JP2021004768A - Method and apparatus for manufacturing radioactive nuclide - Google Patents

Abstract

To manufacture a radioactive nuclide using a comparatively small-sized electron beam accelerator with high efficiency.SOLUTION: A material 25 for emitting a bremsstrahlung radiation and a neutron by irradiation with an electron beam is arranged on the upstream side to an irradiation direction of an electron beam 11, and a raw material 20 for producing the same kind of radioactive nuclide due to a nuclear reaction by the bremsstrahlung radiation and a nuclear reaction by the neutron is arranged on its rear part. A target radioactive nuclide can be efficiently manufactured using the two different nuclear reactions.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for producing a radionuclide that emits radiation such as gamma rays, alpha rays, and beta rays, and particularly relates to a method and an apparatus for producing a radionuclide using an electron beam accelerator.

Radionuclides that emit gamma rays such as technetium-99m (Tc-99m) are widely used as diagnostic agents, and radionuclides that emit alpha rays such as actinium 225 (Ac-225) are widely used as therapeutic agents. ing.

Conventionally, these radionuclides have been produced as fission products using nuclear reactors, but the number of manufacturing facilities using nuclear reactors is small and unevenly distributed all over the world, and there are problems with risks related to facility operation and a large amount. Due to problems such as the need for significant investment and maintenance costs, manufacturing methods that do not utilize fission reactions have been developed.

For example, since technetium 99m is produced by the decay of molybdenum 99 (Mo-99), a method of activating molybdenum 98 using neutrons (Mo-98 (n, γ) Mo-99) or There is a method (Mo-100 (n, 2n) Mo-99) for producing by utilizing the reaction between molybdenum 100 and neutrons. These manufacturing methods can be realized by using an accelerator that accelerates neutrons. However, the method using neutrons requires a large accelerator, and also requires a large shield around the targets Mo-98 and Mo-100, which causes a problem that the device becomes large.

As another production method using an accelerator, a method of irradiating Mo-100 with accelerated protons has also been studied, but in this method, Mo-99 and Tc-99m are produced, and at the same time, technetium-99 (Tc-99) is produced. ) Is also generated, and Tc-99m having a high specific activity cannot be produced.

On the other hand, regarding actinium 225, at present, the only facilities that can supply clinically usable amounts are three laboratories such as the Institute for Transuranium Element (ITU) in Germany, and accelerators were used. Development of a manufacturing method is desired. In the production of Ac-225 using an accelerator, a production test using a cyclotron using the reaction between naturally occurring radium-226 (Ra-226) and protons (R-226 (p, n) Ac-225) is underway. However, there are various problems in order to efficiently use the energy of protons, and it has not been put into practical use.

As a method for producing actinium 225 using an accelerator, a method for producing actinium 225 by beta decay of Ra-225 produced by utilizing the Ra-226 (n, 2n) Ra-225 reaction is also being studied. However, in this reaction, deuterons accelerated by the cyclotron are irradiated to targets such as carbon and thorium occlusion metals to generate fast neutrons, so it is essential to shield fast neutrons that are generated in large quantities, and the equipment becomes large. In addition, there is a problem that the entire device structure is activated.

As a solution to the above-mentioned problem of the production method using the reaction with neutrons or protons, Patent Document 1 describes a high-speed electron beam generated by an electron beam accelerator and a substance that generates braking radiation by irradiation of the electron beam ( A method for producing a radionuclide by using a reaction (γ, n) that generates neutrons by irradiation with braking radiation in combination with a target) is disclosed. Electron beam accelerators are much smaller and lighter than neutron and proton accelerators, and do not require large-scale shielding like devices that irradiate neutrons, so manufacturing equipment can be made smaller and lighter. It becomes.

JP-A-2015-99117

The technology described in Patent Document 1 has made it possible to reduce the size and weight of the radionuclide production apparatus, but it also produces actinium 225, which is in great demand as a raw material for therapeutic agents, and technetium Tc99m, which is in great demand as a raw material for diagnostic agents. In order to do so, it is desired to further improve the manufacturing efficiency.

An object of the present invention is to further improve the production efficiency based on a radionuclide production apparatus using an electron beam accelerator.

The present invention focuses on the fact that a material such as a heavy metal emits braking radiation and neutrons by irradiation with an electron beam, and the same type of radionuclide is generated by such a material and a nuclear reaction caused by braking radiation and a nuclear reaction caused by neutrons. The above-mentioned problems are solved by combining with the raw materials to be produced, and a radionuclide can be produced with high efficiency by using a relatively small electron beam accelerator.

That is, the method for producing a radionuclide of the present invention is a method for producing a radionuclide using an electron beam emitted from an electron beam accelerator, and the electron beam is upstream from the irradiation direction of the electron beam. A material that emits braking radiation and neutrons upon receiving the irradiation of the material is arranged, and a raw material that receives the braking radiation and neutrons emitted by the material and produces a radionuclide is arranged on the downstream side of the material. It is characterized by using a raw material in which the radionuclide generated by the irradiation of the braking radiation and the radionuclide generated by the irradiation of the neutron are the same nuclide.

Further, the radionuclide production apparatus of the present invention is arranged upstream of the irradiation direction of the electron beam accelerator and the electron beam emitted from the electron beam accelerator, and receives the irradiation of the electron beam to emit braking radiation and neutrons. A reaction is carried out in which a material to be emitted and a raw material which is arranged on the downstream side of the material and receives the braking radiation and neutrons emitted by the material to generate a radionuclide are stored and an electron beam is used to generate a radionuclide. The reaction chamber to be carried out is provided, and the raw material is characterized in that the radionuclide produced by the irradiation of the braking radiation and the radionuclide produced by the irradiation of the neutron are the same nuclide.

According to the present invention, one nuclide can be produced by using both the braking radiation and the neutron generated from the material, so that the production efficiency can be significantly improved. Other effects of the present invention will be demonstrated in embodiments.

The figure explaining one Embodiment of the manufacturing method of a radionuclide of this invention. Graph showing the relationship between electron beam energy and bremsstrahlung radiation and neutron flux Graph showing the relationship between braking radiation energy and reaction cross section Graph showing the relationship between neutron energy and reaction cross section (A) and (B) are diagrams showing configuration examples of the radionuclide production apparatus of the first embodiment, respectively. The figure which shows the relationship between the thickness of a radiation-producing material and the radiation intensity on the surface of a raw material. The figure which shows the structural example of the radionuclide production apparatus of 2nd Embodiment (A) and (B) are diagrams showing modified examples of the radionuclide production apparatus of the second embodiment, respectively. The figure which shows the material or the container of the radionuclide production apparatus of 3rd Embodiment and the support mechanism thereof. The figure explaining the shape of the material or the container of the radionuclide production apparatus of 3rd Embodiment The figure which shows the structural example of the radionuclide production apparatus of 4th Embodiment The figure explaining the taking-out of the raw material of the radionuclide production apparatus of 4th Embodiment The figure which shows the modification of the radionuclide production apparatus of 4th Embodiment

Hereinafter, embodiments of the radionuclide production method and apparatus of the present invention will be described.

<Embodiment of Radionuclide Production Method>
First, a basic embodiment of the method for producing a radionuclide of the present invention will be described.
In the method for producing a radionuclide of the present invention, a material that generates braking radiation and neutrons by an electron beam emitted from an electron beam accelerator (hereinafter, also simply referred to as a radiation generating material or material) and irradiation of braking radiation and neutrons are applied. A raw material that receives and produces a radionuclide is used. Further, in the method for producing a radionuclide of the present invention, as shown in FIG. 1, the material 25 and the raw material 20 are placed in the front stage and the raw material 20 in the rear stage with respect to the irradiation direction of the electron beam 11. , Place them on top of each other. The raw material is a radionuclide generated by irradiation with braking radiation and a radionuclide produced by a nuclear reaction when irradiated with neutrons, and the radionuclide produced by these two reactions is the same species.

Hereinafter, specific materials and raw materials will be described.
As the radiation generating material, a heavy metal or a compound of a heavy metal can be used. Examples of heavy metals include bismuth, lead, tungsten, and platinum. Such heavy metals can generate both braking radiation and neutrons by irradiating the electron beam with the energy of the electron beam in an appropriate range.

FIG. 2 schematically shows the flux of braking radiation and neutrons generated when a heavy metal material is irradiated with an electron beam. In the figure, the horizontal axis is the energy of the electron beam and the vertical axis is the amount of flux, both of which are arbitrary units. As shown, braking radiation is generated in a wide range of electron beam energy, but neutrons are generated in a narrower energy range than braking radiation. Therefore, electron beam energy is controlled to the range generated by both braking radiation and neutrons. As a result, both braking radiation and neutrons can be generated by electron beam irradiation. Further, the energy of each of the braking radiation and the neutron generated by the electron beam is set to the electron beam energy exceeding the threshold energy capable of causing the necessary nuclear reaction in the raw material placed behind. Since the threshold energy for causing a nuclear reaction differs depending on the type of raw material, the electron beam emitted from the electron beam accelerator 10 is controlled so as to have an appropriate electron beam energy according to the raw material and the combination with the material. In order to change the acceleration energy of the electron beam, the frequency of the high frequency power supply may be changed. Further, it may be changed by using a multi-stage acceleration tube and stopping the acceleration in the subsequent acceleration tube.

As an example, FIGS. 3 and 4 show the relationship between the energy of each of the braking radiation and the neutron theoretically obtained for radium-226 and the reaction cross section of the nuclear reaction by the braking radiation and the neutron. As shown in FIG. 3, it can be seen that the braking radiation causes a (γ, n) reaction at a predetermined energy (threshold value) or higher. Usually, the (γ, n) reaction is caused by a nuclear reaction with a peak called giant resonance between the braking radiation and the nucleus. Therefore, it is desirable that the energy of the braking radiation exceeds this peak. Regarding neutrons, as shown in FIG. 4, when the neutron energy is low, radium-226 changes from the ground state to the excited state, but transmutation does not occur (graph shown in "inelastic"), but the energy exceeds the predetermined energy. Then (n, 2n) reaction occurs (range shown by diagonal line). Therefore, in order to generate neutrons exceeding the threshold energy of the (n, 2n) reaction, it is better to irradiate an electron beam having a relatively high energy, and in FIG. 2, the threshold energy of the (n, 2n) reaction is exceeded. The threshold value of the electron beam for generating neutrons is shown by a single point chain beam.

In this way, both braking radiation and neutrons can be generated, and by irradiating the radiation-generating material with electron beam energy above the threshold, both can be subjected to a nuclear reaction using braking radiation on the raw material placed behind it. A nuclear reaction using neutrons can be generated.

As shown in FIG. 2, the neutron flux is smaller than the flux of the braking radiation, but as can be seen from the reaction cross sections shown in FIGS. 3 and 4, the neutron is irradiated with the braking radiation to generate one neutron. The reaction cross section of the reaction of irradiating one neutron to generate two neutrons is about an order of magnitude larger than that of the reaction to be generated. Therefore, a nuclear reaction using neutrons can contribute to the production of radionuclides as well as a nuclear reaction using braking radiation.

The radionuclide produced by the reaction of irradiating braking radiation to generate one neutron and the radionuclide produced by the reaction of irradiating one neutron to generate two neutrons must be the same radionuclide. Therefore, it is possible to produce a radionuclide in an amount obtained by adding the radionuclides produced by both.

Next, the raw materials will be described.
Radium-226 (Ra-226) or a compound thereof, Renium 187 or a compound thereof (Re-187), Elbium 170 (Er-170) or a compound thereof are used as raw materials for producing the same kind of radioactive nuclei by reaction with braking radiation and neutrons. Compound, erbium 166 (Er-166) and its compounds, palladium 104 (Pd-104) or its compounds, molybdenum 100 (Mo-100) or its compounds, calcium 40 (Ca-40) or its compounds, or any of them. Raw materials can be used. For example, radium-226 is transmuted to radium 225 by reaction with braking radiation (γ, n) and also transmuted to radium 225 by reaction with neutrons (n, 2n). As the compound, for example, oxides, salts, complexes and the like can be used.

The raw material is arranged behind the radiation-producing material with respect to the irradiation direction of the electron beam, and reacts with the braking radiation and the neutron generated by the radiation-producing material, respectively, to generate the same type of radionuclide. As the raw material, a single raw material may be arranged, or a plurality of raw materials may be arranged so as to overlap in the electron beam irradiation direction. When a plurality of raw materials are arranged, the order thereof is not particularly limited, but it is preferable that at least one of the atomic number and the density of the raw materials in the first stage is smaller than that in the raw materials in the latter stage. As a result, the shielding effect of radiation and the like in the previous stage can be reduced, and more braking radiation and neutrons not used in the raw material in the previous stage can be irradiated to the raw material in the latter stage.

The materials and raw materials can be used in a solid or liquid state, and in the case of a liquid or powder, they may be stored in a container. As the material of the container, a material that does not contribute to the nuclear reaction by itself and is composed of elements having a small density and atomic number is preferable, and specifically, beryllium, carbon, aluminum, and oxides thereof. And compounds such as boronide can be used. By storing the raw material in the container, safety can be maintained even when the liquid raw material is used or when the solid raw material is changed to the liquid state.

Next, as an example, an embodiment of producing actinium 225 (Ac-225) and technetium-99m (Tc-99m) as nuclides used as therapeutic agents or raw material nuclides thereof will be described. In this embodiment, bismuth is used as a radiation generating material, and as a raw material, a raw material containing radium (Ra-226) or a compound thereof (hereinafter, simply referred to as a radium-containing material) is used in the first stage, and molybdenum (Mo-) is used in the second stage. A raw material containing 100) or a compound thereof (hereinafter, simply referred to as a molybdenum-containing material) is used.

By irradiating bismuth with an electron beam, braking radiation and neutrons are generated. When the generated braking radiation and neutrons are applied to the radium-containing raw material, radium 225 (Ra-225) is produced by the nuclear reaction (Ra-226 (γ, n) Ra-225) between the braking radiation and radium 226. .. This nuclear reaction is a reaction that produces one neutron. In the case of neutrons, radium 225 (Ra-225) is produced by a nuclear reaction (Ra-226 (n, 2n) Ra-225) between one neutron and radium 226 (Ra-226). This reaction is a reaction that produces two neutrons, and radium 225 (Ra-225), which is the same nuclide as the nuclear reaction between braking radiation and radium 226, is produced. Radium 225 becomes actinium (Ac-225) by beta decay.

As described above, since the same radionuclide is produced by irradiating the braking radiation and the neutron, the production amount can be expected to increase as compared with the method of irradiating only the braking radiation or only the neutron.

Further, the braking radiation generated from bismuth and irradiated to the radium-containing raw material and the rest of the neutrons are irradiated to the molybdenum-containing raw material installed in the second stage. A reaction (Mo-100 (γ, n) Mo-99) that produces one neutron occurs by a nuclear reaction between bremsstrahlung radiation and molybdenum 100, and molybdenum 99 (Mo-99) is produced. In addition, a nuclear reaction between neutrons and molybdenum 100 causes a reaction (Mo-100 (n, 2n) Mo-99) that produces two neutrons per irradiation of one neutron, and molybdenum 99 (Mo-99) is produced. Will be done. The produced molybdenum 99 becomes technetium-99m (Tc-99m) by beta decay.

In this case as well, since the same radionuclide is produced by irradiating the braking radiation and neutrons, an increase in the production amount can be expected.

Radium 225 (Ra-225) produced from the raw material of the first stage becomes actinium 225 (Ac-225), which is a progeny nuclide, with a half-life of 14.8 days. Actinium 225 is a typical alpha ray emitting nuclide as a raw material nuclide of a therapeutic drug, and when it is provided for a therapeutic drug, it is not a nuclide that emits alpha rays after being separated and purified, but a radioactivity unnecessary for treatment. The raw material Ra-225 for nuclide production and the produced Ra-225 are separated. For the separation and purification, for example, the method described in Patent Document 1 can be adopted. Actinium 225 also undergoes an alpha decay to progeny nuclides such as Francium Fr-221, astatine At-217, and bismuth Bi-213 after a predetermined half-life, but these progeny nuclides also emit alpha rays in the same manner as actinium 225. It is a nuclide and can be used therapeutically.

Mo-99 produced by the reaction of the raw materials in the latter stage becomes Tc-99m, which is a progeny nuclide, with a half-life of 66 hours. Tc-99m is a gamma-ray emitting nuclide that is typical as a raw material nuclide for diagnostic agents, and when it is provided for therapeutic agents, it is separated and purified from raw materials Mo-99 and Mo-100, which are unnecessary nuclides for diagnosis. To do.

Ra-226 and Mo-99 remaining after separating and purifying Ac-225 and Tc-99m, respectively, can be reused as raw materials. As a result, the amount of Mo-99 and Ra-226, which are relatively expensive raw materials for producing radionuclides, can be reduced.

Although the embodiments for producing actinium 225 (Ac-225) and technetium-99m (Tc-99m) have been described above, the raw materials in the first and second stages may be interchanged. Further, the radiation generating material is not limited to bismuth, and other heavy metals such as lead may be used.

As described above, according to the production method of the present embodiment, a material that emits braking radiation and neutrons by electron beam irradiation is used, and a raw material for producing the same type of nuclide by nuclear reaction between the braking radiation and neutrons is used as a raw material. As a result, the production efficiency of radionuclides can be improved. Further, by arranging a plurality of raw materials as raw materials so as to be stacked behind the material, it is possible to produce different types of nuclides in the same manufacturing process. This makes it possible to efficiently produce radionuclides, which are raw material nuclides for a plurality of medical (diagnostic and therapeutic) drugs. Further, since the manufacturing method of the present embodiment uses braking radiation and neutrons generated by electron beam irradiation, a smaller electron beam accelerator can be used as compared with an accelerator such as a cyclotron, and the entire system can be made smaller and cheaper. it can.

Next, a manufacturing apparatus for realizing the production of the radionuclide described above will be described.

<First Embodiment>
As shown in FIG. 5A, the radionuclide production apparatus 100 of the present embodiment includes an electron beam accelerator 10 that emits a high-speed electron beam, a material 25 that receives the radiation of the electron beam to generate braking radiation, and the like. It includes a reaction chamber 30 in which a raw material 20 for producing a radionuclide is arranged. The electron beam accelerator 10 is a device that drives electrons emitted from an electron gun into an accelerating tube, accelerates them by an electric field in the accelerating tube, and emits them as an electron beam 11, and various beam energies are available. .. These known electron beam accelerators can be used in the radionuclide production apparatus of the present embodiment.

The reaction chamber 30 is arranged in close proximity to the electron beam accelerator 10, has an opening through which the electron beam 11 emitted from the electron beam accelerator 10 is transmitted, and supports the radiation generating material 25 and the raw material 20 inside, respectively. The mechanisms 40 and 50 are provided. When a plurality of different kinds of raw materials are used as the raw materials, the support mechanism 50 may be a mechanism for independently supporting the plurality of raw materials.

In the present embodiment, the irradiation direction of the electron beam 11 emitted from the electron beam accelerator 10 is the horizontal direction, and the radiation generating material 25 and the raw material 20 are horizontal to the positions where the electrons are irradiated by the support mechanisms 40 and 50. They are arranged so as to overlap in the direction, that is, along the irradiation direction of the electron beam. Note that "arranged so as to overlap" includes the case where the electron beam irradiation direction is deviated from the direction intersecting with the electron beam irradiation direction, and when they are in close contact with each other, for example, a substance that transmits radiation or the like, a gas in the reaction chamber, or a container for raw materials Alternatively, it also includes a case where a part of a mechanism for supporting the raw material is intervened.

The support mechanisms 40 and 50 may be simply a plate-shaped member on which the raw material is placed or an arm-shaped member that supports the raw material from the side, and the mechanism and shape thereof are not limited as long as they do not interfere with the irradiation of the electron beam. Absent. Further, the support mechanisms 40 and 50 may be provided with a moving mechanism or a rotating mechanism for taking out or exchanging the radiation generating material 25 and the raw material 22 after the reaction. The reaction chamber 30 is composed of or covered with a material that shields electron beams and radiation generated in the process of producing radionuclides.

The radiation generating material 25 contains simple substances or compounds such as bismuth, lead, tungsten, and platinum, as described in the above-mentioned production method. In the case of heavy metals, the radiation generating material 25 can be fixed to the support mechanism 40 as it is, but it may be put in a container and fixed to the support mechanism 40. As the structural material of the container for materials, a material composed of beryllium, carbon, aluminum composed of elements having a small density and atomic number, and compounds such as oxides and boron compounds thereof may be used. .. When the energy of the electron beam 11 is applied to the material 25, most of the energy is applied to the material 25. Therefore, the material 25 generates heat, and when the solid material 25 is used, the material 25 may exceed the melting point and become a liquid. In particular, when bismuth or lead or a compound thereof is used as the material 25, there is a high possibility that it will become a liquid because of its low melting point. By storing in a container. Even when it becomes a liquid, the liquid remains in the container, so that the soundness of the material 25 is maintained. When beryllium is used as the structural material of the material container, neutrons and the raw material 20 are generated because relatively high energy neutrons are generated by the nuclide reaction between the braking radiation generated by the material 25 and beryllium which is the container material. The amount of radionuclides produced by the nuclear reaction with the raw material nuclides inside can be increased.

It is desirable that the thickness of the radiation generating material 25 in the electron beam irradiation direction is determined so that the intensity of the braking radiation and the neutron flux passing therethrough on the surface of the raw material is maximized. As schematically shown in FIG. 6, the flux strength increases as the thickness increases, but if it is too thick, it decreases due to the shielding effect of the material 25, and there is a thickness that maximizes the strength. For each of the braking radiation and neutrons, the thickness that maximizes the flux intensity on the surface of the raw material is obtained by actual measurement or simulation, and the thickness that maximizes the flux intensity of one (for example, neutron) and the other (for example, braking radiation) A value between the thickness that maximizes the flux strength, for example, the average value thereof, can be the thickness of the material 25.

The raw material 20 produces the same kind of radioactive nuclei by reacting with braking radiation and neutrons, and specifically, radium-226 (Ra-226) or a compound thereof, Renium 187 or a compound thereof (Re-187), Elbium 170 (Er-170) or its compounds, Elbium 166 (Er-166) and its compounds, Palladium 104 (Pd-104) or its compounds, Molybdenum 100 (Mo-100) or its compounds, or Calcium 40 (Ca- 40) or a compound thereof.

As the raw material 20, a single raw material may be used as shown in FIG. 5 (A), but as shown in FIG. 5 (B), a plurality of raw materials 20A and 20B are stacked in the electron beam irradiation direction. It may be arranged. In this case, as the raw materials 20A and 20B, the same kind of raw materials may be used, or different kinds of raw materials may be used. When the same type of nuclide is used, the production efficiency of the same type of nuclide can be increased, and when different types of nuclides are used, a plurality of types of nuclide can be produced in the same production process.

When a plurality of raw materials are arranged in an overlapping manner, it is preferable that at least one of the atomic number and the density of the raw materials in the first stage is smaller than that in the raw materials in the latter stage. As a result, the shielding effect of radiation and the like in the previous stage can be reduced, and more braking radiation and neutrons not used in the raw material in the previous stage can be irradiated to the raw material in the latter stage. For example, molybdenum 100 (Mo-100) or a compound thereof is used as a raw material in the first stage, and radium 226 (Ra-226) or a compound thereof is used as a raw material in the second stage.

The raw material 20 is fixed to the support mechanism 50 in a state of being installed or stored in the container as needed. By storing the raw material 20 in the container, safety can be maintained even when the liquid raw material is used or when the solid raw material is changed to the liquid state. As the structural material of the raw material container, the same material as the above-mentioned material container can be used.

The radionuclide production apparatus of the present embodiment brakes by irradiating the radiation generating material 25 arranged in the irradiation direction with the electron beam emitted from the electron beam accelerator 10 according to the radionuclide production method described above. Generates radiation (γ-rays) and neutrons. The generated braking radiation and neutrons cause a nuclear reaction with the raw material 20, respectively. Since the nuclide produced by the reaction with the braking radiation (γ, n) and the nuclide produced by the reaction with the neutron (n, 2n) are the same in the raw material 20, one nuclide is produced by two different reactions. To.

When another raw material 21 is arranged and supported after the raw material 20, the braking radiation and neutrons that have passed through the raw material 20 also react with the raw material 21 by nuclear reaction (γ, n) or (n). 2n) produces one nuclide. By using different types of raw materials 20 and 21, different nuclides can be produced in the first stage and the second stage. Further, by using a raw material having a density or atomic number smaller than that of the raw material 21 in the latter stage as the raw material 20 in the first stage, the amount of braking radiation and neutrons irradiated to the raw material 21 can be secured, and the production efficiency in the latter stage is lowered. Can be prevented.

Although the basic embodiment of the apparatus for realizing the method for producing a radionuclide of the present invention has been described above, the specific embodiment of the apparatus in consideration of the exchange of raw materials and the like will be further described below.

<Second embodiment>
In the first embodiment, the irradiation direction of the electron beam was the horizontal direction in the present embodiment, but the radionuclide production apparatus of the present embodiment has the electron beam accelerator 10 and the reaction chamber so that the irradiation direction of the electron beam is vertical. The feature is that 30, the material 25, and the raw material 20 are arranged. The reaction caused by the material 25, the type of raw material, and the irradiation of the electron beam is the same as that described in the above-mentioned production method, and the description thereof is omitted here.

As shown in FIG. 7, in the radionuclide production apparatus 100A of the present embodiment, the electron beam accelerator 10 is installed vertically in the upper part of the reaction chamber 30, and the radiation generating material 25 and the raw material 20 are irradiated with an electron beam. They are arranged so as to overlap along the direction (vertical direction). Alternatively, as shown in FIG. 8A, the electron beam accelerator 10 may be installed horizontally, and the electron beam 11 may be irradiated to the material 25 from above by using the deflection electromagnet device 60.

According to the present embodiment, since the electron beam irradiation direction is vertical, for example, even if the material 25 is easily liquefied or the raw material 20 is a liquid or powder, FIG. 8B By storing and arranging the container 70 as shown in the above, the electron beam irradiation surface can be evenly arranged, and the electron beam irradiation can be performed evenly. Further, a robust support mechanism for installing the relatively heavy electron beam accelerator 10 in the upper part of the reaction chamber 30 can be eliminated. Further, the reaction chamber 30 is arranged in a radiation-shielded basement chamber or the like, an electron beam accelerator 10 is installed on the floor above the reaction chamber 30, and the electron beam accelerator 10 is connected by a deflection magnet device 60, depending on the facility where the manufacturing apparatus is installed. The irradiation direction can be selected, and the degree of freedom in the installation location and arrangement of the electron beam accelerator and the reaction chamber is increased.

<Third Embodiment>
The present embodiment is characterized in that the support mechanism 40 of the radiation generating material 25 is provided with a mechanism for suppressing heat generation at the braking radiation and the neutron generation location (material). Other than that, it is the same as the radionuclide production apparatus of the first embodiment or the second embodiment. Hereinafter, the mechanism for suppressing heat generation of the present embodiment will be described by taking the radionuclide production apparatus 100A in which the electron beam irradiation direction is vertical as an example.

The radiation generating material 25 and its supporting mechanism 40 of the present embodiment are shown in FIG. This support mechanism includes a rotary movement mechanism having a motor (not shown) installed outside the reaction chamber 30, a rotary shaft 41 connected to the motor, and a jig 42 fixed to the rotary shaft 41. The material 25 or the container 70 for storing the material 25 has a cylindrical shape (the shape seen from the electron beam irradiation direction is a donut shape) in which the central portion is hollowed out concentrically, so that the rotating shaft 41 is located at the center of the material 25. The inside thereof is fixed to the jig 42. In the figure, two places are fixed, but the fixed places are not limited to two places. Further, the jig 42 is preferably provided with a chuck or the like for detachably fixing the material 25, and in that case, the material 25 or the container 70 is fixed to the jig 42 via the chuck.

As shown in FIG. 10, the size of the material 25 is half the difference between the outer peripheral diameter L1 and the inner peripheral diameter L2 {(L1-L2) / 2}, which is the same as the diameter D of the irradiation area of the electron beam. The size is about or larger. Further, the rotation mechanism is installed in the reaction chamber 30 so that a part of the material 25 is positioned at the electron beam irradiation position. The raw material 20 (20A, 20B in the case of a plurality) is arranged behind the electron beam irradiation region of the material 25.

In the radionuclide production apparatus of the present embodiment, by rotating the material 25 during electron beam irradiation, the heat generated by the material 25 due to the generation of braking radiation and neutrons by receiving high electron beam energy is dispersed in the material. Therefore, deterioration of the material can be prevented. Further, the material 25 is constantly irradiated with an electron beam in a part of the region even during rotation, and the raw material 20 arranged behind the material 25 is continuously irradiated with braking radiation and neutrons from that region, and the nuclear reaction is maintained. ..

Although FIG. 9 shows a case where the material support mechanism 40 is a rotation mechanism as a mechanism for alleviating heat generation, a mechanism for reciprocating the material in the horizontal direction (direction orthogonal to the electron beam irradiation direction) is adopted. It is also possible to do. Further, instead of the means for mechanically moving the material, or in addition to the mechanical means, the support mechanism 40 of the material 25 may be provided with a cooling device such as a water channel for cooling water, or cooling fins may be provided. Is.

Further, although FIG. 9 shows a case where the electron beam irradiation direction is the vertical direction, the same effect can be obtained even in the horizontal direction by simply changing the mounting direction of the rotating shaft 41. it can.

<Fourth Embodiment>
The present embodiment is characterized in that a moving mechanism for taking out the raw material 20 is provided. Hereinafter, the radionuclide production apparatus 100B of the present embodiment will be described with reference to FIG. In this embodiment as well, the device in which the electron beam irradiation direction is the vertical direction will be described as an example, but the electron beam irradiation direction is not limited to the vertical direction.

As shown in FIG. 11, in the radionuclide production apparatus 100B of the present embodiment, the electron beam accelerator 10 is installed vertically in the upper part of the reaction chamber 30, and the electron beam emitted from the electron beam accelerator 10 is irradiated. The radiation generating material 25 and the raw materials 20A and 20B are arranged at such positions so as to overlap each other. The figure shows a state in which the raw material is stored in a container as an example.

Although the support mechanism of the material 25 is not shown, the material 25 may be a fixed support mechanism as shown in FIG. 5, or may be supported by a rotation mechanism or the like as in the third embodiment. .. When supported by a rotating mechanism, the material has a donut-shaped shape, a part of the area is arranged at the electron beam irradiation position, and the area at the irradiation position is moved by the rotating mechanism.

The mechanism 50 that supports the raw materials 20A and 20B is a rotating shaft 52A that is connected to the motor 51 installed outside the reaction chamber 30 and the rotating shaft of the motor 51 and is independently controlled as a mechanism for moving the raw materials. 52B, a jig 53A for connecting the rotary shaft 52A and the raw material 20A, and a jig 53B for connecting the rotary shaft 52B and the raw material 20B. When the material 25 is supported by the rotating mechanism, the rotating shaft may be coaxial with the rotating shafts 52A and 52B of the mechanism 50. As a result, the configurations of the support mechanisms 40 and 50 can be made compact.

The raw materials 20A and 20B were fixed to the jigs 53A and 53B by a detachable mechanism (not shown), respectively, and the rotation shafts 52A and 52B were rotated so as to be displaced from the positions overlapping in the electron beam irradiation direction as shown in FIG. You can move to the position and exchange or take out the raw materials. The reaction chamber 30 may be provided with a spare chamber 35 provided with an opening / closing door capable of maintaining airtightness with the reaction chamber 30 at the raw material extraction position in order to maintain the airtightness of the reaction chamber when the raw material is taken out. In that case, with the reaction chamber 30 and the reserve chamber 35 open (closed to the outside), the raw material is moved to the reserve chamber 35, and after closing between the reaction chamber 30 and the reserve chamber 35, The raw material is taken out from the spare chamber 35 or the raw material is exchanged in the spare chamber.

As for the timing of taking out and exchanging raw materials, the time to reach the required production amount and the time to be replaced differ depending on the type of raw material, so under time management, the raw material is taken out manually or automatically via a robot arm or the like / Perform replacement work. The automatic control is performed based on the time and replacement period for reaching the required production amount in advance.

In this way, when nuclides are produced using a plurality of raw materials by providing a moving mechanism that operates independently for each of the plurality of raw materials, one raw material is taken out or exchanged using another raw material. The production can be continued, and the decrease in the operating rate due to the exchange of raw materials can be prevented.

As the raw material moving mechanism, in addition to the mechanism consisting of the rotation axis and the jig described above, as shown in FIG. 13, the raw materials 20A and 20B are expanded and contracted to move in parallel in the direction orthogonal to the electron beam irradiation direction. The mechanism 55 may be adopted. The drive unit 57 of the expansion / contraction mechanism 55 is installed in, for example, the spare chamber 35. In the radionuclide production apparatus 100C shown in FIG. 13, the radiation generating material 25 is supported by the rotating shaft 41, and the electron beam irradiation region is changed.

According to the present embodiment, the support mechanism for the raw material is provided with a moving mechanism for taking out the raw material, so that the raw material can be smoothly taken out and exchanged. In particular, by providing a mechanism for taking out that can be driven independently for each of a plurality of raw materials, it is possible to take out raw materials according to the required production amount of nuclides, and appropriate manufacturing control is performed including consideration of half-life and the like. be able to.

Although FIGS. 11 to 13 show an embodiment in which a plurality of raw materials 20A and 20B are arranged, this embodiment can also be applied to a case where only one raw material is arranged.

According to the present invention, there are radionuclides that emit alpha rays such as actinium 225 (Ac-225), which is in great demand as a raw material nuclide for therapeutic agents, and Tc-99m, which is in great demand as a raw material for diagnostic agents. It is possible to provide a radionuclide production system capable of efficiently producing a radionuclide that emits gamma rays and a nuclide that emits beta rays with a small and lightweight device.

10: Electron beam accelerator, 20, 20A, 20B: Raw material, 25: Radiation generation material, 30: Reaction chamber, 40: Material support mechanism, 50: Raw material support mechanism, 60: Deflection magnet device, 70: For material Container, 100, 100A, 100B, 100C: Radionuclide production apparatus.

Claims (15)

A method for producing radionuclides using electron beams emitted from an electron beam accelerator.
A material that is irradiated with the electron beam and emits braking radiation and neutrons is arranged on the upstream side of the electron beam irradiation direction, and the braking radiation and neutrons emitted by the material are received on the downstream side of the material. A raw material for producing a radionuclide is arranged, and as the raw material, a raw material in which the radionuclide generated by the irradiation of the braking radiation and the radionuclide generated by the irradiation of the neutron are the same nuclide is used. A method for producing radionuclides. The method for producing a radionuclide according to claim 1.
A method for producing a radionuclide, wherein the material is a heavy metal or a compound of a heavy metal. The method for producing a radionuclide according to claim 1.
The raw materials are radium-226 (Ra-226), renium 187 (Re-187), erbium 170 (Er-170), erbium 166 (Er-166), palladium 104 (Pd-104), molybdenum 100 (Mo-100). ), Calcium 40 (Ca-40) or a method for producing a radioactive nuclei, which is one or more selected from compounds thereof. The method for producing a radionuclide according to claim 1.
A method for producing a radionuclide, wherein the raw material contains a first raw material and a second raw material arranged on the downstream side of the first raw material. The method for producing a radionuclide according to claim 4.
A method for producing a radionuclide, which comprises using a substance having either an atomic number or a density smaller than that of the second raw material as the first raw material. The method for producing a radionuclide according to claim 1.
The thickness of the material in the irradiation direction of the electron beam is equal to or greater than the thickness of the material having the maximum intensity of the braking radiation and the neutron on the surface of the material. A method for producing a radionuclide, which is characterized by having a thickness in the range of 1 or less. Electron beam accelerator and
A material that is arranged on the upstream side with respect to the irradiation direction of the electron beam emitted from the electron beam accelerator and emits braking radiation and neutrons by being irradiated by the electron beam, and a material that is arranged on the downstream side of the material and described above. It is equipped with a reaction chamber that stores the raw materials that generate radionuclides by receiving the bremsstrahlung radiation and neutrons emitted by the material, and conducts a reaction that produces radionuclides using electron beams.
The raw material is a radionuclide production apparatus characterized in that the radionuclide produced by irradiation with the braking radiation and the radionuclide generated by irradiation with neutrons are the same radionuclide. The radionuclide production apparatus according to claim 7.
The material or the container for storing the material has a shape surrounded by concentric circles having different diameters when viewed from the irradiation direction of the electron beam, and the electron beam is irradiated to a part of the circumferential direction. A radionuclide production apparatus characterized in that it is eccentric with respect to the irradiation direction of the electron beam and is rotatably supported with the center of the concentric circle as a rotation axis. The radionuclide production apparatus according to claim 7.
A radionuclide production apparatus further comprising a moving mechanism for moving the raw material from a position on the extension of the irradiation direction of the electron beam to a raw material extraction position. The radionuclide production apparatus according to claim 9.
The raw material includes a first raw material and a second raw material arranged on an extension of the irradiation direction of the electron beam, and the moving mechanism is provided for each of the first raw material and the second raw material. A radionuclide production device characterized by being The radionuclide production apparatus according to claim 9.
The radionuclide production apparatus is characterized in that the moving mechanism is a rotating mechanism that rotates the raw material or a container for storing the raw material with an axis parallel to the irradiation direction of the electron beam as a rotation axis. The radionuclide production apparatus according to claim 9.
The radionuclide production apparatus, characterized in that the moving mechanism is a telescopic mechanism that translates the raw material or a container for storing the raw material in a direction orthogonal to the irradiation direction of the electron beam. The radionuclide production apparatus according to claim 7.
A radionuclide production apparatus characterized in that the irradiation direction of the electron beam is a horizontal direction, and the material and the raw material are arranged so as to be stacked in the horizontal direction. The radionuclide production apparatus according to claim 7.
A radionuclide production apparatus characterized in that the irradiation direction of the electron beam is a vertical direction, and the material and the raw material are arranged vertically. The radionuclide production apparatus according to claim 14.
The electron beam accelerator is arranged so that the irradiation direction of the electron beam is in the horizontal direction, and a deflecting magnet device that changes the irradiation direction of the electron beam is arranged between the electron beam accelerator and the reaction chamber. A radionuclide production apparatus characterized in that.

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