Method and apparatus for producing radioactive isotopes

Abstract

To provide a method and an apparatus capable of efficiently producing volatile radioactive isotopes including an astatine isotope.SOLUTION: Provided is a method of producing radioactive isotopes, including: an evaporation step of heating a target to evaporate a radioactive isotope by heating; a mixing step of mixing the evaporated radioactive isotope and an aerosol with each other; a collection step of collecting, through a collection filter, the radioactive isotope and the aerosol mixed in the mixing step; a cleaning step of cleaning the collection filter by ultrasonic cleaning; and a recovery step of recovering a cleaning liquid used in the cleaning step.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE 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, it is possible 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-particle-emitting drugs. Astatine-211 in particular is one of the most promising radioisotopes, as it has a short half-life and decays quickly 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] For this reason, a method for quickly separating the produced astatine-211 is required. A separation technique that utilizes the difference in melting and boiling points with the target material, bismuth, is known as a quick and simple separation method. However, with this conventional separation technique, astatine-211 adheres to the walls of the pipes in the collection or transport section, making it necessary to elute or collect the adhered astatine-211 using an organic solvent or alkaline solution.

[0005] Therefore, the present inventors have developed a new separation technique using an aerosol, which reduces the adhesion of astatine-211 to the walls of pipes and the like. [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 problems, and the problem to be solved by the present invention is to provide a method and apparatus for producing a radioisotope 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 an evaporation process for heating a target and evaporating the radioisotope by heating, a mixing process for mixing the evaporated radioisotope with an aerosol, a collection process for collecting the radioisotope and aerosol mixed in the mixing process with a collection filter, a cleaning process for cleaning the collection filter using ultrasonic cleaning, and a recovery process for recovering the cleaning liquid used in the cleaning process.

[0011] A radioisotope manufacturing apparatus according to an embodiment of the present invention is characterized in that it comprises a target heating furnace which heats a target and evaporates the radioisotope by heating, an aerosol generator which generates an aerosol to be mixed with the evaporated radioisotope, a filter housing section which collects the mixed radioisotope and aerosol with a collecting filter, a cleaning mechanism which supplies a cleaning liquid and applies ultrasonic vibrations to clean the collecting filter, and a cleaning liquid recovery section which recovers the cleaning liquid after cleaning the collecting filter. Effect of the Invention

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

[0013] [Figure 1] FIG. 2 is a flow chart showing a method for producing a radioisotope according to the first embodiment. [Diagram 2] FIG. 1 is a diagram illustrating a schematic configuration of a radioisotope production apparatus according to a first embodiment. [Diagram 3] 4 is a graph showing the aerosol component cleaning recovery rate according to the first embodiment in comparison with the conventional technique. [Figure 4] FIG. 11 is a flow diagram showing a method for producing a radioisotope according to a second embodiment. [Diagram 5] FIG. 1 is a diagram illustrating a schematic configuration of a radioisotope production apparatus according to a second embodiment. [Figure 6] 13 is a graph showing the relationship between the KCl washing recovery rate and the dehydration rate according to the second embodiment. [Figure 7] FIG. 13 is a diagram illustrating a schematic configuration of a radioisotope production apparatus according to a third embodiment. [Figure 8] FIG. 13 is a diagram illustrating a schematic configuration of a radioisotope production apparatus according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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] 2, the radioisotope manufacturing 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, a filter housing section 6, a cleaning liquid storage section 7, a cleaning liquid recovery section 8, an ultrasonic cleaning device 9, solenoid valves 10a and 10b, and a control computer 11. The control computer 11 automatically controls the switching operations of the solenoid valves 10a and 10b, the operation and stop of the ultrasonic cleaning device 9, etc., based on a preset program.

[0017] In this device, a dry carrier gas, for example, an inert gas such as nitrogen, argon, or helium, is fed into an aerosol generator 4 by a carrier gas cylinder 1, a carrier gas flow rate control valve 2, and a differential pressure gauge 3. A substance that serves as an aerosol source, for example, a solid such as KCl, NaCl, or NaOH, is placed in the aerosol generator 4, and the salt is heated to near its melting point, whereby the sublimated components come into contact with the introduced carrier gas, and the sublimated components are precipitated by a change in temperature to form an aerosol. The aerosol is, for example, a particle with a particle size of about 1 nm to about 1 mm. The carrier gas containing the aerosol thus generated is introduced into a radioisotope-containing target heating furnace 5. In this way, the radioisotope is mixed with the aerosol, and the radioisotope adheres to the aerosol, thereby reducing the amount of radioisotope lost due to adhesion to piping during transportation of the radioisotope. In addition, the radioisotope is in a form that is easily captured by a collection filter.

[0018] 1, in the first embodiment, first, in a radioisotope-containing target heating furnace 5, a target containing a volatile radioisotope such as astatine-211 is heated, and the radioisotope present in the target is evaporated and gasified (101). 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 of 337°C or higher, which is the boiling point of astatine, and a temperature of 500°C or lower, which is lower than the boiling point of the bismuth target. As a result, astatine-211 is gasified and separated from the bismuth target.

[0019] Next, gasified radioisotopes such as astatine-211 are mixed with and attached to the aerosol generated in the aerosol generator 4 (102). The radioisotopes and aerosol are then 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 (103). The collection filter attached to the filter housing 6 can be, for example, a filter made of glass fiber.

[0020] In the device shown in Fig. 2, cleaning liquid is stored in the cleaning liquid storage section 7, and in the process of collection by the collection filter described above, the cleaning liquid storage section 7 is separated by the solenoid valve 10a. When collection is completed, the solenoid valve 10a is switched to the cleaning liquid storage section 7 side by a control computer 11 programmed in advance with time settings, etc., and the solenoid valve 10b is closed to allow the cleaning liquid to flow from the cleaning liquid storage section 7 into the filter housing section 6. Then, the control computer 11 remotely starts the ultrasonic cleaning device 9 to perform ultrasonic cleaning (104). This ultrasonic cleaning causes the aerosols and radioisotopes collected in the collection filter to be separated.

[0021] When the above cleaning process is completed, the ultrasonic cleaning device 9 is remotely stopped by the control computer 11, and the solenoid valve 10b is opened to introduce the cleaning liquid in the filter housing section 6 into the cleaning liquid recovery section 8, and the radioisotopes contained in the cleaning liquid are recovered (105).

[0022] As described above, in this embodiment, when performing cleaning to separate the aerosols and radioisotopes captured on the collecting filter in the filter housing portion 6, ultrasonic cleaning is performed by supplying ultrasonic waves to the cleaning liquid from the ultrasonic cleaning device 9. This makes it possible to efficiently separate the aerosols and radioisotopes that were previously difficult to separate by cleaning while remaining captured on the collecting filter, and to improve the recovery rate.

[0023] The graph in Figure 3 shows the results of measuring the potassium ion concentration in the cleaning solution with an ion meter after passing a gas containing KCl aerosol through a collection filter for one hour to collect the aerosol, and then cleaning for a specified period of time to determine the aerosol component cleaning recovery rate (%). The left side of Figure 3 shows the case where cleaning was performed without using ultrasonic waves, and the right side shows the case where cleaning was performed with ultrasonic waves. Ultrasonic cleaning was performed for a total of three minutes using multiple frequency patterns of 28 kHz, 45 kHz, and 100 kHz, each for three seconds. Each test was performed multiple times, and the range of the measurement results obtained is shown by the square area.

[0024] As shown in Figure 3, when cleaning was performed without using ultrasonic waves, the aerosol component cleaning recovery rate was in the range of 78% or less. On the other hand, when cleaning was performed using ultrasonic waves, the aerosol component cleaning recovery rate was stably achieved at 86% or more. In this way, by using ultrasonic cleaning, the ultrasonic vibration makes it easier for the collected matter that has entered the fibers of the collection filter to come into contact with the liquid, improving the recovery rate of the cleaning liquid and the recovery rate of the radioisotopes contained in the cleaning liquid.

[0025] Second embodiment Next, a second embodiment will be described. Fig. 4 is a flow diagram showing steps of a method for producing a radioisotope according to the second embodiment, and Fig. 5 is a diagram showing a schematic configuration of an apparatus for producing a radioisotope according to the second embodiment.

[0026] 5, the radioisotope manufacturing apparatus according to the second 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, a filter housing section 6, a cleaning liquid storage section 7, a cleaning liquid recovery section 8, pumps 9a, 9b, solenoid valves 10a, 10b, and a control computer 11. The control computer 11 automatically controls the switching operations of the solenoid valves 10a, 10b, the operation and stop of the pumps 9a, 9b, etc., based on a preset program.

[0027] As shown in FIG. 4, in the method for producing a radioisotope according to the second embodiment, similar to the first embodiment shown in FIG. 1, first, a target containing a volatile radioisotope such as astatine-211 is heated in a radioisotope-containing target heating furnace 5, and the radioisotopes such as astatine-211 present in the target are evaporated and gasified (201).

[0028] Next, the gasified radioactive isotope is mixed with and attached to the aerosol generated in the aerosol generator 4 (202), transported 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 (203).

[0029] Next, when the collection is completed, the solenoid valve 10a is switched to the cleaning liquid reservoir 7 side by the control computer 11, which is programmed with a time setting in advance, and the solenoid valve 10b is closed, and the cleaning liquid is poured from the cleaning liquid reservoir 7 into the filter housing 6 for cleaning (204). This cleaning causes the aerosols and radioisotopes collected on the collection filter to be separated. Note that in this cleaning process, ultrasonic cleaning may be used as in the first embodiment.

[0030] When the above-mentioned cleaning process is completed, the control computer 11 opens the solenoid valve 10b to introduce the cleaning liquid in the filter housing section 6 into the cleaning liquid recovery section 8, and operates the pump 9b to suck water from the filter housing section 6, thereby suctioning and dehydrating the collection filter, and recovering the cleaning liquid and the radioisotopes contained in the cleaning liquid (205).

[0031] 5, a pump 9a is also provided on the cleaning liquid storage section 7 side. This pump 9a can be operated when the cleaning liquid is flowed from the cleaning liquid storage section 7 into the filter housing section 6 to push the cleaning liquid into the filter housing section 6, thereby improving the cleaning efficiency.

[0032] As described above, in the second embodiment, when the cleaning liquid in the filter accommodating section 6 is recovered in the cleaning liquid recovery section 8, suction dehydration is performed, thereby making it possible to improve the recovery rate of the cleaning liquid and to improve the recovery rate of radioisotopes such as astatine-211 contained in the cleaning liquid.

[0033] The graph in Figure 6 shows the results of investigating the relationship between the "recovery rate (%) of KCl," an aerosol component, and the "dehydration rate (%) = volume of recovered liquid / volume of added liquid." As shown in the graph in Figure 6, under conditions of low dehydration rate, the washing recovery rate of KCl also decreases. This is because a certain amount of water remains in the filter, causing recovery losses; the recovery rate can be improved by reducing this remaining water.

[0034] Third embodiment Next, a third embodiment will be described. Fig. 7 is a diagram showing a schematic configuration of a radioisotope manufacturing apparatus according to the third embodiment. This third embodiment relates to a modified example of the second embodiment shown in Fig. 5, and the same reference numerals are used to designate parts corresponding to those in the second embodiment, and duplicated explanations will be omitted.

[0035] In this third embodiment, a solenoid valve 10c is provided between the solenoid valve 10a and the filter accommodating portion 6, and a solenoid valve 10d is provided between the solenoid valve 10b and the pump 9b. A circulation line 12 is provided between the solenoid valves 10c and 10d, and a pump 9c is inserted in this circulation line 12. In this third embodiment, a control computer 11 automatically controls the switching operations of the solenoid valves 10a, 10b, 10c, and 10d, and the operation and stopping of the pumps 9a, 9b, and 9c based on a preset program.

[0036] In the third embodiment having the above configuration, the cleaning liquid can be circulated through the filter housing section 6 by the circulation line 12, which allows the contact time between the cleaning liquid and the collection filter to be extended with the same amount of cleaning liquid, thereby improving the recovery rate of radioisotopes without causing a decrease in the concentration of the cleaning liquid.

[0037] (Fourth embodiment) Next, a fourth embodiment will be described. Fig. 8 is a diagram showing a schematic configuration of a radioisotope manufacturing apparatus according to the fourth embodiment. This fourth embodiment is a modified example of the third embodiment shown in Fig. 7, and the same reference numerals are used to designate parts corresponding to those of the third embodiment, and duplicated explanations will be omitted.

[0038] In this fourth embodiment, a radioactivity meter 13 for measuring the radioactivity inside the filter housing portion 6 is provided, and a measurement signal from this radioactivity meter 13 is input to a control computer 11. In this fourth embodiment, as in the above-described third embodiment, the control computer 11 automatically controls the switching operations of the solenoid valves 10a, 10b, 10c, and 10d, the operation and stop of the pumps 9a, 9b, and 9c, etc., based on a preset program.

[0039] In the fourth embodiment having the above configuration, the end of circulatory cleaning is determined from the rate of change in radioactivity observed by the radioactivity measuring instrument 13 when the cleaning liquid is circulated, and the control computer 11 opens and closes the solenoid valves 10c and 10d, stops the pump 9c, and starts the pump 9b, to automatically separate and recover the radioisotopes. Note that the measurement of radioactivity by the radioactivity measuring instrument 13 may measure the change in radioactivity from the radioisotopes captured on the capturing filter in the filter housing portion 6, or may measure the change in radioactivity from the radioisotopes that have migrated to the cleaning liquid in the cleaning liquid recovery portion or the like.

[0040] 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 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]

[0041] 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...cleaning liquid storage section, 8...cleaning liquid recovery section, 9...ultrasonic cleaning device, 9a, 9b, 9c...pump, 10a, 10b, 10c, 10d...solenoid valve, 11...control computer, 12...circulation line, 13...radioactivity measuring instrument.

Claims

1. an evaporation step of heating the target and evaporating the radioisotope by heating; mixing the vaporized radioisotope with the aerosol; a collection step of collecting the radioisotope and the aerosol mixed in the mixing step with a collection filter; a cleaning step of cleaning the collection filter using ultrasonic cleaning; a recovery step of recovering the cleaning solution used in the cleaning step; A method for producing a radioisotope, comprising:

2. A method for producing a radioisotope according to claim 1, comprising the steps of: The recovery step includes a step of dehydrating the collection filter by suction. A method for producing a radioisotope, comprising the steps of:

3. an evaporation step of heating the target and evaporating the radioisotope by heating; mixing the vaporized radioisotope with the aerosol; a collection step of collecting the radioisotope and the aerosol mixed in the mixing step with a collection filter; a cleaning step of cleaning the collection filter; a recovery step of recovering the cleaning solution used in the cleaning step, the recovery step including a step of dehydrating the collection filter by suction; A method for producing a radioisotope, comprising:

4. A method for producing a radioisotope according to claim 3, comprising the steps of: In the cleaning step, the cleaning liquid is circulated through the collection filter. A method for producing a radioisotope, comprising the steps of:

5. A method for producing a radioisotope according to claim 4, comprising the steps of: A radioactivity measuring device detects a change in the amount of the radioisotope trapped on the trapping filter or a change in the amount of the radioisotope transferred to the cleaning solution, and stops circulation of the cleaning solution in the cleaning step. A method for producing a radioisotope, comprising the steps of:

6. A method for producing a radioisotope according to any one of claims 1 to 5, comprising the steps of: The target is a bismuth target and produces astatine-211. A method for producing a radioisotope, comprising the steps of:

7. a target heating furnace for heating the target and evaporating the radioisotope by heating; an aerosol generator for generating an aerosol for mixing with the vaporized radioisotope; A filter housing section for collecting the mixed radioisotope and aerosol with a collection filter; a cleaning mechanism for cleaning the collection filter by supplying a cleaning liquid and applying ultrasonic vibrations to the collection filter; a cleaning liquid recovery unit that recovers the cleaning liquid after cleaning the collection filter; A radioisotope manufacturing apparatus comprising:

8. The radioisotope production apparatus according to claim 7, The cleaning liquid recovery unit has a pump that dehydrates the collection filter by suction. A method for producing a radioisotope, comprising the steps of:

9. a target heating furnace for heating the target and evaporating the radioisotope by heating; an aerosol generator for generating an aerosol for mixing with the vaporized radioisotope; A filter housing section for collecting the mixed radioisotope and aerosol with a collection filter; a cleaning mechanism for supplying a cleaning liquid to clean the collection filter; a cleaning liquid recovery unit having a pump that recovers the cleaning liquid after cleaning the collection filter and dehydrates the collection filter by suction; A radioisotope manufacturing apparatus comprising:

10. The radioisotope production apparatus according to claim 9, The cleaning mechanism has a circulation line that circulates the cleaning liquid through the collection filter. A radioisotope manufacturing apparatus comprising:

11. The radioisotope production apparatus according to claim 10, a radioactivity measuring device for detecting a change in the amount of the radioisotope trapped on the trapping filter or a change in the amount of the radioisotope transferred to the cleaning liquid; a control computer that determines the end time of cleaning based on a measurement signal from the radioactivity measuring device, and controls the cleaning mechanism to stop circulating the cleaning liquid and recover the cleaning liquid in the cleaning liquid recovery unit; A radioisotope manufacturing apparatus comprising:

12. The radioisotope production apparatus according to any one of claims 7 to 11, The target is a bismuth target and produces astatine-211. A radioisotope manufacturing apparatus comprising:

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