CN204798657U - A beam plastic body for treatment is caught to neutron - Google Patents
A beam plastic body for treatment is caught to neutron Download PDFInfo
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- CN204798657U CN204798657U CN201520281118.6U CN201520281118U CN204798657U CN 204798657 U CN204798657 U CN 204798657U CN 201520281118 U CN201520281118 U CN 201520281118U CN 204798657 U CN204798657 U CN 204798657U
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Abstract
The utility model provides a beam plastic body for treatment is caught to neutron, including the beam entry, the target, border on in the slow fast body of target, the encirclement is at the external reflector of slowly inviting, personally experience sth. Part of the body with the thermal neutron absorption that the slow fast body borders on, the setting is in internal radiation shield and the beam export of beam plastic, the nuclear reaction takes place in order to produce the neutron with the proton beam that incides from the beam entry for the target, the neutron forms the neutron beam of injecing a main shaft, delay the fast body subzone to the super -heated in of will slowing down from the neutron that the target produced, the material that delays the fast body is by containing liF, li2CO3, al2O3, alF3, at least a material among caF2 or the mgF2 is made, it becomes piece through powder sintering process by powder or powder pressed compact through powder sintering equipment, the reflector will deviate the neutron of main shaft and lead back the main shaft in order to improve super -heated neutron beam intensity, the thermal neutron absorption body and function is in the absorption heat neutron in order to avoid when treatment and shallow layer normal structure to cause too much dosage, neutron and photon that the radiation shield is used for shielding the seepage shine the normal structure dosage in district in order to reduce the non -.
Description
Technical field
This utility model relates to a kind of beam-shaping body, particularly relates to a kind of beam-shaping body for neutron capture treatment.
Background technology
Along with the development of atomics, radiation cure one of the Main Means becoming treatment of cancer such as such as cobalt 60, linear accelerator, electron beam.But conventional photonic or electronic therapy are subject to the restriction of the physical condition of lonizing radiation own, while killing tumor cell, also can normal structures a large amount of in beam approach be damaged; In addition because tumor cell is to the difference of lonizing radiation sensitivity, traditional radiation therapy is often not good for the treatment effect of the malignant tumor (as: multirow glioblastoma multiforme (glioblastomamultiforme), melanocytoma (melanoma)) compared with tool radiation resistance.
In order to reduce the radiation injury of tumor surrounding normal tissue, the target therapy concept in chemotherapy (chemotherapy) is just applied in radiation cure; And for the tumor cell of radiation resistance, also develop actively has the radiation source of high relative biological effect (relativebiologicaleffectiveness, RBE) at present, as proton therapeutic, heavy particle therapy, neutron capture treatment etc.Wherein, neutron capture treatment is in conjunction with above-mentioned two conceptions of species, as the treatment of boron neutron capture, gathers by the specificity of boracic medicine at tumor cell, coordinates neutron beam regulation and control accurately, provides and selects than the better treatment of cancer of conventional radiation.
Boron neutron capture treatment (BoronNeutronCaptureTherapy, BNCT) be utilize boracic (
10b) medicine has the characteristic of high capture cross section to thermal neutron, by
10b (n, α)
7li neutron capture and karyokinesis reaction produce
4he and
7li two heavy burden charged particle.See figures.1.and.2, which respectively show boron neutron capture reaction schematic diagram and
10b (n, α)
7li neutron capture nuclear equation formula, the average energy of two charged particles is about 2.33MeV, has High Linear transfer (LinearEnergyTransfer, LET), short range feature, the linear energy transfer of alpha-particle and range are respectively 150keV/ μm, 8 μm, and
7li heavy burden particle is then 175keV/ μm, 5 μm, the integrated range of two particle is about equivalent to a cell size, therefore the radiation injury caused for organism can be confined to cell level, when boracic drug selectivity be gathered in tumor cell, suitable neutron of arranging in pairs or groups penetrates source, just under normal tissue does not cause the prerequisite of too major injury, the object that tumor cell is killed in local can be reached.
Because the effect of boron neutron capture treatment depends on tumor cell position boracic drug level and thermal neutron quantity, therefore the binary lonizing radiation treatment of cancer (binarycancertherapy) that is otherwise known as; It can thus be appreciated that, except the exploitation of boracic medicine, in the research that the neutron improvement of penetrating source flux and quality is treated at boron neutron capture, occupy key player.
Utility model content
Flux and the quality in source is penetrated in order to improve neutron, an aspect of the present utility model provides a kind of beam-shaping body for neutron capture treatment, it comprises beam entrance, target, be adjacent to the slow body of target, be enclosed in reflector external slowly, the thermal neutron absorber adjacent with slow body, be arranged on the radiation shield in beam-shaping body and beam outlet, target and the proton beam generation nuclear reaction from the incidence of beam entrance are to produce neutron, neutron forms neutron beam, neutron beam limits a main shaft, slow body by the neutron degradation that produces from target to epithermal neutron energy district, the material of slow body is by containing LiF, Li
2cO
3, Al
2o
3, AlF
3, CaF
2or MgF
2in at least one material make, wherein the material of slow body becomes block by powder sintering process by powder or powder compact through powder sintered equipment, the neutron departing from main shaft is led back to main shaft to improve epithermal neutron intensity of beam by reflector, when thermal neutron absorber is for absorbing thermal neutron to avoid treatment and shallow-layer normal structure caused multiple dose, radiation shield is for shielding the neutron of seepage and photon to reduce the normal tissue dose in non-irradiated district.
Beam-shaping body is further used for the treatment of accelerator boron neutron capture, proton beam is accelerated by accelerator by the treatment of accelerator boron neutron capture, target is made of metal, proton beam accelerates to the energy being enough to overcome target atom core coulomb repulsion, with target generation nuclear reaction to produce neutron, beam-shaping physical ability by neutron slowly to epithermal neutron energy district, and reduce thermal neutron and fast neutron content, epithermal neutron energy district is between 0.5eV to 40keV, hanker subzone and be less than 0.5eV, fast-neutron range is greater than 40keV, reflector is made up of the material having neutron reflection ability strong, thermal neutron absorber is made up of the material large with thermal neutron action section.
As one preferably, reflector is made up of at least one in Pb or Ni, thermal neutron absorber by
6li makes, and is provided with air duct between thermal neutron absorber and beam outlet, and radiation shield comprises the photon shielding of being made up of Pb and the neutron shield of being made up of PE.
In order to effectively slow down to neutron beam, on the one hand, as one preferably, what slow body was arranged to that two rightabouts adjoin each other is cone-shaped.
Further, cone-shapedly comprise the first diameter, Second bobbin diameter and the 3rd diameter, the first diameter length is 1cm-20cm, and Second bobbin diameter length is 30cm-100cm, and the 3rd diameter length is 1cm-50cm, and the density of the material of slow body is the 80%-100% of solid density.
Again further, clearance channel is set between slow body and reflector to improve epithermal neutron flux.
On the other hand, powder sintered equipment is hot-press sintering equipment or discharging plasma sintering equipment.
Preferably, hot-press sintering equipment comprise heating furnace, powder in the pressue device be placed in heating furnace, mould, loading mould or powder compact and for controlling the control device that hot-press sintering equipment normally works.
As another kind preferably, discharging plasma sintering equipment comprises the first electrode, the second electrode, is placed in conductive die between the first electrode and the second electrode, provides the impulse current generator of pulse current to mould, the pressue device with the pressing means for pressurizeing and the control device for control impuls electric current transmitter and pressue device, at least one in first electrode and the second electrode can move, and the first electrode and at least one in the second electrode are connected with pressue device thus can add the powder be pressed in mould.
Discharging plasma sintering equipment comprises the displacement measurement system of the displacement for measuring pressue device further, for controlling the atmosphere control system of atmosphere in mould, for the water-cooling system cooled, for measuring the temperature measuring equipment of the temperature in discharging plasma sintering equipment.
" cylinder " or " bar shape " described in this utility model embodiment refers to the structure substantially constant to the overall trend of its outline of opposite side along the side of direction as shown, a wherein contour line of outline can be line segment, as the contour line of the correspondence of cylindrical shape, also can be the circular arc close to line segment that curvature is larger, the contour line of the correspondence of sphere body shape as larger in curvature, the whole surface of outline can be rounding off, also can be non-rounding off, as done a lot of projection and groove on the surface of cylindrical shape or the larger sphere body shape of curvature.
" cone " or " cone-shaped " described in this utility model embodiment refers to the structure diminished gradually along the side of direction as shown to the overall trend of its outline of opposite side, a wherein contour line of outline can be line segment, as the contour line of the correspondence of cone shape, also can be circular arc, as the contour line of the correspondence of sphere body shape, the whole surface of outline can be rounding off, also can be non-rounding off, as done a lot of projection and groove on the surface of cone shape or sphere body shape.
Accompanying drawing explanation
Fig. 1 is boron neutron capture reaction schematic diagram.
Fig. 2 is
10b (n, α)
7li neutron capture nuclear equation formula.
Fig. 3 is the floor map of the beam-shaping body for neutron capture treatment in this utility model first embodiment, wherein, between slow body and reflector, is provided with clearance channel.
Fig. 4 is the floor map of the beam-shaping body for neutron capture treatment in this utility model second embodiment, and wherein, slow body is arranged to bicone, and the clearance channel position in the first embodiment is filled with slow body material.
Fig. 5 is the floor map of the beam-shaping body for neutron capture treatment in this utility model the 3rd embodiment, and wherein, slow body is arranged to bicone, and the clearance channel position in the first embodiment is filled with reflector material.
Fig. 6 is the neutron yield rate figure of the two differential of neutron energy and neutron angle.
Fig. 7 is the floor map of the beam-shaping body for neutron capture treatment in this utility model the 4th embodiment, and wherein, slow body is arranged to cylinder.
Fig. 8 is the floor map of the beam-shaping body for neutron capture treatment in this utility model the 5th embodiment, and wherein, slow body is arranged to cylinder+cone.
Fig. 9 is the preparation facilities schematic diagram of the slow body material in one of them embodiment of this utility model, and wherein, this preparation facilities is discharging plasma sintering equipment.
Figure 10 is the preparation facilities schematic diagram of the slow body material in one of them embodiment of this utility model, and wherein, this preparation facilities is hot-press sintering equipment.
Detailed description of the invention
Neutron capture treatment increases gradually as a kind of means application in recent years of effective Therapeutic cancer, wherein common with the treatment of boron neutron capture, and the neutron of supply boron neutron capture treatment can by nuclear reactor or accelerator supply.Embodiment of the present utility model is treated for accelerator boron neutron capture, the basic module of accelerator boron neutron capture treatment generally includes accelerator, target and hot removal system for accelerating charged particle (as proton, deuteron etc.) and beam-shaping body, wherein accelerating charged particles and metal targets effect produce neutron, the characteristic such as materialization according to required neutron yield rate and energy, available accelerating charged particles energy and size of current, metal targets selects suitable nuclear reaction, and the nuclear reaction often come into question has
7li (p, n)
7be and
9be (p, n)
9b, these two kinds of reactions are all the endothermic reaction.The energy threshold of two kinds of nuclear reactions is respectively 1.881MeV and 2.055MeV, desirable neutron source due to the treatment of boron neutron capture is the epithermal neutron of keV energy grade, if use the proton bombardment lithium metal target of energy only a little higher than threshold values in theory, the neutron of relative mental retardation can be produced, slow process that must be not too many just can be used for clinical, but the proton-effect cross section of lithium metal (Li) and beryllium metal (Be) two kinds of targets and threshold values energy is not high, for producing enough large neutron flux, the proton of higher-energy is usually selected to carry out initiated core reaction.
Desirable target should possess high neutron yield rate, generation neutron energy distribution close to epithermal neutron energy district (will be described in more detail below), without wearing by force too much that radiation produces, safety is cheaply easy to operation and the characteristic such as high temperature resistant, but in fact also cannot find the nuclear reaction meeting all requirements, in embodiment of the present utility model, adopt the metal target of lithium.But well known to those skilled in the art, the material of target also can be made up of other metal materials except the above-mentioned metal material talked about.
Requirement for hot removal system is then different according to the nuclear reaction selected, as
7li (p, n)
7be because of the fusing point of metal targets (lithium metal) and thermal conductivity coefficient poor, to the requirement of hot removal system just comparatively
9be (p, n)
9b is high.Adopt in embodiment of the present utility model
7li (p, n)
7the nuclear reaction of Be.
No matter the neutron source of boron neutron capture treatment is from the nuclear reaction of nuclear reactor or accelerator charged particle and target, generation be all mixed radiation field, namely beam contains neutron, the photon of mental retardation to high energy; Boron neutron capture for deep tumor is treated, and except epithermal neutron, remaining radiation content is more, and the ratio causing the non-selective dosage of normal structure to deposit is larger, and therefore these can cause the radiation of unnecessary dosage to reduce as far as possible.Except air beam quality factor, for more understanding the dose distribution that neutron causes in human body, use human body head tissue prosthese to carry out Rapid Dose Calculation in embodiment of the present utility model, and be used as the design reference of neutron beam with prosthese beam quality factor, will be described in more detail below.
The neutron source that International Atomic Energy Agency (IAEA) treats for clinical boron neutron capture, given five air beam quality factors suggestion, these five suggestions can be used for the quality of more different neutron source, and be provided with as select neutron the way of production, design beam-shaping body time reference frame.These five suggestions are as follows respectively:
Epithermal neutron beam flux Epithermalneutronflux>1x10
9n/cm
2s
Fast neutron pollutes Fastneutroncontamination<2x10
-13gy-cm
2/ n
Photon contamination Photoncontamination<2x10
-13gy-cm
2/ n
Thermal and epithermal neutron flux ratio thermaltoepithermalneutronfluxratio<0.05
Middle electron current and flux ratio epithermalneutroncurrenttofluxratio>0.7
Note: epithermal neutron energy district is between 0.5eV to 40keV, and hanker subzone and be less than 0.5eV, fast-neutron range is greater than 40keV.
1, epithermal neutron beam flux:
In neutron beam flux and tumor, boracic drug level determines the clinical treatment time jointly.If tumor boracic drug level is enough high, the requirement for neutron beam flux just can reduce; Otherwise, if boracic drug level is low in tumor, then need high flux epithermal neutron to give tumor enough dosage.The epithermal neutron number that IAEA is every square centimeter per second for the requirement of epithermal neutron beam flux is greater than 10
9, the neutron beam under this flux roughly can control treatment time in one hour for current boracic medicine, and short treatment time, except having superiority to patient location and comfort level, also more effectively can utilize the holdup time that boracic medicine is limited in tumor.
2, fast neutron pollutes:
Because fast neutron can cause unnecessary normal tissue dose, what therefore look is pollution, and this dosage size and neutron energy are proportionate, and therefore should reduce the content of fast neutron in neutron beam design as far as possible.Fast neutron pollutes and is defined as the adjoint fast neutron dosage of unit epithermal neutron flux, and the suggestion that IAEA pollutes fast neutron is for being less than 2x10
-13gy-cm
2/ n.
3, photon contamination (gamma-ray contamination):
Gamma-rays belongs to wears radiation by force, non-selectively can cause the organized dosage deposition of institute on course of the beam, therefore the exclusive requirement that gamma-rays content is also neutron beam design is reduced, gamma-ray contamination is defined as the adjoint gamma-rays dosage of unit epithermal neutron flux, IAEA to the suggestion of gamma-ray contamination for being less than 2x10
-13gy-cm
2/ n.
4, thermal and epithermal neutron flux ratio:
Because thermal neutron decay speed is fast, penetration capacity is poor, after entering human body, most of energy deposition is at skin histology, except the neutron source that the Several Epidermal Tumors such as melanocytoma need be treated as boron neutron capture with thermal neutron, thermal neutron content should be reduced for deep tumor such as cerebromas.IAEA advises as being less than 0.05 thermal and epithermal neutron flux ratio.
5, middle electron current and flux ratio:
Middle electron current and flux ratio represent the directivity of beam, and before ratio larger expression neutron beam, tropism is good, and before high, the neutron beam of tropism can reduce because neutron disperses the normal surrounding tissue dosage caused, and also improve in addition and can treat the degree of depth and pendulum pose gesture elasticity.IAEA centering electron current and flux ratio are advised as being greater than 0.7.
Utilize prosthese to obtain in-house dose distribution, according to the dose versus depth curve of normal structure and tumor, push away to obtain prosthese beam quality factor.Following three parameters can be used for the comparison carrying out different neutron beam treatment benefit.
1, effective therapeutic depth:
Tumor dose equals the degree of depth of normal structure maximal dose, the position after this degree of depth, and the dosage that tumor cell obtains is less than normal structure maximal dose, namely loses the advantage of boron neutron capture.This parameter represents the penetration capacity of neutron beam, and the medicable tumor depth of the larger expression of effective therapeutic depth is darker, and unit is cm.
2, effective therapeutic depth close rate:
The i.e. tumor dose rate of effective therapeutic depth, also equals the maximum dose rate of normal structure.Because normal structure reception accumulated dose is the factor that impact can give tumor accumulated dose size, the therefore length of parameter influence treatment time, the irradiation time that the larger expression of effective therapeutic depth close rate gives needed for tumor doses is shorter, and unit is cGy/mA-min.
3, dose therapeutically effective ratio:
From brain surface to effective therapeutic depth, the mean dose ratio that tumor and normal structure receive, is referred to as dose therapeutically effective ratio; The calculating of mean dose, can be obtained by dose versus depth curvilinear integral.Dose therapeutically effective ratio is larger, and the treatment benefit representing this neutron beam is better.
Have in design to make beam-shaping body and compare foundation, except beam quality factor and above-mentioned three parameters in the air of five IAEA suggestions, in this utility model embodiment, also utilize the following parameter good and bad for assessment of the performance of neutron beam dosage:
1, the proton electric current that irradiation time≤30min(accelerator uses is 10mA)
2,30.0RBE-Gy can treat the degree of depth >=7cm
3, tumor maximal dose >=60.0RBE-Gy
4, normal cerebral tissue maximal dose≤12.5RBE-Gy
5, skin maximal dose≤11.0RBE-Gy
Note: RBE(RelativeBiologicalEffectiveness) be relative biological effect, the biological effect that can cause due to photon, neutron is different, so dosage item is as above multiplied by the relative biological effect of different tissues respectively in the hope of dose,equivalent.
Penetrate flux and the quality in source to improve neutron, embodiment of the present utility model is the improvement proposed for the beam-shaping body for the treatment of for neutron capture, as one preferably, is the improvement for the beam-shaping body for the treatment of for accelerator boron neutron capture.As shown in Figure 3, the beam-shaping body 10 for neutron capture treatment in this utility model first embodiment, it comprises beam entrance 11, target 12, adjoin the slow body 13 with target 12, be enclosed in the reflector 14 outside slow body 13, the thermal neutron absorber 15 adjacent with slow body 13, be arranged on the radiation shield 16 in beam-shaping body 10 and beam outlet 17, target 12 and the proton beam generation nuclear reaction from beam entrance 11 incidence are to produce neutron, neutron forms neutron beam, neutron beam limits a major axis X, slow body 13 by the neutron degradation that produces from target 12 to epithermal neutron energy district, the neutron departing from major axis X is led back to major axis X to improve epithermal neutron intensity of beam by reflector 14, clearance channel 18 is set between slow body 13 and reflector 14 to improve epithermal neutron flux, thermal neutron absorber 15 for absorb thermal neutron with avoid treatment time and shallow-layer normal structure caused multiple dose, radiation shield 16 is for shielding the neutron of seepage and photon to reduce the normal tissue dose in non-irradiated district.
Proton beam is accelerated by accelerator by the treatment of accelerator boron neutron capture, and as a kind of preferred embodiment, target 12 is made up of lithium metal, and proton beam accelerates to the energy being enough to overcome target atom core coulomb repulsion, occurs with target 12
7li (p, n)
7be nuclear reaction is to produce neutron.Beam-shaping body 10 by neutron slowly to epithermal neutron energy district, and can reduce thermal neutron and fast neutron content, and slow body 13 is made by having the material that fast neutron action section is large, epithermal neutron action section is little, and as a kind of preferred embodiment, slow body 13 is by D
2o, AlF
3, Fluental
tM, CaF
2, Li
2cO
3, MgF
2and Al
2o
3in at least one make.Reflector 14 is made up of the material having neutron reflection ability strong, and as a kind of preferred embodiment, reflector 14 is made up of at least one in Pb or Ni.Thermal neutron absorber 15 is made up of the material large with thermal neutron action section, as a kind of preferred embodiment, thermal neutron absorber 15 by
6li makes, and is provided with air duct 19 between thermal neutron absorber 15 and beam outlet 17.Radiation shield 16 comprises photon shielding 161 and neutron shield 162, and as a kind of preferred embodiment, radiation shield 16 comprises the photon shielding 161 of being made up of plumbous (Pb) and the neutron shield 162 of being made up of polyethylene (PE).
Wherein, it is cone-shaped that slow body 13 is arranged to that two rightabouts adjoin each other, direction as shown in Figure 3, and the left side of slow body 13 is diminish gradually towards left side cone-shaped, the right side of slow body 13 is diminish gradually towards right side cone-shaped, and both adjoin each other.As one preferably, it is cone-shaped that the left side of slow body 13 is set to diminish gradually towards left side, and its allothimorph shape also can be arranged in right side and this cone-shapedly adjoins each other, as bar shape etc.Reflector 14 is enclosed in around slow body 13 closely, clearance channel 18 is provided with between slow body 13 and reflector 14, so-called clearance channel 18 refers to the region easily allowing neutron beam pass through of the sky do not covered with solid material, as this clearance channel 18 can be set to air duct or vacuum passage.Be close to the thermal neutron absorber 15 of slow body 13 setting by very thin one deck
6li material is made, and the photon be made up of the Pb shielding 161 in radiation shield 16 can be set to one with reflector 14, also can be arranged to split, and the neutron shield 162 of being made up of PE in radiation shield 16 can be arranged on the position of contiguous beam outlet 17.Between thermal neutron absorber 15 and beam outlet 17, be provided with air duct 19, in this region, the sustainable major axis X that led back to by the neutron departing from major axis X is to improve epithermal neutron intensity of beam.Prosthese B is arranged on distance beam outlet 17 about 1cm places.Well known to those skilled in the art, photon shielding 161 can be made up of other materials, as long as play the effect of shielding photon, neutron shield 162 also can be made up of other materials, also can be arranged on other local, as long as the condition of shielding seepage neutron can be met.
In order to compare the difference of the beam-shaping body being provided with clearance channel and the beam-shaping body not arranging clearance channel, as shown in Figure 4 and Figure 5, which respectively show the second embodiment adopting slow body to fill clearance channel and the 3rd embodiment adopting reflector to fill clearance channel.First with reference to Fig. 4, this beam-shaping body 20 comprises beam entrance 21, target 22, adjoin the slow body 23 with target 22, be enclosed in the reflector 24 outside slow body 23, the thermal neutron absorber 25 adjacent with slow body 23, be arranged on the radiation shield 26 in beam-shaping body 20 and beam outlet 27, target 22 and the proton beam generation nuclear reaction from beam entrance 21 incidence are to produce neutron, neutron forms neutron beam, neutron beam limits a major axis X 1, slow body 23 by the neutron degradation that produces from target 22 to epithermal neutron energy district, the neutron departing from major axis X 1 is led back to major axis X 1 to improve epithermal neutron intensity of beam by reflector 24, it is cone-shaped that slow body 23 is arranged to that two rightabouts adjoin each other, the left side of slow body 23 is diminish gradually towards left side cone-shaped, the right side of slow body 23 is diminish gradually towards right side cone-shaped, both adjoin each other, thermal neutron absorber 25 for absorb thermal neutron with avoid treatment time and shallow-layer normal structure caused multiple dose, radiation shield 26 is for shielding the neutron of seepage and photon to reduce the normal tissue dose in non-irradiated district.
As one preferably, target 22 in second embodiment, slow body 23, reflector 24, thermal neutron absorber 25 and radiation shield 26 can identical with the first embodiment, and radiation shield 26 wherein comprises the photon shielding 261 of being made up of plumbous (Pb) and the neutron shield 262 of being made up of polyethylene (PE), this neutron shield 262 can be arranged on beam and export 27 places.Air duct 28 is provided with between thermal neutron absorber 25 and beam outlet 27.Prosthese B1 is arranged on distance beam outlet 27 about 1cm places.
Please refer to Fig. 5, this beam-shaping body 30 comprises beam entrance 31, target 32, adjoin the slow body 33 with target 32, be enclosed in the reflector 34 outside slow body 33, the thermal neutron absorber 35 adjacent with slow body 33, be arranged on the radiation shield 36 in beam-shaping body 30 and beam outlet 37, target 32 and the proton beam generation nuclear reaction from beam entrance 31 incidence are to produce neutron, neutron forms neutron beam, neutron beam limits a major axis X 2, slow body 33 by the neutron degradation that produces from target 32 to epithermal neutron energy district, the neutron departing from major axis X 2 is led back to major axis X 2 to improve epithermal neutron intensity of beam by reflector 34, it is cone-shaped that slow body 33 is arranged to that two rightabouts adjoin each other, the left side of slow body 33 is diminish gradually towards left side cone-shaped, the right side of slow body 33 is diminish gradually towards right side cone-shaped, both adjoin each other, thermal neutron absorber 35 for absorb thermal neutron with avoid treatment time and shallow-layer normal structure caused multiple dose, radiation shield 36 is for shielding the neutron of seepage and photon to reduce the normal tissue dose in non-irradiated district.
As one preferably, target 32 in 3rd embodiment, slow body 33, reflector 34, thermal neutron absorber 35 and radiation shield 36 can identical with the first embodiment, and radiation shield 36 wherein comprises the photon shielding 361 of being made up of plumbous (Pb) and the neutron shield 362 of being made up of polyethylene (PE), this neutron shield 362 can be arranged on beam and export 37 places.Air duct 38 is provided with between thermal neutron absorber 35 and beam outlet 37.Prosthese B2 is arranged on distance beam outlet 37 about 1cm places.
Adopt MCNP software (being the common software bag for calculating neutron, photon, charged particle or coupling neutron/photon/charged particle transport problem in 3 D complex geometry based on DSMC developed by Los Alamos National Laboratories of the U.S. (the LosAlamosNationalLaboratory)) analog computation to these three kinds of embodiments below:
Wherein, as following table one shows the performance of beam quality factor in these three kinds of embodiments in air (in form, each name lexeme is same as above, does not repeat them here, lower same):
table one: beam quality factor in air
Wherein, as following table two shows the performance in dose form these three kinds of embodiments present:
table two: dosage shows
Wherein, as following table three shows the good and bad simulation value of parameter in these three kinds of embodiments of assessment neutron beam dosage performance:
table three: the parameter that the performance of assessment neutron beam dosage is good and bad
Note: can learn from above-mentioned three tables: the beam-shaping body being provided with clearance channel between slow body and reflector, the treatment benefit of its neutron beam is best.
Because the neutron produced from lithium target has the higher characteristic of Forward averaging energy, as shown in Figure 6, the average neutron energy of neutron scattering angle between 0 °-30 ° is about 478keV, and the average neutron energy of neutron scattering angle between 30 °-180 ° about only has 290keV, if can by the geometry changing beam-shaping body, forward direction neutron and slow body is made to produce more collision, and side direction neutron just can arrive beam outlet through less collision, then should reach the slow optimization of neutron in theory, efficient raising epithermal neutron flux.Set about from the geometry of beam-shaping body below, evaluate the impact of geometry for epithermal neutron flux of different beam-shaping body.
As shown in Figure 7, it illustrates the geometry of the beam-shaping body in the 4th embodiment, this beam-shaping body 40 comprises beam entrance 41, target 42, adjoin the slow body 43 with target 42, be enclosed in the reflector 44 outside slow body 43, the thermal neutron absorber 45 adjacent with slow body 43, be arranged on the radiation shield 46 in beam-shaping body 40 and beam outlet 47, target 42 and the proton beam generation nuclear reaction from beam entrance 41 incidence are to produce neutron, slow body 43 by the neutron degradation that produces from target 42 to epithermal neutron energy district, the neutron departed from leads back to improve epithermal neutron intensity of beam by reflector 44, slow body 43 is arranged to bar shape, preferably, be arranged to cylindrical shape, thermal neutron absorber 45 for absorb thermal neutron with avoid treatment time and shallow-layer normal structure caused multiple dose, radiation shield 46 is for shielding the neutron of seepage and photon to reduce the normal tissue dose in non-irradiated district, air duct 48 is provided with 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, this beam-shaping body 50 comprises beam entrance 51, target 52, adjoin the slow body 53 with target 52, be enclosed in the reflector 54 outside slow body 53, the thermal neutron absorber 55 adjacent with slow body 53, be arranged on the radiation shield 56 in beam-shaping body 50 and beam outlet 57, target 52 and the proton beam generation nuclear reaction from beam entrance 51 incidence are to produce neutron, neutron forms neutron beam, neutron beam limits a major axis X 3, slow body 53 by the neutron degradation that produces from target 52 to epithermal neutron energy district, the neutron departing from major axis X 3 is led back to major axis X 3 to improve epithermal neutron intensity of beam by reflector 54, it is cone-shaped that slow body 53 is arranged to that two rightabouts adjoin each other, the left side of slow body 53 is bar shape, the right side of slow body 53 is diminish gradually towards right side cone-shaped, both adjoin each other, thermal neutron absorber 25 for absorb thermal neutron with avoid treatment time and shallow-layer normal structure caused multiple dose, radiation shield 26 is for shielding the neutron of seepage and photon to reduce the normal tissue dose in non-irradiated district.
As one preferably, target 52 in 5th embodiment, slow body 53, reflector 54, thermal neutron absorber 55 and radiation shield 56 can identical with the first embodiment, and radiation shield 56 wherein comprises the photon shielding 561 of being made up of plumbous (Pb) and the neutron shield 562 of being made up of polyethylene (PE), this neutron shield 562 can be arranged on beam and export 57 places.Air duct 58 is provided with between thermal neutron absorber 55 and beam outlet 57.Prosthese B3 is arranged on distance beam outlet 57 about 1cm places.
Adopt MCNP software to the analog computation of the cylinder+cone in the slow body of the cylinder in the slow body of bicone in the second embodiment, the 4th embodiment and the 5th embodiment below:
Wherein, as following table four shows the performance of beam quality factor in these three kinds of embodiments in air:
table four: beam quality factor in air
Wherein, as following table five shows the performance in dose form these three kinds of embodiments present:
table five: dosage shows
Wherein, as following table six shows the good and bad simulation value of parameter in these three kinds of embodiments of assessment neutron beam dosage performance:
table six: the parameter that the performance of assessment neutron beam dosage is good and bad
Note: can learn from above-mentioned three tables: slow body is arranged at least one is cone-shaped, the treatment benefit of its neutron beam is better.
" cylinder " or " bar shape " described in this utility model embodiment refers to the structure substantially constant to the overall trend of its outline of opposite side along the side of direction as shown, a wherein contour line of outline can be line segment, as the contour line of the correspondence of cylindrical shape, also can be the circular arc close to line segment that curvature is larger, the contour line of the correspondence of sphere body shape as larger in curvature, the whole surface of outline can be rounding off, also can be non-rounding off, as done a lot of projection and groove on the surface of cylindrical shape or the larger sphere body shape of curvature.
" cone " or " cone-shaped " described in this utility model embodiment refers to the structure diminished gradually along the side of direction as shown to the overall trend of its outline of opposite side, a wherein contour line of outline can be line segment, as the contour line of the correspondence of cone shape, also can be circular arc, as the contour line of the correspondence of sphere body shape, the whole surface of outline can be rounding off, also can be non-rounding off, as done a lot of projection and groove on the surface of cone shape or sphere body shape.
Penetrate in the flux of source an important improvement, be necessary that the material that slow body is discussed is made, hereafter for the first embodiment and accompanying drawing 3, slow body 13 be further described.
Slow body 13 presents antipodal pair of two cone directions cone structure, and the material of slow body 13 is by containing AlF
3or CaF
2or MgF
2in at least one material make, slow body 13 has the first diameter D1, Second bobbin diameter D2 and the 3rd diameter D3.First diameter D1 place is provided with opening to hold target 12, and Second bobbin diameter D2 is set to the full-size place of two cone structure.For BNCT, in order to reach enough slow effects, first diameter D1 length is 1cm-20cm, Second bobbin diameter D2 length is 30cm-100cm, 3rd diameter D3 length is 1cm-50cm, and as one preferably, the first diameter D1 length is 10cm, Second bobbin diameter D2 length is 70cm, and the 3rd diameter D3 length is 30cm.In order to obtain large-sized slow body 13 like this, and the density of its material is the 80%-100% of solid density, provides the preparation of following three kinds of slow body materials.
1. long brilliant
First with MgF
2for example, be please CN102925963A with further reference to utility application publication number, be introduced as the reference of long brilliant preparation at this in full.As long brilliant mode, usually will plant brilliant and contain MgF
2powder put into crucible, grow MgF by certain mode
2monocrystalline.
Need to give special heed to, so-called " monocrystalline " refers to single crystal of single growth molding here, and is not single crystal grain (namely only have a kind of crystal form and only contain a crystal grain, in this crystal grain, molecule, courtyard are all arrange regularly).Better understanding be that this single crystal grain is corresponding from multiple crystal grain (namely the size and shape of each crystal grain is different, and orientation is also in disorder, does not have obvious profile, does not also show anisotropy).Hereafter about the definition of " monocrystalline " with identical herein.
Through investigation, AlF
3, CaF
2, LiF, Li
2cO
3and Al
2o
3also can be prepared by similar mode.
2. powder sintered
By MgF
2or AlF
3or CaF
2powder or powder compact further combined with getting up, will there is the physical and chemical processes such as mutual flowing, diffusion, dissolving, recrystallize in powder particle in sintering process, makes powder fine and close further, eliminates part or all of hole wherein.Sintering processing can have a variety of, as solid-phase sintering, i.e. below the fusing point of sintering temperature each constituent element in body of powder; Liquid-phase sintering, if namely have two or more constituent elements in powder compact, sintering likely carries out more than the fusing point of certain constituent element, thus occurs a small amount of liquid phase in powder compact during sintering; Hot pressed sintering, namely when sintering, applies pressure to body of powder, and to promote its densification process, hot pressing is shaping powder and sinter bonded, directly obtains the technical process of goods; Discharge plasma sintering, namely the ON-OFF DC pulse voltage by being occurred by particular power source control device is added on powder body test portion, except the sintering facilitation (discharge impact pressure and Joule heating) caused except the machining that usually discharges can be utilized, the sintering facilitation caused by Spark Discharges (producing high-temperature plasma instantaneously) produced between pulsed discharge initial stage powder body is also effectively utilized to be realized the Fast Sintering technology of densification by TRANSIENT HIGH TEMPERATURE field.The material of slow body becomes block by powder sintering process by powder or powder compact through powder sintered equipment.
Well known to those skilled in the art, other sintering processing also can realize MgF
2or AlF
3or CaF
2in at least one or several mixture as the preparation of the material of slow body.As one preferably, hereafter 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 heated are integrated, programming rate is fast, sintering time is short, sintering temperature is low, crystal grain is even, be conducive to controlling the fine structure of sintered body, to obtain the density of material high, and have simple to operate, repeatability is high, safe and reliable, save space, save the energy and low cost and other advantages.Discharge plasma sintering is added between powder particle due to By Impulsive Current, the both positive and negative polarity of electric field induce is there is between powder particle, discharge between granule under pulse current effect, activated plasma, the intergranular contact portion of energetic particle hits produced by electric discharge, make material produce evaporation and play purification and activation, power storage in the dielectric layer of cluster of grains, the repid discharge of dielectric layer generation batch (-type).Owing to there is pulse current between powder or powder compact, and pulse current is moment, interrupted, altofrequency generation, at the heat discharge that the non-contact site of powder particle produces, and the Joule heat that powder particle contact site produces, all greatly facilitate the diffusion of powder particle atom, much bigger than under usual hot pressing condition of its diffusion coefficient, thus reach powder sintered rapid.Moreover, due to adding of pulse current, make electric discharge position in powder and joule heat position all can movement fast, enable the sintering homogenization of powder or powder compact.In discharge plasma sintering process, when discharging between granule, the instantaneous generation of meeting is up to the localized hyperthermia of several thousand degree to 10,000 degree, evaporation and fusing is caused at particle surface, cervical region is formed at grain contact point, be delivered to particle surface immediately from heating center due to heat and spread to surrounding, cervical region cools fast and makes vapour pressure lower than other positions.It is another important feature of discharge plasma sintering process that gaseous substance condenses upon that neck formation transmits higher than the evaporation-solidify of ordinary sinter method.Crystal grain is by the effect of Current Heating with vertical uniaxial pressure, and bulk diffusion, grain boundary decision is all strengthened, and accelerates sintering densification process, therefore can obtain high-quality sintered body with lower temperature and shorter time.Discharge plasma sintering process can be regarded as the result of granule electric discharge, conductive heater and pressurization comprehensive function.
Please refer to Fig. 9, there is disclosed a kind of schematic diagram of discharging plasma sintering equipment.Discharging plasma sintering equipment 100 comprises the first electrode 101, second electrode 102, be placed in the conductive die 103 between the first electrode 101 and the second electrode 102, the impulse current generator 104 of pulse current is provided to mould 103, with the pressing means 1051 for pressurizeing, the pressue device 105 of 1052 and the control device 106 for control impuls current feedback circuit 104 and pressue device 105, at least one in first electrode 101 and the second electrode 102 can move, pressing means 1051, at least one in 1052 can move, as one preferably, first electrode 101 and pressing means 1051 are fixed, second electrode 102 and pressing means 1052 can move, thus can add and be pressed on powder in mould 103 or powder compact 107.As one preferably, conductive die 103 is set to lead or graphite.Discharging plasma sintering equipment 100 comprises the displacement measurement system 108 of the displacement for measuring pressue device 105 further, for controlling the atmosphere control system 109 of atmosphere in described mould 103, for controlling the water-cooling system 111 that water-cooled vacuum room 110 cools, for measuring the temperature measuring equipment 112 of the temperature in discharging plasma sintering equipment 100.Mould 103 and powder or the logical upper pulse current of powder compact 107, except providing except discharge impact pressure and Joule heat sinter, the sintering facilitation caused by Spark Discharges (producing high-temperature plasma instantaneously) produced between pulsed discharge initial stage powder body is utilized to realize Fast Sintering by TRANSIENT HIGH TEMPERATURE field further, thus make powder or powder compact 107 become block from pulverulence, so-called bulk is formed in one, and do not need as long brilliant mode, be spliced into applicable slow body size by monocrystalline by operations such as polishing or polishings.
This discharging plasma sintering equipment 100 utilizes DC pulse current direct-electrifying to sinter and pressurization, controls heating rate and sintering temperature through control device 106 by the size of regulating impulse DC current.Whole sintering process can be carried out under vacuum conditions, also can carry out in protective atmosphere, as oxygen or hydrogen.
Under oxygen atmosphere, be sintered thing surface adsorption due to oxygen or chemical reaction effect occurs, plane of crystal is made to form the non-stoichiometric compound of cation omission type, cation room increases, make the oxygen in closed pore directly can enter lattice simultaneously, and equally with oxygen ion vacancy to spread along surface, diffusion and sintering accelerate.When sinter controlled by positive diffusions time, oxidizing atmosphere or partial pressure of oxygen higher and be conducive to cation room formed, acceleration of sintering; When spreading control by anion, reducing atmosphere or lower partial pressure of oxygen will cause oxygen ion vacancy to produce and acceleration of sintering.
In a hydrogen atmosphere during sintered sample, because hydrogen atom radius is very little, be easy to spread and be conducive to the elimination of closed pore, the material of the types such as aluminium oxide sinters the sintered body sample that can obtain close to solid density under hydrogen atmosphere.
Sintering temperature is one of crucial parameter in plasma Fast Sintering process.The determination of sintering temperature will consider the density requirements of sintered body sample phase in version at high temperature, the growth rate of crystal grain, the prescription of sample and sample.Generally, along with the rising of sintering temperature, sample density entirety is in rising trend, and this illustrates that sintering temperature has obvious impact to sample density degree, and sintering temperature is higher, and in sintering process, mass transfer speed is faster, and sample is more closely knit.
But temperature is higher, the growth rate of crystal grain is faster, and its mechanical property is poorer.And temperature is too low, the density of sample is just very low, can't meet the quality requirement.Contradiction between temperature and grain size requires a suitable parameter in the selection of temperature.
Extend the temperature retention time under sintering temperature, generally all can complete by acceleration of sintering to some extent, improve the microstructure of sample, this is comparatively obvious to the sintering of VISCOUS FLOW mechanism, and less on the sintering impact of bulk diffusion and surface diffusion mechanism.In sintering process, general insulation only 1 minute time, the density of sample just reaches more than 96.5% of solid density, along with the prolongation of temperature retention time, the density of sample increases, but excursion is not very large, although illustrate that the density of temperature retention time to sample has a certain impact, action effect is not clearly.But the temperature retention time extended unreasonably under sintering temperature, crystal grain is sharply grown up at this moment, and the effect of aggravation secondary recrystallization, be unfavorable for the performance requirement of sample, and time too short meeting causes the densification of sample to decline, and therefore needs to select suitable temperature retention time.
The quickening of time heating rate, make the temperature that sample reaches required in a short period of time, the growth time of crystal grain can greatly reduce, this is not only conducive to suppressing growing up of crystal grain, obtain fine grain of uniform size pottery, can also save time, energy savings and improve the utilization rate of agglomerating plant.But due to the restriction of equipment itself, heating rate is too fast can cause a devastating effect to equipment.Therefore quickening heating rate as much as possible in admissible scope.But, be reflected in the experimental data of actual measurement.Different from sintering temperature and temperature retention time, the impact of heating rate on sample density demonstrates contrary result, namely along with the increase of heating rate, sample density performance alligatoring downward trend gradually, have scholar to propose this is because the raising of heating rate is equivalent to shorten temperature retention time near sintering temperature, thus sample density can decline to some extent.In the high-temperature sintering process of reality, temperature-rise period is generally divided into three phases, to be respectively from about room temperature to 600 DEG C, 600 DEG C to about 900 DEG C, 900 DEG C to sintering temperature: the first stage is the preparatory stage, and heating rate is relatively slow; Second stage is controlled being rapidly heated the stage, and heating rate general control is 100 ~ 500 (DEG C/min); Phase III is the buffer stage heated up, and this phase temperature slowly rises to sintering temperature, and temperature retention time is generally 1 ~ 7 minute, and furnace cooling after insulation, cooldown rate can reach 300 DEG C/min.
Powder carries out compressing with sintering immediately after abundant discharge process.There is serious plastic deformation in sintered material, apply forming pressure and be conducive to strengthening contact between powder particle, increase sintering area, discharge residual gas between sintered powder, improve product intensity, density and surface smoothness thereof under the combined effect of resistance Joule heat and pressure.The size of forming pressure generally according to the compressibility of sintered powder with determine the requirement of the performance such as density of sintered material, intensity, generally within the scope of 15 ~ 30MPa, sometimes may up to 50MPa, even higher.Usually, forming pressure is larger, and the density of sintered material is higher.The pressurization persistent period also has a great impact density of sintered material, looks the physical dimension of the kind of sintered material, powder size and institute's sintered material and different suitable pressing time, needs to be determined by experiment.Experiment proves, the pressurization persistent period is equal to or slightly greater than discharge time, and this is the essential condition obtaining the most high-density sintered material.From sintering and solid state reaction mechanism easy understand, pressure is larger, and in sample, particle packing is tightr, and it is accelerated that mutual contact point and contact area increase sintering.Such sample that can make obtains better density, and can effective inhibiting grain growth and reduction sintering temperature.Therefore the pressure selected is generally 30 ~ 50Mpa.But there are some researches show, when when sintering, external pressure is 30Mpa and 50Mpa, the density difference of sample is also little, and this illustrates that density is only comparatively obvious within the specific limits with the phenomenon of pressure increase.
Discharge plasma sintering has following advantage compared to conventional sintering technique: sintering velocity is fast; Improve the performance of material microstructure and raising material.
Well known to those skilled in the art, mould can use other conductive material to make, and discharging plasma sintering equipment also can be arranged to two electrodes and all maintain static, and only has at least one pressing means to move.
The technical process of discharge plasma sintering is divided into four-stage.First stage: apply initial pressure to powder sample, make fully to contact between powder particle, can produce even and sufficient plasma discharging subsequently in powder sample; Second stage: apply pulse current, under the effect of pulse current, powder particle contact point produces plasma discharging, and particle surface is due to the micro-exothermic phenomenon of activation generation; Phase III: close the pulse power, carry out resistance heated to sample, until reaching predetermined sintering temperature and till sample shrinks completely; Fourth stage: release.The main technologic parameters such as conservative control initial pressure, sintering time, forming pressure, pressurization persistent period, sintering temperature, heating rate can obtain the good material of combination property.
Due to the arch bridge effect between powder particle, they generally can not fully contact, therefore, in order to make to produce in sample evenly and the plasma of fully electric discharge during electric spark sintering, farthest activated particle surface is to accelerate sintering densification process, need to apply suitable initial pressure to sintered powder, powder particle is fully contacted.The large I of initial pressure is different with sintered powder kind, sintered part size and performance.First pressing is too small, and electric discharge phenomena are confined in amount of powder, causes powder local melting; Pressure is excessive, will suppress electric discharge, and then delays to sinter diffusion process.According to existing document, for making discharge sustain carry out fully, this initial pressure is generally no more than 10MPa.
When powdered sample good with electric spark sintering electric conductivity, because resistance heated is carried out from the outside of sample and inside simultaneously, therefore sintering time is extremely short, or even moment, but sintering time length should look powder quality, kind and performance and different, is generally a few second to a few minutes; When sintering large-scale, refractory metal powder material, even reach dozens of minutes.Sintering time is comparatively large on product density impact, for making densification process fully be carried out, needs to guarantee certain sintering time.
It is generally acknowledged, it is very favourable for being rapidly heated in discharge plasma sintering process to the sintering of powder, because it suppress the non-densifying mechanism of material and have activated the densification Mechanism of material, therefore, improve heating rate, the densification degree of sample can be made to be improved.
As one preferably, discharge plasma sintering process comprises the steps: to fill mould 103 with appropriate powder or powder compact 107; Powder in mobile pressue device 105 pairs of moulds 103 or powder compact 107 pressurize; Open impulse current generator 104 to be conducted electricity by mould 103 thus to produce plasma by control device 106, powder particle surface is activated and is generated heat; Sintering in bulk.Discharge plasma sintering process comprises the steps: that control device 106 command displacement measuring system 108 is to guarantee that displacement measurement system 108 normally works further, control device 106 controlled atmospher control system 109 is to guarantee that atmosphere in mould 103 is when normal work, control device 106 controls water-cooling system 111 to guarantee that it is when normal work, and control device 106 control temperature measuring device 112 is to guarantee that temperature in discharging plasma sintering equipment 100 is when normal work.So-called normal work refers to discharging plasma sintering equipment and the alarm signals such as the vision of human perception, sense of touch or audition does not occur, and as alarm lamp lights, alarm lamp sounds, and instruction vibration etc. of reporting to the police is like this.
2.2 hot pressed sintering
Hot pressed sintering is filled in model by dry powder, then add flanging heating from limit, single shaft direction, makes molding and sinter a kind of sintering method simultaneously completed.Hot pressing and sintering technique production technology is very abundant, and classification is at present without unified standard and standard.Vacuum hotpressing, atmosphere hot pressing, vibrations hot pressing, balanced hot pressing, high temperature insostatic pressing (HIP), reaction hot-pressing and ultra-high pressure sintering can be divided into according to present situation.Hot pressed sintering pressurizes due to heating and carries out simultaneously, and powder is in hot plastic state, and contribute to the carrying out of the contact diffusion of granule, flowing mass transport process, thus briquetting pressure is only cold pressing 1/10; Can also sintering temperature be reduced, shorten sintering time, thus resist grain growth, obtain that crystal grain is tiny, density is high and mechanical, that electric property is good product.
Slow body material is prepared in order to adopt hot-pressing sintering technique, please refer to Figure 10, hot-press sintering equipment 200 mainly comprises heating furnace 201, the pressue device 202 be placed in heating furnace 201, mould 203, load powder in mould 203 or powder compact 204 and control device 205.Heating furnace 201 is usually using electricity as thermal source, and heating element heater is by SiC, MoSi or nickel reeling, platinum wire, molybdenum filament etc.Pressue device 202 requires that speed is mild, pressurize is constant, pressure flexible, generally has lever and fluid pressure type.According to the requirement of material character, pressure atmosphere can be air also can be reducing atmosphere or inert atmosphere.Mould 203 requires high strength, high temperature resistant, antioxidation and not cohering with hot-pressed material, and mould 203 thermal coefficient of expansion should be consistent with hot-pressed material or approximate, as one preferably, adopts graphite jig in the present embodiment.Control device 205 makes hot-press sintering equipment 200 when normal work.So-called normal work refers to discharging plasma sintering equipment and the alarm signals such as the vision of human perception, sense of touch or audition does not occur, and as alarm lamp lights, alarm lamp sounds, and instruction vibration etc. of reporting to the police is like this.
With MgF
2adopting hot-pressing sintering technique to prepare the slow body of target is example, and its technological process of production roughly comprises the steps, MgF
2it is prepared by raw material that---------------cooling is come out of the stove, and---high temperature insostatic pressing (HIP) high temperature sintering---cools---grinding, polishing, bonding---finished product of coming out of the stove to high temperature hot pressing sintering to high temperature sintering to proceed to mould for raw mill, screening process.
As one preferably, at the treatment step that this omission powder processing step of preorder and the sintering of postorder complete.Hot-pressing sintering technique comprises the steps: to fill mould 203 with appropriate powder or powder compact 204; Open hot pressing furnace 201 with preset pressure and temperature parameter; Powder in mobile pressue device 202 pairs of moulds 203 or powder compact 204 pressurize; Control device 205 controls hot-press sintering equipment 200 when normal work; Energising is to sinter in bulk.
What needs further illustrated is, step " powder in mobile pressue device 202 pairs of moulds 203 or powder compact 204 pressurize " in hot-pressing sintering technique can as precharge, also synchronously can carry out with energising, " be energized to sinter in bulk " by step " powder in mobile pressue device 202 pairs of moulds 203 or powder compact 204 pressurize " and step and unite two into one.
Some parameters listing long crystalline substance, discharge plasma sintering and hot pressed sintering in following table compare, as the material of the slow body application in the beam-shaping body of the neutron capture treatment disclosed in a kind of this utility model of being more convenient for, especially need to manufacture Second bobbin diameter D2 is maximum reach the precondition of the size of 100cm under, here suggestion uses the powder sintered slow body material made, and concrete detailed description in detail please see below.
table seven: the comparison of long crystalline substance and powder sintering process
Though only list MgF in upper table
2, AlF
3and CaF
2these three kinds slow body materials adopt the parameter of as above technique to compare, but well known to those skilled in the art, other three kinds slow body material LiF, Li
2cO
3and Al
2o
3also contrast can be made easily.
Can learn from upper table, although the density adopting long brilliant mode to prepare slow body material can reach close to solid density, as reached 99.99% of solid density, but because monocrystalline size is less, want to reach the large-sized slow body material require of target to be spliced by a lot of monocrystalline, also may need in process to carry out other operations such as mirror finish to it, not only consuming time very long, and cost and technology difficulty all very large.
The density adopting powder sintered mode to prepare slow body material also can reach the 80%-100% of solid density.As one preferably, the density of slow body material reaches 99.99% of solid density.Substantially indiscriminate compared with the solid density of the slow body material that solid density and long crystal type obtain while, it is all with the obvious advantage in the size obtained, time, cost and technology difficulty.Slow its actual size of body material adopting discharge plasma sintering to prepare obtains as required, a kind of mode can customize out the mould being applicable to needs, another kind of mode adopts common die, as the mould of diameter 70cm* thickness 2cm, then carry out splicing by several just can complete, in cost and technology difficulty all with under vacuum heating-press sintering and the equal prerequisite of HIP sintering, its manufacturing time only needs the time of about 1 month.
The beam-shaping body for neutron capture treatment that this utility model discloses is not limited to the content described in above embodiment and the structure represented by accompanying drawing.The change apparently that basis of the present utility model is made the material of wherein component, shape and position, to substitute or amendment, all within the scope that this utility model is claimed.
Claims (10)
1. the beam-shaping body for neutron capture treatment, it is characterized in that: described beam-shaping body comprises beam entrance, target, be adjacent to the slow body of described target, be enclosed in described reflector external slowly, the thermal neutron absorber adjacent with described slow body, be arranged on the radiation shield in described beam-shaping body and beam outlet, described target and the proton beam generation nuclear reaction from the incidence of described beam entrance are to produce neutron, described neutron forms neutron beam, described neutron beam limits a main shaft, described slow body by the neutron degradation that produces from described target to epithermal neutron energy district, the material of described slow body is by containing LiF, Li
2cO
3, Al
2o
3, AlF
3, CaF
2or MgF
2in at least one material make, the material of wherein said slow body becomes block by powder sintering process by powder or powder compact through powder sintered equipment, the neutron departing from described main shaft is led back to described main shaft to improve epithermal neutron intensity of beam by described reflector, when described thermal neutron absorber is for absorbing thermal neutron to avoid treatment and shallow-layer normal structure caused multiple dose, described radiation shield is for shielding the neutron of seepage and photon to reduce the normal tissue dose in non-irradiated district.
2. the beam-shaping body for neutron capture treatment according to claim 1, it is characterized in that: described beam-shaping body is further used for the treatment of accelerator boron neutron capture, proton beam is accelerated by accelerator by the treatment of accelerator boron neutron capture, described target is made of metal, described proton beam accelerates to the energy being enough to overcome target atom core coulomb repulsion, with described target generation nuclear reaction to produce neutron, described beam-shaping physical ability by neutron slowly to epithermal neutron energy district, and reduce thermal neutron and fast neutron content, described epithermal neutron energy district is between 0.5eV to 40keV, describedly hanker subzone and be less than 0.5eV, described fast-neutron range is greater than 40keV, described reflector is made up of the material having neutron reflection ability strong, described thermal neutron absorber is made up of the material large with thermal neutron action section.
3. according to claim 2 for neutron capture treatment beam-shaping body, it is characterized in that: described reflector is made up of at least one in Pb or Ni, described thermal neutron absorber by
6li makes, and is provided with air duct between described thermal neutron absorber and the outlet of described beam, and described radiation shield comprises the photon shielding of being made up of Pb and the neutron shield of being made up of PE.
4. the beam-shaping body for neutron capture treatment according to claim 1, is characterized in that: it is cone-shaped that described slow body is arranged to that two rightabouts adjoin each other.
5. the beam-shaping body for neutron capture treatment according to claim 4, it is characterized in that: describedly cone-shapedly comprise the first diameter, Second bobbin diameter and the 3rd diameter, described first diameter length is 1cm-20cm, described Second bobbin diameter length is 30cm-100cm, described 3rd diameter length is 1cm-50cm, and the density of the material of described slow body is the 80%-100% of solid density.
6. the beam-shaping body for neutron capture treatment according to claim 1, is characterized in that: arrange clearance channel between described slow body and described reflector to improve epithermal neutron flux.
7. the beam-shaping body for neutron capture treatment according to claim 1, is characterized in that: described powder sintered equipment is hot-press sintering equipment or discharging plasma sintering equipment.
8. the beam-shaping body for neutron capture treatment according to claim 7, is characterized in that: described hot-press sintering equipment comprises heating furnace, powder in the pressue device be placed in described heating furnace, mould, the described mould of loading or powder compact and for controlling the control device that described hot-press sintering equipment normally works.
9. the beam-shaping body for neutron capture treatment according to claim 7, it is characterized in that: described discharging plasma sintering equipment comprises the first electrode, second electrode, be placed in the conductive die between described first electrode and described second electrode, the impulse current generator of pulse current is provided to described mould, with the pressue device of the pressing means for pressurizeing and the control device for controlling described pulse current transmitter and described pressue device, at least one in described first electrode and the second electrode can move, described first electrode and at least one in the second electrode are connected with described pressue device thus can add the powder be pressed in described mould.
10. the beam-shaping body for neutron capture treatment according to claim 9, it is characterized in that: described discharging plasma sintering equipment comprises the displacement measurement system of the displacement for measuring pressue device further, for controlling the atmosphere control system of atmosphere in described mould, for the water-cooling system cooled, for measuring the temperature measuring equipment of the temperature in described discharging plasma sintering equipment.
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520281118.6U CN204798657U (en) | 2015-05-04 | 2015-05-04 | A beam plastic body for treatment is caught to neutron |
| EP19184558.5A EP3570294B1 (en) | 2015-05-04 | 2016-04-18 | Beam shaping body 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 |
| JP2017557373A JP6843766B2 (en) | 2015-05-04 | 2016-04-18 | Beam shaping assembly for neutron capture therapy |
| 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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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016177270A1 (en) * | 2015-05-04 | 2016-11-10 | 南京中硼联康医疗科技有限公司 | Beam shaping body for neutron capture therapy |
| CN106310540A (en) * | 2015-05-04 | 2017-01-11 | 南京中硼联康医疗科技有限公司 | Beam shaping body for neutron capture therapy |
| CN106798969A (en) * | 2015-11-26 | 2017-06-06 | 南京中硼联康医疗科技有限公司 | For the beam-shaping body of neutron capture treatment |
| CN106938124A (en) * | 2016-01-04 | 2017-07-11 | 南京中硼联康医疗科技有限公司 | The slow material of neutron |
| CN106980136A (en) * | 2016-01-15 | 2017-07-25 | 南京中硼联康医疗科技有限公司 | Radiation detecting system and radiation line detecting method for neutron capture treatment system |
| CN107240430A (en) * | 2016-03-28 | 2017-10-10 | 南京中硼联康医疗科技有限公司 | Screening arrangement for beam-shaping body |
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