226Ra isotope target for producing 225Ac and application thereof

Abstract

The invention relates to the design of a radium target for preparing 225Ac through a photo-nuclear reaction in the technical field of production of a mechanical produced medical isotope 225Ac, in particular to a 226Ra isotope target for producing 225Ac and application of the 226Ra isotope target. The 226Ra isotope target comprises a nickel substrate, a 226Ra isotope sample, a nickel electroplated layer and a nickel protective shell; wherein the 226Ra isotope samples are uniformly concentrated at the central position of the nickel substrate, the nickel electroplated layer covers the outer surfaces of the 226Ra isotope samples, and the nickel substrate and the nickel electroplated layer wrap the 226Ra isotope samples in the middle; and the nickel protective shell wraps the nickel electroplated layer. The 226Ra isotope target can be applied to an electron linear accelerator and can be used as a raw material target for producing 225Ac through a photo-nuclear reaction, and the production quantity of the 225Ac isotope can be increased.

Description

Technical Field

[0001] The present invention relates to an apparatus for producing medical isotopes 225 Ac production technology in the photonuclear reaction preparation 225 Ac radium target design, specifically involving a method for producing 225 Ac 226 Ra isotope targets and their applications. Background Art

[0002] Radionuclides used for targeted tumor therapy usually use beta decay nuclides, alpha decay nuclides, and Auger electron decay nuclides. The energy transfer line density of alpha particles is close to the optimal energy transfer line density value of radiation therapy (100 keV / μm), and the range in soft tissue is about 30-80 μm, which is equivalent to the diameter of 5 to 10 tumor cells. It can effectively kill tumor cells while minimizing damage to adjacent normal tissue cells. Therefore, alpha nuclide targeted therapy drugs have good application prospects for microtumors, scattered tumors, and micrometastatic tumors.

[0003] Limited by the strict requirements of radiopharmaceuticals on the half-life, radioactivity purity, pharmacokinetics and stability of radionuclide carriers, the only α-radioactive nuclides found to be suitable for treatment are 225 Ac, 223 Ra, 211 At 212 Pb, 149 Tb, 212 Bi, 213 Bi, 227 Th, 230 U and a few others. Among them, 225 Ac and its daughter nuclei can emit four alpha particles with energies of 5.5MeV to 8.4MeV during the decay process. As one of the emerging and most promising alpha therapeutic nuclides, Ac can be used in the development of emerging targeted alpha therapeutic drugs. As one of the rarest medical isotopes known, 225 The preparation, production and supply of Ac are much more difficult than those of common medical radionuclides.

[0004] at present 225 There are several main ways to produce Ac: (1) through a thorium-actinium generator. 229 Th decays naturally to produce no carrier 225 Ac; (2) Low-energy proton reaction in radium target, using proton accelerator 226 Ra isotope target production 225 Ac, the nuclear reaction formula is 226 Ra(p, 2n)→ 225 Ac; (3) Thorium target high energy proton reaction, bombardment with protons 232 Th target production225 Ac, the nuclear reaction formula is 232 Th(p, x) 225 Ra → 225 Ac; (4) radium target photonuclear reaction, using high-energy gamma rays generated by electron accelerator through conversion target 226 Ra isotope target production 225 Ac, the nuclear reaction formula is 226 Ra(γ, n) 225 Ra → 225 Ac; (5) based on fast reactor preparation 225 Ac, the nuclear reaction formula is 226 Ra(μ - , nν) 225 Fr → 225 Ac; currently disclosed in the prior art 225 The annual output of Ac basically does not exceed 2 Curies. 225 The high-cost production of Ac requires the use of an electron linear accelerator to irradiate the radium target. However, under the irradiation of the neutron source of the electron linear accelerator, the thermal deposition energy density in the isotope target is very large, but the melting point of the radium element is low, only 963K, and the softening temperature is even lower; in addition, radium is a second main group element, and its chemical properties are very active. It is easily oxidized in the air to form radium oxide, and combined with water and carbon dioxide in the air to form radium carbonate. And the radium element will continue to decay and release radioactive gas radon-222 (Rn-222), which will continue to accumulate and cause environmental pollution and irreversible damage to the human body. Therefore, radium materials cannot be used alone as targets for the preparation of medical isotopes. How to design an effective radium target structure is a technical difficulty that needs to be solved. Summary of the invention

[0005] The present invention is directed to using an electron linear accelerator to 226 Ra isotope is used as raw material and produced by photonuclear reaction 225 Ac medical isotope technology, 226 Ra single substance has defects in physical properties as a target material. A method for producing 225 Ac 226 Ra isotope target, the 226 The Ra isotope target is a capsule-shaped target material. 226 Ra isotope targets can be used to produce electron linear accelerators with an energy of 35 MeV and a current of 2 mA. 225 Ac isotope, and 225 The annual production of Ac isotopes can reach more than 100 Ci.

[0006] One for production 225 Ac 226 Ra isotope target, the226 The Ra isotope target comprises a nickel substrate, 226 Ra isotope sample, nickel electroplating layer and nickel protective shell; wherein, 226 The Ra isotope sample is evenly concentrated in the center of the nickel substrate, and the nickel electroplating layer covers 226 Ra isotope sample outer surface, and the nickel substrate and nickel electroplating layer will 226 The Ra isotope sample is wrapped in the middle; the nickel protective shell covers the surface of the nickel electroplating layer.

[0007] Furthermore, the thickness of the nickel substrate ranges from 20 micrometers to 2 millimeters.

[0008] Furthermore, the 226 The thickness of the Ra isotope samples ranges from 10 μm to 3 mm.

[0009] Furthermore, the thickness of the nickel electroplating layer ranges from 10 micrometers to 10 millimeters.

[0010] Furthermore, the thickness of the nickel protective shell ranges from 10 micrometers to 10 millimeters.

[0011] On the other hand, the present invention provides a 226 Ra isotope target production 225 Ac application, specifically, using an electron beam to 226 The Ra isotope target is irradiated for 2 hours to 10 days, so that the 226 Ra isotope target output isotope 225 Ac.

[0012] Furthermore, the energy of the electron beam is 35 MeV, and the current intensity is 2 mA.

[0013] Furthermore, the 226 The number of the Ra isotope targets is at least one.

[0014] Further, using an electron beam to 226 The irradiation time of the Ra isotope target is 20 hours to 10 days.

[0015] Furthermore, the 226 The number of Ra isotope targets is one, two or four; and all 226 The center of the Ra isotope target is in a straight line with the center of the electron beam spot.

[0016] Technical effects: (1) The present invention adopts a nickel-radium-nickel-nickel capsule target structure design, which can effectively encapsulate 226 Ra isotope samples can avoid irradiation 226Ra raw materials are washed away by the surrounding cooling water, resulting in loss, which can improve the precious target material 226 The utilization rate of Ra.

[0017] (2) The capsule structure adopted by the present invention effectively protects 226 At the same time, the Ra isotope target material is made of nickel, a material with high thermal conductivity, because the substrate and protective shell are made of nickel, when the radium target is irradiated by the beam, 226 The Ra isotope target sample was cooled well.

[0018] (3) Using the design of the present invention 226 Ra isotope target structure can make 226 The radon produced by the decay of Ra is contained between the nickel substrate and the nickel electroplating layer and does not leak into the environment, thus playing a role in protecting the environment and the human body.

[0019] (4) Using the design of the present invention 226 The Ra isotope target structure can be irradiated with electron beams with energies greater than 10 MeV, which can greatly improve 225 Production of Ac isotopes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention 226 Schematic diagram of the working of Ra isotope target in the terminal target area of ​​the electron beam.

[0021] Figure 2 The present invention 226 Schematic diagram of the cross-sectional structure of the Ra isotope target.

[0022] Figure 3 Is to use one, two, four pieces of the present invention 226 After the Ra isotope target was irradiated for 20 hours in an electron linear accelerator with an energy of 35 MeV and a flux of 2 mA, 225 Activity change curve of Ac isotope as the cooling days increase.

[0023] Figure 4 Is to use a piece of the present invention 226 After the Ra isotope target was irradiated for 20 hours and 10 days respectively under an electron linear accelerator with an energy of 35 MeV and a flux of 2 mA, 225 Activity change curve of Ac isotope as the cooling days increase.

[0024] Figure 5 Is to use a piece of the present invention 226 After irradiation of the Ra isotope target for 10 days in an electron linear accelerator with an energy of 35 MeV and a flux of 2 mA, 225 Ra and 225Activity change curve of Ac isotope as the cooling days increase.

[0025] In the figure: 1. Electron beam; 2. Target chamber; 3. Tungsten conversion target; 4. 226 Ra isotope target; 41. nickel substrate; 42. 226 Ra isotope sample; 43. Nickel electroplating layer; 44. Nickel protective shell. DETAILED DESCRIPTION

[0026] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and therefore, the present invention is not limited to the limitations of the specific embodiments disclosed below.

[0027] To improve the production of electron linear accelerator 225 Raw material target used in Ac—— 226 The physical strength of the Ra isotope target is achieved by photonuclear reaction in an electron linear accelerator with an energy of 35 MeV and a current of 2 mA. 225 The annual output of Ac exceeds 100 Ci. The present invention provides a method for producing 225 Ac 226 Ra isotope target.

[0028] One for production 225 Ac 226 Ra isotope target, the 226 Ra isotope target 4 adopts a capsule-shaped target material structure and can be used in electron linear accelerators as a photonuclear reaction production 225 Ac raw material target; 226 The Ra isotope target 4 includes a nickel substrate 41, 226 Ra isotope sample 42, nickel electroplating layer 43 and nickel protective shell 44; wherein, 226 The Ra isotope sample 42 is uniformly concentrated in the center of the nickel substrate 41, and the nickel electroplating layer 43 covers 226 The outer surface of the Ra isotope sample 42, and the nickel substrate 41 and the nickel electroplating layer 43 will 226 The Ra isotope sample 42 is wrapped in the middle; the nickel protective shell 44 covers the surface of the nickel electroplating layer 43.

[0029] Said 226 The preparation method of the Ra isotope target 4 comprises: firstly, electroplating a Ra isotope target 41 on a nickel substrate 41 226 Ra electrolyte method, will 226 The Ra isotope sample 42 is electroplated on the surface of one side of the nickel substrate 41.226 The Ra isotope sample 42 is required to have a certain thickness and be distributed within a range of 1 cm in diameter with the center of the nickel substrate 41 as the center; secondly, the nickel substrate 41 is electroplated with 226 A nickel electroplating layer 43 is continuously electroplated on one side of the Ra isotope sample 42. The nickel electroplating layer 43 has a certain thickness, and the nickel electroplating layer 43 and the nickel substrate 41 are fully covered. 226 Finally, a prefabricated nickel protective shell 44 is covered on one side of the nickel electroplating layer 43 in a snap-fit ​​manner to further 226 The Ra isotope sample 42 provides structural support and can also prevent the high-speed cooling water from washing after high-flux gamma ray target shooting. 226 Ra isotope sample 42 leaked.

[0030] like Figure 2 As shown, in this embodiment 226 The Ra isotope target 4 is a nickel substrate 41, 226 The target structure is a capsule-shaped structure consisting of a Ra isotope sample 42, a nickel electroplating layer 43, and a nickel protective shell 44. The length, width, and height of the nickel substrate 41 are 20 mm × 20 mm × 1 mm. 226 The Ra isotope material is electroplated to the center of the nickel substrate 41 to form a cylindrical shape with a uniform distribution and a diameter of 10 mm and a thickness of 2.316 mm. 226 Ra isotope sample 42; then 226 A nickel electroplating layer 43 is electroplated on one side of the Ra isotope sample 42. The length and width of the nickel electroplating layer 43 are 20 mm × 20 mm. The nickel electroplating layer 43 evenly covers 226 The thickness of the Ra isotope sample 42 is b=5 mm, and the thickness of the nickel electroplating layer 43 in contact with the nickel substrate 41 is d=1.68 mm. 226 In order to improve the structural strength and cooling effect of the Ra isotope target 4, a nickel protective shell 44 is covered on one side of the nickel electroplating layer 43. The length × width dimensions of the nickel protective shell 44 are 25 mm × 25 mm. The thickness of the portion where the nickel protective shell 44 connects with the bottom surface of the nickel electroplating layer 43 is c = 1 mm, and the thickness of the portion where the nickel protective shell 44 connects with the nickel substrate 41 is a = 5 mm.

[0031] The present invention adopts capsule type 226 The structure of Ra isotope target 4 can be produced by electron linear accelerator target shooting 225 In the application of Ac, nickel is used as a material with excellent thermal properties, high strength and corrosion resistance. 226 The structural support material of Ra isotope target 4 effectively supports the 226Ra isotope sample 42; In addition, through simulation calculation, the capsule 226 Ra isotope target 4 can be used in electron linear acceleration with energy of 35MeV and current of 2mA. 225 The annual output of Ac has increased to more than 100 times.

[0032] The present invention is used to produce 225 Ac 226 The working position of the Ra isotope target 4 in the target chamber 2 of the electron linear accelerator is shown in FIG. Figure 1 As shown, the target chamber 2 contains a tungsten conversion target 3 and the target of the present invention. 226 Ra isotope target 4; tungsten conversion target 3 is used to convert the electrons emitted by the electron accelerator into photons, generating bremsstrahlung radiation, thereby 226 Ra isotope target 4 is irradiated to produce 225 Ac. The present invention 226 One to four Ra ​​isotope targets 4 can be used in the target chamber 2. In this embodiment, one, two, and four Ra ​​isotope targets are used respectively. 226 Ra isotope target 4 electron linear accelerator 225 The Ac production effect was tested; three tungsten conversion targets 3 were used in the target chamber 2, and the thickness of each tungsten conversion target 3 was 1 mm. 226 The Ra isotope target 4, the three tungsten conversion targets 3, the target chamber 2, and the beam spot center of the electron beam 1 are in a straight line. 226 When one, two, and four Ra ​​isotope targets 4 are used, each 226 The masses of the Ra isotope samples 42 are 1 g, 0.5 g, and 0.25 g, respectively. 226 The spacing between the Ra isotope targets 4 is 1.5 mm. 226 The distance between the Ra isotope sample 42 and the nearest tungsten conversion target 3 is 2 mm, and the distance between adjacent tungsten conversion targets 3 is 1.5 mm. The overall size of the target chamber 2 is 60.0 mm×60 mm×77.5 mm. The parameters of the electron beam 1 are energy of 35 MeV, current intensity of 2 mA, beam spot distribution of Gaussian type, and spatial distribution half-height width of 15 mm.

[0033] Use one, two, or four pieces of the present invention respectively 226 After the Ra isotope target 4 is irradiated for 20 hours in the electron beam 1 drawn from the electron linear accelerator, 225 The activity of Ac isotopes changes with cooling days. Figure 3 When the cooling time is 15 days, one, two, or four tablets are used. 226 Ra isotope target 4 225 The total yields of Ac were 0.18Ci, 0.17Ci and 0.13Ci respectively, using one piece226 Ra isotope target 4 225 Ac has the highest yield.

[0034] Then use a 226 The Ra isotope target 4 was irradiated in the electron beam 1 from the electron linear accelerator for 20 hours and 10 days respectively. 225 The results of the variation of Ac yield activity with cooling days are as follows: Figure 4 When the cooling days are 15 days, 225 The yield of Ac reached the highest level when irradiated for 20 hours and 10 days 225 The Ac yields are 0.18Ci and 2.12Ci respectively, so the best irradiation time is 10 days.

[0035] After one irradiation, 226 The isotopes produced in the Ra isotope target 4 are not only 225 Ac, also contains its parent nucleus 226 Ra, such as Figure 5 As shown, therefore 225 The calculation of the total yield of Ac should take into account 226 The yield of Ra and the impact of subsequent extraction process. The extraction is carried out by a stage extraction method known in the art. 226 The first test was carried out 15 days after the Ra isotope target 4 was irradiated by electron beam current 1. 225 Ac was separated and extracted, and then the 225 The second extraction of Ac was carried out 15 days later for the final 225 The extraction of Ac, if calculated based on the theoretical value that the efficiency of each extraction reaches 100%, the extraction efficiency of three consecutive extractions is 225 The total activity of Ac is close to the end of irradiation. 225 Total activity of Ra. Figure 5 It can be seen that after 10 days of irradiation 226 Ra isotope target 4 225 The activity of Ra is 3.91 Ci. If the electron accelerator with energy of 35 MeV and current of 2 mA is used for 300 days per year, 117.3 Ci can be extracted. 225 Ac isotope.

Claims

1. A kind of product for production 225 Ac 226 The Ra isotope target is characterized by: Said 226 The Ra isotope target comprises a nickel substrate, 226 Ra isotope sample, nickel electroplating layer and nickel protective shell; wherein, 226 The Ra isotope sample is evenly concentrated in the center of the nickel substrate, and the nickel electroplating layer covers 226 Ra isotope sample outer surface, and the nickel substrate and nickel electroplating layer will 226 The Ra isotope sample is wrapped in the middle; the nickel protective shell wraps the nickel electroplating layer.

2. The method for producing the 225 Ac 226 The Ra isotope target is characterized by: The thickness of the nickel substrate ranges from 20 micrometers to 2 millimeters.

3. The method for producing the 225 Ac 226 The Ra isotope target is characterized by: Said 226 The thickness of the Ra isotope samples ranges from 10 μm to 3 mm.

4. The method for producing the 225 Ac 226 The Ra isotope target is characterized by: The thickness of the nickel electroplating layer ranges from 10 micrometers to 10 millimeters.

5. The method for producing the 225 Ac 226 The Ra isotope target is characterized by: The thickness of the nickel protective shell ranges from 10 micrometers to 10 millimeters.

6. The method according to any one of claims 1 to 5 226 Ra isotope target production 225 The application of Ac is characterized by: Using electron beam current 226 The Ra isotope target is irradiated for 2 hours to 10 days, so that the 226 Ra isotope target output isotope 225 Ac.

7. According to claim 6 226 Ra isotope target production 225 The application of Ac is characterized by: The energy of the electron beam is 35 MeV and the current intensity is 2 mA.

8. According to claim 6 226 Ra isotope target production 225 The application of Ac is characterized by: Said 226 The number of the Ra isotope targets is at least one.

9. The method according to claim 6 226 Ra isotope target production 225 The application of Ac is characterized by: Using electron beam current 226 The irradiation time of the Ra isotope target is 20 hours to 10 days.

10. The method according to claim 8 226 Ra isotope target production 225 The application of Ac is characterized by: Said 226 The number of Ra isotope targets is one, two or four; and all 226 The center of the Ra isotope target is in a straight line with the center of the electron beam spot.

Images