Solid target system for simultaneously producing Ge-68 nuclides and PET nuclides under high-power beam

Abstract

The invention provides a solid target system for simultaneously producing Ge-68 and PET nuclides under a high-power beam, and the system comprises an intermediate-energy cyclotron which is used for transmitting an intermediate-energy high-intensity proton beam; the cascade target is arranged beside the intermediate-energy cyclotron and comprises a shell, and a first aluminum target body, a second aluminum target body, a Ga4Ni alloy capsule target and a metal sealing target which are sequentially arranged along the emission direction of the intermediate-energy high-current proton beam, and the shell is filled with cooling water; the target film is erected between the intermediate energy cyclotron and the first aluminum target body; the helium cooling unit is erected between the target film and the first aluminum target body; and the control unit is used for controlling to start the helium cooling unit and the medium-energy cyclotron, so that the medium-energy high-intensity proton beam sequentially passes through the target film, the first aluminum target body, the shell and the cooling water, then enters the Ga4Ni alloy capsule target to produce Ge-68 nuclide, and then enters the metal sealing target to produce PET nuclide. The method has the beneficial effects that the melting of the target material can be reduced, the probability of direct chemical reaction of molten Ga and Nb is reduced, and the types of nuclide production are increased.

Description

Technical Field

[0001] The invention relates to the technical field of isotope production, and in particular to a solid target system for simultaneously producing Ge-68 and PET nuclides under a high-power beam. Background Art

[0002] International Atomic Energy Agency (IAEA) recommended applications nat Ga (p,xn) 68 Ge nuclear reaction produces Ge-68. The existing accelerator-based Ge-68 isotope production facilities in the world include BLIP at Brookhaven National Laboratory in the United States, IPF at Los Alamos National Laboratory in the United States, ISAC at TRIUMF Laboratory in Canada, SAIF at iThemba LABS in South Africa, etc. The beam current intensity of these high-energy accelerator facilities is in the hundreds of microamperes. Due to the different excitation curves of each nuclide, only irradiation in the corresponding energy range can obtain the optimal nuclide yield, and the energy range of the accelerator is much larger than the energy range of a single target material. If the energy of each accelerator can only be used for one target material, metal Ga, at a time, only a small part of the accelerator's energy range can be used. Therefore, Brookhaven National Laboratory, Los Alamos National Laboratory and the South African National Accelerator Center designed a cascade target scheme of Sr-82 / Ge-68 and Ac-225 / Ge-68 / Pd-103 for high-energy accelerators. At present, medium-energy cyclotrons in the 20-30MeV energy range have attracted much attention due to their high reliability, high availability, low operating cost and easy production of SPET and PET nuclides. How to better utilize the energy of proton beams and design an efficient Ge-68 solid target production system suitable for medium-energy cyclotrons has become a challenge.

[0003] Due to the very special chemical properties of metallic Ga, its low melting point and high chemical activity, the Brookhaven National Laboratory, Los Alamos National Laboratory and the South African National Accelerator Center in the United States often use Nb capsules to wrap metal Ga targets for irradiation to prepare Ge-68. It was found in the isotope production process that the proton beam is usually concentrated on a certain point of the Ga target, causing the Ga target to melt and react with Nb, destroying the Nb capsule at the atomic scale, causing small holes and cracks in the target under irradiation, and then causing target material loss, cooling system contamination, and reduced isotope yield. In the past, low-energy solid target systems for producing positron nuclides were mainly based on unsealed solid targets and solid targets sealed with rubber rings. The high heat generated by high-power irradiation causes the target layer to separate from the metal base layer, and the target material is lost to the water-cooling or helium-cooling system, resulting in a decrease in the yield of the target nuclides and circulating cooling pollution. However, rubber has poor sealing properties and a low upper temperature tolerance limit. Therefore, traditional Nb capsule targets and PET rubber sealed solid targets are not suitable for solid target systems that simultaneously produce Ge-68 and PET nuclides under high-power proton beams.

[0004] Therefore, it is urgent to design a solid target system suitable for the high-power proton beam of medium-energy cyclotron to produce Ge-68 and PET nuclides at the same time. The design of the capsule target assembly of this system should be able to meet the needs of long-term high-current irradiation to produce isotope Ge-68, reduce the melting of the target material, reduce the probability of direct chemical reaction between molten Ga and Nb, avoid target damage, and increase the yield of Ge-68. The design of the PET nuclide solid target assembly of this system should be simple and practical, with good sealing, reduce target leakage, and be able to efficiently use low-energy protons that penetrate the Ga target to produce PET nuclides, thereby increasing the types of nuclides produced. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to realize a capsule target assembly that can meet the demand for long-term high-current irradiation to produce isotope Ge-68, reduce the melting of the target material, and reduce the probability of direct chemical reaction between molten Ga and Nb; and how to realize a sealed target assembly that is simple and practical, has good sealing performance, and reduces target material leakage, and increases the types of nuclides produced. In order to overcome the defects of the above-mentioned prior art (or related technology), the present invention provides a solid target system for simultaneously producing Ge-68 and PET nuclides under a high-power beam.

[0006] The present invention provides a solid target system for simultaneously producing Ge-68 and PET nuclides under high-power beam flow, comprising: A medium-energy cyclotron accelerator for continuous emission of medium-energy high-current proton beams; A cascade target is arranged beside the medium-energy cyclotron, the cascade target comprises a shell, a first aluminum target body, a second aluminum target body, a Ga4Ni alloy capsule target and a metal sealed target, the first aluminum target body is fixed to one end of the shell facing the medium-energy cyclotron, the second aluminum target body is fixed to one end of the shell facing away from the medium-energy cyclotron, the Ga4Ni alloy capsule target and the metal sealed target are both fixed in the shell by a bracket, and the Ga4Ni alloy capsule target and the metal sealed target are arranged in sequence along the emission direction of the medium-energy high-current proton beam, and the shell is filled with cooling water; a target film, mounted between the medium energy cyclotron and the first aluminum target; a helium cooling unit, arranged between the target film and the first aluminum target body, and used for continuously releasing helium gas between the target film and the first aluminum target body to cool the target film and the first aluminum target body; A control unit is respectively connected to the medium-energy cyclotron and the helium cooling unit, and is used to control the helium cooling unit to continuously release helium, and control the medium-energy cyclotron to emit the medium-energy high-current proton beam, so that the medium-energy high-current proton beam passes through the target membrane, the first aluminum target body, the shell and the cooling water in sequence, and then is incident on the Ga4Ni alloy capsule target to produce Ge-68 nuclides, and then passes through the Ga4Ni alloy capsule target and is incident on the metal sealing target to produce PET nuclides.

[0007] Compared with the prior art, the solid target system for simultaneously producing Ge-68 and PET nuclides under high-power beam current in the present application has the following advantages: In the present application, the penetration ability of protons in Ga targets and the excitation curves of different target materials are efficiently utilized, and the thickness of Ga4Ni alloy capsule targets is reasonably designed, so that the proton incident energy in the second stage just matches the production reaction energy window of PET nuclides, thereby increasing the types of nuclides produced. The Ga4Ni alloy capsule target with good inclusiveness can utilize the forced convection heat exchange between the cooling water in the outer shell and itself to achieve heat removal under high-power production, thereby meeting the needs of long-term high-current irradiation production of isotope Ge-68. In addition, compared with traditional metal Ga targets, Ga is alloyed in the present application, which increases the melting point of the target material, avoids the melting of the target material, and reduces the probability of direct chemical reaction between molten Ga and Nb.

[0008] In a possible implementation, the Ga4Ni alloy capsule target includes: A first metal base layer, wherein a first circular groove is formed on the top of the first metal base layer; a Ga4Ni alloy layer, disposed in the first circular groove of the first metal base layer; A first metal cover layer is fixedly connected to the top of the first metal base layer to seal the first circular groove.

[0009] In a possible implementation, the Ga4Ni alloy capsule target includes: Two first metal base layers, each of the two first metal base layers has a first circular groove at one opposite end thereof, and a metal protective coating is disposed on the inner wall of the first circular groove; Two Ga4Ni alloy layers are respectively disposed in the first circular grooves of the two first metal base layers; The opposite ends of the two first metal base layers are fixedly connected to seal the two first circular grooves.

[0010] Compared with the prior art, the above technical solution can provide two structural solutions of Ga4Ni alloy capsule targets for technicians to choose from, so as to meet different needs.

[0011] In a possible implementation, the first metal base layer and the first metal cover layer are made of Nb, Ti or Inconel.

[0012] Compared with the prior art, the above technical solution can make the first metal base layer and the first metal cover layer have the characteristics of electrical conductivity, thermal conductivity, high hardness and corrosion resistance.

[0013] In a possible implementation manner, the material of the metal protective coating is Re or Ta, and the thickness of the metal protective coating is greater than 5 μm.

[0014] Compared with the prior art, the above technical solution can make the metal protective coating have the characteristics of electrical conductivity, thermal conductivity, and resistance to Ga metal chemical corrosion.

[0015] In a possible implementation, the metal sealing target includes: a second metal base layer, wherein a second circular groove and an annular groove are formed on the top of the second metal base layer with the same center, and the inner diameter of the annular groove is larger than the diameter of the second circular groove; a target material layer disposed in the second circular groove; an indium ring, embedded in the annular groove; A second metal cover layer is covered on the top of the second metal base layer to seal the second circular groove and the annular groove.

[0016] Compared with the prior art, after adopting the above technical solution, based on the soft and plastic characteristics of the indium ring, it is filled in the reserved annular groove and pressed to form an airtight seal. Only pressure is required without heating. This solves the problem that the target layer and the metal base layer of the previous unsealed solid target are separated during the irradiation process, the cooling water is lost, and the target nuclide yield is reduced and the circulating water is polluted. Compared with the solid target sealed with a rubber ring, the sealing is better and the upper temperature limit is much higher than that of the rubber seal. Therefore, it can withstand stronger beam currents and higher power irradiation, thereby realizing a sealed target assembly that is simple and practical, has good sealing, and reduces target material leakage.

[0017] In a possible implementation, the material of the second metal base layer and the second metal cover plate layer is any one of Al, Cu, Ag, Au, Nb, Ta, Ti, and Inconel.

[0018] Compared with the prior art, the above technical solution can make the second metal base layer and the second metal cover layer have the characteristics of electrical conductivity, thermal conductivity, high hardness and corrosion resistance.

[0019] In a possible implementation, the material of the target layer is 68 Zn, 64 You, nat Y. 124 TeO2, 44 Any one of CaCO3.

[0020] In a possible implementation manner, when the metal sealing target is fixed in the housing, the second metal cover plate layer faces the Ga4Ni alloy capsule target.

[0021] In one possible embodiment, the PET nuclide includes 68 Ga, 64 Cu, 89 Zr, 124 I and 44 Sc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall layout of the present invention; Figure 2 It is the system structure principle diagram of the present invention; Figure 3 This is a schematic diagram of the design of the Ga4Ni alloy capsule target of the present invention; Figure 4 It is a schematic diagram of the design of the metal sealing target of the present invention; Figure 5 It is a schematic diagram of the process flow of the Ga4Ni alloy capsule target of the present invention; Explanation of the reference numerals: 1. medium energy cyclotron; 2. cascade target; 21. outer shell; 22. first aluminum target body; 23. second aluminum target body; 24. Ga4Ni alloy capsule target; 241. first metal base layer; 242. first circular groove; 243. Ga4Ni alloy layer; 244. first metal cover layer; 245. metal protective coating; 25. metal sealing target; 251. second metal base layer; 252. second circular groove; 253. annular groove; 254. target material layer; 255. indium ring; 256. second metal cover layer; 26. cooling water; 3. target film; 4. helium cooling unit; 5. control unit. DETAILED DESCRIPTION

[0023] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0024] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] See also Figure 1 and Figure 2 The embodiment of the present application discloses a solid target system for simultaneously producing Ge-68 and PET nuclides under high-power beam flow, so as to improve the utilization rate of proton beam flow, reasonably utilize the excitation curves of different target materials, thereby increasing the types of nuclides produced; and solve the problems of target damage and reduced nuclide yield in the prior art. To achieve the above purpose, the present application adopts the following technical solutions: A medium-energy cyclotron 1, a cascade target 2, a target film 3, a helium cooling unit 4 and a control unit 5 are configured to emit a medium-energy high-current proton beam through the medium-energy cyclotron 1; the target material of the cascade target 2 determines its energy range and target material thickness according to the current maximum energy of the medium-energy cyclotron 1, the target structure and its nuclear reaction cross section; the specific structure of the cascade target 2 includes a shell 21, a first aluminum target body 22, a second aluminum target body 23, a Ga4Ni alloy capsule target 24 and a metal sealing target 25, the first aluminum target body 22 is fixed to one end of the shell 21 facing the medium-energy cyclotron 1, the second aluminum target body 23 is fixed to one end of the shell 21 facing away from the medium-energy cyclotron 1, and the Ga4Ni alloy capsule target 24 is fixed to the other end of the shell 21 facing away from the medium-energy cyclotron 1. The Ga4Ni alloy capsule target 24 and the metal sealed target 25 are fixed in the housing 21 by a bracket, and the Ga4Ni alloy capsule target 24 and the metal sealed target 25 are arranged in sequence along the emission direction of the medium-energy high-current proton beam, and the housing 21 is filled with cooling water 26; the helium cooling unit 4 includes at least one diaphragm pump, one heat exchanger, one temperature sensor, one pressure sensor, one radiation sensor and one gas filtering device; the cooling water 26 is provided by a water cooling unit, and the water cooling unit includes an adjustable ball valve and a flow meter. The helium cooling unit 4 and the water cooling unit also include a plurality of solenoid valves and fluid delivery pipelines; the control unit 5 includes a host computer, a programmable logic controller (PLC), control software and communication protocols, etc.

[0026] Continue to see Figure 1 After the medium-energy high-current proton beam passes through the target film 3, the first aluminum target body 22, the shell 21 of the cascade target 2 and the cooling water 26, it first reduces part of its energy, which is about 2-3 MeV; the nuclide produced by the incident on the Ga4Ni alloy capsule target 24 is Ge-68; by consulting the reaction cross-section data of natural Ga and protons in the nuclear reaction database, it is known that the suitable energy range for Ge-68 production is 13-40 MeV; after calculation by the Monte Carlo simulation software SRIM, when the thickness of the Ga4Ni alloy capsule target 24 is about 1.5 mm, the proton energy can be reduced from 30 MeV to 13.5 MeV, so that the second proton incident energy just matches 68 Ga, 64 Cu, 89 Zr, 124 I and 44 The production reaction energy window of positron nuclides such as Sc, wherein in the present application, PET nuclides refer to radioactive nuclides used in positron emission tomography (PET) examinations.

[0027] See also Figure 3In the present application, two structural design schemes are provided for the Ga4Ni alloy capsule target 24. The first structural design scheme includes a first metal substrate layer 241, a Ga4Ni alloy layer 243 and a first metal cover layer 244. The top of the first metal substrate layer 241 is provided with a first circular groove 242; the Ga4Ni alloy layer 243 is arranged in the first circular groove 242 of the first metal substrate layer 241; the first metal cover layer 244 is fixedly connected to the top of the first metal substrate layer 241 to seal the first circular groove 242; the second structural design scheme includes two first metal substrate layers 241 and two Ga4Ni alloy layers 243. The opposite ends of the two first metal substrate layers 241 are respectively provided with first circular grooves 242, and the inner wall of the first circular groove 242 is provided with a metal protective coating 245. The two Ga4Ni alloy layers 243 are respectively arranged in the first circular grooves 242 of the two first metal substrate layers 241, and the opposite ends of the two first metal substrate layers 241 are fixedly connected to seal the two first circular grooves 242.

[0028] Continue to see Figure 3 The first metal base layer 241 and the first metal cover layer 244 are made of Nb, Ti or Inconel (nickel-based alloy), which are inert metals with electrical conductivity, thermal conductivity, high hardness and corrosion resistance. The metal protective coating 245 is made of Re or Ta with a thickness of at least 5 μm, which is an inert metal with electrical conductivity, strong thermal conductivity and resistance to chemical corrosion of Ga metal.

[0029] Continue to see Figure 3 The present application also provides a preparation process of the Ga4Ni alloy layer 243, including a melting method and an electroplating method, wherein the melting method includes the following steps: Step A1, in a helium atmosphere, using a high frequency heater to heat the metal Ni and the metal Ga, and stirring and mixing the molten alloy; Step A2, pouring the Ga4Ni molten alloy into the Nb, Ti or Inconel capsule base template while it is still hot, until a convex meniscus protrudes above the capsule flange; Step A3, placing the capsule base filled with Ga4Ni alloy for a certain period of time, cooling it to room temperature, and then placing it in a refrigerator to cool it down and further solidify it after forming a solid alloy; The electroplating process includes the following steps: Step B1, the electroplating tank used is a constant temperature water bath vertical plating tank with a stirring function, 15-20 g of metal gallium is dissolved in 9-12 M HNO3, continuously heated and stirred, and then 98% H2SO4 is added to precipitate Ga2(SO4)3; Step B2, dissolving Ga2(SO4)3 precipitate in water, adjusting the pH value of the solution to 2-2.5 with ammonia solution, heating the solution to 40-50 °C, adding 10-15 g of NiSO4 to prepare the final plating solution, and the final volume of the plating solution is 400-500 mL; Step B3: Ga-Ni is electro-deposited using constant current electrolysis technology and the current density is adjusted to 20-60 mA / cm 2 , the temperature is 25-100°C, and the speed of rotation and stirring is maintained at about 300-800 rpm during the electroplating process; Step B4, selecting the electroplating time according to the required Ga-Ni layer thickness, usually after 6-8 hours to obtain a Ga4Ni alloy target, in which the Ga mass content is not less than 60% and the thickness is greater than 20mg / cm 2 .

[0030] Continue to see Figure 3 The present application also provides a further heat treatment and welding process of the Ga4Ni alloy capsule, comprising the following steps: Step C1, using a milling machine to remove excess Ga4Ni alloy on the capsule base, and processing it until the surface of the Ga4Ni alloy is flush with the surface of the capsule flange; Step C2, in a helium atmosphere, using a high-frequency heater to heat the capsule base to the melting point of metal Ga, melt the metal Ga that has not formed an alloy, pour the capsule base, and remove the free metal phase; Step C3, placing the capsule base, cooling it to room temperature, and then placing it in a refrigerator for low-temperature refrigeration; Step C4, using a milling machine to remove excess Ga4Ni alloy on the capsule base and process it until the surface is flush with the capsule flange surface; Step C5, placing the capsule base filled with Ga4Ni alloy and the capsule cover plate, or two capsule bases filled with Ga4Ni alloy together, aligning them in place, vacuum-packing the entire assembly in a shrink film, and then returning it to the refrigerator; Step C6, the capsule is placed in a refrigerator, transported to an electron beam or laser welding site, the capsule target substrate and its cover are mounted in a chuck in a vacuum chamber of the equipment, and pumped to a high vacuum; Step C7, the electron gun or laser is in a stationary state during the welding process, and the capsule is rotated and welded.

[0031] See also Figure 4The design structure of the metal sealing target 25 includes a second metal base layer 251, a target material layer 254, an indium ring 255 and a second metal cover layer 256. The top of the second metal base layer 251 is provided with a concentric second circular groove 252 and an annular groove 253, and the inner diameter of the annular groove 253 is larger than the diameter of the second circular groove 252; the target material layer 254 is arranged in the second circular groove 252; the indium ring 255 is embedded in the annular groove 253, and the indium ring can be replaced by indium wire; the second metal cover layer 256 is covered on the top of the second metal base layer 251 to seal the second circular groove 252 and the annular groove 253.

[0032] Continue to see Figure 4 The second metal base layer 251 and the second metal cover layer 256 are made of Al, Cu, Ag, Au, Nb, Ta, Ti or Inconel, which are inert metals that are electrically conductive, thermally conductive, hard and corrosion resistant. The target layer 254 can be made of an electroplated metal layer ( 68 Zn, 64 Ni、Metallic Flakes( nat Y、Oxide( 124 TeO2) and metal salt powders ( 44 CaCO3), to achieve low-energy proton irradiation, production 68 Ga, 64 Cu, 89 Zr, 124 I and 44 Sc.

[0033] Continue to see Figure 4 The present application also provides a preparation process of the metal sealing target 25, comprising the following steps: Step D1, place the metal sheet ( nat Y) is inserted into the second circular groove 252 of the second metal base layer 251, and the oxide ( 124 TeO2) particles or metal salts ( 44 CaCO3) particles, the target particles are pressed and filled in the second circular groove 252, for the electroplating target layer ( 68 Zn, 64 Ni), electrodepositing the metal salt in the second circular groove 252; Step D2, inserting the metal indium wire into the annular groove 253 of the second metal base layer 251; Step D3, pressing the second metal cover layer 256 onto the indium wire and the second metal base layer 251 to encapsulate the target layer 254. The indium wire is soft and plastic. When placed between two surfaces, it will fill all the gaps between the two surfaces, thereby forming an airtight seal.

[0034] Continue to see Figure 1In summary, the solid target system for simultaneously producing Ge-68 and PET nuclides under high-power beam provided by the present application has the following advantages: 1) Efficient cascade target design By efficiently utilizing the penetration ability of protons in Ga targets and the excitation curves of different target materials, the thickness of Ga4Ni alloy capsule target 24 is reasonably designed to make the proton incident energy in the second stage just match 68 Ga, 64 Cu, 89 Zr, 124 I and 44 The production reaction energy window of positron nuclides such as Sc increases the types of nuclides produced, and the Ga4Ni alloy capsule target 24 with good tolerance utilizes the forced convection heat exchange between the cooling water 26 in the housing 21 and the Ga4Ni alloy capsule target 24 to achieve heat removal under high power production; 2) Preparation of radiation-resistant and high-melting-point Ga4Ni alloy capsule target 24 The present application is based on a corrosion-resistant inert metal substrate and adopts an electrodeposition or melting method that is simple to operate and has a stable process to prepare a Ga4Ni alloy capsule target 24. Compared with the traditional metal Ga target layer, the present application alloys Ga, increases the melting point of the target material, avoids the melting of the target material, and reduces the probability of direct chemical reaction between molten Ga and Nb; 3) Anti-corrosion metal coating Compared with the traditional Nb capsule target with direct encapsulation, the present application adopts Re or Ta metal with excellent chemical corrosion resistance as the metal protective coating 245 in the capsule target to isolate the Ga4Ni alloy layer 243 and the first metal substrate layer 241, so as to prevent the molten Ga from directly reacting with Nb, resulting in small holes, cracks and the like in the target under irradiation, and Ta is not easily dissolved by acid, and the dissolution product of Re is anion, which is easy to chemically separate; it does not affect the effect of subsequent chromatographic separation, and compared with precious metal coatings such as platinum, gold, and silver, Re or Ta is cheaper and more available, and has fewer inorganic impurities; 4) Preheating process of alloy target Compared with the previous methods after target preparation, the present application is based on the problem of uneven metallographic phase of metal alloy formed by electroplating or melting, and the problem of free metal phase. A process is added before ion beam or laser welding to heat treat the target in advance and remove the molten free Ga in advance to avoid the target material melting during irradiation. 5) Simple and efficient metal sealing method Based on the soft and plastic properties of indium wire, the present application fills it into the annular groove 253 reserved on the upper and lower surfaces, and presses it to form an airtight seal. Only pressure is required without heating, which solves the problem of previous unsealed solid targets. During the irradiation process, the target layer and the metal base layer are separated, and cooling water is lost, resulting in a decrease in the yield of target nuclides and pollution of circulating water. In addition, the metal sealed target 25 in the present application has better sealing than the solid target sealed with a rubber ring, and the upper temperature limit is much higher than that of the rubber seal. Therefore, it can withstand stronger beam and higher power irradiation, and is more suitable for solid target systems that simultaneously produce Ge-68 and PET nuclides under high-power proton beams.

[0035] Example 1 See also Figure 5 The processing method of the capsule molten alloy target for producing Ge-68 by a high-current proton cyclotron described in Example 1 of the present application includes: melting metal gallium and metal nickel, solidifying at low temperature to form an alloy, and co-depositing the two metals gallium and nickel on a niobium capsule target substrate to prepare a gallium-nickel alloy target layer; after milling, heat treating the target layer to remove the free metal phase; assembling the target pieces, extracting a vacuum, and electron beam welding to obtain a capsule alloy target that can withstand high-power irradiation; after the alloy target pieces are irradiated by ACSI-FLEX 30 MeV, an alloy target containing Ge-68 is obtained, which specifically includes the following steps: 1. Preparation of alloy target layer In a helium atmosphere, a high-frequency heater is used to heat the metal Ni and metal Ga to 1600°C, and the molten alloy is stirred and mixed. The molten alloy is poured into the Nb capsule base template while hot until a raised meniscus is formed about 1 mm above the Nb capsule flange. The alloy is placed on the capsule base and cooled to room temperature to form a solid alloy. The alloy is then placed in a refrigerator and cooled to about -5°C for further low-temperature solidification. 2. Target pretreatment Use a milling machine to remove excess Ga-nickel alloy, and process it until the surface of the Ga-nickel alloy is flush with the surface of the Nb capsule flange. In a helium atmosphere, use a high-frequency heater to heat the capsule base to 500 ° C, sinter for 2 h, remove the free metal Ga that has not formed an alloy, and place the capsule base to cool to room temperature, and then put it in a refrigerator to cool to about -5 ° C, refrigerate it at low temperature, and then use a milling machine to remove excess Ga, and process it until the Ga surface is flush with the surface of the Nb flange, and then place the capsule base and the capsule cover, or two capsule bases together, align them in place, vacuum-pack the entire assembly in a shrink film, and then put it back into the refrigerator; 3. Target welding Niobium materials are difficult to cold weld and must be electron beam welded. The capsule is transported to the electron beam welding site in a refrigerated box. The capsule target substrate and its cover are installed in the chuck in the vacuum chamber of the equipment and pumped to a vacuum degree of less than 0.1 mbar. The electron gun is stationary during the welding process, and the capsule is rotated. The welding speed is about 25 mm / s. 4. High power irradiation of Ga4Ni alloy target The radioactive Ge-68 alloy target was prepared by directly irradiating the Ga4Ni alloy target layer with a thickness of 3 mm using ACSI-FLEX 30 MeV 500μA.

[0036] Example 2 Continue to see Figure 5 The processing method of the capsule electroplating alloy target for producing Ge-68 by high-current proton cyclotron described in Example 2 of the present application includes: dissolving gallium salt and nickel salt in a sulfuric acid solution, using the electroplating principle to make gallium and nickel co-deposit on a niobium target substrate to prepare a gallium-nickel alloy target layer; after milling, heat-treating the target layer to remove the free metal phase; assembling the target parts, extracting vacuum, and electron beam welding to obtain a capsule alloy target that can withstand high-power irradiation, which specifically includes the following steps: 1. Preparation of Ga4Ni alloy target by electroplating Dissolve 18g of metallic gallium in 10 M HNO3, keep heating and stirring, then add 98% H2SO4 to precipitate Ga2(SO4) 3， The Ga2(SO4)3 precipitate was dissolved in water, and the pH value of the solution was adjusted to 2 with an ammonia solution. The solution was heated to 45 °C, and 12 g of NiSO4 was added to prepare the final electroplating solution. The final volume of the electroplating solution was 450 mL. Ga-Ni was electroplated using a constant current electrolysis technique, and the current density was adjusted to 25 mA / cm2. The temperature was 60 °C, and the speed of rotation and stirring was maintained at about 500 rpm during the electroplating process. After 8 hours, a Ga4Ni alloy target was obtained; 2. Target pretreatment and welding, same as in Example 1; 3. Metal seal of yttrium target A natural yttrium metal sheet of about 450 μm is inserted into the second circular groove 252 of the aluminum second metal base layer 251; a metal indium wire is inserted into the annular groove 253 of the second metal base layer 251, and an aluminum second metal cover plate layer 256 is pressed onto the indium wire and the aluminum second metal base layer 251 to encapsulate the target material layer 254. The indium wire is soft and plastic and fills the surface gap to form an airtight seal; 4. High power irradiation cascade target Using ACSI-FLEX 30 MeV 500μA proton irradiation, the high-current proton beam first reduces part of its energy by about 2-3 MeV after passing through the target membrane 3, the outer shell 21 of the cascade target 2 and the cooling water 26; the nuclide produced by the incident proton on the gallium-nickel alloy target is Ge-68; consulting the ENDF nuclear database, the reaction cross section between gallium and protons shows that the suitable energy range for Ge-68 production is 13-40 MeV; after calculation by the Monte Carlo simulation software SRIM, when the thickness of the gallium-nickel alloy target is about 1.5 mm, the proton energy can be reduced from 30 MeV to 13.5 MeV, and the irradiation produces an alloy target containing radioactive Ge-68; Among them, after the proton beam passes through the gallium-nickel alloy target, there is still an energy range below 13.5 MeV that is incident on the natural yttrium target; the nuclide produced by the incident on the natural yttrium target is Zr-89; consulting the nuclear database, the reaction cross section between natural yttrium and protons shows that the suitable energy range for the production of Zr-89 is 9-13.5 MeV; after calculation by the Monte Carlo simulation software SRIM, when the thickness of the natural yttrium target is about 0.45 mm, the proton energy can be reduced from 13.5 MeV to 9 MeV, and irradiation produces a metal target containing radioactive Zr-89.

[0037] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0038] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A solid target system for simultaneously producing Ge-68 and PET nuclides under high-power beam, characterized in that: include: a medium energy cyclotron (1), used for continuously emitting a medium energy high current proton beam; A cascade target (2) is arranged beside the medium-energy cyclotron (1), the cascade target (2) comprising a housing (21), a first aluminum target body (22), a second aluminum target body (23), a Ga4Ni alloy capsule target (24) and a metal sealed target (25), the first aluminum target body (22) being fixed to one end of the housing (21) facing the medium-energy cyclotron (1), the second aluminum target body (23) being fixed to one end of the housing (21) facing away from the medium-energy cyclotron (1), the Ga4Ni alloy capsule target (24) and the metal sealed target (25) being fixed in the housing (21) by a bracket, and the Ga4Ni alloy capsule target (24) and the metal sealed target (25) being arranged in sequence along the emission direction of the medium-energy high-current proton beam, and the housing (21) being filled with cooling water (26); a target film (3) mounted between the medium-energy cyclotron (1) and the first aluminum target body (22); a helium cooling unit (4), mounted between the target film (3) and the first aluminum target body (22), and used for continuously releasing helium between the target film (3) and the first aluminum target body (22) to cool the target film (3) and the first aluminum target body (22); A control unit (5) is connected to the medium-energy cyclotron (1) and the helium cooling unit (4) respectively, and is used to control the helium cooling unit (4) to continuously release helium, and to control the medium-energy cyclotron (1) to emit the medium-energy high-current proton beam, so that the medium-energy high-current proton beam passes through the target membrane (3), the first aluminum target body (22), the shell (21) and the cooling water (26) in sequence and then is incident on the Ga4Ni alloy capsule target (24) to produce Ge-68 nuclides, and then passes through the Ga4Ni alloy capsule target (24) and is incident on the metal sealing target (25) to produce PET nuclides.

2. The solid target system according to claim 1, characterized in that: The Ga4Ni alloy capsule target (24) comprises: a first metal base layer (241), wherein a first circular groove (242) is formed at the top of the first metal base layer (241); a Ga4Ni alloy layer (243) disposed in the first circular groove (242) of the first metal base layer (241); A first metal cover plate layer (244) is fixedly connected to the top of the first metal base layer (241) to seal the first circular groove (242).

3. The solid target system according to claim 1, characterized in that: The Ga4Ni alloy capsule target (24) comprises: Two first metal base layers (241), each of the two first metal base layers (241) having a first circular groove (242) formed at one opposite end thereof, and a metal protective coating (245) being provided on an inner wall of the first circular groove (242); Two Ga4Ni alloy layers (243) are respectively arranged in the first circular grooves (242) of the two first metal base layers (241); The opposite ends of the two first metal base layers (241) are fixedly connected to seal the two first circular grooves (242).

4. The solid target system according to claim 2 or claim 3, characterized in that: The first metal base layer (241) and the first metal cover plate layer (244) are made of Nb, Ti or Inconel.

5. The solid target system according to claim 3, characterized in that: The material of the metal protective coating (245) is Re or Ta, and the thickness of the metal protective coating (245) is greater than 5 μm.

6. The solid target system according to claim 1, characterized in that: The metal sealing target (25) comprises: a second metal base layer (251), wherein a second circular groove (252) and an annular groove (253) having the same center are formed on the top of the second metal base layer (251), and the inner diameter of the annular groove (253) is greater than the diameter of the second circular groove (252); a target material layer (254) disposed in the second circular groove (252); an indium ring (255) embedded in the annular groove (253); A second metal cover plate layer (256) is disposed on the top of the second metal base layer (251) to seal the second circular groove (252) and the annular groove (253).

7. The solid target system according to claim 6, characterized in that: The material of the second metal base layer (251) and the second metal cover plate layer (256) is any one of Al, Cu, Ag, Au, Nb, Ta, Ti, and Inconel.

8. The solid target system according to claim 6, characterized in that: The material of the target layer (254) is 68 Zn, 64 You, nat Y. 124 TeO2, 44 Any one of CaCO3.

9. The solid target system according to claim 6, characterized in that: When the metal sealing target (25) is fixed in the housing (21), the second metal cover plate layer (256) faces the Ga4Ni alloy capsule target (24).

10. The solid target system according to claim 1, characterized in that: The PET nuclides include 68 Ga, 64 Cu, 89 Zr, 124 I and 44 Sc.

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