Manufacturing process for a component for the production of Astat-211, component and use

Abstract

The invention relates to a method for manufacturing a component (6) with a target (7) formed from bismuth for the production of Astat-211, characterized in that powder (3) formed from bismuth is pressed in a press (1) under the application of heat. The invention relates to a component that can be manufactured according to the method, and to the use of the component on a cyclotron for the production of Astat-211.

Description

[0001] The invention relates to the fabrication of a component with a target for the production of Astat-211 at the cyclotron. The invention also relates to a component fabricated according to the method and its use.

[0002] Astat-211 is a radioactive isotope of the element astatine. Astat-211 has a relatively short half-life of approximately 7.2 hours. It decays via alpha emission. Alpha particles possess high energy but have a very short range in tissue. This allows for the targeted destruction of cancer cells without significantly damaging the surrounding healthy tissue.

[0003] Astat-211 can be produced at a cyclotron using a bismuth-based target. The cyclotron accelerates charged particles to high energies. These accelerated particles are then directed onto the target to produce Astat-211.

[0004] The object of the invention is to manufacture a component with a target with which Astat-211 can be efficiently produced.

[0005] The object of the invention is achieved by a method with the features of the first claim. The dependent claim relates to a component manufactured according to the method. The dependent claims relate to advantageous embodiments.

[0006] To solve the problem, bismuth powder can be compressed in a press. Heat can be applied during and / or after the compression process to further improve the results. The heat allows the workpiece to achieve its final shape. The temperature during heat application can remain below the melting point of bismuth, so the powder material does not melt. A heating device can be provided for this purpose.

[0007] With minimal technical effort, a target can be produced with a surface that allows for good thermal contact for cooling. If adequate cooling is achieved, Astat-211 can be produced with high efficiency. In particular, no post-processing of the surfaces is required to obtain a high-performance target.

[0008] During manufacturing, the powder material does not melt, or at least not completely. This inherently leads to a characteristic porosity in the material. Porosity reduces the target's thermal conductivity. Reduced thermal conductivity hinders cooling. Insufficient cooling capacity results in poor target performance for the production of Astat-211. Therefore, porosity in the material is undesirable.

[0009] The inventors have discovered that the porosity in the material can be kept so low by compressing the powder under heat that there is no practically relevant deterioration in the target's thermal conductivity. It is therefore possible to produce a target capable of efficiently manufacturing Astat-211 by compressing the powder under heat. The surface properties of such a target are particularly advantageous, as they enable good thermally conductive contact.

[0010] Since the shape of a press can be easily modified, the manufacturing process can be adapted to desired shapes with minimal technical effort. The target's shape can therefore be easily adjusted to fit a cyclotron holder. The target's dimensions can also be easily adjusted.

[0011] The target can be a disc that appears circular when viewed from above. The target can also be a disc that appears square or polygonal when viewed from above.

[0012] The target can be at least 0.1 mm thick. The target cannot be thicker than 1 mm, 0.5 mm, or 0.3 mm.

[0013] The target can be pressed with a pressure of at least 5 tons, at least 10 tons, at least 20 tons, or at least 30 tons. The maximum possible pressure is generally limited solely by the maximum technically possible pressing force of the press used. The target can be treated with a temperature of at least 100 °C, at least 150 °C, or at least 200 °C during its production. Alternatively, the target can be treated with a temperature of no more than 270 °C, no more than 250 °C, or no more than 220 °C during its production. The lower limit of the temperature can be chosen such that the green body obtained by pressing is sintered.

[0014] The target should be thin to allow for rapid cooling. Therefore, after compression, the target should be no thicker than 5 mm, 1 mm, or 0.5 mm. However, the target should not be too thin to efficiently produce Astat-211. Therefore, after compression, the target should be no thinner than 0.1 mm or 0.5 mm.

[0015] The target can be applied to a metal substrate. The substrate can mechanically stabilize the component. The substrate can be cooled during the production of Astat-211 to prevent the target from melting. Therefore, the target should have good thermal contact with the substrate to allow for adequate cooling.

[0016] The powder can be compressed together with the support. This compression creates a particularly efficient thermal interface between the support and the target. The target can then be cooled effectively during the production of Astat-211. Therefore, Astat-211 can be further improved and produced with exceptional efficiency.

[0017] The support can be made of metal. The support can be a solid piece. The shape and / or strength of the support are generally not, or at least hardly, altered by the pressing process. The support can be made of aluminum or copper. Aluminum and copper are soft metals compared to iron, with good thermal conductivity. These properties mean that a particularly suitable target can be produced by pressing with the support, which can be effectively cooled.

[0018] Heat can be applied during and / or after pressing the film to the target. This heat treatment can further improve the thermally conductive bond between the target and the film, thereby increasing the component's performance.

[0019] Pressure ranges and temperature ranges can be selected in the same way as they were selected when compressing the powder.

[0020] The carrier can be at least 0.5 mm thick to be mechanically stable enough. The carrier cannot be thicker than 3 mm to ensure adequate cooling of the target.

[0021] During the production of Astat-211, Astat-210 can also be formed in addition to the desired Astat-211. This can occur if the charged particles (alpha particles) are accelerated to excessively high energies. The formation of Astat-210 must be avoided because it decays into the radiotoxic Po-210.

[0022] If a cyclotron cannot vary the energy of charged particles, their energy can be reduced by absorption in a suitable material before they reach the target. Therefore, a foil of appropriate thickness can be placed in front of the target. For example, the foil can be at least 1 µm or at least 2 µm thick. The foil can also be no more than 20 µm or no more than 30 µm thick.

[0023] The foil can be made of aluminum. This reduces the energy of the charged particles, thus suppressing the formation of Astat-210. The foil can either be mounted at a certain distance from the target or applied directly to the target.

[0024] Once the film is applied to the target, there is direct contact between the target and the film. This direct contact has the advantage that the film can be cooled together with the target. Therefore, it is not necessary to cool the film separately to prevent it from melting. Good thermal contact between the film and the target should then be present. The surface of the target, created by the compaction of the powder, contributes to this particularly good thermally conductive contact.

[0025] Furthermore, the use of a foil can prevent Astat-211 from escaping unintentionally during production.

[0026] After the powder is compacted, the resulting target can be pressed with a foil. The foil can be made of aluminum. This foil can serve to reduce the energy of particles during the production of Astat-211. The foil can then be placed on the front of the target, where the particles impact during Astat-211 production. A support can be placed on the back of the target during the pressing process with the foil. This pressing creates a particularly good thermally conductive contact between the target and the foil.

[0027] The invention also relates to a component for the production of Astat-211, which can be manufactured according to one of the aforementioned methods. The component can comprise a carrier. The carrier can be made of metal. The component can comprise a target. The target can be applied to the carrier. The target can be made of bismuth. The target can have microscopically small pores. The carrier can be free of microscopically small pores.

[0028] Microscopic pores are pores that can only be made visible through microscopic analysis. They are not visible to the naked eye. These microscopic pores can be visualized using scanning electron microscopy (SEM).

[0029] The invention also relates to the use of the component on a cyclotron for the production of Astat-211.

[0030] They show Fig. 1: Press for manufacturing processes; Fig. 2: manufactured component; Fig. 3: Mounting bracket with component during Astat-211 production; Fig. 4: Component with foil.

[0031] The Fig. Figure 1 shows a cross-sectional sketch of a press 1, inside which a carrier 2 can be located. Powder 3 can be located inside the press 1. The powder 3 can be on the carrier 2. The powder 3 and the carrier 2 can be compressed using a press ram 4 of the press 1. The press 1 can include a heating device 5 to heat the interior of the press 1 during the pressing process. The press ram 4 can have a polished surface to obtain a particularly suitable surface finish on the target.

[0032] The purity level of the bismuth powder can be at least 99%, or at least 99.9%, or at least 99.99% in order to obtain a particularly high-performance target.

[0033] In the Fig. Figure 2 shows a manufactured component 6, comprising a carrier 2 and a target 7. The target 7 can consist of compressed powder and therefore still contain microscopically small pores.

[0034] In the Fig. Figure 3 shows a bracket 8 with a component 6 attached to it. The component 6 can be screwed or clamped to the bracket 8. The bracket 8 can have an opening adjacent to the support 2 of the component 6. A cooling fluid can pass through this opening to the support 2 in order to cool the support 2 and thus the target 7. The bracket 8 can be part of a channel 9 through which a cooling fluid can flow during the production of Astat-211. The bracket 8 can be arranged on a cyclotron. A particle beam 10 can strike the target 7 from the cyclotron, preferably at an acute angle, so that a thin target 7 is sufficient and yet a sufficiently long path is allowed for efficient Astat-211 production, which the particles of the particle stream 10 can traverse in the target 7.

[0035] Alternatively or additionally, a target can be cooled from the front using a gas stream. The gas can, for example, consist of helium.

[0036] The target material, i.e., Target 7, can consist of bismuth-209 (Bi-209), the stable isotope of the element bismuth. Bismuth-209 can be converted into astatine-211 by bombardment with alpha particles. After the reaction has taken place in the target, the resulting astatine-211 can be extracted from the material of Target 7. After extraction, Target 7 is generally not reused. In other words, it is not reused, at least not in principle.

[0037] A particle beam 10 coming from the cyclotron can also strike target 7 perpendicularly. This can be done for practical reasons. However, the yield of Astat-211 is then usually lower.

[0038] In the Fig. Figure 4 shows a component 6 that additionally includes a foil 11. The foil 11 can be made of aluminum. The foil 11 may have been pressed onto the target 7 using a press. Press 1, which was already used according to [reference to relevant section], may have been used. Fig. 1 was previously used for compressing the powder 3.

Claims

[1] Method for manufacturing a component (6) with a bismuth-based target (7) for the production of Astat-211, characterized by , that powder (3) formed from bismuth is pressed in a press (1) with the application of heat. [2] Method according to claim 1, characterized by , that the powder (3) is pressed together with a metal carrier (2). [3] Method according to the preceding claim, characterized by that the support (2) is made of aluminium or copper. [4] Method according to any one of the preceding claims, characterized by that it is pressed with a pressure of at least 10 tons. [5] Method according to any one of the preceding claims, characterized by , that during or after pressing the target (7) is brought to a temperature that is less than 240°C and more than 200°C. [6] Method according to any one of the preceding claims, characterized by, that after pressing the target (7) is pressed with a film (11). [7] Method according to the preceding claim, characterized by , that the foil (11) is made of aluminium. [8] Method according to any one of the preceding claims, characterized by that heat is applied during and / or after the pressing process. [9] Component for the production of Astat-211, producible according to a method according to one of the preceding claims, comprising a metal carrier (2), comprising a bismuth target (7) on the carrier (2), characterized by that the target has microscopically small pores. [10] Use of the component according to the preceding claim on a cyclotron for the production of Astat-211.

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