JP7505082B2 - Method for producing astatine isotopes and device for separating and recovering astatine isotopes - Google Patents

Description

Embodiments of the present invention relate to a method for producing astatine isotopes and an apparatus for separating and recovering astatine isotopes.

In recent years, cancer treatment using alpha rays has been attracting attention. This is because alpha rays have a short range, and cancer treatment using alpha ray drugs can selectively attack targeted cancer cells, with minimal impact on normal cells.

Among the radiation sources for cancer treatment using alpha-ray drugs, astatine-211 is the most promising radioisotope because it has a short half-life and decays rapidly into stable nuclei.

International Publication No. 2015/195042

Astatine-211 is expected to be a radiation source for cancer treatment, but because its half-life is short, if separation takes too long, most of the astatine-211 produced will disappear, so a rapid separation method is needed.

To date, there are two main methods that have been developed and investigated for separating and recovering the produced astatine-211.

The first method involves dissolving the astatine-211 produced in the target material together with the bismuth target material in acid, dissolving the astatine in the solution, and then purifying the astatine from this solution using techniques such as solvent extraction. However, there are issues with this method, such as the time required for separation procedures such as dissolution and extraction, and the large amount of waste generated.

The second method is to separate astatine by heating, taking advantage of the difference in boiling and melting points between the astatine to be separated and recovered and aluminum, which may be commonly used as a film for the bismuth target, the target material. With this method, astatine-211 adheres to the walls of the recovery section and the capillary, which is the transport section, and so it is necessary to elute and recover the adhered astatine-211 using an organic solvent or alkaline solution.

In addition to these methods, a method using a gas jet has long been known for superheavy elements as a general technique for quickly and continuously separating and recovering synthesized nuclides. In this method, the synthesized nuclides that are ejected from the rear of the target material due to recoil during beam irradiation for nuclide synthesis are transported in helium gas or the like in the presence of an aerosol such as potassium iodide. However, little research has been done on whether this method can be applied to astatine.

Embodiments of the present invention aim to efficiently and quickly separate astatine isotopes from radionuclides used in cancer treatment and other applications.

In order to achieve the above-mentioned object, the method for producing an astatine isotope according to this embodiment includes an irradiation step of irradiating an irradiation sample containing bismuth, which is an irradiated element, with helium accelerated by an accelerator, and a recovery step of recovering the astatine isotope produced in the irradiation step, the recovery step including a step of adsorbing the gaseous astatine isotope onto an aerosol which is particles of potassium chloride or potassium iodide, and transferring the gaseous astatine isotope to a recovery container via a recovery tube using helium gas, a step of dissolving the aerosol adsorbing the astatine isotope and the astatine isotope in a solution in the recovery container to recover the astatine isotope, and a step of releasing the helium gas which has flowed into the recovery container to the atmosphere via an exhaust filter.

1 is a longitudinal sectional view showing a configuration of an apparatus for irradiating an irradiation sample in an astatine isotope production apparatus according to a first embodiment. FIG. 1 is a vertical cross-sectional view showing a configuration of an astatine isotope separation and recovery device according to a first embodiment. FIG. 1 is a flow chart showing the steps of a method for producing an astatine isotope according to a first embodiment. FIG. 2 is a flow chart showing a detailed procedure for separating astatine isotopes in the method for producing astatine isotopes according to the first embodiment. FIG. 2 is a flow chart showing a detailed procedure for recovering an astatine isotope in the method for producing an astatine isotope according to the first embodiment. FIG. 4 is a vertical cross-sectional view showing a configuration of an apparatus for producing an astatine isotope according to a second embodiment. FIG. 11 is a perspective view showing a configuration of a transport portion of an irradiation sample in an apparatus for producing an astatine isotope according to a second embodiment. FIG. 4 is a flow chart showing the procedure of a method for producing an astatine isotope according to a second embodiment. FIG. 11 is a flow diagram showing a detailed procedure for transferring an irradiation sample into a heating vessel in a method for producing an astatine isotope according to a second embodiment. FIG. 11 is a vertical cross-sectional view showing a configuration of an apparatus for producing an astatine isotope according to a third embodiment. FIG. 11 is a flow chart showing the procedure of a method for producing an astatine isotope according to a third embodiment. FIG. 11 is a flow diagram showing a procedure for transporting an irradiation sample in a method for producing an astatine isotope according to a third embodiment. 15 is a cross-sectional view taken along line XIII-XIII of FIG. 14, showing the configuration of an apparatus for producing an astatine isotope according to a fourth embodiment. 14 is a partial cross-sectional view taken along line XIV-XIV of FIG. 13, showing the configuration of an apparatus for producing an astatine isotope according to a fourth embodiment. FIG. 15 is a vertical cross-sectional view showing a detailed configuration of part A in FIG. 14 of the apparatus for producing an astatine isotope according to the fourth embodiment. FIG. 11 is a flow chart showing the procedure of a method for producing an astatine isotope according to a fourth embodiment.

The following describes a method for producing astatine isotopes and a separation and recovery device according to an embodiment of the present invention, with reference to the drawings. Here, identical or similar parts are given common reference numerals, and duplicated descriptions are omitted.

[First embodiment]
FIG. 1 is a vertical cross-sectional view showing the configuration of an irradiation unit 110 for irradiating an irradiation sample in an apparatus for producing an astatine isotope according to the first embodiment.

The irradiation section 110 has a reaction vessel 20 and a vacuum pump 70 for irradiating the irradiation sample 10 with helium accelerated by an accelerator from the radiation irradiation device 1.

The reaction vessel 20 has a vessel body 21 and a sample holder 24. The sample holder 24 is provided in the vessel body 21 and holds the irradiation sample 10 in a horizontal position. The irradiation sample 10 has an irradiation material tray 12 and a bismuth irradiation material 11 stored therein. Here, the bismuth irradiation material 11 is solid bismuth at room temperature. The material of the irradiation material tray 12 is, for example, aluminum, which is nuclear stable when irradiated with helium accelerated by an accelerator, does not produce secondary products, and has a higher melting point than bismuth and astatine. The number of irradiation samples 10 mounted on the sample holder 24 may be two or more as shown in FIG. 1, or may be one.

The container body 21 is also fitted with an irradiation window 22 that allows the helium accelerated by the accelerator from the radiation irradiation device 1 to pass through. Here, the helium accelerated by the accelerator that passes through the irradiation window 22 is positioned so that it reaches the bismuth irradiation material 11 in the irradiation material tray 12.

When the irradiation sample 10 is irradiated with helium accelerated by an accelerator, the bismuth-209 in the irradiation sample 10 is converted to astatine-211, producing astatine-211.

When the energy of the helium accelerated by the accelerator reaches about 30 MeV, not only astatine-211 but also astatine-210 is produced. Astatine-210 undergoes beta decay to become polonium-210. Since polonium-210 is an alpha radiation source and does not emit gamma rays, it can be considered a hazardous material in the sense that its presence is difficult to detect. Therefore, in order to prevent the production of polonium-210, the energy of the helium accelerated by the accelerator is managed with an upper limit set, for example, at about 29 MeV.

The vessel body 21 is also provided with an exhaust port 28, which is connected to a vacuum pump 70. The vacuum pump 70 has the ability to reduce the pressure inside the reaction vessel 20 to a predetermined level. Here, the predetermined pressure is set based on conditions that keep the reduction in the strength and energy of the helium that reaches the bismuth irradiation material 11 within a predetermined range, relative to the helium that is accelerated by the accelerator and emitted from the radiation irradiation device 1.

The container body 21 further has an opening 25 for inserting and removing the irradiation sample 10, which is closed by a closing lid 26.

Figure 2 is a vertical cross-sectional view showing the configuration of the astatine isotope separation and recovery device 120 according to the first embodiment. The separation and recovery device 120 is a device for separating and recovering astatine-211 produced in the irradiation sample 10 irradiated with helium accelerated by an accelerator in the irradiation section 110.

The separation and recovery device 120 has a heating container 30, an aerosol supply section 40, a recovery section 50, and an exhaust section 60.

The heating container 30 has a container body 31, a sample holder 32, and a heater 37.

The sample holder 32 is located inside the container body 31 and holds the irradiated sample 10 brought into the container body 31. The configuration of the sample holder 32 is not limited to the two-stage configuration shown in FIG. 2. It may be set based on the insertion and removal of the irradiated sample 10, its positional relationship with the heater 37, etc.

The heater 37 is a plurality of electric heaters attached to the container body 31. Note that the number of heaters is not limited to multiple, and may be one. Furthermore, the heater 37 is not limited to an electric heater, and may be, for example, a heat transfer tube through which a heated fluid passes.

The heater 37 has a capacity to heat the inside of the container body 31 and raise the temperature of the irradiated irradiation sample 10 to a predetermined temperature. Here, the predetermined temperature is a temperature above the boiling point of astatine and below the boiling point of bismuth. It is also a temperature above the melting point of bismuth. By raising the temperature to the predetermined temperature, the bismuth becomes liquid and the astatine becomes gaseous.

Table 1 shows the melting points (°C) and boiling points (°C) of astatine and bismuth. It also shows aluminum as an example of a material that can be used for the irradiated material tray 12 of the irradiated sample 10. The temperatures are shown with the decimal point omitted.

The container body 31 is formed with an opening 38 for inserting and removing the irradiation sample 10, an aerosol supply port 33, and a recovery port 34. The aerosol supply port 33 is connected to the aerosol supply section 40. The recovery port 34 is connected to the recovery section 50.

The aerosol supply unit 40 is a device for supplying an aerosol to the container body 31. The aerosol supply unit 40 has a supply container 41, a gas supply unit 45, a supply pipe 42, and a stop valve 43. The supply container 41 is a part that generates or stores the aerosol. Here, the aerosol is, for example, particles of potassium chloride, potassium iodide, or the like. The particle size of the particles is, for example, about 1 nm to about 1 mm. The gas supply unit 45 supplies a carrier gas for moving the aerosol, for example, an inert gas such as helium gas.

The aerosol generated or stored in the supply container 41 is introduced into the container body 31 of the heating container 30 through the supply pipe 42 by gas from the gas supply unit 45 in response to the opening and closing of the stop valve 43. Astatine that has become gaseous in the container body 31 is adsorbed onto the aerosol.

The recovery section 50 recovers the astatine adsorbed to the aerosol.

The recovery section 50 has a recovery container 51, a dissolving liquid 52 in the recovery container 51, and a recovery pipe 53 that connects the recovery port 34 of the heating container 30 to the recovery container 51.

The dissolving liquid 52 held in the collection container 51 dissolves the aerosol. Here, the dissolving liquid is water or an alkaline solution. The alkaline solution is preferably one that corresponds to the components of the aerosol, such as potassium hydroxide when the aerosol is potassium chloride or potassium iodide.

The tip of the recovery tube 53 inside the recovery container 51 is open below the surface of the dissolving liquid 52 and is submerged.

The collection container 51 is connected to the exhaust section 60 as a vent line. The exhaust section 60 has an exhaust pipe 61 and an exhaust filter 62. The gas that flows into the collection container 51 is released to the atmosphere via the exhaust filter 62.

Figure 3 is a flow diagram showing the steps of the method for producing an astatine isotope according to the first embodiment.

In the method for producing an astatine isotope, first, an irradiation sample is prepared (step S10). Here, the irradiation sample 10 is not limited to the form in which the bismuth irradiated material 11 is held in the irradiated material tray 12 as shown in Figures 1 and 2. For example, the bismuth irradiated material 11 may be sealed in aluminum or the like.

Next, the irradiated sample 10 is placed in the reaction vessel 20 (step S20). That is, as shown in FIG. 1, the irradiated sample 10 is loaded onto the sample holder 24 in the reaction vessel 20 through the access opening 25.

Next, the irradiation sample 10 is irradiated with helium accelerated by an accelerator (step S30). Prior to irradiation with helium accelerated to an appropriate energy by the accelerator, the pressure inside the container body 21 is reduced to a predetermined level by the vacuum pump 70.

Next, the irradiation sample 10 is transferred to the heating container 30 (step S40).

Next, the astatine isotopes produced are separated (step S50).

Figure 4 is a flow diagram showing the detailed steps of astatine isotope separation in the method for producing astatine isotopes according to the first embodiment.

In step S50 for separating astatine isotopes, the inside of the heating container 30 is first sealed (step S51). Next, the temperature inside the heating container 30 is increased (step S52). Specifically, the temperature inside the heating container 30 is increased to a predetermined temperature.

Next, the generated astatine isotopes are collected (step S60).

Figure 5 is a flow diagram showing the detailed procedure for recovering astatine isotopes in the method for producing astatine isotopes according to the first embodiment.

In the astatine isotope recovery step S60, first, the aerosol is transferred from the aerosol supply unit 40 into the heating container 30 (step S61). That is, the stop valve 43 is opened, and the aerosol is injected into the heating container 30 with gas from the gas supply unit 45.

The aerosol with adsorbed astatine is then transferred to the collection section 50 (step S62). Steps S61 and S62 are performed continuously by supplying the supply gas. As a result, the gas containing the aerosol is sprayed into the dissolving liquid 52 in the collection container 51 of the collection section 50. The aerosol in the gas containing the aerosol sprayed into the dissolving liquid 52 dissolves in the dissolving liquid 52 together with the astatine adhering to the astatine. The undissolved carrier gas flows into the exhaust section 60 and passes through the exhaust filter 62 to be discharged to the outside air or recycled.

Next, the astatine isotope is recovered from the dissolving solution 52 in the recovery container 51 (step S63). This recovery can be easily performed by ordinary chemical processing.

In conventional methods where astatine-211 separated in the heating section is transported using only a carrier gas, astatine-211 adheres to the walls of the recovery section and the capillary, which is the transport section, making it necessary to elute and recover the adhered astatine-211 using an organic solvent or alkaline solution.

In contrast, this embodiment uses a method in which astatine-211 generated by irradiating bismuth-209 with helium accelerated by an accelerator is separated in a heating vessel 31, and then the astatine-211 is aerosol-adsorbed and transported to the recovery section 50. As a result, astatine-211 can be prevented from adhering to the pathway leading to the recovery section, such as the capillary, improving recovery efficiency, and eliminating the need to treat waste liquid generated by cleaning.

As described above, the astatine isotope production apparatus 100 according to this embodiment and the astatine isotope production method using the same can efficiently and quickly separate astatine isotopes.

Second Embodiment
The second embodiment is a modification of the first embodiment.

In the first embodiment, the irradiation sample 10 irradiated in the reaction vessel 20 is removed from the access opening 25 formed in the reaction vessel 20 and loaded onto the sample holder 32 in the vessel body 31 from the access opening 38 formed in the heating vessel 30.

On the other hand, in the second embodiment, the irradiation sample 10 irradiated in the reaction vessel 20 is transferred from inside the reaction vessel 20 into the heating vessel 30 without being taken out. In other respects, it is the same as the first embodiment.

Figure 6 is a vertical cross-sectional view showing the configuration of the astatine isotope production apparatus according to the second embodiment. Also, Figure 7 is a perspective view showing the configuration of the irradiated sample transport portion of the astatine isotope production apparatus according to the second embodiment.

The astatine isotope production apparatus 100a has an intermediate section 130 disposed between the irradiation section 110 and the separation/recovery apparatus 120.

The intermediate section 130 has an intermediate section container 131, a turntable 132, and a rotation drive section 133.

The intermediate vessel 131 is sandwiched between the vessel body 21 of the reaction vessel 20 and the vessel body 31 of the heating vessel 30, and has a rotation drive unit 133 provided therein and a turntable 132 mounted on the rotation drive unit 133 and rotated by the rotation drive unit 133.

The irradiation sample 10 is placed on the turntable 132. A portion of the turntable 132 protrudes into the interior of each of the container body 21 of the reaction container 20 and the container body 31 of the heating container 30. Therefore, the irradiation sample 10 placed on the turntable 132 can be placed inside each of the container body 21 of the reaction container 20 and the container body 31 of the heating container 30.

As shown in FIG. 7, the vessel body 21 of the reaction vessel 20 has an access opening 25, and the vessel body 31 of the heating vessel 30 has an access opening 38, so that the irradiation sample 10 mounted on the turntable 132 and the sample 10 are not interfered with when the turntable 132 rotates.

For this reason, the container body 21 is provided with a reaction container partition door 27 for closing the loading/unloading opening 25, and the container body 31 is provided with a heating container partition door 35 for closing the loading/unloading opening 38. When closed, the reaction container partition door 27 and the heating container partition door 35 each come into close contact with the turntable 132, ensuring sealing.

Moreover, the intermediate section 130 is connected to a vacuum pump (not shown), so that the inside of the intermediate container 131 can be put into a vacuum state.

Furthermore, the middle section 130 has an opening for access to the outside, although this is not shown.

The aerosol supply section 40 and the recovery section 50 are the same as in the first embodiment.

Figure 8 is a flow diagram showing the steps of the method for producing an astatine isotope according to the second embodiment.

The preparation of the irradiation sample 10 in step S10 is the same as in the first embodiment.

Next, the irradiation sample 10 is placed on the turntable 132 in the reaction vessel 20 (step S20a).

Next, the irradiation sample 10 is irradiated with helium accelerated by an accelerator (step S30).

Next, the irradiation sample 10 is transferred into the heating container 30 (step S40a).

Figure 9 is a flow diagram showing the detailed procedure for transferring an irradiation sample into a heating vessel in a method for producing an astatine isotope according to the second embodiment.

In step S40a for transferring the irradiation sample into the heating vessel, the intermediate section 130 is first placed in a vacuum state (step S41a).

Next, the reaction vessel partition door 27 and the heating vessel partition door 35 are both opened (step S42a).

Next, the turntable 132 is rotated (step S43a). The turntable 132 is rotated, for example, by 180 degrees. As a result, the irradiation sample 10 that was mounted on the turntable 132 inside the reaction vessel 20 moves into the heating vessel 30.

Next, the reaction vessel partition door 27 and the heating vessel partition door 35 are closed (step S44a).

As described above, in the second embodiment, the irradiated sample 10 can be moved from the reaction vessel 20 to the heating vessel 30 without being taken out. The irradiated sample 10 can also be taken in and out at the intermediate section 130. As a result, for example, the irradiated sample 10 can be irradiated and transferred to the heating device 20 without breaking the vacuum state in the reaction vessel 20, improving the efficiency of astatine production.

[Third embodiment]
FIG. 10 is a vertical cross-sectional view showing the configuration of an apparatus 100b for producing an astatine isotope according to the third embodiment.

The third embodiment is a modification of the first embodiment. In the third embodiment, similar to the second embodiment, the irradiation sample 10a irradiated in the reaction vessel 20 is transferred from inside the reaction vessel 20 into the heating vessel 30 without being taken out. In other respects, it is similar to the first embodiment.

Here, the irradiation sample 10a in this embodiment has the bismuth irradiation material 11 and an irradiation material storage section 13 that stores it so that the bismuth irradiation material 11 does not flow out regardless of the position of the irradiation sample 10a.

The astatine isotope manufacturing apparatus 100b has an irradiation section 110, a separation and recovery device 120, and an intermediate section 130 that connects these.

The irradiation section 110 differs from the first embodiment in the way the irradiation sample 10a is put into and taken out of the reaction vessel 20. A closing lid 26a and an entrance sample holder 24a are provided at the introduction portion of the irradiation sample 10a into the reaction vessel 20. The irradiation sample 10a is introduced by opening the closing lid 26a, and is first held in the entrance sample holder 24a. The entrance sample holder 24a can be opened and closed by a drive unit (not shown), and holds the irradiation sample 10a in the closed state, and the irradiation sample 10a falls downward due to gravity in the open state.

The irradiation spot inside the reaction vessel 20 is provided with an irradiation spot sample holder 24b. The irradiation spot sample holder 24b can also be opened and closed by a drive unit (not shown) like the entrance sample holder 24a. When the entrance sample holder 24a, which holds the irradiation sample 10a, opens while the irradiation spot sample holder 24b does not hold an irradiation sample 10a and is closed, the irradiation sample 10a held by the entrance sample holder 24a falls by gravity and is held by the irradiation spot sample holder 24b.

The intermediate section 130 has a communication pipe 134 that connects the reaction vessel 20 and the heating vessel 30, a first gate valve 135 and a second gate valve 136 provided in the communication pipe 134, and an exhaust section 137 that connects to the communication pipe 134.

The irradiated sample 10a can be stored in the portion of the communication pipe 134 between the first gate valve 135 and the second gate valve 136.

The exhaust section 137 is provided with a stop valve 137a. The exhaust section 137 can transfer the pressure in the portion of the communication pipe 134 between the first gate valve 135 and the second gate valve 136 to a substantially vacuum state.

A sample holder 32 is provided inside the heating vessel 30. The sample holder 32 is capable of holding the irradiation sample 10a that passes through the connecting tube 134 and enters the heating vessel 30 due to gravity.

Figure 11 is a flow diagram showing the steps of a method for producing an astatine isotope according to the third embodiment.

The preparation of the irradiation sample 10a in step S10 is the same as in the first embodiment.

Next, the irradiation sample 10a is introduced into the reaction vessel 20 (step S20b). Specifically, the closing lid 26a is opened, the irradiation sample 10a is introduced, and is held by the inlet sample holder 24a. Furthermore, the inlet sample holder 24a is opened, and the irradiation sample 10a that falls due to gravity is held by the irradiation location sample holder 24b.

Next, the irradiation sample 10a is irradiated with helium accelerated by an accelerator (step S30).

Next, the irradiation sample 10a is transferred into the heating container 30 (step S40b).

Figure 12 is a flow diagram showing the procedure for transporting an irradiation sample in the method for producing an astatine isotope according to the third embodiment.

The irradiation sample transfer step S40b includes the following steps:

First, a vacuum state is created between the first gate valve 135 and the second gate valve 136 (step S41b). In detail, the stop valve 137a is opened, and the exhaust section 137 reduces the pressure in the portion of the communication pipe 134 between the first gate valve 135 and the second gate valve 136 to a pressure similar to the pressure inside the reaction vessel 20.

Next, the first gate valve 135 is opened (step S42b). By opening the first gate valve 135, the portion of the communication pipe 134 between the first gate valve 135 and the second gate valve 136 is connected to the space inside the vessel body 21 of the reaction vessel 20.

Next, the irradiation location sample holder 24b is opened (step S43b). As a result, the irradiation sample 10a held in the irradiation location sample holder 24b in the container body 21 falls due to gravity and is held by the second gate valve 136 (step S44b).

The portion of the communication pipe 134 between the first gate valve 135 and the second gate valve 136 is pressurized to the same pressure as inside the heating container 30 (step S45b).

Next, the second gate valve 136 is opened (step S46b). By opening the second gate valve 136, the irradiation sample 10a held in the second gate valve 136 falls by gravity into the heating container 30. The irradiation sample 10a that has moved into the heating container 30 is held by the sample holder 32 in the heating container 30.

As described above, in the third embodiment, as in the second embodiment, the irradiation sample 10a can be moved from the reaction vessel 20 to the heating vessel 30 without being taken out. As a result, for example, the vacuum state in the reaction vessel 20 can be maintained while the irradiation sample 10a is irradiated and transferred to the heating device 20, improving the efficiency of astatine production.

[Fourth embodiment]
Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 14 showing the configuration of the astatine isotope production apparatus according to the fourth embodiment, Fig. 14 is a partial cross-sectional view taken along line XIV-XIV in Fig. 13 showing the configuration of the astatine isotope production apparatus according to the fourth embodiment, and Fig. 15 is a vertical cross-sectional view showing the detailed configuration of part A in Fig. 14 of the astatine isotope production apparatus according to the fourth embodiment.

First, the irradiation sample is a tape-shaped irradiation sample 15. As shown in FIG. 15, the tape-shaped irradiation sample 15 has a base tape 15a and a bismuth layer 15b formed on one surface of the base tape 15a. The material of the base tape 15a is, for example, aluminum. The thickness of the base tape 15a is, for example, 1 to several microns (μm). The thickness of the bismuth layer 15b is, for example, 50 to 100 nm.

As shown in FIG. 13, the astatine isotope production apparatus 100c in this embodiment has a reaction vessel 20, an aerosol supply section 40, a collection section 50, and an exhaust section 60. Therefore, it does not have a heating section as an astatine separation device. The aerosol supply section 40, the collection section 50, and the exhaust section 60 are the same as those in the first embodiment.

As shown in FIG. 14, the reaction vessel 20 is formed with an aerosol inlet 28a that communicates with the aerosol supply section 40, an exhaust port 28 that communicates with the collection section 50, and an irradiation window 22.

The reaction vessel 20 is also configured to allow multiple tape-shaped irradiation samples 15 to be continuously passed through it and continuously irradiated. For this reason, the reaction vessel 20 has multiple roller mechanisms.

That is, the reaction vessel 20 has an inlet roller 23 for introducing a plurality of tape-shaped irradiation samples 15 into the reaction vessel 20, and an outlet roller 29 for removing the plurality of tape-shaped irradiation samples 15 from the reaction vessel 20. Furthermore, as shown in FIG. 15, the reaction vessel 20 has an inlet-side first branch roller 23a, an inlet-side second branch roller 23b, an outlet-side first merging roller 29a, and an outlet-side second merging roller 29b. Note that the inlet roller 23 and the outlet roller 29 are provided with respective driving units, but the driving units are not shown. Here, the driving unit may be provided only on the outlet roller 29. Also, the inlet-side first branch roller 23a, the inlet-side second branch roller 23b, the outlet-side first merging roller 29a, and the outlet-side second merging roller 29b each have only a guide function of rotating in response to the movement of the tape-shaped irradiation sample 15.

The entrance roller 23 and the exit roller 29 each have a pair of rotating parts, and transport the tape-shaped irradiation sample 15 in the rotational direction while sandwiching it between these rotating parts. The entrance roller 23 and the exit roller 29 are each provided on a corresponding wall.

Figure 15 shows a case where there are four tape-shaped irradiation samples 15. However, the number of tape-shaped irradiation samples 15 may be other than four. The number of rollers in the reaction vessel 20 may be set according to the number of tape-shaped irradiation samples 15.

By arranging the entrance side first branch roller 23a after the entrance roller 23 and arranging the entrance side second branch roller 23b after the entrance side first branch roller 23a, the spacing between the four tape-shaped irradiation samples 15 sent out from the entrance roller 23 is ensured. Conversely, by arranging the exit side first merging roller 29a after the entrance side second branch roller 23b and arranging the exit side second merging roller 29b after the exit side first merging roller 29a and before the exit roller 29, the four tape-shaped irradiation samples 15 with the spacing between them are integrated so as to overlap and sent out from the exit roller 29.

Figure 16 is a flow diagram showing the steps of a method for producing an astatine isotope according to the fourth embodiment.

First, an irradiation sample is prepared (step S10c). Here, the irradiation sample is a tape-shaped irradiation sample 15.

Next, the tape-shaped irradiation samples 15 are transported into the reaction vessel 20 at a predetermined speed (step S20c). Here, all of the tape-shaped irradiation samples 15 are mounted in a direction such that the bismuth layer 15b is disposed on the opposite side to the direction of the radiation irradiation device 1.

Next, the tape-shaped irradiation sample 15 is irradiated with helium accelerated by an accelerator, and the generated astatine isotopes are separated (step S30c). Astatine isotopes are generated by irradiating bismuth with helium accelerated by an accelerator. At this time, the astatine atoms recoil, that is, fly out in the direction opposite to the direction of the radiation irradiation device 1. In this embodiment, since the bismuth layer 15b is thin, the astatine isotopes that fly out due to recoil fly out outside the bismuth layer 15b, that is, into the space behind the tape-shaped irradiation sample 15 when viewed from the radiation irradiation device 1.

Next, gas containing aerosol is injected into and discharged from the reaction vessel 20 (step S40c). Specifically, the stop valve 43 is opened, and the aerosol is driven by the carrier gas and flows into the reaction vessel 20. The tape-shaped irradiation samples 15 are arranged at intervals from one another to form a flow path, through which the gas containing aerosol passes. The astatine isotope that has migrated to the back side of the tape-shaped irradiation sample 15 is adsorbed by the aerosol.

Next, the astatine isotope generated from the discharged aerosol is collected (step S50c). That is, the aerosol to which the astatine isotope has been adsorbed flows into the collection container 50, and the astatine isotope is collected.

As described above, in this embodiment, by using a tape-shaped irradiation sample 15 that is thin in the direction of irradiation with helium accelerated by an accelerator, astatine can be separated in the reaction vessel 20 by utilizing the recoil phenomenon. In addition, since the irradiation sample 15 is in the form of a tape, the irradiation position can be changed continuously. In this way, in this embodiment, astatine isotopes can be continuously generated and separated. In addition, the generated astatine isotopes can be continuously transported to the recovery section 50.

As a result, in this embodiment, astatine isotopes can be separated efficiently and quickly.

[Other embodiments]
Although the embodiments of the present invention have been described above, the embodiments have been presented as examples and are not intended to limit the scope of the invention.

Furthermore, the features of each embodiment may be combined. For example, the features of the second embodiment may be combined with the features of the third embodiment.

Furthermore, the embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention.

Embodiments and variations thereof are within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as described in the claims.

1...Radiation irradiation device, 10, 10a...Irradiation sample, 11...Bismuth irradiation material, 12...Irradiation material tray, 13...Irradiation material storage section, 15...Tape-shaped irradiation sample, 15a...Base tape, 15b...Bismuth layer, 20...Reaction vessel, 21...Vessel body, 22...Irradiation window, 23...Inlet roller, 23a...Inlet side first branch roller, 23b...Inlet side second branch roller, 24...Sample holder, 24a...Inlet sample holder, 24b...Irradiation location sample holder, 25...Inlet/outlet opening, 26, 26a...Closing lid, 27...Reaction vessel partition door, 28...Exhaust port, 28a...Aerosol inlet, 29...Outlet roller, 29a...Outlet side first merging roller, 29b...Outlet side second merging roller, 30...Heating vessel, 31...Vessel body, 32...Sample holder Holding part, 33... aerosol supply port, 34... recovery port, 35... heating container partition door, 37... heater, 38... loading and unloading opening, 40... aerosol supply part, 41... supply container, 42... supply piping, 43... stop valve, 45... gas supply part, 50... recovery part, 51... recovery container, 52... dissolving liquid, 53... recovery pipe, 60... exhaust part, 61... exhaust pipe, 62... exhaust filter, 70... vacuum pump, 100, 100a, 100b, 100c... astatine isotope production device, 110... irradiation part, 120... separation and recovery device, 130... intermediate part, 131... intermediate container, 132... turntable, 133... rotation drive part, 134... connecting pipe, 135... first gate valve, 136... second gate valve, 137... exhaust part, 137a... stop valve

Claims (2)

an irradiation step of irradiating an irradiation sample containing bismuth as an irradiated element with helium accelerated by an accelerator;
a recovery step of recovering the astatine isotope produced in the irradiation step;
having
The recovery step includes a step of adsorbing the gaseous astatine isotope onto an aerosol , which is a particle of potassium chloride or potassium iodide, and transferring the astatine isotope to a recovery vessel via a recovery tube using helium gas; a step of dissolving the aerosol adsorbing the astatine isotope and the astatine isotope in a solution in the recovery vessel to recover the astatine isotope; and a step of releasing the helium gas flowing into the recovery vessel to the atmosphere via an exhaust filter.
2. A method for producing an astatine isotope comprising the steps of: a heating vessel capable of heating an irradiation sample containing an irradiated element and irradiated with helium accelerated by an accelerator;
an aerosol supply unit for adsorbing the astatine isotope generated by irradiating the irradiated element with helium accelerated by the accelerator by the heating onto an aerosol of potassium chloride or potassium iodide particles and transporting the astatine isotope by helium gas;
a recovery pipe serving as a flow path for the helium gas containing the aerosol having the astatine isotope adsorbed thereon from the heating vessel;
a recovery vessel for retaining therein a dissolving liquid for dissolving the aerosol having adsorbed the astatine isotope, which is ejected from the recovery pipe together with the helium gas, together with the astatine isotope;
an exhaust section that releases the helium gas that has flowed into the recovery container from the recovery container to the atmosphere via an exhaust filter;
Equipped with
The heating vessel heats the irradiation sample to a temperature lower than the boiling point of the irradiated element and higher than the boiling point of the astatine isotope.
2. A device for separating and recovering astatine isotopes.

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