Radionuclide separation and recovery method and apparatus

Abstract

To provide a radionuclide separation and recovery method and apparatus that can suppress the mixed amount of impurities, such as a target material, during the separation and recovery of radionuclides.SOLUTION: A radionuclide separation and recovery method includes: a target material heating step of heating a target material to gasify radioactive isotopes; a target material component removal step of removing target material components volatilized from the target material; an aerosol generation step of generating aerosols; a transport step of adhering the radioactive isotopes to the aerosols and transporting them; and a recovery step of recovering the radioactive isotopes transported by the transport step.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method for separating and recovering radioactive nuclides and an apparatus for separating and recovering radioactive nuclides. [Background technology]

[0002] In cancer treatment, radionuclides that emit alpha rays are attracting attention. Compared to other types of radiation, alpha rays use up their energy over a short distance, so when used on cancer cells, they have the advantage of causing greater damage to the cancer cells while causing less damage to normal cells. By combining radionuclides that emit alpha rays with targeted drugs, it is possible to selectively attack cancer cells and achieve high effectiveness. For this reason, various radioisotopes that emit alpha rays are being considered for use as drugs.

[0003] Astatine-211 has a short half-life of 7.2 hours and decays rapidly into stable nuclides, which has the advantage of shortening the treatment time, making it one of the radioisotopes most promising for use as a drug.

[0004] Astatine-211 has a short half-life and is produced using an accelerator. From the viewpoint of availability and ease of handling of raw materials, it is mainly produced by irradiating accelerated helium ions onto bismuth.

[0005] Astatine-211 is separated from bismuth, recovered, and then synthesized into a pharmaceutical product. However, because its half-life is short at 7.2 hours, if the separation, recovery, and pharmaceutical production take a long time, the amount of astatine-211 produced decreases, which increases the production cost. For this reason, there is a demand for separation, recovery, and pharmaceutical production in a short time.

[0006] A separation technology that utilizes the difference in melting and boiling points between the target material, bismuth, is used as a quick and simple separation method. Conventionally, separation and recovery are performed as follows: An aerosol is introduced, the target material is heated to evaporate astatine-211, and the astatine-211 is then attached to the aerosol. The aerosol is transported to a room temperature filter via piping, etc., and the astatine-211-attached aerosol is captured and recovered by the filter.

[0007] However, this conventional method has the problem that when the astatine-211 is heated, gasified, and separated, the bismuth also evaporates and is transported together with the astatine-211, resulting in a large amount of bismuth being mixed into the product. If the amount of bismuth mixed in is large, it is possible that the synthesis rate will decrease during labeling of the targeted drug, which is undesirable. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2015 / 195042 [Patent Document 2] International Publication No. 2019 / 088113 [Patent Document 3] International Publication No. 2019 / 112034 [Non-patent literature]

[0009] [Non-Patent Document 1] E. Aneheim, “Automated astatination of biomolecules - a stepping stone towards multicenter clinical trials,” Science Reports, 2015. Summary of the Invention [Problem to be solved by the invention]

[0010] As described above, when radioactive nuclides such as astatine isotopes are heated and gasified, and then separated and recovered, there is a problem in that a large amount of target material is mixed in.

[0011] The present invention has been made in response to the above-mentioned conventional problems, and an object of the present invention is to provide a method for separating and recovering radioactive nuclides and an apparatus for separating and recovering radioactive nuclides, which can reduce the amount of impurities such as target materials mixed in when separating and recovering radioactive nuclides including astatine isotopes. [Means for solving the problem]

[0012] One aspect of the radioactive nuclide separation and recovery method of the present invention is characterized by comprising a target material heating step of heating a target material to gasify radioactive isotopes, a target material component removal step of removing target material components that have volatilized from the target material, an aerosol generation step of generating an aerosol, a transport step of attaching the radioactive isotopes to the aerosol and transporting them, and a recovery step of recovering the radioactive isotopes transported by the transport step.

[0013] One aspect of the radioactive nuclide separation and recovery device of the present invention is characterized by comprising a target material heating mechanism that heats a target material to gasify radioactive isotopes, a target material component removal mechanism that removes target material components that have volatilized from the target material, an aerosol generation mechanism that generates an aerosol, a transport unit that attaches the radioactive isotopes to the aerosol and transports them, and a recovery mechanism that recovers the radioactive isotopes transported by the transport unit. Effect of the Invention

[0014] According to an embodiment of the present invention, it is possible to provide a radioactive nuclide separation and recovery method and a radioactive nuclide separation and recovery device that can reduce the amount of impurities such as target materials mixed in when separating and recovering radioactive nuclides including astatine isotopes. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a flow diagram showing a radioactive nuclide separation and recovery method according to a first embodiment. [Diagram 2] FIG. 1 is a block diagram showing a schematic configuration of a radioactive nuclide separation and recovery device according to a first embodiment. [Diagram 3] FIG. 1 is a flow diagram showing a radioactive nuclide separation and recovery method according to a first embodiment. [Figure 4] FIG. 1 is a flow diagram showing a radioactive nuclide separation and recovery method according to a first embodiment. [Diagram 5] FIG. 5 is a flow diagram showing a radioactive nuclide separation and recovery method according to a second embodiment. [Figure 6] FIG. 11 is a block diagram showing a schematic configuration of a radioactive nuclide separation and recovery apparatus according to a second embodiment. [Figure 7] FIG. 11 is a flow diagram showing a radionuclide separation and recovery method according to a third embodiment. [Figure 8] FIG. 11 is a block diagram showing a schematic configuration of a radioactive nuclide separation and recovery apparatus according to a third embodiment. [Figure 9] FIG. 1 is a flow diagram showing a conventional method for separating and recovering radioactive nuclides. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a radioisotope production method and a radioisotope production apparatus according to an embodiment will be described with reference to the drawings.

[0017] (First embodiment) First, the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a flow diagram showing a radionuclide separation and recovery method of the first embodiment, and Figure 2 is a block diagram showing a schematic configuration of a radionuclide separation and recovery apparatus 10 of the first embodiment.

[0018] As shown in Fig. 2, the radionuclide separation and recovery apparatus 10 of the first embodiment includes a target material heating mechanism 11. The target material heating mechanism 11 is connected to an aerosol generation mechanism 12, which is connected to a carrier gas supply mechanism 13. A carrier gas (e.g., nitrogen gas, argon gas, helium gas, etc.) is supplied from the carrier gas supply mechanism 13, and this carrier gas passes through the aerosol generation mechanism 12 and flows into the target material heating mechanism 11 together with an aerosol. In the aerosol generation mechanism 12, a predetermined aerosol component, for example, an aerosol component such as KCl, NaCl, NaOH, etc., is heated to generate an aerosol, and the generated aerosol is generated in the radionuclide separation and recovery apparatus 10. The aerosol is, for example, a particle having a particle size of about 1 nm to about 1 µm.

[0019] In addition, a target material component removal mechanism 14 is connected to the target material heating mechanism 11 so as to be downstream of the flow of the above-mentioned carrier gas, a transport unit 15 is connected downstream of the target material component removal mechanism 14, and a recovery mechanism 16 is connected downstream of the transport unit 15. In addition, the radionuclide separation and recovery device 10 is equipped with pressure gauges 17 and 18 for measuring the internal pressure.

[0020] In the target material heating mechanism 11, the target material is heated to a high temperature in order to evaporate and release the target radioactive nuclide from the target material. For example, when using bismuth as the target material to produce astatine-211 as a radioactive nuclide, in order to evaporate and release astatine from bismuth, it is necessary to heat the bismuth target to a predetermined temperature, for example, a temperature of 337°C or higher, which is the boiling point of astatine, and a temperature of 400°C to 500°C or lower. In this case, the components of the target material (bismuth) evaporate (gasify) together with the radioactive nuclide, and some of them may become aerosol-like when cooled and move to the collection section. For this reason, in the first embodiment, a target material component removal mechanism 14 is provided.

[0021] Fig. 1 is a flow diagram showing the steps of a method for separating and recovering radioactive nuclides using the radioactive nuclide separation and recovery device 10 having the above-mentioned configuration. As shown in Fig. 1, the method for separating and recovering radioactive nuclides of the first embodiment includes an aerosol generation step (101) for generating an aerosol in the aerosol generation mechanism 12, a target material heating step (102) for heating the target material in the target material heating mechanism 11 to gasify the radioactive isotopes, a target material component removal step (103) for removing target material components volatilized from the target material in the target material component removal mechanism 14, a transport step (104) for attaching the radioactive isotopes to the aerosol and transporting them, and a recovery step (105) for recovering the transported radioactive isotopes.

[0022] According to the radionuclide separation and recovery method of the first embodiment having the above-mentioned configuration, the target material component removal step (103) for collecting the components of the evaporated (gasified) target material is included, so that the target material can be removed before the recovery step (105). For comparison, FIG. 9 shows a flow diagram of a conventional radionuclide separation and recovery method. As shown in FIG. 9, the conventional method does not include a step corresponding to the target material component removal step (103) in the first embodiment shown in FIG. 1.

[0023] In the first embodiment, various mechanisms can be used as the target material component removal mechanism 14 for removing the vaporized target material components. As an example, as shown in FIG. 3, a remover such as a material that alloys with the vaporized target material components can be used to perform the target material component removal step (103a) using the remover. In this case, the remover reacts with the target material components to form an alloy, which is removed from the gas phase. The remover preferably has a high melting point and is not highly toxic to the human body as an impurity. If the melting point is low, there is a concern that the remover components will melt and volatilize, increasing the amount of impurities. Also, impurities that are highly toxic to the human body are not preferable because even a small amount of impurity can be harmful.

[0024] In the case of astatine, bismuth is used as the target material. Various materials that can be alloyed with bismuth are known. In order to evaporate and release astatine from bismuth, as described above, it is necessary to heat it to a temperature of, for example, about 400°C to 500°C. Therefore, when the target material is bismuth, examples of materials that do not melt at the above temperature and have low toxicity include Al, Ag, Au, Pt, Cu, Ni, Zn, Y, Tm, Sn, etc. By using these as a single element or an alloy as a remover, it is possible to alloy the vaporized bismuth with the remover and remove the bismuth from the gas phase.

[0025] However, the remover is not limited to these and can be any material that does not evaporate easily and is not highly toxic to the human body. There are no restrictions on the structure of the remover, but it is preferable to use a honeycomb structure or a filter shape with fine holes that allows gas to flow and react easily. If a filter shape with fine holes is used, the pores should preferably be of a size that does not trap aerosols (1 μm or less) that bind to radioactive nuclides, and it is preferable to use pores with a diameter of, for example, 100 μm or more.

[0026] Alternatively, instead of using the above-mentioned removal agent, the target material component removal step (103b) may be performed using, for example, a filter capable of removing target material components and not trapping aerosols (1 μm or less) that bind to radioactive nuclides, as shown in FIG. 4.

[0027] Second embodiment Next, a second embodiment will be described with reference to Figures 5 and 6. Figure 5 is a flow diagram showing a radionuclide separation and recovery method of the second embodiment, and Figure 6 is a block diagram showing a schematic configuration of a radionuclide separation and recovery device 20 of the second embodiment. In Figures 5 and 6, the same reference numerals are used for parts corresponding to those in Figures 1 and 2 described above, and duplicated explanations will be omitted.

[0028] In the first embodiment shown in Figures 1 and 2, the aerosol is supplied when the target material is heated, but in the second embodiment, as shown in Figures 5 and 6, the aerosol is supplied after the target material heating step. That is, the aerosol is supplied after the target material heating step (102) and the target material component removal step (103).

[0029] In this case, the method of removing the target material components in the target material component removal mechanism 14 and the target material component removal step (103) can be other methods in addition to the method using a remover that alloys with the vaporized target material components as in the first embodiment or the method using a filter.

[0030] For example, by performing a cooling step (103c) in which evaporated (gasified) components of the target material generated from the target material are cooled by the cooling mechanism 14a, precipitation occurs on the surface of the cooling mechanism 14a or precipitation and grain growth occurs in the gas phase. The target material is then removed from the gas phase by precipitation on the surface of the cooling mechanism 14a or by thermophoresis of particles. In this case, the physical amount of the radioactive nuclides is small and they do not precipitate even at room temperature, so the impact on the recovery of the radioactive nuclides is small.

[0031] Furthermore, a target material component removal step 103 may be performed in which the target material precipitated by performing the cooling step (103c) is removed by a target material component removal mechanism 14 consisting of a filter having fine holes. In this case, as shown in Fig. 5, if the target material component removal step 103 is performed before the addition of the aerosol from the aerosol generation step (101), the filter used therefor may be a filter capable of collecting the aerosol (1 µm or less). Also, even in the configuration of the second embodiment in which the aerosol is supplied after the target material heating step, the target material component removal step 103 can be performed using a remover that alloys with the target material, as in the first embodiment.

[0032] Third embodiment Next, a third embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a flow diagram showing a radionuclide separation and recovery method of the third embodiment, and Fig. 8 is a block diagram showing a schematic configuration of a radionuclide separation and recovery device 30 of the third embodiment. In Fig. 7 and Fig. 8, the same reference numerals are used for the parts corresponding to Figs. 1 to 4 described above, and duplicated explanations will be omitted.

[0033] When the aerosol is supplied after the target material is heated as in the second embodiment, an oxygen gas introduction mechanism 19 may be provided in the radioactive nuclide separation and recovery apparatus 30 as shown in FIG. 8, and an oxygen gas introduction step (106) may be provided between the target material heating step (102) and the target material component removal step (103) as shown in FIG. 7, so that oxygen gas is added to the gas generated from the target material.

[0034] When the target material is oxidized by introducing oxygen gas, the saturated vapor pressure of the oxide is lower than that of the non-oxidized material, so that the volatilized target material components cannot be gasified and precipitate when oxidized. By removing the precipitated particles using a cooling mechanism, filter, etc. in the target material component removal step (103), it is possible to prevent the components of the target material from being mixed with radionuclides such as astatine.

[0035] In the above embodiment, the target material is mainly bismuth, and the radionuclide is astatine-211. However, the present invention is not limited to this, and the present invention can be applied to the production of other radionuclides using other target materials.

[0036] Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0037] 10...radionuclide separation and recovery device, 11...target material heating mechanism, 12...aerosol generation mechanism, 13...carrier gas supply mechanism, 14a...cooling mechanism, 14...target material component removal mechanism, 15...transport section, 16...recovery mechanism, 17...pressure gauge, 18...pressure gauge, 19...oxygen gas introduction mechanism, 20...radionuclide separation and recovery device, 30...radionuclide separation and recovery device.

Claims

1. a target material heating step of heating the target material to gasify the radioisotope; a target material component removing step of removing target material components volatilized from the target material; an aerosol generating step of generating an aerosol; a transport step of attaching the radioisotope to the aerosol and transporting it; a recovery step of recovering the radioisotope transported by the transport step; A method for separating and recovering radioactive nuclides, comprising:

2. The method for separating and recovering radioactive nuclides according to claim 1, The target material component removing step uses a substance that forms an alloy with the target material component as a remover. A method for separating and recovering radioactive nuclides.

3. The method for separating and recovering radioactive nuclides according to claim 2, the target material is bismuth and the radioisotope is astatine-211; The substance used as the remover is a single element of Al, Ag, Au, Pt, Cu, Ni, Zn, Y, Tm, or Sn, or an alloy containing these elements. A method for separating and recovering radioactive nuclides.

4. The method for separating and recovering radioactive nuclides according to claim 2 or 3, The structure of the remover is a honeycomb structure. A method for separating and recovering radioactive nuclides.

5. The method for separating and recovering radioactive nuclides according to claim 2 or 3, The structure of the remover has pores. A method for separating and recovering radioactive nuclides.

6. The method for separating and recovering radioactive nuclides according to claim 2 or 3, After the target material component removing step, The radioisotope is attached to the aerosol generated in the aerosol generating step. A method for separating and recovering radioactive nuclides.

7. The method for separating and recovering radioactive nuclides according to claim 6, An oxygen gas introduction step of introducing oxygen gas before the target material component removal step. A method for separating and recovering radioactive nuclides.

8. The method for separating and recovering radioactive nuclides according to claim 6, A cooling step is performed before the target material component removing step. A method for separating and recovering radioactive nuclides.

9. a target material heating mechanism for heating the target material to gasify the radioisotope; a target material component removal mechanism for removing target material components volatilized from the target material; an aerosol generating mechanism that generates an aerosol by heating an aerosol component and generates the generated aerosol; A transport unit that transports the radioisotope by attaching it to the aerosol; a recovery mechanism that recovers the radioisotope transported by the transport unit; A radioactive nuclide separation and recovery apparatus comprising:

10. The radionuclide separation and recovery apparatus according to claim 9, The target material component removing mechanism uses a substance that forms an alloy with the target material as a remover. A radioactive nuclide separation and recovery device characterized by the above.

11. The radionuclide separation and recovery apparatus according to claim 10, the target material is bismuth and the radioisotope is astatine-211; The substance used as the remover is a single element of Al, Ag, Au, Pt, Cu, Ni, Zn, Y, Tm, or Sn, or an alloy containing these elements. A radioactive nuclide separation and recovery device characterized by the above.

12. The radionuclide separation and recovery apparatus according to claim 10 or 11, The structure of the remover is a honeycomb structure. A radioactive nuclide separation and recovery device characterized by the above.

13. The radionuclide separation and recovery apparatus according to claim 10 or 11, The structure of the remover has pores. A radioactive nuclide separation and recovery device characterized by the above.

14. The radionuclide separation and recovery apparatus according to claim 10 or 11, An oxygen gas introduction mechanism for oxidizing the target material components is provided. A radioactive nuclide separation and recovery device characterized by the above.

15. The radionuclide separation and recovery apparatus according to claim 10 or 11, A cooling mechanism for cooling the target material components is provided. A radioactive nuclide separation and recovery device characterized by the above.

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