Radioisotope manufacturing method and manufacturing device

Abstract

To provide methods and devices for producing radioisotopes that efficiently produce volatile radioisotopes including an astatine isotope.SOLUTION: A method includes: a pretreatment step for attaching a soluble substance to a collection part; a heating step for heating a target and vaporizing a radioisotope for separation; a collection step for collecting the radioisotope separated in the heating step through the collection part that has undergone the pretreatment step; and a cleaning recovery step for cleaning and recovering a radioactive substance collected in the collection step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a method and apparatus for producing a radioisotope. [Background technology]

[0002] In recent years, cancer treatment using alpha rays has been attracting attention. Because alpha rays have a short range, they can be used to selectively attack targeted cancer cells using drugs that emit alpha rays. Therefore, cancer treatment using alpha rays has the advantage of causing less damage to normal cells.

[0003] Various radioisotopes are being considered as alpha-emitting agents. Astatine-211, in particular, is one of the most promising radioisotopes because it has a short half-life and decays rapidly into stable nuclides. However, because its half-life is only 7.2 hours, if separation is performed too slowly, the amount of astatine-211 produced will decrease.

[0004] Therefore, a rapid method for separating the produced astatine-211 is required. A separation technique that utilizes the difference in melting and boiling points between astatine-211 and the target material, bismuth, is known as a rapid and simple separation method. However, with this conventional separation technique, astatine-211 adheres to the walls of the piping in the recovery or transport section, making it necessary to elute or recover the adhered astatine-211 using an organic solvent or alkaline solution.

[0005] Therefore, the present inventors have developed a new separation technique using aerosols, which reduces the adhesion of astatine-211 to the walls of pipes and other structures. [Prior art documents] [Patent documents]

[0006] [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]

[0007] [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]

[0008] As described above, when volatile radioisotopes such as astatine isotopes are gasified and collected using a filter, there is a problem that some radioisotopes cannot be washed and recovered from the filter, resulting in a low recovery rate of the radioisotopes.

[0009] The present invention has been made in response to the above-mentioned conventional circumstances, and the problem to be solved by the present invention is to provide a method and apparatus for producing radioisotopes that can efficiently produce volatile radioisotopes such as astatine isotopes. [Means for solving the problem]

[0010] A method for producing a radioisotope according to an embodiment of the present invention is characterized by comprising a pretreatment step of attaching a soluble substance to a collection section, a heating step of heating a target to vaporize and separate the radioactive isotopes, a collection step of collecting the radioactive isotopes separated in the heating step in the collection section that has undergone the pretreatment step, and a cleaning and recovery step of cleaning and recovering the radioactive substance collected in the collection step.

[0011] A radioisotope manufacturing apparatus according to an embodiment of the present invention is characterized by comprising a heating unit that heats a target and vaporizes and separates radioisotopes, a collection unit that collects the radioisotopes separated in the heating unit, and a pre-treatment unit that attaches a soluble substance to the collection unit. [Effects of the Invention]

[0012] According to an embodiment of the present invention, it is possible to provide a method and apparatus for producing a radioisotope that can efficiently produce volatile radioisotopes such as astatine isotopes. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a flow chart showing a method for producing a radioisotope according to a first embodiment. [Figure 2] 1 is a diagram schematically illustrating the general configuration of a radioisotope manufacturing apparatus according to a first embodiment. [Figure 3] 1 is a graph showing the recovery rate of astatine 211 according to the first embodiment in comparison with the prior art. [Figure 4] 10 is a graph showing the relationship between the amount of adhesion to the filter and pressure. [Figure 5] FIG. 10 is a diagram schematically illustrating the general configuration of a radioisotope manufacturing apparatus according to a second embodiment. [Figure 6] FIG. 10 is a diagram schematically illustrating the general configuration of a radioisotope manufacturing apparatus according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a radioisotope production method and a radioisotope production apparatus according to an embodiment will be described with reference to the drawings.

[0015] (First embodiment) First, a description will be given of the first embodiment. Fig. 1 is a flow diagram showing the steps of a method for producing a radioisotope according to the first embodiment, and Fig. 2 is a diagram showing a schematic configuration of an apparatus for producing a radioisotope according to the first embodiment.

[0016] As shown in FIG. 2, the radioisotope production apparatus according to the first embodiment includes a carrier gas cylinder 1, a carrier gas flow control valve 2, a differential pressure gauge 3, an aerosol generator 4, a radioisotope-containing target heating furnace 5, and a filter housing 6. The aerosol generator 4 generates an aerosol of, for example, KCl, NaCl, NaOH, or the like. The aerosol is, for example, particles with a particle size of about 1 nm to 1 mm. By attaching the radioisotope to these aerosols, it is possible to reduce the amount of radioisotope lost due to attachment to piping during transportation of the radioisotope.

[0017] 1, in the first embodiment, filter pretreatment is first performed (step 1). That is, a collection filter is attached to the filter housing 6, and a gas containing an aerosol containing a soluble salt such as KCl as a soluble substance is generated in the aerosol generator 4. This gas is then passed through the filter housing 6 for a predetermined time, causing the soluble substance (soluble salt) to adhere to the surface of the collection filter. Alternatively, a collection filter that has been pretreated in advance may be attached to the filter housing 6.

[0018] The soluble salt may be any salt that dissolves in a liquid solvent at room temperature and pressure, such as water or an organic solvent, used in the washing and recovery process described below. In addition to KCl, for example, NaOH, NaCl, KI, etc. can be used.

[0019] Thereafter, a target containing a volatile radioactive substance such as astatine-211 is heated in the radioisotope-containing target heating furnace 5, and the astatine-211 present in the target is gasified (step 2). In the radioisotope-containing target heating furnace 5, for example, a bismuth target or the like is irradiated with accelerated helium ions (alpha rays), and the bismuth target is heated by a heating mechanism (not shown) to a predetermined temperature, for example, a temperature equal to or higher than 337°C, which is the boiling point of astatine, and lower than the boiling point of the bismuth target, for example, about 500°C.

[0020] Furthermore, the gasified astatine-211 is attached to the aerosol generated in the aerosol generator 4, carried by the flow of carrier gas from the carrier gas cylinder 1, and collected by a collection filter attached to the filter housing 6 installed downstream (step 3).

[0021] After the above steps are performed for a predetermined time, the collection filter is removed from the filter housing portion 6, and the collection filter is washed with a solution such as water, and the astatine-211 collected on the collection filter is recovered (step 4).

[0022] As described above, in this embodiment, in step 1, a pretreatment is performed on the collection filter. This pretreatment allows a soluble salt, which is a soluble substance, to be attached to the surface of the collection filter in advance. This pretreatment makes it easier for astatine-211 to be released from the collection filter in the cleaning and recovery step, allowing for efficient recovery. Note that, for example, a filter made of glass fiber or the like can be used as the collection filter.

[0023] Figure 3 shows the results of comparing astatine-211 recovery when a collection filter was pretreated with KCl and NaOH using the process shown in Figure 1 with astatine-211 recovery when astatine-211 was recovered without pretreatment. For KCl, the pretreatment of the collection filter was performed using a He carrier gas containing KCl aerosol. For NaOH, ten filters were immersed in 250 ml of NaOH solution at the specified concentration (0.5 or 5 wt%), then immersed in fresh NaOH solution after 10 minutes, and then immersed in fresh NaOH solution after another 10 minutes. After a total of three immersions, the filters were dried in a vacuum oven (room temperature, minimum pressure).

[0024] The figure also shows the results of separating and recovering approximately 250 kBq of astatine-211 using a He carrier gas containing KCl aerosol at 3 L / min, followed by cleaning and recovery with approximately 10 mL of 0.01 M NaOH solution. The radioactivity of astatine-211 adhering to a repaired filter was measured with a Ge semiconductor detector before and after cleaning. The separation and recovery rate for the pre-treated filter, in which 30 mg of KCl was pre-attached (shown in the center of Figure 3), was improved by 40% to 90% compared to the comparison filter without pre-treatment (shown in the left side of Figure 3). The separation and recovery rate for the pre-attached filter with NaOH (shown in the right side of Figure 3) was improved by 40% to 75% compared to the comparison filter without pre-treatment (shown in the left side of Figure 3).

[0025] As in the above-described embodiment, soluble salts and the like attached to the collection filter by pretreatment of the collection filter are mixed into the washed and recovered material, and may become impurities depending on the intended use of the washed and recovered material. Therefore, in order to more efficiently recover astatine-211 from the collection filter, it is desirable to control the amount of soluble salts and the like attached to the collection filter.

[0026] In this case, the amount of soluble salts adhering to the collection filter can be measured online (without removing it from the device) by measuring the differential pressure applied to the collection filter using a differential pressure gauge 3 installed upstream of the device, as shown in Figure 2. Figure 4 shows the relationship between the weight of potassium (K) adhering to the collection filter on the vertical axis and the pressure measured by the differential pressure gauge 3 on the horizontal axis.

[0027] As shown in Figure 4, there is a certain relationship between the pressure value measured by the differential pressure gauge 3 and the weight of soluble salts adhering to the collection filter, and the amount of soluble salts adhering can be estimated by measuring the pressure with the differential pressure gauge 3. Therefore, by adjusting the pretreatment time for the collection filter while measuring the pressure with the differential pressure gauge 3, the amount of soluble salts adhering can be controlled to an appropriate amount. Note that the amount of soluble salts adhering to the collection filter can be controlled not only by measuring the pressure, but also by measuring the weight of the filter and the electrical resistance caused by the material adhering to the filter.

[0028] (Second embodiment) Next, a second embodiment will be described with reference to Fig. 5. Note that parts corresponding to those in the radioisotope manufacturing apparatus of the first embodiment shown in Fig. 2 are given the same reference numerals, and duplicated explanations will be omitted.

[0029] 5, in the radioisotope manufacturing apparatus according to the second embodiment, a chemical tank 7 and a switching valve 8 for injecting a chemical containing a soluble salt into a filter housing section 6 are provided downstream of a radioisotope-containing target heating furnace 5, and a dryer 9 is provided in the filter housing section 6. The chemical tank 7, the switching valve 8, and the dryer 9 correspond to a pretreatment section that performs a pretreatment process on the collection filter.

[0030] In the second embodiment having the above configuration, the pretreatment process for the collection filter can be performed by switching the switching valve 8, injecting a chemical containing a soluble salt from the chemical tank 7 into the filter housing portion 6, and drying in the dryer 9. In addition to drying in the dryer 9 that uses heating or the like, drying may also be performed by passing a carrier gas for drying from the carrier gas cylinder 1.

[0031] In the second embodiment having the above configuration, a pretreatment process for the trapping filter can be carried out by injecting a chemical containing a soluble salt from the chemical tank 7 into the filter housing 6. Therefore, the aerosol generator 4 used in the pretreatment process for the trapping filter in the first embodiment is not necessarily required. However, as shown in FIG. 6, a configuration including the aerosol generator 4 may be used in the separation and recovery process of astatine-211.

[0032] Although several 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 embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0033] 1...Carrier gas cylinder, 2...Carrier gas flow control valve, 3...Differential pressure gauge, 4...Aerosol generator, 5...Radioisotope-containing target heating furnace, 6...Filter housing, 7...Chemical liquid tank, 8...Switching valve, 9...Dryer.

Claims

1. a pretreatment step of attaching soluble substances to a collection section; a heating step of heating the target to vaporize and separate the radioisotopes; a collection step of collecting the radioisotopes separated in the heating step in the collection unit that has been subjected to the pretreatment step; a cleaning and recovery step of cleaning and recovering the radioactive materials captured in the capture step; A method for producing a radioisotope, comprising:

2. 2. The method for producing a radioisotope according to claim 1, The radioisotopes separated in the heating step are transported to the collection section by an aerosol generated by an aerosol generator. A method for producing a radioisotope, comprising:

3. 3. The method for producing a radioisotope according to claim 2, A pretreatment step is performed in which the soluble substance is attached to the collection section by the aerosol generated by the aerosol generator. A method for producing a radioisotope, comprising:

4. The method for producing a radioisotope according to claim 3, The differential pressure of a carrier gas that sends the aerosol generated by the aerosol generator to the collection section is detected, and the amount of the soluble substance that is attached to the collection section in the pretreatment step is controlled. A method for producing a radioisotope, comprising:

5. 3. A method for producing a radioisotope according to claim 1 or 2, comprising: The pretreatment step is carried out by injecting a chemical solution containing the soluble substance into the collection unit and drying it. A method for producing a radioisotope, comprising:

6. 3. A method for producing a radioisotope according to claim 1 or 2, comprising: Produce astatine-211 A method for producing a radioisotope, comprising:

7. a heating unit that heats the target and vaporizes and separates the radioactive isotopes; a collection unit that collects the radioisotopes separated in the heating unit; a pre-treatment section for attaching soluble substances to the collection section; A radioisotope manufacturing apparatus comprising:

8. The radioisotope manufacturing apparatus according to claim 7, The pretreatment unit has a chemical solution injection mechanism that injects a chemical solution containing the soluble substance into the collection unit. A radioisotope manufacturing apparatus characterized by:

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