A solid target system for simultaneous production of Ge-68 and PET nuclides under high power beam

Abstract

The present invention provides a solid target system for simultaneously producing Ge-68 and PET nuclides under a high-power beam current, comprising: a medium-energy cyclotron for emitting a medium-energy high-intensity proton beam; a cascade target disposed beside the medium-energy cyclotron, including a housing and a first aluminum target body, a second aluminum target body, a Ga4Ni alloy capsule target and a metal sealed target sequentially arranged along the emission direction of the medium-energy high-intensity proton beam, and the housing is filled with cooling water; a target film disposed between the medium-energy cyclotron and the first aluminum target body; a helium cooling unit disposed between the target film and the first aluminum target body; and a control unit for controlling the startup of 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 housing and the cooling water and then is incident on the Ga4Ni alloy capsule target to produce the Ge-68 nuclide, and then is incident on the metal sealed target to produce the PET nuclide. The beneficial effects are that the present invention can reduce the melting of the target material, reduce the probability of direct chemical reaction between molten Ga and Nb, and increase the types of nuclide production.

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:

[0007] A medium-energy cyclotron accelerator for continuous emission of medium-energy high-current proton beams;

[0008] A cascade target is arranged beside the medium energy cyclotron, and the cascade target includes a housing, a first aluminum target body, a second aluminum target body, and a Ga4 Ni alloy capsule target and metal sealing target, the first aluminum target body is fixed on the end of the shell facing the medium energy cyclotron, the second aluminum target body is fixed on the end of the shell facing away from the medium energy cyclotron, the Ga 4 The Ni alloy capsule target and the metal sealing target are both fixed in the housing by a bracket, and the Ga 4 The Ni alloy capsule target and the metal sealing target are sequentially arranged along the emission direction of the medium-energy high-current proton beam, and the housing is filled with cooling water;

[0009] a target film, mounted between the medium energy cyclotron and the first aluminum target;

[0010] 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;

[0011] a control unit, connected to the medium-energy cyclotron and the helium cooling unit, respectively, for controlling the helium cooling unit to continuously release helium, and controlling the medium-energy cyclotron to emit the medium-energy high-current proton beam, so that the medium-energy high-current proton beam sequentially passes through the target film, the first aluminum target body, the housing and the cooling water, and then enters the Ga 4 The Ge-68 nuclide is produced on the Ni alloy capsule target and then passes through the Ga 4 The Ni alloy capsule target is then incident on the metal sealed target to produce the PET nuclide.

[0012] 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:

[0013] In this application, the penetration ability of protons in Ga targets and the excitation curves of different target materials are efficiently utilized to rationally design Ga 4 The thickness of the Ni alloy capsule target makes the proton incident energy in the second stage just match the production reaction energy window of PET nuclides, increasing the types of nuclides produced, and the inclusion of Ga 4 The Ni alloy capsule target 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, meeting the needs of long-term high-current irradiation to produce isotope Ge-68; and compared with traditional metal Ga targets, Ga is alloyed in this 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.

[0014] In a possible implementation manner, the Ga 4 Ni alloy capsule targets include:

[0015] A first metal base layer, wherein a first circular groove is formed on the top of the first metal base layer;

[0016] One Ga 4 A Ni alloy layer is disposed in the first circular groove of the first metal base layer;

[0017] A first metal cover layer is fixedly connected to the top of the first metal base layer to seal the first circular groove.

[0018] In a possible implementation manner, the Ga 4 Ni alloy capsule targets include:

[0019] 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;

[0020] Two Ga 4 A Ni alloy layer is respectively disposed in the first circular grooves of the two first metal base layers;

[0021] The opposite ends of the two first metal base layers are fixedly connected to seal the two first circular grooves.

[0022] Compared with the prior art, the above technical solution can provide two kinds of Ga 4 The structural scheme of Ni alloy capsule target is provided for technicians to choose in order to meet different needs.

[0023] In a possible implementation, the first metal base layer and the first metal cover layer are made of Nb, Ti or Inconel.

[0024] Compared with the prior art, the above technical solution can make the first metal base layer and the first metal cover plate layer have the characteristics of electrical conductivity, thermal conductivity, high hardness and corrosion resistance.

[0025] 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.

[0026] 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.

[0027] In a possible implementation, the metal sealing target includes:

[0028] 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;

[0029] a target material layer disposed in the second circular groove;

[0030] an indium ring, embedded in the annular groove;

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] In a possible implementation, the material of the target layer is 68 Zn, 64 You, nat Y. 124 TeO 2 , 44 CaCO 3 Any one of .

[0036] In a possible implementation manner, when the metal sealing target is fixed in the housing, the second metal cover plate layer faces the Ga 4 Ni alloy capsule target.

[0037] In one possible embodiment, the PET nuclide includes 68 Ga, 64 Cu, 89 Zr, 124 I and 44 Sc. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall layout of the present invention;

[0039] Figure 2 It is the system structure principle diagram of the present invention;

[0040] Figure 3 The Ga of the present invention 4 Schematic diagram of the design of Ni alloy capsule target;

[0041] Figure 4 It is a schematic diagram of the design of the metal sealing target of the present invention;

[0042] Figure 5 The Ga of the present invention 4 Schematic diagram of the process flow of Ni alloy capsule target;

[0043] Description of reference numerals: 1, medium energy cyclotron; 2, cascade target; 21, housing; 22, first aluminum target; 23, second aluminum target; 24, Ga 4 Ni alloy capsule target; 241, first metal base layer; 242, first circular groove; 243, Ga 4 Ni 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

[0044] 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.

[0045] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] 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:

[0047] 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 Ga 4 Ni alloy capsule target 24 and metal sealing target 25, the first aluminum target body 22 is fixed on the end of the shell 21 facing the medium energy cyclotron 1, the second aluminum target body 23 is fixed on the end of the shell 21 facing away from the medium energy cyclotron 1, Ga 4 The Ni alloy capsule target 24 and the metal sealing target 25 are fixed in the housing 21 by a bracket, and Ga 4 The Ni alloy capsule target 24 and the metal sealing target 25 are arranged in sequence along the emission direction of the medium-energy high-current proton beam, and the outer shell 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 number 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.

[0048] 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; then it is incident on the Ga 4 The nuclide produced on the Ni alloy capsule target 24 is Ge-68. According to the reaction cross section data of natural Ga and protons in the nuclear reaction database, the suitable energy range for Ge-68 production is 13-40 MeV. After calculation by the Monte Carlo simulation software SRIM, Ga 4 When the thickness of the Ni 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 incident proton energy of the second stage 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.

[0049] See also Figure 3 In this application, Ga4 The Ni alloy capsule target 24 provides two structural design solutions. The first structural design solution includes a first metal substrate layer 241, a Ga 4 Ni alloy layer 243 and first metal cover layer 244, the top of the first metal base layer 241 is provided with a first circular groove 242; Ga 4 The Ni alloy layer 243 is disposed in the first circular groove 242 of the first metal base layer 241; the first metal cover layer 244 is fixedly connected to the top of the first metal base layer 241 to seal the first circular groove 242; the second structural design includes two first metal base layers 241 and two Ga 4 The Ni alloy layer 243, the two first metal base layers 241 have first circular grooves 242 at opposite ends, and the inner wall of the first circular groove 242 is provided with a metal protective coating 245. 4 The Ni alloy layer 243 is disposed in the first circular grooves 242 of the two first metal base layers 241 , respectively. The opposite ends of the two first metal base layers 241 are fixedly connected to seal the two first circular grooves 242 .

[0050] 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.

[0051] Continue to see Figure 3 , this application also provides Ga 4 The preparation process of the Ni alloy layer 243 includes a melting method and an electroplating method, wherein the melting method includes the following steps:

[0052] 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;

[0053] Step A2: While hot, 4 The Ni molten alloy is poured into the Nb, Ti or Inconel capsule base template until a raised meniscus is protruding above the capsule flange;

[0054] Step A3, fill Ga 4 The Ni alloy capsule substrate is placed for a certain period of time, cooled to room temperature, and after forming a solid alloy, it is placed in a refrigerator to cool and further solidify;

[0055] The electroplating process includes the following steps:

[0056] Step B1: The electroplating tank used is a constant temperature water bath vertical plating tank with stirring function. 15-20 g of metal gallium is dissolved in 9-12 M HNO 3 In the mixture, heating and stirring were continued, and then 98% H 2 SO 4 , used to precipitate Ga 2 (SO 4 ) 3 ;

[0057] Step B2, Ga 2 (SO 4 ) 3 The precipitate was dissolved in water, the pH of the solution was adjusted to 2-2.5 with ammonia solution, the solution was heated to 40-50 °C, and 10-15 g of NiSO 4 Prepare the final plating solution, the final volume of the plating solution is 400-500 mL;

[0058] 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;

[0059] Step B4, select the electroplating time according to the required Ga-Ni layer thickness, usually after 6-8 hours, Ga 4 Ni alloy target, the Ga 4 In the Ni alloy target, the Ga content is not less than 60% and the thickness is greater than 20mg / cm 2 .

[0060] Continue to see Figure 3 , this application also provides the above-mentioned Ga 4 The further heat treatment and welding process of the Ni alloy capsule includes the following steps:

[0061] Step C1, using a milling machine, remove the excess Ga 4 Ni alloy is removed and processed to Ga 4 The Ni alloy surface is flush with the capsule flange surface;

[0062] 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;

[0063] Step C3, placing the capsule base, cooling it to room temperature, and then placing it in a refrigerator for low-temperature refrigeration;

[0064] Step C4, using a milling machine, remove the excess Ga 4 The Ni alloy is removed and the surface is machined to be flush with the capsule flange surface;

[0065] Step C5, fill Ga 4 Ni alloy capsule base and capsule cover, or two filled with Ga 4 The Ni alloy capsule substrates are placed together, aligned into place, and the entire assembly is vacuum-wrapped in shrink film before being returned to the freezer;

[0066] 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;

[0067] Step C7, the electron gun or laser is in a stationary state during the welding process, and the capsule is rotated and welded.

[0068] See also Figure 4 The 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.

[0069] 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 TeO 2 ) and metal salt powders ( 44 CaCO 3 ), realize the production of low energy proton irradiation 68 Ga, 64 Cu, 89 Zr, 124 I and 44 Sc.

[0070] Continue to see Figure 4The present application also provides a preparation process of the metal sealing target 25, comprising the following steps:

[0071] 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 TeO 2 ) particles or metal salts ( 44 CaCO 3 ) 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;

[0072] Step D2, inserting the metal indium wire into the annular groove 253 of the second metal base layer 251;

[0073] 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.

[0074] Continue to see Figure 1 In 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:

[0075] 1) Efficient cascade target design

[0076] Efficiently utilize the proton penetration ability in Ga targets and the excitation curves of different target materials to rationally design Ga 4 The thickness of the Ni alloy capsule target 24 is such that the proton incident energy in the second stage is exactly matched to 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 inclusion of Ga 4 The Ni alloy capsule target 24 is cooled by the cooling water 26 in the housing 21 and the Ga 4 Forced convection heat transfer between the Ni alloy capsule targets 24 enables heat removal under high power production;

[0077] 2) Prepare radiation-resistant and high-melting-point Ga 4 Ni alloy capsule target 24

[0078] This application is based on a corrosion-resistant inert metal substrate and adopts a simple and stable process of electrodeposition or melting to prepare Ga 4Ni 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;

[0079] 3) Anti-corrosion metal coating

[0080] Compared with the conventional Nb capsule target directly encapsulated, the present application uses Re or Ta metal with excellent chemical corrosion resistance as the metal protective coating 245 in the capsule target to isolate Ga 4 The Ni alloy layer 243 and the first metal substrate layer 241 prevent the molten Ga from reacting directly with Nb, which would cause small holes and cracks in the target under irradiation. Ta is not easily dissolved by acid, and the dissolved product of Re is an anion, which is easy to chemically separate. It does not affect the effect of subsequent chromatographic separation. Compared with precious metal coatings such as platinum, gold, and silver, Re or Ta is cheaper and more available, and has fewer inorganic impurities.

[0081] 4) Preheating process of alloy target

[0082] 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.

[0083] 5) Simple and efficient metal sealing method

[0084] 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.

[0085] Example 1

[0086] See also Figure 5The 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:

[0087] 1. Preparation of alloy target layer

[0088] 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.

[0089] 2. Target pretreatment

[0090] 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;

[0091] 3. Target welding

[0092] 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.

[0093] 4. High power irradiation of Ga 4 Ni alloy target

[0094] ACSI-FLEX 30 MeV 500μA direct irradiation of Ga with a thickness of 3 mm 4 Ni alloy target layer to prepare an alloy target containing radioactive Ge-68.

[0095] Example 2

[0096] 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:

[0097] 1. Preparation of Ga by electroplating 4 Ni alloy target

[0098] 18g of metallic gallium was dissolved in 10 M HNO3, heated and stirred continuously, and then 98% H2SO4 was added to precipitate Ga 2 (SO 4 ) 3， Will Ga 2 (SO 4 ) 3 The 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 constant current electrolysis technology. The current density was adjusted to 25 mA / cm2 and the temperature was 60 °C. During the electroplating process, the rotation and stirring speed was maintained at about 500 rpm. After 8 hours, Ga 4 Ni alloy target;

[0099] 2. Target pretreatment and welding, same as in Example 1;

[0100] 3. Metal seal of yttrium target

[0101] 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;

[0102] 4. High power irradiation cascade target

[0103] 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;

[0104] 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.

[0105] 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.

[0106] 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), The alloy capsule target (24) and the metal sealing target (25) are provided, wherein the first aluminum target body (22) is fixed to one end of the housing (21) facing the medium-energy cyclotron (1), and the second aluminum target body (23) is fixed to one end of the housing (21) facing away from the medium-energy cyclotron (1). The alloy capsule target (24) and the metal sealing target (25) are both fixed in the housing (21) via a bracket, and the The alloy capsule target (24) and the metal sealing 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); 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), connected to the intermediate energy cyclotron (1) and the helium cooling unit (4), respectively, and used for controlling the helium cooling unit (4) to continuously release helium, and controlling the intermediate energy cyclotron (1) to emit the intermediate energy high current proton beam, so that the intermediate energy high current proton beam sequentially passes through the target film (3), the first aluminum target body (22), the housing (21), and the cooling water (26), and then enters the target film (3), the first aluminum target body (22), the housing (21), and the cooling water (26). The Ge-68 nuclide is produced on the alloy capsule target (24) and then passes through the The alloy capsule target (24) is then incident on the metal sealed target (25) to produce a PET nuclide; 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).

2. The solid target system according to claim 1, characterized in that: Said The alloy capsule target (24) comprises: A first metal base layer (241), wherein a first circular groove is formed at the top of the first metal base layer (241); one an alloy layer (243), disposed in the first circular groove 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.

3. The solid target system according to claim 1, characterized in that: Said The 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 formed at one opposite end thereof, and a metal protective coating (245) being provided on an inner wall of the first circular groove; two An alloy layer (243) is respectively disposed in the first circular grooves 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.

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 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.

7. The solid target system according to claim 1, characterized in that: The material of the target layer (254) is , , , , Any one of .

8. The solid target system according to claim 1, characterized in that: When the metal sealing target (25) is fixed in the housing (21), the second metal cover plate layer (256) faces the Alloy capsule target (24).

9. The solid target system according to claim 1, characterized in that: The PET nuclides include , , , and .

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