet 17.Spoke Penetrating shielding 16 includes photon shielding 161 and neutron shield 162, and as a kind of preferred embodiment, radiation shield 16 includes by lead (Pb) shielding of photon made of 161 and the neutron shield 162 made of polyethylene (PE).
Wherein, slow body 13 is arranged to two opposite directions and adjoins each other cone-shaped, as shown in Figure 3 direction, slowly To be gradually smaller cone-shaped towards left side, the right side of slow body 13 is towards the gradually smaller cone in right side in the left side of body 13 Shape, the two adjoin each other.Preferably as one kind, the left side of slow body 13 is set as gradually smaller cone-shaped towards left side, And right side also can be set into its allothimorph shape with this it is cone-shaped adjoin each other, such as bar shape.Reflector 14 closely surrounds Around slow body 13, clearance channel 18 is provided between slow body 13 and reflector 14, what so-called clearance channel 18 referred to It is the empty easy region for allowing neutron beam to pass through of unused solid material covering, leads to as the clearance channel 18 can be set to air Road or vacuum passage.The thermal neutron absorber 15 being arranged close to slow body 13 is by very thin one layer6Li material is made, radiation The shielding of the photon made of Pb 161 in shielding 16 can be arranged with reflector 14 be integrated, and also can be set into fission, and spoke Penetrating the neutron shield 162 made of PE in shielding 16 can be set in the position of neighbouring beam outlet 17.In thermal neutron absorber 15 and beam outlet 17 between be provided with air duct 19, in this region the sustainable neutron that will deviate from major axis X lead back to major axis X with Improve epithermal neutron intensity of beam.Prosthese B setting exports at 17 about 1cm apart from beam.It is well known to those skilled in the art, light Son shielding 161 can be made of other materials, as long as playing the role of shielding photon, neutron shield 162 can also be by it He is made material, also can be set elsewhere, as long as can satisfy the condition of shielding leakage neutron.
In order to compare the difference of the beam-shaping body and the beam-shaping body of not set clearance channel that are provided with clearance channel, As shown in Figure 4 and Figure 5, which respectively show adopt by clearance channel using the second embodiment of slow body filling and by clearance channel The 3rd embodiment filled with reflector.With reference first to Fig. 4, which includes beam entrance 21, target 22, adjoining With the slow body 23 of target 22, the reflector 24 being enclosed in outside slow body 23, the thermal neutron absorber 25 adjacent with slow body 23, Radiation shield 26 in beam-shaping body 20 and beam outlet 27, target 22 and the proton beam incident from beam entrance 21 are set Nuclear reaction occurs to generate neutron, neutron forms neutron beam, and neutron beam limits a major axis X 1, and slow body 23 will be from target For 22 neutron degradations generated to epithermal neutron energy area, it is superthermal to improve that the neutron that reflector 24 will deviate from major axis X 1 leads back to major axis X 1 Neutron beam intensity, slow body 23 be arranged to two opposite directions adjoin each other it is cone-shaped, the left side of slow body 23 be towards Left side is gradually smaller cone-shaped, and to be gradually smaller cone-shaped towards right side, the two adjoins each other on the right side of slow body 23, heat Neutron absorber 25 caused multi-dose for absorbing thermal neutron with shallow-layer normal tissue when treatment, radiation shield 26 is used The normal tissue dose in non-irradiated area is reduced in the neutron and photon that shield leakage.
Preferably as one kind, target 22, slow body 23, reflector 24, thermal neutron absorber 25 in second embodiment Can be identical as in first embodiment with radiation shield 26, and radiation shield therein 26 includes the photon made of lead (Pb) Shielding 261 and the neutron shield 262 made of polyethylene (PE), the neutron shield 262 can be set at beam outlet 27.? Air duct 28 is provided between thermal neutron absorber 25 and beam outlet 27.Prosthese B1 setting is exporting 27 about apart from beam At 1cm.
Referring to figure 5., the beam-shaping body 30 include beam entrance 31, target 32, the adjacent slow body 33 with target 32, It is enclosed in the reflector 34 outside slow body 33, the thermal neutron absorber 35 adjacent with slow body 33, is arranged in beam-shaping body 30 Interior radiation shield 36 and beam outlet 37, target 32 with from the incident proton beam of beam entrance 31 occur nuclear reaction to generate in Son, neutron formed neutron beam, neutron beam limit a major axis X 2, slow body 33 by the neutron degradation generated from target 32 extremely Epithermal neutron energy area, the neutron that reflector 34 will deviate from major axis X 2 lead back to major axis X 2 to improve epithermal neutron intensity of beam, slowly Body 33 is arranged to two opposite directions and adjoins each other cone-shaped, and the left side of slow body 33 is towards the gradually smaller cone in left side Shape, to be gradually smaller cone-shaped towards right side, the two adjoins each other on the right side of slow body 33, and thermal neutron absorber 35 is for inhaling Caused multi-dose with shallow-layer normal tissue when receiving thermal neutron to avoid treatment, radiation shield 36 be used to shield the neutron of leakage with Photon is to reduce the normal tissue dose in non-irradiated area.
Preferably as one kind, target 32, slow body 33, reflector 34, thermal neutron absorber 35 in 3rd embodiment Can be identical as in first embodiment with radiation shield 36, and radiation shield therein 36 includes the photon made of lead (Pb) Shielding 361 and the neutron shield 362 made of polyethylene (PE), the neutron shield 362 can be set at beam outlet 37.? Air duct 38 is provided between thermal neutron absorber 35 and beam outlet 37.Prosthese B2 setting is exporting 37 about apart from beam At 1cm.
It (is below by Los Alamos National Laboratories of the U.S. (LosAlamos National using MCNP software That Laboratory) develops is used to calculate neutron, the photon, electrification in 3 D complex geometry based on Monte Carlo method Particle or coupling neutron/photon/charged particle transport problem common software packet) simulation of these three embodiments is calculated:
Wherein, as to show the performance of beam quality factor in air in these three embodiments (in table each for following table one Name lexeme is same as above, and details are not described herein, similarly hereinafter):
Table one: beam quality factor in air
Wherein, performance in these three embodiments is shown as following table two shows dosage:
Table two: dosage performance
Wherein, as following table three shows mould of the parameter of assessment neutron beam dosage performance superiority and inferiority in these three embodiments Quasi- numerical value:
Table three: the parameter of assessment neutron beam dosage performance superiority and inferiority
Note: it can be learnt from three above-mentioned tables: be provided with the beam of clearance channel between slow body and reflector The treatment benefit of shaping body, neutron beam is best.
Since the neutron generated from lithium target has the higher characteristic of Forward averaging energy, as shown in fig. 6, neutron scattering angle The average neutron energy spent between 0 ° -30 ° is about 478keV, and average neutron of the neutron scattering angle between 30 ° -180 ° Energy about only has 290keV, if can be more to neutron and the generation of slow body before making by the geometry for changing beam-shaping body Collision, and lateral neutron can reach beam outlet through less collision, then should theoretically can reach neutron slowly optimizes, and has The raising epithermal neutron flux of efficiency.Set about below from the geometry of beam-shaping body, to evaluate different beam-shaping bodies Influence of the geometry for epithermal neutron flux.
As shown in fig. 7, it illustrates the geometry of the beam-shaping body in fourth embodiment, the beam-shaping body 40 packet Include beam entrance 41, target 42, the adjacent slow body 43 with target 42, the reflector 44 being enclosed in outside slow body 43, with it is slow The adjacent thermal neutron absorber 45 of body 43, the radiation shield 46 being arranged in beam-shaping body 40 and beam outlet 47, target 42 Nuclear reaction occurs to generate neutron with from the incident proton beam of beam entrance 41, slow body 43 subtracts the neutron generated from target 42 Speed is to epithermal neutron energy area, and the neutron that reflector 44 will deviate from is led back to improve epithermal neutron intensity of beam, and slow body 43 is arranged At bar shape, it is preferable that be arranged to cylindrical shape, thermal neutron absorber 45 is for absorbing thermal neutron to avoid when treatment and shallow-layer Normal tissue caused multi-dose, and radiation shield 46 is used to shield neutron and the photon of leakage to reduce normal group of non-irradiated area Dosage is knitted, is provided with air duct 48 between thermal neutron absorber 45 and beam outlet 47.
As shown in figure 8, it illustrates the geometry of the beam-shaping body in the 5th embodiment, the beam-shaping body 50 packet Include beam entrance 51, target 52, the adjacent slow body 53 with target 52, the reflector 54 being enclosed in outside slow body 53, with it is slow The adjacent thermal neutron absorber 55 of body 53, the radiation shield 56 being arranged in beam-shaping body 50 and beam outlet 57, target 52 With nuclear reaction occurs from the incident proton beam of beam entrance 51 to generate neutron, neutron forms neutron beam, and neutron beam limits A piece major axis X 3, for slow body 53 by from the neutron degradation that target 52 generates to epithermal neutron energy area, reflector 54 will deviate from main shaft The neutron of X3 leads back to major axis X 3 to improve epithermal neutron intensity of beam, and slow body 53 is arranged to what two opposite directions adjoined each other Cone-shaped, the left side of slow body 53 is bar shape, and the right side of slow body 53 is gradually smaller cone-shaped, the two phase towards right side It is mutually adjacent, multi-dose, spoke were caused with shallow-layer normal tissue when thermal neutron absorber 25 is for absorbing thermal neutron to avoid treatment Shielding 26 is penetrated for shielding neutron and the photon of leakage to reduce the normal tissue dose in non-irradiated area.
Preferably as one kind, target 52, slow body 53, reflector 54, thermal neutron absorber 55 in the 5th embodiment Can be identical as in first embodiment with radiation shield 56, and radiation shield therein 56 includes the photon made of lead (Pb) Shielding 561 and the neutron shield 562 made of polyethylene (PE), the neutron shield 562 can be set at beam outlet 57.? Air duct 58 is provided between thermal neutron absorber 55 and beam outlet 57.Prosthese B3 setting is exporting 57 about apart from beam At 1cm.
Below using MCNP software to the slow of the cylinder in the slow body of bicone in second embodiment, fourth embodiment Cylinder+cone simulation in body and the 5th embodiment calculates:
Wherein, as following table four shows performance of the beam quality factor in these three embodiments in air:
Table four: beam quality factor in air
Wherein, performance in these three embodiments is shown as following table five shows dosage:
Table five: dosage performance
Wherein, as following table six shows mould of the parameter of assessment neutron beam dosage performance superiority and inferiority in these three embodiments Quasi- numerical value:
Table six: the parameter of assessment neutron beam dosage performance superiority and inferiority
Note: it can be learnt from three above-mentioned tables: slow body is arranged to at least one is cone-shaped, neutron beam It is preferable to treat benefit.
" cylinder " described in the embodiment of the present invention or " bar shape " refer to along diagram direction side to the other side its A wherein contour line for the structure that the overall trend of outer profile is basically unchanged, outer profile can be line segment, such as cylindrical shape Corresponding contour line is also possible to the biggish circular arc close to line segment of curvature, such as the corresponding wheel of the biggish sphere body shape of curvature The whole surface of profile, outer profile can be rounding off, be also possible to non-rounding off, such as in cylindrical shape or curvature Many protrusions and groove are done in the surface of biggish sphere body shape.
" cone " described in the embodiment of the present invention or " cone-shaped " refer to along diagram direction side to the other side its A wherein contour line for the gradually smaller structure of the overall trend of outer profile, outer profile can be line segment, such as cone shape Corresponding contour line, is also possible to circular arc, and such as the corresponding contour line of sphere body shape, the whole surface of outer profile can be round and smooth Transition, it is also possible to non-rounding off, has such as done many protrusions and groove on the surface of cone shape or sphere body shape.
In terms of source flux is penetrated in an important improvement, it is necessary to discuss that the material of slow body is made, it is hereafter real with first For applying example and attached drawing 3, slow body 13 is further described.
Slow body 13 shows the antipodal double cone structures in two cone directions, and the material of slow body 13 is by containing AlF3Or CaF2Or MgF2At least one of material be made, slow body 13 have first diameter D1, second diameter D2 and third Diameter D3.Opening is provided at first diameter D1 to accommodate target 12, second diameter D2 is set as the maximum of double cone structures At size.For BNCT, in order to reach enough slow speed effect, first diameter D1 length is 1cm-20cm, second diameter D2 length is 30cm-100cm, and third diameter D3 length is 1cm-50cm, and preferably as one kind, first diameter D1 length is 10cm, second diameter D2 length are 70cm, and third diameter D3 length is 30cm.Such large-sized slow body 13 in order to obtain, And the density of its material is the 80%-100% of theoretical density, provides the preparation of following three kinds slow body materials.
1. long brilliant
First with MgF2For, with further reference to application for a patent for invention Publication No. CN102925963A, herein in full Introduce the reference as long brilliant preparation.As long brilliant mode, usually by kind of crystalline substance and contain MgF2Powder be put into crucible, lead to It crosses certain mode and grows MgF2Monocrystalline.
It needs to give special heed to, so-called here " monocrystalline " refers to the molding single crystal of single growth, and is not Single crystal grain (only has a kind of crystalline form and contains only a crystal grain, molecule, courtyard are all to arrange regularly in the crystal grain).More What is understood well is this single crystal grain (size and shape of i.e. each crystal grain is different, and it is also in disorder for being orientated from multiple crystal grain , without apparent shape, also do not show anisotropy) it is corresponding.Below with respect to " monocrystalline " definition with it is where like.
By investigation, PbF4、AlF3、 CaF2And Al2O3It can also be prepared by similar mode.
2. powder sintered
With MgF2Powder or MgF2Addition accounts for MgF2The 0.1-5%'s of powder weight6The mixed-powder of LiF is Example, to carry out powder sintered introduction, it is preferable that below with MgF2Addition accounts for MgF2The 0.1-5%'s of powder weight6Powder sintered introduction is carried out for the mixed-powder of LiF.
Slow body plays particularly important role in beam-shaping body, is responsible for the slow heavy responsibility of neutron and appoints greatly, It needs to lower fast neutron intensity as much as possible, and excessively slowly cannot be thermal neutron by neutron, on the other hand, it is also necessary to lower and subtract The gamma-rays derived during speed.Research has shown that equably inserting a small amount of contain in slow body6The material of Li, Gamma-ray intensity can be effectively lowered, though neutron intensity will be made slightly to subtract, but still possesses the quality of original beam.Through further Research, by MgF2Powder doping accounts for MgF2The 0.1-5%'s of powder weight6The powder of LiF mixes, compared to individually not Addition6The MgF of LiF powder2Powder, the mixed-powder can be more efficiently absorbed thermal neutron and effectively inhibit gamma-rays.
By MgF2Powder doping accounts for MgF2The 0.1-5%'s of powder weight contains6The material mixing of Li is as a kind of Slow body material, well known to those skilled in the art, this contains6The material of Li can be any be easy to and MgF2Powder is entrained in Any physical form together, as this contains6The material of Li can be liquid, be also possible to powder.This contains6The material of Li can To be any be easy to and MgF2Any compound of powder doping together, this contains6The material of Li can be6LiF or6Li2CO3.Preferably as one kind, by MgF2Powder and account for MgF2The 0.1-5%'s of powder weight6The powder or powder of LiF Last green compact further combined with getting up, during the sintering process powder particle to occur mutually to flow, diffusion, dissolution, the objects such as recrystallization Physicochemical process keeps powder further fine and close, eliminates some or all of holes.Sintering processing can there are many kinds of, such as Solid-phase sintering, i.e. sintering temperature are in body of powder below the fusing point of each constituent element；Liquid-phase sintering, i.e., in powder compact if there are two types of Above constituent element, sintering is possible to carry out more than the fusing point of certain constituent element, thus occurs on a small quantity in powder compact when sintering Liquid phase；Hot pressed sintering applies pressure to body of powder that is, in sintering, to promote its densification process, hot pressing be powder at Shape and sinter bonded are got up, and the technical process of product is directly obtained；Discharge plasma sintering is filled by controlling particular power source The ON-OFF DC pulse voltage for setting generation is added on powder sample, in addition to that can be promoted using sintering caused by usual electro-discharge machining Outside into effect (discharge impact pressure and Joule heating), it is existing also to efficiently use the spark discharge generated between pulsed discharge initial stage powder The sintering facilitation as caused by (moment generates high-temperature plasma) realizes the quick burning of densification by TRANSIENT HIGH TEMPERATURE field Knot technology.The material of slow body becomes block by powder or powder compact by powder sintering process through powder sintered equipment.
Well known to those skilled in the art, other sintering processings can also realize MgF2Or AlF3Or CaF2Or PbF4In At least one or several mixtures add again6Preparation of the powder of LiF as the material of slow body.Preferably as one kind, under Text is using hot pressed sintering and discharge plasma sintering as powder sintered embodiment.
2.1 discharge plasma sintering
Discharge plasma sintering melts plasma activation, hot pressing, resistance heating are integrated, heating rate is fast, sintering time is short, Sintering temperature is low, crystal grain is uniform, is conducive to control the fine structure of sintered body, obtains the consistency height of material, and has behaviour The advantages that making simple, reproducibility height, safe and reliable, saving space, saving the energy and is at low cost.Discharge plasma sintering is due to strong Pulse current is added between powder particle, there are the positive and negative anodes of electric field induction between powder particle, the particle under pulse current effect Between discharge, excite plasma, by electric discharge generate the intergranular contact portion of energetic particle hits, make substance generate steaming Breaking-out is used and plays purification and activation, and in the dielectric layer of cluster of grains, dielectric layer generation is intermittent quickly to put power storage Electricity.Since there are pulse currents between powder or powder compact, and pulse current is moment, interrupted, high-frequency generation, in powder Powder is all greatly facilitated not in contact with the position heat discharge generated and the Joule heat of powder particle contact site generation in particle The diffusion of particle atom, diffusion coefficient is than much greater under usual hot pressing condition, to reach powder sintered rapid. Furthermore due to the addition of pulse current, fast move electric discharge position and joule heat position in powder all can, make powder or The sintering of powder compact can homogenize.During discharge plasma sintering, when discharging between particle, can instantaneously it generate up to several Thousand degree to 10,000 degree of localized hyperthermia, causes to evaporate and melt in particle surface, neck is formed in grain contact point, due to heat Particle surface is transmitted to from fever center immediately and is spread around, and neck is quickly cooled down and makes vapour pressure lower than other positions. It is the another of discharge plasma sintering process that gaseous substance, which condenses upon neck and forms the evaporation higher than ordinary sinter method-solidification transmitting, One important feature.By the effect of Current Heating and vertical uniaxial pressure, body diffusion, grain boundary decision are all added crystal grain By force, sintering densification process is accelerated, therefore the sintered body of high quality can be obtained with lower temperature and shorter time.It puts Electric plasma agglomeration process can be regarded as the result of particle electric discharge, conductive heater and comprehensive function of pressurizeing.
Fig. 9 is please referred to, there is disclosed a kind of schematic diagrames of discharging plasma sintering equipment.Discharging plasma sintering equipment 100 include first electrode 101, second electrode 102, the conductive die 103 being placed between first electrode 101 and second electrode 102, Impulse current generator 104 to the offer pulse current of mold 103, the pressurization with the pressing means 1051,1052 for pressurization Device 105 and control device 106 for controlling impulse current generator 104 and pressurizing device 105, first electrode 101 and At least one of two electrodes 102 can move, and at least one of pressing means 1051,1052 can move, as a kind of excellent Selection of land, first electrode 101 and pressing means 1051 are fixed, and second electrode 102 and pressing means 1052 can move, so as to pressurize The powder or powder compact 107 being placed in mold 103.Preferably as one kind, conductive die 103 is set as lead or graphite.It puts Electric plasma sintering equipment 100 further comprises the displacement measurement system 108 for measuring the displacement of pressurizing device 105, is used for Control the atmosphere control system 109 of atmosphere in the mold 103, the water-cooling system cooled down for controlling water-cooled vacuum room 110 111, for measuring the temperature measuring device 112 of the temperature in discharging plasma sintering equipment 100.Mold 103 and powder or powder The logical upper pulse current of last green compact 107 further utilizes pulse other than offer discharge impact pressure and Joule heat are sintered Sintering facilitation caused by the Spark Discharges (moment generates high-temperature plasma) generated between electric discharge initial stage powder is logical It crosses TRANSIENT HIGH TEMPERATURE field and realizes Fast Sintering, so that powder or powder compact 107 become blocky from pulverulence, so-called piece Shape is integrally formed, and without such as long brilliant mode, is spliced by monocrystalline by the processes such as polishing or polishing and is suitble to slow body Size.
The discharging plasma sintering equipment 100 is sintered and pressurizes using DC pulse current direct-electrifying, through control device 106 control heating rate and sintering temperature by adjusting the size of pulsed direct current.Entire sintering process can be in vacuum environment Lower progress can also carry out in protective atmosphere, such as oxygen or hydrogen.
Under oxygen atmosphere, since oxygen is sintered object adsorption or chemical reaction effect occurs, form plane of crystal The non-stoichiometric compound of cation omission type, cation vacancy increases, while be directly entered the oxygen in closed pore can Lattice, and be diffused as oxygen ion vacancy along surface, spread and be sintered acceleration.When sintering is controlled by positive diffusions When, oxidizing atmosphere or partial pressure of oxygen are higher and be conducive to cation vacancy and formed, acceleration of sintering；When spreading control by anion, also Primordial Qi atmosphere or lower partial pressure of oxygen will lead to oxygen ion vacancy and generate simultaneously acceleration of sintering.
In a hydrogen atmosphere when sintered sample, due to hydrogen atom radius very little, it is easy to spread and is conducive to closed pore It eliminates, the material of the types such as aluminium oxide is sintered the available sintered body sample close to theoretical density under hydrogen atmosphere.
Sintering temperature is crucial an one of parameter during plasma Fast Sintering.The determination of sintering temperature will consider Sintered body sample phase transition at high temperature, the growth rate of crystal grain, the quality requirement of sample and sample density requirements.One As in the case of, with the raising of sintering temperature, sample consistency is integrally in rising trend, this illustrate sintering temperature to sample densification Degree degree has apparent influence, and sintering temperature is higher, and mass transfer speed is faster in sintering process, and the sample the easy to be closely knit.
But temperature is higher, the growth rate of crystal grain is faster, and mechanical property is poorer.And temperature is too low, sample Consistency is just very low, can't meet the quality requirement.Contradiction between temperature and grain size requires a conjunction in the selection of temperature Suitable parameter.
Extend the soaking time under sintering temperature, generally can all complete acceleration of sintering to some extent, improve the aobvious of sample Micro-structure, this is more obvious to the sintering of VISCOUS FLOW mechanism, and on the sintering of bulk diffusion and surface diffusion mechanism influence compared with It is small.During the sintering process, general heat preservation only 1 minute when, the density of sample just reaches 96.5% or more of theoretical density, with guarantor The consistency of the extension of warm time, sample increases, but variation range is not very greatly, to illustrate soaking time to the consistency of sample Although having a certain impact, function and effect are not apparent.But unreasonably extend the soaking time under sintering temperature, it is brilliant Grain in this time, grow up by play of having to go to the toilet, aggravation secondary recrystallization effect, is unfavorable for the performance requirement of sample, and the time too short can cause The densification of sample declines, it is therefore desirable to select suitable soaking time.
The quickening of time heating rate, so that sample reaches required temperature, the growth of crystal grain in a short period of time Time can greatly reduce, this not only contributes to inhibit growing up for crystal grain, obtain fine grain ceramics of uniform size, moreover it is possible to when saving Between, it is energy saving and improve agglomerating plant utilization rate.But due to the limitation of equipment itself, heating rate is too fast to setting It is standby to will cause damaging influence.Therefore the quickening heating rate in permissible range as far as possible.But in the reality of actual measurement Reflection in data is tested to arrive.Different from sintering temperature and soaking time, influence of the heating rate to sample consistency is shown on the contrary As a result, i.e. with the increase of heating rate, the trend that is gradually reduced of sample consistency performance roughening, scholar propose this be because For near sintering temperature the raising of heating rate be equivalent to and shorten soaking time, thus sample consistency can be declined. In actual high-temperature sintering process, temperature-rise period is generally divided into three phases, respectively from room temperature to 600 DEG C or so, 600 DEG C To 900 DEG C or so, 900 DEG C to sintering temperature: the first stage is the preparation stage, and heating rate is relatively slow；Second stage Be it is controllable be rapidly heated the stage, heating rate general control is 100 ~ 500 (DEG C/min)；Phase III is the buffering rank of heating Section, the phase temperature are slowly increased to sintering temperature, and soaking time is usually 1 ~ 7 minute, and furnace cooling after heat preservation, cooling rate can Up to 300 DEG C/min.
Powder carries out compression moulding and sintering immediately after being substantially discharged processing.Agglomerated material is in resistance Joule heat and pressure Collective effect under occur serious plastic deformation, apply forming pressure and be conducive to enhance contact between powder particle, increase and burn Residual gas, raising product intensity, density and its surface smoothness between junction area, discharge sintering powder.Forming pressure it is big It is small generally to be determined according to the compressibility of sintering powder and the requirement to performances such as density of sintered material, intensity, generally 15~30 Within the scope of MPa, it there may come a time when up to 50 MPa, it is even higher.In general, forming pressure is bigger, the density of agglomerated material is higher. The pressurization duration also has a great impact to density of sintered material, the type of suitable pressing time view agglomerated material, powder Granularity and the geometric dimension of institute's agglomerated material and it is different, need to be determined by experiment.It is demonstrated experimentally that pressurization the duration be equal to or Slightly larger than discharge time, this is the necessary condition for obtaining most high-density agglomerated material.Reason is easy from sintering and solid phase reaction mechanism Solution, pressure is bigger, and particle packing is closer in sample, and mutual contact point and contact area increase sintering are accelerated.In this way Sample can be made to obtain better consistency, and crystal grain can effectively be inhibited to grow up and reduce sintering temperature.Therefore the pressure of selection Generally 30 ~ 50Mpa.But with studies have shown that the consistency of sample differs when being sintered, external pressure is 30Mpa and 50Mpa And less, this illustrates that the phenomenon that consistency increases with pressure is more obvious only within a certain range.
Discharge plasma sintering has the advantage that sintering velocity is fast compared to conventional sintering technique；Improve the micro- knot of material Structure and the performance for improving material.
Well known to those skilled in the art, mold can be used other conductive materials and be made, and discharge plasma sintering is set It is fixed for two electrodes also can be set into, and only at least one pressing means can move.
The technical process of discharge plasma sintering is divided into four-stage.First stage: apply to powder sample initial Pressure makes to come into full contact between powder particle, so as to be then able in powder sample generate uniformly and adequately electric discharge etc. from Son；Second stage: applying pulse current, and under the action of pulse current, powder particle contact point generates plasma discharging, particle Surface generates micro- exothermic phenomenon due to activation；Phase III: closing the pulse power, resistance heating is carried out to sample, until reaching Until scheduled sintering temperature and sample are shunk completely；Fourth stage: release.Rationally control initial pressure, sintering time, The main technologic parameters such as forming pressure, pressurization duration, sintering temperature, heating rate can get the good material of comprehensive performance Material.
Due to the arch bridge effect between powder particle, they cannot generally be come into full contact with, therefore, in order to make electric spark sintering When generated in sample uniformly and the plasma that is substantially discharged, farthest activated particle surface is to accelerate densified sintering product Change process needs to apply initial pressure appropriate to sintering powder, comes into full contact with powder particle.The size of initial pressure can The difference with sintering powder kind, sintered part size and performance.First pressing is too small, and electric discharge phenomena are confined in amount of powder, Lead to powder local melting；Pressure is excessive, will inhibit to discharge, and then delays to be sintered diffusion process.According to existing literature, It is sufficiently carried out to continue electric discharge, this initial pressure is generally no more than 10MPa.
When powdered sample preferable with electric spark sintering electric conductivity, due to resistance heating from sample outwardly and inwardly It carries out simultaneously, therefore sintering time is extremely short, even moment, but sintering time length should regard powder quality, kind and performance And it is different, generally several seconds to a few minutes；When sintering is large-scale, refractory metal powder material when, even up to dozens of minutes.It burns The knot time is affected to product density, to enable densification process sufficiently to carry out, therefore, to assure that certain sintering time.
It is generally believed that it is highly advantageous for being rapidly heated during discharge plasma sintering to the sintering of powder, because it presses down Therefore the densification Mechanism made the non-densifying mechanism of material and had activated material improves heating rate, can make the cause of sample Degree of densification is improved.
Preferably as one kind, discharge plasma sintering process includes the following steps: with suitable powder or powder compact 107 filling molds 103；Mobile pressurizing device 105 in mold 103 powder or powder compact 107 pressurize；Pass through control device 106 opening impulse current generators 104 with mold 103 is conductive to generate plasma, powder particle surface be activated and Fever；It is sintered blocking.Discharge plasma sintering process further comprises following steps: 106 command displacement of control device measurement system For system 108 to ensure that displacement measurement system 108 works normally, control device 106 controls atmosphere control system 109 to ensure mold For atmosphere in 103 in the case of normal work, control device 106 controls water-cooling system 111 to ensure it in normal work Under situation, control device 106 controls temperature measuring device 112 to ensure the temperature in discharging plasma sintering equipment 100 just Often in the case of work.So-called normal work refers to that the vision of human perception, touching do not occur for discharging plasma sintering equipment The alarm signals such as feel or the sense of hearing, if alarm lamp lights, alarm lamp sounds, and police instruction vibration etc. is such.
2.2 hot pressed sintering
Hot pressed sintering is that dry powder is filled into model, then heats from uniaxial direction in pressurization, makes to form and burn Tie a kind of sintering method being completed at the same time.Hot pressing and sintering technique production technology very abundant is classified at present without unified standard and mark It is quasi-.Vacuum hotpressing, atmosphere hot pressing, vibration hot pressing, balanced hot pressing, hot isostatic pressing, reaction hot-pressing can be divided into according to status and surpassed High-pressure sinter.Hot pressed sintering is due to heating pressurization while carrying out, and powder is in hot plastic state, and the contact for facilitating particle is expanded It dissipates, the progress of flowing mass transport process, thus briquetting pressure is only 1/10 be cold-pressed；Sintering temperature can also be reduced, when shortening sintering Between, it grows up to resist crystal grain, obtains that crystal grain is tiny, consistency is high and mechanical, the good product of electric property.
In order to prepare slow body material using hot-pressing sintering technique, Figure 10 is please referred to, hot-press sintering equipment 200 mainly includes Heating furnace 201, the pressurizing device 202 being placed in heating furnace 201, mold 203, the powder or powder compact being packed into mold 203 204 and control device 205.Heating furnace 201 usually using electricity as heat source, heating element by SiC, MoSi or nickel reeling, platinum wire, Molybdenum filament etc..Pressurizing device 202 requires that speed is gentle, pressure maintaining is constant, pressure flexible modulation, generally there is lever and fluid pressure type.Root According to the requirement of material properties, pressure atmosphere can be air and be also possible to reducing atmosphere or inert atmosphere.Mold 203 requires high-strength Degree, high temperature resistant, anti-oxidant and do not cohere with hot-pressed material, 203 thermal expansion coefficient of mold should be consistent or approximate with hot-pressed material, work Preferably for one kind, graphite jig is used in the present embodiment.Control device 205 is working normally hot-press sintering equipment 200 In the case of.So-called normal work refers to that the vision of human perception, tactile do not occur or listens for discharging plasma sintering equipment The alarm signals such as feel, if alarm lamp lights, alarm lamp sounds, and police instruction vibration etc. is such.
With MgF2For preparing the slow body of target using hot-pressing sintering technique, the technological process of production generally comprises following step Suddenly, MgF2--- raw material grinding, screening process --- are transferred to mold --- high temperature sintering --- high temperature hot pressing burning for raw material preparation Knot --- cooling to come out of the stove --- hot isostatic pressing high temperature sintering --- cooling --- grinding, polishing, bonding --- finished product of coming out of the stove.
As a kind of processing step that the powder processing step and postorder sintering for preferably, omitting preamble herein are completed. Hot-pressing sintering technique includes the following steps: to fill mold 203 with suitable powder or powder compact 204；Open hot pressing furnace 201 with Preset pressure and temperature parameter；Mobile pressurizing device 202 in mold 203 powder or powder compact 204 pressurize；Control device 205 control hot-press sintering equipments 200 are in the case of normal work；It is powered blocking to be sintered.
It should be further noted that " mobile pressurizing device 202 is in mold 203 for the step in hot-pressing sintering technique Powder or powder compact 204 pressurize " it can be used as precharge, it synchronous with energization can also carry out, i.e., by step " mobile pressurization dress Powder or powder compact 204 in 202 pairs of molds 203 is set to pressurize " and step " energization is blocking to be sintered " be combined into one.
Some parameters that long brilliant, discharge plasma sintering and hot pressed sintering are listed in following table compare, more just as one kind The material of slow body application in the beam-shaping body of the neutron capture treatment disclosed in the present invention, especially needs to manufacture the Two diameter D2 maximums reach under the precondition of the size of 100cm, it is recommended here that use powder sintered manufactured slow body material, tool Body is described in detail see hereafter.
Table seven: long brilliant and powder sintering process comparison
Note: upper table is omitted the 0.1-5%'s respectively added as powder main material6LiF powder, though in upper table only List MgF2+LiF、AlF3+ LiF and CaF2These three slow body materials of+LiF are compared using the parameter of technique as above, but ability Known to field technique personnel, other slow body material such as Al2O3+ LiF can also easily make comparison.
Although from upper table it is known that the density for preparing slow body material by the way of long crystalline substance can reach close to theory Density such as reaches the 99.99% of theoretical density, but since single crystal size is smaller, to reach the large-sized slow body material of target Material needs to be spliced by many monocrystalline, it may also be desirable to carry out the other processes such as mirror-finishing to it in the process, not only It is time-consuming very long, and cost and technology difficulty are all very big.
The density that slow body material is prepared by the way of powder sintered can also reach the 80%-100% of theoretical density.Make Preferably for one kind, the density of slow body material reaches the 99.99% of theoretical density.It is obtained in theoretical density and long crystal type The theoretical density of slow body material compared to substantially it is indiscriminate simultaneously, in the size of acquisition, time, cost and technology difficulty side Face is with the obvious advantage.It is obtained as required using slow its actual size of body material that discharge plasma sintering is prepared, one Kind mode can customize out the mold for being suitble to needs, and another way uses common die, such as the mould of diameter 70cm* thickness 2cm Then tool splice and can be completed by several, burn with vacuum heating-press sintering and hot isostatic pressing in cost and technology difficulty Tie it is equally matched under the premise of, only need 1 month or so time on manufacturing time.
The beam-shaping body for neutron capture treatment that the present invention discloses is not limited to interior described in above embodiments Structure represented by appearance and attached drawing.On the basis of the present invention done aobvious of the material and shape to wherein component and position and Easy insight changes, substitutes or modifies, all within the scope of protection of present invention.

Claims (10)

1. it is a kind of for neutron capture treatment beam-shaping body, it is characterised in that: the beam-shaping body include beam entrance, Target, the slow body for being adjacent to the target are enclosed in the slow external reflector, hanker with what the slow body abutted Sub- absorber, setting are exported in the intracorporal radiation shield of the beam-shaping and beam, the target with from the beam entrance Nuclear reaction occurs for incident proton beam to generate neutron, and the neutron forms neutron beam, and the neutron beam limits a master Axis, the slow body is by from the neutron degradation that the target generates to epithermal neutron energy area, and the material of the slow body is by containing PbF4、Al2O3、AlF3、CaF2Or MgF2One of or multiple mixed materials and occupy and described contain PbF4、Al2O3、AlF3、 CaF2Or MgF2One of or the weight percent of multiple mixed materials be that 0.1-5% containing6The material of Li element mixes system At wherein the material of the slow body by hot-pressing sintering technique or is put through hot-press sintering equipment or discharging plasma sintering equipment Electric plasma sintering process becomes block by powder or powder compact, and the hot-press sintering equipment includes heating furnace, is placed in described add It pressurizing device, mold in hot stove, the powder being packed into the mold or powder compact and is set for controlling the hot pressed sintering The standby control device worked normally, the hot-pressing sintering technique include the following steps: to be filled with suitable powder or powder compact The mold；The hot pressing furnace is opened with preset pressure and temperature parameter；The mobile pressurizing device is to the powder in the mold End or powder compact pressurization；The control device controls the hot-press sintering equipment in the case of normal work；It is powered to burn Form block, the neutron that the reflector will deviate from the main shaft leads back to the main shaft to improve epithermal neutron intensity of beam, described Multi-dose, the radiation shield were caused with shallow-layer normal tissue when thermal neutron absorber is for absorbing thermal neutron to avoid treatment For shielding neutron and the photon of leakage to reduce the normal tissue dose in non-irradiated area.
2. the beam-shaping body according to claim 1 for neutron capture treatment, it is characterised in that: the beam-shaping Body is further used for the treatment of accelerator boron neutron capture, the treatment of accelerator boron neutron capture by accelerator by proton beam acceleration, The target is made of metal, and the proton beam accelerates to the energy for being enough to overcome target atom core coulomb repulsion, with the target Nuclear reaction occurs for material to generate neutron, and neutron slowly to epithermal neutron energy area, and is reduced thermal neutron by the beam-shaping physical efficiency And fast neutron content, epithermal neutron energy area is described to hanker subzone less than 0.5eV between 0.5eV to 40keV, described Fast-neutron range is greater than 40keV, and the reflector with the strong material of neutron reflection ability by being made, the thermal neutron absorber It is made of the material big with thermal neutron action section.
3. it is according to claim 2 for neutron capture treatment beam-shaping body, it is characterised in that: the reflector by At least one of Pb or Ni are made, the thermal neutron absorber by6Li is made, and the thermal neutron absorber and the beam go out Air duct is equipped between mouthful, the radiation shield includes the shielding of the photon made of Pb and the neutron shield made of PE.
4. the beam-shaping body according to claim 1 for neutron capture treatment, it is characterised in that: the slow body is set Be set to two opposite directions adjoin each other it is cone-shaped.
5. the beam-shaping body according to claim 4 for neutron capture treatment, it is characterised in that: the cone-shaped packet First diameter, second diameter and third diameter are included, the first diameter length is 1cm-20cm, and the second diameter length is 30cm-100cm, the third diameter length are 1cm-50cm, and the density of the material of the slow body is the 80%- of theoretical density 100%.
6. it is according to claim 1 for neutron capture treatment beam-shaping body, it is characterised in that: the slow body and Clearance channel is set to improve epithermal neutron flux, the material of the slow body is by containing MgF between the reflector2Powder and Occupy MgF2Powder weight is 0.1-5%'s6LiF powder is mixed.
7. the beam-shaping body according to claim 5 for neutron capture treatment, it is characterised in that: the first diameter Place is provided with opening to accommodate target.
8. the beam-shaping body according to claim 1 for neutron capture treatment, it is characterised in that: the slow body is extremely It is cone-shaped comprising one less.
9. it is according to claim 1 for neutron capture treatment beam-shaping body, it is characterised in that: it is described electric discharge etc. from Sub- agglomerating plant include first electrode, second electrode, the conductive die being placed between the first electrode and the second electrode, To the impulse current generator of mold offer pulse current, the pressurizing device with the pressing means for pressurization and for controlling Make the control device of the pulse current transmitter and the pressurizing device, at least one in the first electrode and second electrode A to move, at least one of the first electrode and second electrode are connected to pressurize and set with the pressurizing device Powder in the mold；The discharge plasma sintering process includes the following steps: suitable powder filling the mould Tool；The mobile second electrode pressurizes to the powder in the mold；By control device open impulse current generator with incite somebody to action To generate plasma, powder particle surface is activated and generates heat conductive die conduction；It is sintered blocking.
10. the beam-shaping body according to claim 9 for neutron capture treatment, it is characterised in that: described electric discharge etc. Ion agglomerating plant further comprises the displacement measurement system for measuring the displacement of pressurizing device, for controlling in the mold The atmosphere control system of atmosphere, for cooling water-cooling system, for measuring the temperature in the discharging plasma sintering equipment Temperature measuring device, the discharge plasma sintering process further comprises following steps: described in control device control Displacement measurement system to ensure that the displacement measurement system works normally, the control device control the atmosphere control system with Ensure that atmosphere is in the case of normal work in the mold, the control device controls the water-cooling system to ensure the water Cooling system works normally, and the control device controls the temperature measuring device to ensure in the discharging plasma sintering equipment Temperature in the case of normal work.
CN201510579928.4A 2015-05-04 2015-09-11 Beam-shaping body for neutron capture treatment Active CN106512233B (en)

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CN201811294328.3A CN109589503A (en) 2015-09-11 2015-09-11 Discharging plasma sintering equipment and sintering process
CN201811294323.0A CN109568808A (en) 2015-09-11 2015-09-11 Hot-press sintering equipment and sintering process
CN201510579928.4A CN106512233B (en) 2015-09-11 2015-09-11 Beam-shaping body for neutron capture treatment
CN201811294634.7A CN109568809B (en) 2015-09-11 2015-09-11 Neutron retarding material
CN201811467047.3A CN109568812B (en) 2015-09-11 2015-09-11 Beam shaping body for neutron capture therapy
CN201680022431.5A CN107921273B (en) 2015-05-04 2016-04-18 Beam-shaping body for neutron capture treatment
EP19184558.5A EP3570294B1 (en) 2015-05-04 2016-04-18 Beam shaping body for neutron capture therapy
JP2017557373A JP6843766B2 (en) 2015-05-04 2016-04-18 Beam shaping assembly for neutron capture therapy
EP16789264.5A EP3254729B1 (en) 2015-05-04 2016-04-18 Beam shaping body for neutron capture therapy
RU2017142120A RU2682972C1 (en) 2015-05-04 2016-04-18 Applied in the neutron capture therapy beam formation element
PCT/CN2016/079568 WO2016177270A1 (en) 2015-05-04 2016-04-18 Beam shaping body for neutron capture therapy
US15/704,495 US10328286B2 (en) 2015-05-04 2017-09-14 Beam shaping assembly for neutron capture therapy
US16/401,328 US10617893B2 (en) 2015-05-04 2019-05-02 Beam shaping assembly for neutron capture therapy
US16/727,216 US20200188695A1 (en) 2015-05-04 2019-12-26 Powder sintering device for moderator

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CN201811294634.7A Division CN109568809B (en) 2015-09-11 2015-09-11 Neutron retarding material
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