EP3682454A1 - Method for obtaining a solid target for radiopharmaceuticals production - Google Patents
Method for obtaining a solid target for radiopharmaceuticals productionInfo
- Publication number
- EP3682454A1 EP3682454A1 EP18780233.5A EP18780233A EP3682454A1 EP 3682454 A1 EP3682454 A1 EP 3682454A1 EP 18780233 A EP18780233 A EP 18780233A EP 3682454 A1 EP3682454 A1 EP 3682454A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- supporting element
- isotope
- target
- precursor
- cyclotron
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 69
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 53
- 239000007787 solid Substances 0.000 title claims abstract description 10
- 229940121896 radiopharmaceutical Drugs 0.000 title description 10
- 239000012217 radiopharmaceutical Substances 0.000 title description 10
- 230000002799 radiopharmaceutical effect Effects 0.000 title description 9
- 230000008093 supporting effect Effects 0.000 claims abstract description 114
- 239000002243 precursor Substances 0.000 claims abstract description 65
- 239000000463 material Substances 0.000 claims abstract description 29
- 230000002285 radioactive effect Effects 0.000 claims abstract description 26
- 238000004090 dissolution Methods 0.000 claims abstract description 25
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- 239000010949 copper Substances 0.000 claims description 16
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 14
- 229910052802 copper Inorganic materials 0.000 claims description 14
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 14
- 238000005219 brazing Methods 0.000 claims description 12
- 229910003460 diamond Inorganic materials 0.000 claims description 10
- 239000010432 diamond Substances 0.000 claims description 10
- 230000008569 process Effects 0.000 claims description 10
- 229910052594 sapphire Inorganic materials 0.000 claims description 10
- 239000010980 sapphire Substances 0.000 claims description 10
- 238000004544 sputter deposition Methods 0.000 claims description 10
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 9
- 230000008878 coupling Effects 0.000 claims description 7
- 238000010168 coupling process Methods 0.000 claims description 7
- 238000005859 coupling reaction Methods 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 7
- 239000010453 quartz Substances 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 239000004411 aluminium Substances 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 3
- 238000007747 plating Methods 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 3
- 229920000544 Gore-Tex Polymers 0.000 claims description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 2
- 150000001722 carbon compounds Chemical class 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims description 2
- 239000003989 dielectric material Substances 0.000 claims description 2
- 239000011521 glass Substances 0.000 claims description 2
- 229910021397 glassy carbon Inorganic materials 0.000 claims description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 239000010931 gold Substances 0.000 claims description 2
- 229910021389 graphene Inorganic materials 0.000 claims description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 2
- 239000000395 magnesium oxide Substances 0.000 claims description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 2
- 239000007769 metal material Substances 0.000 claims description 2
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 claims description 2
- 238000005546 reactive sputtering Methods 0.000 claims description 2
- 229910052710 silicon Inorganic materials 0.000 claims description 2
- 239000010703 silicon Substances 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims 1
- 229920000642 polymer Polymers 0.000 claims 1
- 239000000843 powder Substances 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 10
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- 238000012360 testing method Methods 0.000 description 9
- 238000004070 electrodeposition Methods 0.000 description 8
- 238000013459 approach Methods 0.000 description 7
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- 230000017525 heat dissipation Effects 0.000 description 6
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- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
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- 238000003825 pressing Methods 0.000 description 4
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- 229910052713 technetium Inorganic materials 0.000 description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000013590 bulk material Substances 0.000 description 3
- 238000001465 metallisation Methods 0.000 description 3
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- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000002739 metals Chemical group 0.000 description 2
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- 230000004048 modification Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000005240 physical vapour deposition Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000000047 product Substances 0.000 description 2
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- 238000005096 rolling process Methods 0.000 description 2
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- 230000001225 therapeutic effect Effects 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical group [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000004696 Poly ether ether ketone Substances 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- JUPQTSLXMOCDHR-UHFFFAOYSA-N benzene-1,4-diol;bis(4-fluorophenyl)methanone Chemical compound OC1=CC=C(O)C=C1.C1=CC(F)=CC=C1C(=O)C1=CC=C(F)C=C1 JUPQTSLXMOCDHR-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
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- 239000000356 contaminant Substances 0.000 description 1
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- 238000001816 cooling Methods 0.000 description 1
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- 238000001962 electrophoresis Methods 0.000 description 1
- 238000001652 electrophoretic deposition Methods 0.000 description 1
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- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000009206 nuclear medicine Methods 0.000 description 1
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- 230000001737 promoting effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
- G21G1/00—Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation or particle bombardment, e.g. producing radioactive isotopes
- G21G1/04—Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation or particle bombardment, e.g. producing radioactive isotopes outside nuclear reactors or particle accelerators
- G21G1/10—Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation or particle bombardment, e.g. producing radioactive isotopes outside nuclear reactors or particle accelerators by bombardment with electrically charged particles
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H6/00—Targets for producing nuclear reactions
Definitions
- the present invention relates to the field of radionuclides production and, in particular, to a method for obtaining a target or solid state target, for use in the production of radiopharmaceuticals for diagnostic and therapeutic purposes, through use of a particle accelerator, more particularly a cyclotron.
- the present invention also relates to a system for production of said radionuclides.
- Nuclear Medicine is a branch of medicine that uses radiopharmaceuticals both for diagnostic and therapeutic purposes.
- 99m Tc 99m Tc is an extremely important radioactive isotope, used in almost all types of traditional diagnostic exams.
- 99m Tc is currently extracted from portable generators containing the precursor radioactive isotope "Mo coming from fission reactors, which use highly enriched 235 U. As of today, 95% of 99 Mo is produced by five plants which are over 50 year old and, since the stable supply of "Mo cannot be guaranteed in the future, alternative routes for the production of 99m Tc based on particle accelerators (cyclotrons) were developed.
- the reaction 100 Mo(p,2n) 99m Tc is considered to be the most favourable for the direct production of 99m Tc by means of a cyclotron, starting from the precursor isotope 100 Mo, and it was found that, in order to obtain the maximum production of 99m Tc with minimal impurities by means of small medical cyclotrons (e.g., GE PETtrace supporting a standard current of about 100 ⁇ ), it is necessary to impart the protons in the cyclotron, intended to hit a target formed by a layer of enriched 100 Mo and having a thickness of the order of about 100 ⁇ , applied to a corresponding supporting element (in technical jargon also backing), an energy optionally comprised between about 10 MeV and about 22 MeV.
- small medical cyclotrons e.g., GE PETtrace supporting a standard current of about 100 ⁇
- an energy optionally comprised between about 10 MeV and about 22 MeV.
- the radiopharmaceutical production requires that the targets to be used in combination with a cyclotron meet two fundamental requirements: they must guarantee a high level of heat dissipation, so as to be able to apply the maximum current that can be delivered by the cyclotron, during the irradiation of the target, and obtain the maximum production yield; and they must also ensure a high inertia of the supporting element in (standard) conditions of the target dissolution, to guarantee the chemical and radiochemical purity of the final product.
- metal Mo targets are considered the most suitable for the purpose, since the metal Mo target provide high production yields of 99m Tc.
- one target can be manufactures by means of a preparation step of a coin or pellet of precursor isotope of Mo, followed by a subsequent step of adhesion to a supporting element.
- the precursor isotope of Mo is directly deposited on a supporting element.
- 100 Mo is commercially available in the form of metal powder, therefore different research groups have proposed the transformation of the powder of 100 Mo in a dense and not porous pellet or sheets - using different methods, including pressing, sintering and lamination - to be applied to a respective supporting element.
- targets of Mo were made which support currents of the order of hundreds of ⁇ and standard procedures are considered rolling, starting from dust or beads of Mo, produced by melting the powder through e-beam [1, 2, 11], or recasting of the Mo powders followed by remodelling through rolling.
- the targets produced according to the first approach have shown, however, not to be fully satisfactory. In fact, they showed to be adequate for manufacturing, since it is very difficult to provide a good thermal contact between the pellets or sheets of Mo and the supporting element, during irradiation by the cyclotron.
- the electrodeposition process from aqueous solution is very inefficient. In fact, only a percentage quantity of Mo below 2% remains deposited onto the support material, due to the high affinity of Mo with the oxygen of the aqueous solution. Moreover, it has been reported [15] that the co-deposition of molybdenum with zinc is much more efficient.
- the electrodeposition in ionic liquids or molten salts [2, 16, 17] provides for a better quality of the layer of Mo, but requires expensive equipment and more difficult protocols.
- Mo films were obtained having a sufficient thickness, resistant to a current of 300 ⁇ , at conditions of target inclined, at power density reduced with respect to an orthogonal target and same intensity of current delivered [1, 18].
- the actual targets support up to 500 ⁇ .
- PVD methods of direct deposition of Mo have also been considered, which include a thermal spray (Thermal spray) [19], cathodic arc [2], argon [20] and xenon [21]sputtering FIB.
- the process of standard production of 99m Tc with the reaction 100 Mo(p, 2n) 99m Tc provides, as mentioned above, for the irradiation by a cyclotron of a target comprising enriched 100 Mo and, after such irradiation, a standard step of dissolution of Mo and of the mixture of Tc in H2O2 at a high temperature, optionally comprised between 60°C and 90°C.
- a standard step of dissolution of Mo and of the mixture of Tc in H2O2 at a high temperature optionally comprised between 60°C and 90°C.
- the transition, post transition and refractory metals used up to now as support materials are not perfectly chemically inert under these conditions, even very small amounts of impurities in the mixture of Mo, Tc, H2O2 can compromise the production of the radiopharmaceutical.
- the main object of the present invention is to improve the state of the art in the field of production, through small sized particle accelerators (for example GE PETtrace), of radionuclides in general and 99m Tc, in particular.
- small sized particle accelerators for example GE PETtrace
- Another object of the present invention is to provide for a method for obtaining a target, which target can be used in the production of a radionuclide, allowing obtaining a high thickness and a high uniformity of the precursor isotope coupled to the respective supporting element, with respect to the traditional targets.
- a further object of the present invention is to provide for a method for obtaining a target, which target can be used in the production of a radionuclide, allowing obtaining low oxidation levels and a high adhesion of the precursor isotope coupled to the respective supporting element, with respect to the traditional targets.
- a further object of the present invention is to provide for a method for obtaining a target, which target can be used in the production of a radionuclide, allowing reducing impurities generated in the production process, with respect to the traditional targets.
- a still further object of the present invention is to provide for a system for the production of a radiopharmaceutical, allowing optimizing the radiopharmaceutical production, with respect to the traditional systems.
- Figure 1 shows a ta rget which can be obtained by means of a preferred embodiment of the method of the present invention
- Figure 2 shows the main steps of the preferred embodiment of the method for obtaining the target of Figure 1;
- Figure 3 shows process parameters relating to a step of the method of Figure 2;
- Figure 4 illustrates the main elements of a system for dissolving the target of Figure 1
- Figure 5 is a scaled-up representation with parts in cross-section and in transparency, of some elements of the dissolution system of Figure 4;
- Figures 6a and 6b show some images relating to results of experimental tests conducted on a target obtained according to the method of the present invention.
- radioactive isotope 99m Tc the teachings of the present invention can be used for the production of other radioactive isotopes of medical interest, among which, purely by way of example, 68 Zn for the production of 64,67 Cu, radioactive isotopes 68 Ga, 89 Y or na Y for the production of 89 Zr, 52 Cr for the production of 52 Mn, nat Ti for the production of 48 V, the nat ⁇ 63 Cu for the production of 62,63 Zn, etc. are mentioned.
- a method for obtaining a solid target (represented in Figure 1 with reference numeral 1) for the production of at least one radionuclide by cyclotron is indicated with reference numeral 100 a nd comprises at least one first step (step 110) of providing at least one first supporting element 2, having at least one first surface 21, intended to support in use at least one precursor isotope 3, and at least one second surface 22 opposite to the first surface 21; and at least one second step (step 120) of application of said at least one precursor isotope 3 on the first surface 21.
- the first supporting element 2 typically has a substantially flat configuration, for example circular or elliptical or rectangular in plan, with opposite surfaces 21 and 22 theirbetween, and can be obtained in bulk material, or in the form of layer, applicable, as will be explained hereinafter, to one second supporting element 4.
- the first supporting element 2 is advantageously made of a chemically inert material (dielectric) under the conditions of dissolution of the precursor isotope 3 applied thereto and of the radioactive isotope produced after the irradiation by the cyclotron, in a deprived or not oxygen atmosphere), more in particular it is a material that is chemically inert with respect to a dissolution mixture with which it is intended to come into contact for further chemical separation between precursor isotope a nd radioactive isotope obtained, following the irradiation by the cyclotron.
- a chemically inert material dielectric
- the chemically inert material (dielectric) at the conditions of dissolution which makes up the first supporting element 2
- the chemically inert material (dielectric) at the conditions of dissolution comprises a material chosen among sapphire, synthetic diamond, quartz, glass, silicon, carbon compounds, glassy carbon, silicon oxide, aluminium oxide, magnesium oxide, zirconium oxide, advanced ceramics, or DLC (Diamond-like carbon or synthetic diamond), graphene, polymeric materials and the like or combinations thereof.
- the first supporting element 2 can also be made of copper or copper and diamond or copper electrodeposited on a goretex net, with the first surface 21, intended to support at least one precursor isotope 3, gold covered by sputtering or galvanic plating.
- step 120 of the method according to the present invention of application of at least one precursor isotope 3 on the first surface 21 of the first supporting element 2, it comprises at least one step of magnetron sputtering of said at least one precursor isotope 3 on the first surface 21, allowing to obtain one film of precursor isotope 3 having a high density level.
- the method of the present invention comprises one step 125 of setting the process parameters for said step 120, so that, in said deposition step, the total stress of the system, composed by the first supporting element 2 and the film by precursor isotope 3, is minimized.
- the total stress of the system is given by the residual stress (intrinsic) of the film of precursor isotope 3 applied to the first supporting element 2, and by the stress associated with the thermal discrepancy (in technical jargon also thermal mismatch or Omismatch) between the film of isotope precursor 3 and the first supporting element 2.
- magnetron sputtering technique is particularly advantageous in the present invention, because it can be used for direct deposition of isotopes on fragile - i.e. inclined to break, if subjected to an external force, with no deformation or stretching occurring beforehand - first supporting elements, i.e. the dielectric, ceramic, non-metallic materials mentioned above, including: DLC, quartz, sapphire, etc.
- the intrinsic stress (ointnnsic) in the deposited films depends, as is known, by the energy supplied to the surface of the precursor isotope 3 film, increasing thickness during the deposition.
- the variables significantly involved in the change of energy and, therefore, in the mechanism for the growth of the thickness of said film, are the sputtering gas, the temperature of the sample stage, the bias (i.e. a potential applied to sample holder), etc. Theoretically there is one sputtering gas pressure marking the passage from the traction to the compression stress.
- the frequency of collisions between the atoms of the gaseous phase increases, reducing the kinetic energy of the sputtered atoms and of reflected neutral atoms bombarding the film of precursor isotope 3 during its thickness growth, thereby providing a porous microstructure; the interatomic attraction forces between the edges of the grain, therefore produce a traction stress.
- the atoms of the precursor isotope 3 that are deposited on the first supporting element 2 have a high kinetic energy and the resulting film of precursor isotope 3 has a dense microstructure, promoting compression stress.
- the temperature of the substrate influences, moreover, the kinetic energy of the particles of precursor isotope 3 already deposited on the first supporting element 2.
- a low temperature which depends on the material, the pressure and that, according to the Structure Zone Model is given by Th ⁇ 0.2 with (in Kelvin) where Tdepos is the temperature of the substrate (sample carrier) during the process and T me it is the melting temperature of the material to be deposited, promotes, in fact, a microstructure of columnar type with microscopic voids, associated with a traction stress.
- a high temperature which always depends on the material and the pressure and that, according to the Structure Zone Model is given by Th>0.3, corresponds to an increase in the mobility of the atoms of the precursor isotope 3, which leads to a structure of type bulk and a negligible "thermally induced" stress.
- the step 120 of applying the precursor isotope 3 on said first supporting element 2 comprises a multilayer deposition of said at least one precursor isotope 3, and between a deposition step and the next at least one relaxation time period is optionally provided for, optionally comprised between a few milliseconds to a few hours, during which the layer of precursor isotope 3 applied to the first supporting element 2 is hardening.
- the stress due to thermal mismatch (omismatch) between precursor isotope 3 and first supporting element 2 it is detected, in general, in structures having very different coefficients of thermal expansion, subject to a uniform change of temperature.
- a film of precursor isotope 3 is deposited on one first supporting element, usually at high temperature, i.e. Th > 0.3 as defined above and, in the case of Mo, higher than 500°C, and is subsequently cooled and brought to room temperature, the difference between the coefficients of thermal expansion between the film of precursor isotope 3 and the first supporting element 2 determines the generation of a stress. If the coefficient of thermal expansion of the film of precursor isotope 3 is smaller than that of the first supporting element 2, a compressive stress will result or, vice versa, a traction stress.
- the process parameters set at step 125 of the method according to the present invention, for the application, by magnetron sputtering, of a layer of 100 Mo having a thickness of about 110 ⁇ on a substrate of sapphire (0 13 mm x 0.5 mm, quality IR, with optical finish) and wherein the total stress of the system is minimized, are reported below.
- the film of 100 Mo was deposited by DC magnetron sputtering with a source of planar cathode (2 inches). The deposition was performed on a planar sample holder, heated to 500°C, 6 cm away from the cathode.
- the optimized sputtering parameters are shown in Table 1 ( Figure 3 attached). Experimental tests have demonstrated that the film of Mo deposited with this technique of magnetron sputtering, under conditions shown in Table 1, advantageously possesses the same density of the bulk material, good adhesion to the substrate, greater than 98% of bulk density, and no signs of oxidation.
- the method for obtaining a solid target, usable in the production of at least one radionuclide, according to the present invention may also comprise a further step (step 130) of coupling between said at least one first supporting element 2 and at least one second supporting element 4, at the second surface 22 of the first supporting element 2, said at least one second supporting element 4 comprising at least one material having a high thermal conductivity and mechanical stability, even chemically not inert at the conditions of dissolution of the precursor isotope 3 and of the radioactive isotope produced as a result of irradiation, by a cyclotron.
- Such a second supporting element 4 can be made of a material selected between copper, silver, aluminium and/or their compounds.
- the coupling between the first and second supporting element (2, 4) allows compensating, in part, the low thermal conductivity, for example less than 50W/(mK), of the first supporting element 2 made of dielectric material and obtaining, therefore, for target 1 thereby manufactured, higher levels of heat dissipation during the irradiation of the same, by the cyclotron.
- the thermal conductivity of the sapphire is approximately equal to 40W/(mK) and that of quartz is equal to about 8W/(mk).
- the second supporting element 4 has a flat shape, and delimits a seat 41, suitably configured and provided for coupling with the second surface 22 of the first supporting element.
- the second supporting element 4 may have any configuration, provided it is suitable for insertion in a respective housing seat of the cyclotron used for the production of the radionuclide.
- this step 130 of coupling between the first supporting element 2 and the second supporting element 4 comprises at least one step of vacuum brazing between the first supporting element 2 and at least the second supporting element 4.
- This vacuum brazing step is particularly advantageous for the present invention since it allows obtaining a high thermal and mechanical stability between the first and the second supporting element.
- the brazing step 130 may occur, alternatively, in an inert atmosphere and this helps to prevent oxidation of the metal part and the brazing material used and, therefore, it guarantees a better thermal contact between the two supporting elements 2 and 4.
- the brazing material selected for use in step 130 of the method according to the present invention, will be different depending on the materials of which the first and the second supporting element are made and will be selected in such a way as to reduce to the minimum the stress due to thermal mismatch ( Omismatch) gen erated during the brazing process.
- step 130 of coupling, between the first supporting element 2 and the second supporting element 4 comprises the direct deposition of the first supporting element 2 on at least the second supporting element 4 and in particular, the direct deposition of any one of the materials mentioned above for the first supporting element 2 (among which, DLC, aluminium oxide, zirconium oxide, silicon oxide, etc.) on the second supporting element 4 having a high conductivity, by means of appropriate methods such as CVD, PECVD, reactive sputtering.
- the method according to the present invention further comprises a metallization step (step 115) of at least one second surface 22 of the first supporting element 2, before the coupling step between the second surface and the second supporting element 4 and, optionally, before step 120 of deposition of the film of precursor isotope 3 on the supporting element.
- the metallization is carried out according to known metallization techniques, for example through chemical, electrochemical deposition, PVD deposition, mechanical deposition, etc., using appropriate metals, such as Ti or Ni.
- a target for the production of 99m Tc starting from the precursor isotope of 100 Mo, a target comprising both the first supporting element 2 and the second supporting element 4, coupled by means of vacuum brazing was obtained and composed as follows:
- the first supporting element is made of sapphire (0 13 mm x 0.5 mm, quality IR, optical finish) or synthetic diamond (0 13.5 mm x 0.4 mm, with thermal conductivity 1500W/(mK);
- the second supporting element is made of copper (0 32 mm x 1 mm) having high thermal conductivity
- the brazing material used is a paste of Cu-Ag-Ti, obtained by mixing the powder of the corresponding elements with a binder, the Coccoina i.e. a glue of partially hydrolysed potato starch, and water.
- the percentages of the various components of the brazing material can be the following: metal powder 82%, Coccoina, 7.3% and water 10.7% by weight, with the metal powder thus composed: Cu 35.3 % - Ag 63 % - Ti 1.7 % by weight;
- the second surface 22 of the first supporting element 2 in sapphire or synthetic diamond, destined to come into contact with the second supporting element 4, has previously been metallised with a layer of approximately 1 ⁇ of Ti, deposited by magnetron sputtering.
- the brazing process was carried out in vacuum, at 950°C, maintaining a heating rate of 3°C/min and cooling rate of 2°C/min, to minimize thermomechanical stress in the final target.
- the above described method allows to obtain one target that achieves the objects mentioned above, since it allows a high heat dissipation during the irradiation step, has a high thickness and high uniformity of the precursor isotope 3 coupled to the respective supporting element by magnetron sputtering, low levels of oxidation and a high adhesion of the precursor isotope coupled to the respective first supporting element.
- Such a dissolution system is indicated in the figures by reference 200 and comprises: - at least one target 1, obtained as described above, and
- At least one vial 210 intended to come into contact with the target 1 and defining with it at least one containment cavity 220, for at least one dissolution solution of the precursor isotope 3 and of the produced radioactive isotope, included in the target 1, as a result of irradiation by cyclotron.
- the vial 210 for example made of PEEK, and the target 1 are mutually configured in such a way that the containment cavity 220 remains, in use, delimited between the vial 210 and the first supporting element 2 of the target 1, which is chemically inert under the conditions of dissolution of the precursor isotope 3 and the radioactive isotope produced as a result of irradiation, so that a dissolving solution for that precursor isotope 3 and for its products never comes into contact with the second supporting element 4, during the dissolution step of the target.
- the standard dissolution procedure of the target after irradiation provides for the dissolution of the isotope 100 Mo and the radioactive isotope produced 99m Tc, in a solution of concentrated H2O2, for further chemical separation.
- the second supporting element 4 for example made of copper, would release chemical contamination which would compromise the effectiveness of the method of production of the radioactive isotope 99m Tc.
- the target 1 showed an excellent mechanical stability during the irradiation up to 60 ⁇ current.
- the dissolution of the irradiated material was carried out in a vial in 1 ml of H2O2 at 30% by weight, 70°C and 10 ⁇ of this solution was analysed with a gamma spectrometer of the Research Laboratory of the Department of Medical Physics of the Sant'Orsola Hospital of Bologna.
- the chemical inertia, in particular, of the sapphire and synthetic diamond was proven because no contaminant was present in the solution, and especially the effectiveness of the solid target obtained according to the method of the present invention.
Abstract
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IT102017000102990A IT201700102990A1 (en) | 2017-09-14 | 2017-09-14 | METHOD FOR OBTAINING A SOLID TARGET FOR THE PRODUCTION OF RADIOPHARMACEUTICALS |
PCT/IB2018/056826 WO2019053570A1 (en) | 2017-09-14 | 2018-09-07 | Method for obtaining a solid target for radiopharmaceuticals production |
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IT202200002333A1 (en) * | 2022-02-09 | 2023-08-09 | Comecer Spa | CONTAINER FOR AN ELECTRODEPOSITED SOLID TARGET MATERIAL FOR THE PRODUCTION OF A RADIOISOTOPE |
WO2023183281A1 (en) * | 2022-03-21 | 2023-09-28 | Potentalpha Nükleer Tip Biyoteknoloji Klinik Araştirma Ve Danişmanlik Limited Şirket | Method and apparatus for production of actinium 225 isotope |
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US8257681B2 (en) * | 2008-12-26 | 2012-09-04 | Clear Vascular Inc. | Compositions of high specific activity SN-117M and methods of preparing the same |
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