JP7506055B2 - Target irradiation system and method for recovering radioisotopes from solid targets - Patents.com - Google Patents

Description

The present invention relates to a target irradiation system and a method for recovering radioisotopes from a solid target.

As shown in Patent Document 1, a self-shielded cyclotron system is known that houses a cyclotron and has a self-shield that suppresses radiation emitted from the cyclotron from being emitted to the outside. In recent years, devices have been developed that obtain solid radioisotopes (RI) by irradiating a target having a metal layer with a charged particle beam. Such radioisotopes are used to manufacture radiopharmaceuticals used in PET (positron emission tomography) examinations in hospitals, etc. For example, in Patent Document 2, a target to which a solid radioisotope is attached is transported to a melting device, and the radioisotope is melted in the melting device to recover the RI.

JP 2000-105293 A JP 2014-115229 A

Here, the target becomes radioactive after being irradiated with the charged particle beam. Therefore, it is necessary to remove the target from the irradiation device and quickly dissolve the radioisotopes in a dissolving device.

The present invention aims to provide a target irradiation system that can remove the target from an irradiation device and quickly melt the radioactive isotopes in a melting device, and a method for recovering radioactive isotopes from a solid target.

The target irradiation system of the present invention is a target irradiation system that irradiates a solid target having a metal layer with a charged particle beam emitted from a particle accelerator to generate radioactive isotopes from the metal layer, and is equipped with a target irradiation device that is placed in a room provided in a building and holds the solid target at an irradiation position for the charged particle beam to enable irradiation of the solid target with the charged particle beam, and a melting device that is placed in the room and melts radioactive isotopes attached to the solid target after irradiation of the charged particle beam by the target irradiation device has been completed.

In the target irradiation system according to the present invention, the target irradiation device holds the solid target at the irradiation position of the charged particle beam and enables irradiation of the solid target with the charged particle beam. As a result, radioactive isotopes are formed in the metal layer of the solid target at the location irradiated with the charged particle beam by the target irradiation device. The melting device dissolves the radioactive isotopes attached to the solid target after irradiation with the charged particle beam by the target irradiation device. As a result, it becomes possible to recover the radioactive isotopes by recovering the dissolving liquid. Here, the target irradiation device and the melting device are disposed in a room provided in a building. Therefore, both the process of irradiating the solid target with the charged particle beam and the process of recovering the radioactive isotopes by dissolving them are performed indoors. Therefore, the solid target can be removed from the target irradiation device and the radioactive isotopes can be quickly dissolved in the melting device.

The target irradiation system may further include a support that supports the target irradiation device relative to the floor of the chamber, and the melting device may be supported relative to the floor by the support. In this case, since the target irradiation device and the melting device are supported by a common support, they can be positioned close to each other.

The target irradiation system may further include a transport device that transports the solid target released from the target irradiation device to the melting device. In this case, it is possible to quickly transport the solid target from the target irradiation device to the melting device.

The target irradiation system may be provided in a room, contain the particle accelerator and the target irradiation device, and further include a shielding shield that blocks radiation emitted from the particle accelerator and the target irradiation device, and the melting device may be provided in the shielding shield. In this case, the shielding shield can block radiation when the solid target is transported from the target irradiation device to the melting device.

The target irradiation system further includes a transport device that transports the solid target from the target irradiation device to the melting device, and a control unit, and the control unit may control the transport device to transport the solid target held in the target irradiation device to the melting device after the metal layer is irradiated with the charged particle beam. In this way, the transport of the solid target by the transport device is automatically performed by the control unit. This can further reduce exposure to radiation to workers. In addition, by having the control unit automatically transport the solid target, the working time can be shortened.

The target irradiation system may be provided indoors, house a particle accelerator and a target irradiation device, and further include a shielding shield for blocking radiation emitted from the particle accelerator and the target irradiation device, and may include a container section for covering the melting device within the shielding shield, and an exhaust section for exhausting gas within the container section to the outside of the shielding shield. In this case, when the melting liquid of the melting device is vaporized, the container section prevents the gas from diffusing into the shielding shield. In addition, the gas within the container section is exhausted to the outside of the shielding shield by the exhaust section. This prevents other equipment within the shielding shield from being corroded by the gas.

The target irradiation system may further include a transport device that transports the solid targets, and the transport device may be capable of supporting multiple solid targets. In this case, the transport device can transport multiple solid targets to the irradiation position and the melting position without removing the solid targets along the way. This can reduce the effects of radiation exposure caused by the removal work.

The target irradiation system further includes a support device that supports the solid target, the target irradiation device includes an irradiation port from which a charged particle beam is emitted, the melting device includes a melting port that supplies and recovers the melting liquid, and the support device may be connected to the irradiation port and also to the melting port. In this case, the support device can be used as both a part of the target irradiation device and a part of the melting device.

The dissolution device may be equipped with multiple dissolution ports for supplying and recovering the dissolution liquid. In this case, the dissolution process of multiple radioisotopes can be carried out without the need to replace the dissolution ports.

The target irradiation system is a system that irradiates a solid target having a metal layer with a charged particle beam emitted from a particle accelerator to generate radioisotopes of the metal layer, and includes a target irradiation device that holds the solid target at an irradiation position for the charged particle beam to enable irradiation of the solid target with the charged particle beam, and a melting device that melts the radioisotopes attached to the solid target after irradiation with the charged particle beam by the target irradiation device is completed, and the target irradiation device and the melting device are located in the same room in a building. With this target irradiation system, it is possible to obtain the same actions and effects as the above-mentioned target irradiation system.

The method for recovering radioisotopes from a solid target is a method for recovering radioisotopes from a solid target having a metal layer, the method comprising: irradiating the solid target with a charged particle beam by a target irradiation device arranged in a shielded room provided in a building to generate radioisotopes in the solid target; transporting the solid target, which has been irradiated with the charged particle beam, to a melting device arranged in the shielded room by a transport device capable of transporting the solid target; and melting the radioisotopes attached to the solid target by the melting device. According to this recovery method, the process of irradiating the solid target with a charged particle beam, the process of transporting the solid target, and the process of recovering the radioisotopes by melting are all performed in the shielded room. Therefore, the solid target can be removed from the target irradiation device and the radioisotopes can be quickly dissolved in the melting device. In addition, radiation can be shielded in each process.

The present invention provides a target irradiation system that can remove the target from an irradiation device and quickly melt the radioactive isotopes in a melting device, and a method for recovering radioactive isotopes from a solid target.

1 is a schematic diagram illustrating a self-shielded cyclotron system including a target irradiation system according to an embodiment of the present invention. FIG. 2 is a perspective view of a solid target. FIG. 2 is a close-up view of the target illumination system. 13 is a flowchart showing the processing contents of a control unit. FIG. 2 is an expanded view showing the operation of the target illumination system. FIG. 2 is an expanded view showing the operation of the target illumination system. FIG. 2 is an expanded view showing the operation of the target illumination system. FIG. 2 is an expanded view showing the operation of the target illumination system. FIG. 2 is an expanded view showing the operation of the target illumination system. FIG. 13 is an enlarged view showing a self-shielded cyclotron equipped with a target irradiation system according to a modified example. FIG. 13 is a conceptual configuration diagram showing a target irradiation system according to a modified example. FIG. 13 is a schematic configuration diagram showing a target irradiation system according to a modified example. FIG. 13 is a schematic diagram showing the main parts of the target irradiation system shown in FIG. 12 . FIG. 11 is a perspective view showing an example of a specific structure of a target exchanger. 11 is a cross-sectional view showing a state in which the support device is pressed against an irradiation port. FIG. FIG. 13 is a cross-sectional view showing a state in which the support device is pressed against the dissolution port. FIG. 2 is a front view of the dissolution port. 1 is a schematic diagram illustrating the operation of the target illumination system. 1 is a schematic diagram illustrating the operation of the target illumination system. 1 is a schematic diagram illustrating the operation of the target illumination system. 1 is a schematic diagram illustrating the operation of the target illumination system. 1 is a schematic diagram illustrating the operation of the target illumination system. 1 is a schematic diagram illustrating the operation of the target illumination system.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that in each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

As shown in FIG. 1, the self-shielded cyclotron system 100 is a system installed inside a building 150. The self-shielded cyclotron system 100 according to this embodiment is a system for producing radioisotopes (hereinafter, sometimes referred to as RI) using a charged particle beam. The self-shielded cyclotron system 100 can be used, for example, as a PET cyclotron, and the RI produced by the system is used, for example, for producing radiopharmaceuticals (including radiopharmaceuticals) that are radioisotope-labeled compounds (RI compounds). Examples of radioisotope-labeled compounds used in PET examinations (positron emission tomography examinations) in hospitals and the like include ¹⁸ F-FLT (fluorothymidine), ¹⁸ F-FMISO (fluorosonidazole), and ¹¹ C-raclopride.

The self-shielded cyclotron system 100 includes a cyclotron 2 (particle accelerator), a target irradiation system 3, and a shielding shield 4. The self-shielded cyclotron system 100 is installed on the floor 151 of a building 150 in a cyclotron room 152 inside the building. The cyclotron room 152 is a room covered with concrete (shielding wall). Therefore, by using the self-shielded cyclotron system 100, a user can obtain radioisotopes on the spot inside the building.

The cyclotron 2 is an accelerator that emits a charged particle beam. The cyclotron 2 is a circular accelerator that supplies charged particles from an ion source into an acceleration space, accelerates the charged particles in the acceleration space, and outputs a charged particle beam. The cyclotron 2 has a pair of magnetic poles, a vacuum box, and an annular yoke that surrounds the pair of magnetic poles and the vacuum box. The pair of magnetic poles face each other with a predetermined distance between them in the vacuum box. In the gap between the pair of magnetic poles, the charged particles are multiple-accelerated. Examples of the charged particles include protons and heavy particles (heavy ions). In this embodiment, the cyclotron 2 has a plurality of ports 2a that emit the charged particle beam. A target irradiation device 20, which will be described later, is formed in one of the plurality of ports 2a. The cyclotron 2 adjusts the trajectory of the charged particle beam in the acceleration space to extract the charged particle beam from the desired port 2a.

The shielding shield 4 is provided inside the room (inside the cyclotron room 152), and houses the cyclotron 2 and the target irradiation device 20 described later inside, and shields radiation emitted from the cyclotron 2 and the target irradiation device 20 described later. The shielding shield 4 is arranged inside the building, houses the cyclotron 2 inside, and suppresses radiation emitted from the cyclotron 2 from being emitted into the cyclotron room 152. The shielding shield 4 covers the cyclotron 2 from all directions, thereby shielding radiation in all directions. In this embodiment, the shielding shield 4 has a hexahedral box structure, but the shape is not particularly limited. The shielding shield 4 separates the internal space (cyclotron room 152) of the building 150 from the internal space 120 of the self-shielded cyclotron system 100. The internal space of the building 150 may be configured as a space in which other equipment is installed or through which workers can pass. Therefore, the self-shielded cyclotron system 100 of this embodiment is different from a system in which the cyclotron 2 is simply arranged inside a building, and the surrounding walls constituting the room of the building do not correspond to the shielding shield 4. The walls of the shielding shield 4 are made of materials such as polyethylene, iron, lead, and heavy concrete. In addition to the cyclotron 2, a vacuum pump and wiring for operating the cyclotron 2 are also arranged inside the shielding shield 4. In addition, components of the target irradiation system 3 are also arranged inside the shielding shield 4. Therefore, the shielding shield 4 functions as a support part that supports a target irradiation device 20 described later on a floor 151 of the cyclotron room 152. A melting device 21 described later is supported on the floor 151 by the shielding shield 4 functioning as a support part. With the above-mentioned configuration, the target irradiation device 20 described later and the melting device 21 described later are arranged in the same room (in the cyclotron room 152) provided in the building 150.

The target irradiation system 3 is a part that irradiates a solid target 10 with a charged particle beam and dissolves and collects radioisotopes generated by the irradiation. The target irradiation system 3 is formed near the outer periphery of the cyclotron 2 and is arranged inside the shielding shield 4. The solution containing the radioisotopes obtained by the target irradiation system 3 is sent via a transport pipe 161 to an apparatus 160 such as a purification apparatus that purifies the radioisotopes in the solution or a synthesis apparatus that synthesizes pharmaceuticals.

The solid target 10 will be described with reference to FIG. 2. The solid target 10 includes a target substrate 13 and a metal layer 11. Specifically, as shown in FIG. 2, the solid target 10 includes a metal layer 11 formed as a target material on a target substrate 13 made of a metal plate. The metal layer 11 is not limited to a layer of a high-purity metal, but may be a layer of a metal oxide. The target substrate 13 is set in an apparatus, and the metal layer 11 is irradiated with a charged particle beam B, so that a small amount of radioactive isotopes 12 are generated in the irradiated portion. As a result, the radioactive isotopes 12 are contained in the metal layer 11. As a material for the target substrate 13, a material that is not dissolved in a dissolving solution is adopted, such as Au, Pt, etc. The target substrate 13 shown in FIG. 2 is formed in a disk shape, but the shape and thickness are not particularly limited. Examples of materials for the metal layer 11, which is a target material, include ⁶⁴ Ni, ⁸⁹ Y, ¹⁰⁰ Mo, and ⁶⁸ Zn. Examples of the radioisotope 12 generated corresponding to the metal layer 11 include ⁶⁴ Cu, ⁸⁹ Zr, ^99m Tc, and ⁶⁸ Ga. The metal layer 11 is formed by plating the front surface 10a of the target substrate 13. In addition, the metal layer 11 may be attached to the target substrate 13 without being limited to plating. The metal layer 11 shown in FIG. 2 is formed in a circular shape at the center of the target substrate 13, but the shape and position are not particularly limited. In addition, when the metal layer 11 is irradiated with the charged particle beam B, cooling water or the like is supplied to the rear surface 10b of the target substrate 13. This allows the heat generated by the metal layer 11 (and the target substrate 13) due to the irradiation with the charged particle beam B to be absorbed by the cooling water or the like.

Next, the configuration of the target irradiation system 3 will be described in detail with reference to Fig. 3. The target irradiation system 3 irradiates a solid target 10 having a metal layer 11 with a charged particle beam emitted from a cyclotron 2 to generate radioisotopes of the metal layer 11. The target irradiation system 3 includes a target irradiation device 20, a melting device 21, a transport device 22, and a control unit 50.

The target irradiation device 20 is disposed in a room (inside the cyclotron room 152) provided in the building 150, and is a device that holds the solid target 10 at the irradiation position of the charged particle beam B to enable irradiation of the charged particle beam B to the solid target 10. The target irradiation device 20 holds the solid target 10 having the metal layer 11 at the irradiation position of the charged particle beam B. In addition, when the irradiation of the charged particle beam B to the solid target 10 is completed, the target irradiation device 20 releases the holding of the solid target 10. Specifically, the target irradiation device 20 includes a fixed unit 23 and a movable unit 24. The target irradiation device 20 holds the solid target 10 at the irradiation position RP by sandwiching the solid target 10 between the fixed unit 23 and the movable unit 24. Both the fixed unit 23 and the movable unit 24 are housed in the shielding shield 4.

The fixed unit 23 is a cylindrical member fixed to the outer periphery of the cyclotron 2. The fixed unit 23 is provided in a state where it extends along the irradiation axis BL of the charged particle beam B emitted from the cyclotron 2 and protrudes from the outer periphery of the cyclotron 2. The fixed unit 23 has an internal space 26 for passing the charged particle beam B at a position corresponding to the irradiation axis BL of the charged particle beam B. The internal space 26 is formed so as to extend along the irradiation axis BL with the irradiation axis BL as its center line. The fixed unit 23 and the internal space 26 are arranged so as to be inclined downward with respect to the horizontal direction.

The fixed unit 23 has a surface extending horizontally at the lower end as the facing surface 23a that faces the upper surface of the movable unit 24. The fixed unit 23 holds the solid target 10 at the position of the facing surface 23a. A sealing member such as an O-ring is provided on the facing surface 23a. The facing surface 23a also functions as a sealing surface for the solid target 10 by abutting against the solid target 10 via the sealing member. In this embodiment, the location where the internal space 26 opens on the facing surface 23a (and further the position of the irradiation axis BL therein) corresponds to the irradiation position RP. Therefore, when the target irradiation device 20 holds the solid target 10, the metal layer 11 of the solid target 10 is held so as to be positioned at the opening of the internal space 26.

The fixed unit 23 is provided with a vacuum foil 25 at a midpoint of the internal space 26. The vacuum foil 25 maintains a vacuum in the area of the internal space 26 upstream of the vacuum foil 25.

The fixed unit 23 has a flow path 27 that sprays a gas such as helium onto the charged particle beam B and the vacuum foil 25 arranged at the irradiation position. The flow path 27 has a main flow path 27a and branch flow paths 27b and 27c that branch off from the main flow path 27a. The branch flow path 27b extends toward the vacuum foil 25 and sprays gas onto the vacuum foil 25. The branch flow path 27c extends toward the irradiation position RP of the solid target 10 and sprays gas onto the held solid target 10.

The movable unit 24 moves up and down relative to the fixed unit 23. When placing the solid target 10 on the transport tray 60, the movable unit 24 is positioned at a position spaced downward from the fixed unit 23. When holding the solid target 10 at the irradiation position RP, the movable unit 24 is positioned to sandwich the solid target 10 between itself and the fixed unit 23 (see FIG. 5).

The movable unit 24 has a cylindrical shape extending in the vertical direction. The movable unit 24 is connected to a drive mechanism 28 that moves in the vertical direction at a portion of its outer circumferential surface. A small diameter portion 29 that protrudes upward is formed at the upper end of the movable unit 24. The diameter of the small diameter portion 29 is smaller than at least the diameter of the inner circumferential portion of the transport tray 60 described below. As a result, the small diameter portion 29 passes through a through hole on the inner circumferential side of the transport tray 60 and abuts against the solid target 10, pressing the solid target 10 against the fixed unit 23 above.

The movable unit 24 has a surface extending horizontally at the upper end side of the small diameter portion 29 as an opposing surface 24a that faces the opposing surface 23a of the fixed unit 23. A sealing member such as an O-ring is provided on the opposing surface 24a. The opposing surface 24a abuts against the solid target 10 via the sealing member, and therefore also functions as a sealing surface for the solid target 10. When the target irradiation device 20 holds the solid target 10, the opposing surfaces 23a and 24a sandwich the solid target 10 (see FIG. 5).

The movable unit 24 has an internal space 31 that opens at the opposing surface 24a. The internal space 31 is a space for storing a cooling medium for cooling the solid target 10. A supply pipe 32 for supplying the cooling medium and a discharge pipe 33 for discharging the cooling medium are connected to the internal space 31.

The melting device 21 is disposed inside the room (inside the cyclotron chamber 152) and is a device for melting radioisotopes attached to the solid target 10 after irradiation with the charged particle beam B by the target irradiation device 20. The melting device 21 melts the metal layer 11 containing the radioisotope in the solid target 10. The melting device 21 includes a fixed unit 40 and a movable unit 41. The melting device 21 holds the solid target 10 by sandwiching it between the fixed unit 40 and the movable unit 41. The melting device 21 supplies a dissolving liquid to at least the metal layer 11 while holding the solid target 10, dissolves the metal of the metal layer 11 containing the radioisotope in the dissolving liquid, and recovers the dissolving liquid together with the radioisotope. Hydrochloric acid, nitric acid, or the like is used as the dissolving liquid. The fixed unit 40 and the movable unit 41 are housed in the shielding shield 4.

The fixed unit 40 is disposed at a position spaced from the fixed unit 23 of the target irradiation device 20 on the opposite side of the cyclotron 2. The fixed unit 40 includes a cylindrical main body 48 extending in the vertical direction, and a support portion 49 that supports the main body 48 on the outer periphery. The main body 48 has a surface extending in the horizontal direction at the lower end thereof as an opposing surface 40a that faces the movable unit 41. The solid target 10 is held at the position of the opposing surface 40a. A sealing member such as an O-ring is provided on the opposing surface 40a. The opposing surface 40a abuts against the solid target 10 via the sealing member, and thus also functions as a sealing surface for the solid target 10. The solid target 10 is held at the position of the opposing surface 40a.

The main body 48 has an internal space 42 that opens at the facing surface 40a. The internal space 42 is a dissolving tank for storing a dissolving liquid for dissolving the metal layer 11 of the solid target 10. A supply/suction pipe 43 for supplying the dissolving liquid and a suction pipe 44 for suctioning the dissolving liquid and suctioning the gas in the internal space 42 are connected to the internal space 42. The diameter of the internal space 42 that opens at the facing surface 40a is at least smaller than the diameter of the solid target 10 and larger than the diameter of the metal layer 11. The diameter of the facing surface 40a itself is not particularly limited, but is smaller than the diameter of the solid target 10 in this embodiment.

The support portion 49 is a cylindrical member having an end wall that extends radially outward from the outer circumferential surface of the main body portion 48. The support portion 49 has a through hole 49a at the center for inserting the main body portion 48. A flange portion is formed near the upper end of the main body portion 48. This flange portion engages with the upper edge of the through hole 49a of the main body portion 48.

The movable unit 41 moves up and down relative to the fixed unit 40. When attaching the solid target 10 to the fixed unit 40, the movable unit 41 is positioned at a position spaced downward from the fixed unit 40. When melting the metal layer 11 of the solid target 10 with the melting device 21, the movable unit 41 is positioned to sandwich the solid target 10 between itself and the fixed unit 40 (see FIG. 9).

The movable unit 41 comprises a main body 46 and a receiving tray 47 provided on the upper end side of the main body 46. The main body 46 has a cylindrical shape extending in the vertical direction. A part of the outer circumferential surface of the main body 46 is connected to a drive mechanism (not shown) that moves in the vertical direction. A groove structure for supporting the receiving tray 47 is formed at the upper end of the main body 46.

The receiving tray 47 has a bottom wall 47a that extends horizontally at the upper end of the main body 46, and a side wall 47b that rises upward from the outer periphery of the bottom wall 47a. The bottom wall 47a has a surface that extends horizontally as an opposing surface 41a that faces the opposing surface 40a of the fixed unit 40. The opposing surface 41a abuts against the solid target 10. When the melting device 21 holds the solid target 10, the opposing surfaces 40a and 41a sandwich the solid target 10 (see FIG. 9). The inner diameter of the side wall 47b is larger than the diameter of the solid target 10. In addition, when the solid target 10 is held, the upper end of the side wall 47b is positioned higher than the solid target 10. Therefore, if the melting liquid leaks from the internal space 42 while the metal layer 11 of the solid target 10 is being melted, the receiving tray 47 receives the melting liquid. The bottom wall portion 47 a has a recessed and protruding structure on the lower surface thereof for fitting with the groove structure of the main body portion 46 .

In the dissolving device 21, the main body 48 and the receiving pan 47 that come into contact with the dissolving liquid are configured as replaceable disposable parts. That is, the main body 48 is detachably attached to the support 49. The receiving pan 47 is detachably attached to the main body 46. Here, "detachable" refers to an attachment mode that allows an operator to easily remove the parts through normal maintenance work even after they have been attached once. For example, examples of a removable attachment structure include a structure that is attached by bolting, and a structure that is attached by fitting and engaging with a strength that does not come off during dissolving. For example, a fixing structure such as welding or welding does not fall under the category of a removable mode. The material of the replaceable main body 48 and the receiving pan 47 can be highly acid-resistant, such as Teflon (registered trademark).

The transport device 22 transports the solid target 10 released from the target irradiation device 20 to the melting device 21. The transport device 22 transports the solid target 10 from the target irradiation device 20 to the melting device 21. The transport device 22 is arranged inside the shield 4. The transport device 22 includes a transport tray 60 that transports the solid target 10 placed thereon, and a transport drive unit 61 that drives the transport tray 60. The transport tray 60 is an annular member having a support unit for supporting the solid target 10 on the upper surface side. The transport tray 60 has a groove formed around the entire circumference on the inner edge of the upper surface, and the outer edge of the lower surface side of the solid target 10 is placed on the groove. The transport drive unit 61 is composed of a combination of a drive source and a drive force transmission mechanism not shown. The transport drive unit 61 transports the transport tray 60 to the melting device 21 by moving the transport tray 60 in the horizontal direction from the position of the target irradiation device 20 when transporting the solid target 10 after the charged particle beam irradiation to the melting device 21. The transport drive unit 61 transports the transport tray 60 from the region between the fixed unit 23 and the movable unit 24 of the target irradiation device 20 to the region between the fixed unit 40 and the movable unit 41 of the melting device 21. The transport drive unit 61 may be configured using a known drive source such as a rotary motor and a linear motor, and a drive force transmission mechanism such as a gear and a rod. The transport drive unit 61 may have any configuration as long as it can avoid interference with other members and can perform the desired operation. The position of the transport tray 60 at each stage will be described in detail when explaining the operation described later.

The control unit 50 controls the self-shielded cyclotron system 100. The control unit 50 is composed of a CPU, RAM, ROM, an input/output interface, etc. The control unit 50 determines the control content based on detection signals from each sensor in the device and a program stored in the ROM, and controls each component in the self-shielded cyclotron system 100. The control unit 50 does not have to be composed of one processing device, and may be composed of multiple processing devices. The control unit 50 may be placed inside the shielding shield 4 or outside the shielding shield 4.

The control unit 50 includes an irradiation control unit 51, a holding control unit 52, a melting control unit 53, and a transport control unit 54. The irradiation control unit 51 mainly controls the cyclotron 2 and controls operations related to the irradiation of the charged particle beam B by the cyclotron 2. The holding control unit 52 mainly controls the target irradiation device 20 and controls operations related to the holding of the solid target 10 by the target irradiation device 20. The melting control unit 53 mainly controls the melting device 21 and controls operations related to melting the metal layer 11 of the solid target 10. The transport control unit 54 mainly controls the transport device 22 and controls operations related to the transport of the solid target 10. The transport control unit 54 controls the transport device 22 to transport the solid target 10 held by the target irradiation device 20 to the melting device 21 after the irradiation of the metal layer 11 with the charged particle beam B.

Next, the operation of the target irradiation system 3 will be described together with the contents of the control process by the control unit 50 with reference to Figures 3 to 9. Figure 4 is a flowchart showing the contents of the control process by the control unit 50. Figures 4 to 9 are diagrams showing the state of the target irradiation system 3 at each stage during operation. For the sake of explanation, the control unit 50 and the transport drive unit 61 have been omitted from Figures 4 to 9. Reference symbols that are not used in the explanation may also be omitted as appropriate.

As shown in FIG. 4, the control unit 50 performs a process for setting the solid target 10 in the target irradiation system 3 (step S10). In the process of S10, the control unit 50 places the target irradiation device 20, the melting device 21, and the transport device 22 in their initial positions. The control unit 50 drives the drive units of each component to place the target irradiation system 3 in the state shown in FIG. 3. In this state, the movable unit 24 is placed at a position spaced downward from the fixed unit 23. The movable unit 41 is placed at a position spaced downward from the fixed unit 40. The transport tray 60 is placed at a position spaced downward from the fixed unit 23 and at a reference height. Here, the "reference height" is a predetermined height position between the fixed unit 23 and the movable unit 24 in the height direction, and between the fixed unit 40 and the movable unit 41. At this height position, the transport tray 60 does not interfere with each unit 23, 24, 40, and 41 even if it moves horizontally. The control unit 50 may notify the operator via a monitor or the like that the solid target 10 can be set. When the control unit 50 detects that the operator has placed the solid target 10 on the carrier tray 60, the control unit 50 grasps that the setting of the solid target 10 has been completed. The control unit 50 may detect that the setting of the solid target 10 has been completed by detection by a sensor or an input by the operator.

Next, the control unit 50 performs a process of holding the solid target 10 at the irradiation position RP of the charged particle beam B (step S20: FIG. 4). In S20, the holding control unit 52 of the control unit 50 controls the drive mechanism 28 of the movable unit 24 to move the movable unit 24 upward. As a result, as shown in FIG. 5, the solid target 10 is sandwiched between the fixed unit 23 and the movable unit 24 at the irradiation position RP. In addition, in the process of the movable unit 24 moving upward, the solid target 10 placed on the conveying tray 60 is supported by the movable unit 24 that has passed through the through hole of the conveying tray 60 from below. At this time, the conveying tray 60 may rise while being supported by the movable unit 24. Alternatively, the conveying tray 60 may be driven to rise together with the movable unit 24.

Next, the control unit 50 performs a process of irradiating the solid target 10 with the charged particle beam B (step S30: FIG. 4). In S30, the irradiation control unit 51 of the control unit 50 controls the cyclotron 2 to irradiate the solid target 10 with the charged particle beam B. At this time, the holding control unit 52 controls the flow path system so that helium gas or the like is sprayed from the flow path 27 of the fixing unit 23 to the solid target 10 and the vacuum foil 25. The holding control unit 52 also controls the piping system of the supply pipe 32 and the exhaust pipe 33 to flow a cooling medium into the internal space 31 to cool the solid target 10.

When the process of S30 is completed, the holding control unit 52 of the control unit 50 controls the drive mechanism 28 of the movable unit 24 to move the movable unit 24 downward. This causes the movable unit 24 to return to its initial position as shown in Figure 6. The transport tray 60 also returns to its reference height position with the solid target 10 loaded thereon.

Next, the control unit 50 performs a process of transporting the solid target 10 from the target irradiation device 20 to the melting device 21 (step S40: Figure 4). In S40, the transport control unit 54 of the control unit 50 controls the transport drive unit 61 (see Figure 3) of the transport device 22 to horizontally move the transport tray 60 from the target irradiation device 20 to the position of the melting device 21. As a result, as shown in Figure 7, the transport tray 60 is positioned between the fixed unit 40 and the movable unit 41 while maintaining a position at the reference height in the height direction. As a result, the solid target 10 is positioned at a position facing the opposing surface 40a, which opens into the internal space 42, on the lower side.

Next, the control unit 50 performs a process of setting the solid target 10 in the melting device 21 (step S50: FIG. 4). In S50, as shown in FIG. 8, the melting control unit 53 of the control unit 50 controls the piping system of the suction tube 44 to adsorb the solid target 10 to the facing surface 40a through the internal space 42. Before adsorbing the solid target 10, the conveying tray 60 is raised to press the solid target 10 against the facing surface 40a of the main body 48. As a result, the O-ring (not shown) provided between the solid target 10 and the main body 48 is crushed to seal the internal space. After this, the conveying control unit 54 controls the conveying drive unit 61 (see FIG. 3) to move the conveying tray 60 to a position on the target irradiation device 20 side. This prevents the conveying tray 60 from interfering with the movable unit 41.

In S50, the dissolution control unit 53 controls the drive unit of the movable unit 41 to move the movable unit 41 upward. As a result, as shown in Fig. 9, the solid target 10 is sandwiched between the opposing surface 40a of the fixed unit 40 and the opposing surface 41a of the movable unit 41. At this time, the solid target 10 is housed in the receiving tray 47 and is pressed against the main body 48 from above.

Next, the control unit 50 performs a process of recovering the radioisotopes contained in the metal layer 11 by dissolving the metal layer 11 of the solid target 10 with the dissolving device 21 (step S60: FIG. 4). In S60, the dissolution control unit 53 of the control unit 50 controls the pipeline system of the supply/suction tube 43 to supply the dissolution liquid SL from the supply/suction tube 43 to the internal space 42. The dissolution control unit 53 also controls the pipeline system of the suction tube 44 to suck and recover the dissolution liquid SL in which the radioisotopes are dissolved with the supply/suction tube 43. This completes the control process shown in FIG. 4. After the radioisotopes have been recovered, the operator removes the solid target 10 together with the main body 48 and the receiving tray 47 and takes it out of the shield 4.

As shown in FIG. 1, the solution SL in which the radioisotopes are dissolved is discharged outside the shield 4 and sent to a device 160 such as a refining device for refining the radioisotopes in the solution SL or a synthesis device for synthesizing drugs. The refining device or synthesis device may be located in the same building 150 or in a different building (facility). When the solution SL is transported to a synthesis device or the like in the same building 150, the solution SL is sent to the synthesis device or the like through a transport pipe 161 connected to the supply/suction pipe 43. Since radiation is emitted from the solution SL, the transport pipe 161 is covered with a shield or passes through a shielding wall (floor or wall) of the building 150. When the solution SL is transported to another building, the collected solution SL is stored in a shielding box (a box that suppresses the emission of radiation to the outside, such as a lead box) and transported together with the shielding box by a vehicle or the like.

Next, we will explain the action and effects of the target irradiation system 3 of this embodiment.

The target irradiation system 3 according to this embodiment is a target irradiation system 3 that irradiates a solid target 10 having a metal layer 11 with a charged particle beam B emitted from a cyclotron 2 to generate radioactive isotopes in the metal layer 11, and is equipped with a target irradiation device 20 that is arranged in a cyclotron chamber 152 provided in a building 150 and holds the solid target 10 at an irradiation position for the charged particle beam B to enable irradiation of the solid target 10 with the charged particle beam B, and a melting device 21 that is arranged in the cyclotron chamber 152 and melts radioactive isotopes attached to the solid target 10 after irradiation of the charged particle beam B by the target irradiation device 20 has been completed.

In the target irradiation system 3, the target irradiation device 20 holds the solid target 10 at the irradiation position of the charged particle beam B to enable irradiation of the charged particle beam B to the solid target 10. As a result, radioactive isotopes are formed in the metal layer 11 of the solid target 10 at the location irradiated with the charged particle beam B. In addition, the melting device 21 melts the radioactive isotopes attached to the solid target 10 after irradiation of the charged particle beam B by the target irradiation device 20 is completed. As a result, it is possible to recover the radioactive isotopes by recovering the dissolving liquid. Here, the target irradiation device 20 and the melting device 21 are arranged in a cyclotron chamber 152 provided in the building 150. Therefore, both the process of irradiating the solid target 10 with the charged particle beam and the process of recovering the radioactive isotopes by melting are performed in the cyclotron chamber 152. Therefore, the solid target 10 can be removed from the target irradiation device 20 and the radioactive isotopes can be quickly melted in the melting device 21.

The target irradiation system 3 further includes a shielding shield 4 as a support that supports the target irradiation device 20 against the floor 151 of the cyclotron chamber 152, and the melting device 21 is supported against the floor 151 by the support. In this case, since the target irradiation device 20 and the melting device 21 are supported by a common support, they can be positioned close to each other.

The target irradiation system 3 further includes a transport device 22 that transports the solid target 10, which has been released from the target irradiation device 20, to the melting device 21. In this case, it is possible to quickly transport the solid target 10 from the target irradiation device 20 to the melting device 21.

The target irradiation system 3 is provided in the cyclotron chamber 152, houses the cyclotron 2 and the target irradiation device 20 therein, and further includes a shielding shield 4 that blocks radiation emitted from the cyclotron 2 and the target irradiation device 20, and the melting device 21 is provided in the shielding shield 4. In this case, the shielding shield 4 can block radiation when the solid target 10 is transported from the target irradiation device 20 to the melting device 21.

The target irradiation system 3 further includes a transport device 22 that transports the solid target 10 from the target irradiation device 20 to the melting device 21, and a control unit 50. The control unit 50 controls the transport device 22 to transport the solid target 10 held in the target irradiation device 20 to the melting device 21 after the metal layer 11 is irradiated with the charged particle beam B. As a result, the transport of the solid target 10 by the transport device 22 is automatically performed by the control unit 50. This makes it possible to further reduce exposure to workers. In addition, the control unit 50 automatically transports the solid target 10, thereby shortening the work time.

The target irradiation system 3 is a target irradiation system 3 that irradiates a solid target 10 having a metal layer 11 with a charged particle beam B emitted from a cyclotron 2 to generate radioisotopes of the metal layer 11, and includes a target irradiation device 20 that holds the solid target 10 at the irradiation position of the charged particle beam B to enable irradiation of the solid target 10 with the charged particle beam B, and a melting device 21 that melts the radioisotopes attached to the solid target 10 after irradiation of the charged particle beam B by the target irradiation device 20 is completed, and the target irradiation device 20 and the melting device 21 are arranged in the same cyclotron room 152 provided in a building 150. With this target irradiation system 3, the same actions and effects as those described above can be obtained.

The method for recovering radioisotopes from a solid target 10 is a method for recovering radioisotopes from a solid target 10 having a metal layer 11, in which a target irradiation device 20 arranged in a shielded room provided in a building 150 irradiates the solid target 10 with a charged particle beam B to generate radioisotopes in the solid target 10, and a transport device 22 capable of transporting the solid target 10 transports the solid target 10 after irradiation with the charged particle beam B to a melting device 21 arranged in the shielded room, and the melting device 21 melts the radioisotopes attached to the solid target 10. According to this recovery method, the process of irradiating the solid target 10 with the charged particle beam B, the process of transporting the solid target 10, and the process of recovering the radioisotopes by melting are all performed in the shielded room. Therefore, the solid target can be removed from the target irradiation device 20 and the radioisotopes can be quickly dissolved in the melting device 21. Moreover, radiation can be shielded in each step.

In the self-shielded cyclotron system 100 according to this embodiment, the target irradiation device 20 holds a target having a metal layer 11 at an irradiation position RP of the charged particle beam B. Therefore, the solid target 10 held by the target irradiation device 20 is irradiated with the charged particle beam B. As a result, radioactive isotopes 12 are formed in the metal layer 11 of the solid target 10 at the location irradiated with the charged particle beam B. The melting device 21 also includes a melting device that melts the metal layer 11 containing the radioactive isotope in the solid target 10. This makes it possible to recover the radioactive isotope by recovering the dissolving liquid. The transport device 22 transports the solid target 10 from the target irradiation device 20 in which the charged particle beam B is irradiated to the solid target 10, to the melting device 21 in which the radioactive isotope is recovered. Here, the target irradiation device 20, the melting device 21, and the transport device 22 are arranged in the shielding shield 4. Therefore, the process of irradiating the solid target 10 with the charged particle beam B, the process of recovering the radioisotopes by dissolving them, and the process of transporting the target between these processes are all performed inside the shield 4. Therefore, in each process, the radiation emitted from the solid target 10 after being irradiated with the charged particle beam is blocked by the self-shield. As a result, safety against exposure when obtaining radioisotopes can be further improved.

The self-shielded cyclotron system 100 further includes a control unit 50, which may control the transport device 22 to transport the solid target 10 held in the target irradiation device 20 to the melting device 21 after the metal layer 11 is irradiated with the charged particle beam B. As a result, the transport device 22 automatically transports the solid target 10. This can further improve safety against radiation exposure. In addition, the control unit 50 automatically transports the solid target 10, thereby shortening the operation time.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit and scope of the present invention, as described below.

For example, a configuration as shown in FIG. 10 may be adopted. The self-shielded cyclotron system shown in FIG. 10 may include a storage section 70 that covers the melting device 21 within the shielding shield 4, and an exhaust section 71 that exhausts the gas in the storage section 70 to the outside of the shielding shield 4. The storage section 70 does not cover the target irradiation device 20, but covers only the melting device 21. An opening 70a may be formed in the storage section 70 at a location where the transport tray passes. This opening 70a may be closed when the transport tray does not pass. The exhaust section 71 may have an exhaust pipe that passes from the storage section 70 through the shielding shield 4 and communicates with the outside of the shielding shield 4. The exhaust section 71 may include a pump or the like provided in the exhaust pipe.

As a result, when the dissolving liquid in the dissolving device 21 vaporizes, the storage section 70 prevents the gas from diffusing into the shielding shield 4. In addition, the gas in the storage section 70 is exhausted to the outside of the shielding shield 4 by the exhaust section 71. This prevents other equipment in the shielding shield 4 from being corroded by the gas.

The configuration of the target irradiation system shown in each of the figures of the above-mentioned embodiment is merely an example, and the shape and arrangement may be changed as appropriate as long as it is within the scope of the present invention. For example, the conveying device may employ an arm-shaped gripping unit that grips the target, instead of a conveying tray.

The transport of the target by the transport device was performed automatically by the control unit. Alternatively, the transport device itself may be driven manually by an operator. Even in this case, the target is contained within a self-shielding device, further improving safety against radiation exposure.

A target irradiation system 3 as shown in FIG. 11(a) may also be used. In the example shown in FIG. 11(a), the target irradiation device 20 and the melting device 21 may be arranged in an irradiation chamber 153 separate from the cyclotron chamber 152 in the building 150. At this time, the charged particle beam emitted from the cyclotron 2 is transported from the cyclotron chamber 152 to the target irradiation device 20 in the irradiation chamber 153 via a transport line 155. At this time, the target irradiation device 20 and the melting device 21 are supported on the floor 151 of the irradiation chamber 153 by a support portion 156.

Also, a target irradiation system 3 as shown in Fig. 11(b) may be used. In the example shown in Fig. 11(b), the cyclotron 2, the target irradiation device 20, and the melting device 21 are arranged in the same cyclotron chamber 152. In this case, unlike the configuration shown in Fig. 1, the shielding shield 4 may be omitted.

In the above embodiment, a cyclotron is given as an example of a particle accelerator, but the particle accelerator is not limited to a cyclotron. For example, a linear accelerator may be used as the particle accelerator.

The target irradiation system 200 shown in Fig. 12 may be adopted. The target irradiation system 200 includes a fixing unit 211 of the target irradiation device 210, a fixing unit 221 of the melting device 220, a support device 230, a target exchanger 240, and a control unit 260.

In order to explain the target irradiation system 200, an XYZ coordinate system is set. The X-axis direction is parallel to the horizontal direction. One side in the X-axis direction (the front side of the paper in Figure 12) is the positive side in the X-axis direction. The Y-axis direction is perpendicular to the X-axis direction and parallel to the horizontal direction. One side in the Y-axis direction (the left side of the paper in Figure 12) is the positive side in the Y-axis direction. The up-down direction is the Z-axis direction. The upper side is the positive side in the Z-axis direction.

As shown in FIG. 13, the fixed unit 211 of the target irradiation device 210 has an internal space 213 for passing the charged particle beam B at a position corresponding to the irradiation axis BL of the charged particle beam B. The internal space 213 is formed to extend along the irradiation axis BL with the irradiation axis BL as its center line. In this embodiment, the irradiation axis BL of the charged particle beam B extends parallel to the Y-axis direction. In addition, the charged particle beam B is irradiated from the positive side to the negative side in the Y-axis direction. Therefore, the internal space 213 extends parallel to the Y-axis direction.

The fixed unit 211 has an irradiation port 212 that emits a charged particle beam B. The irradiation port 212 has a surface that extends parallel to the XZ plane as an opposing surface that faces the sealing surface 230a of the support device 230. The irradiation port 212 has an opening that opens into the internal space 213. The charged particle beam B is emitted from the opening.

The fixed unit 221 of the dissolution device 220 is disposed at a position away from the fixed unit 211 of the target irradiation device 210 toward the positive side in the X-axis direction. The fixed unit 221 is provided with a plurality of dissolution ports 222A, 222B for supplying and recovering the dissolution liquid SL. The dissolution ports 222A, 222B may recover radioisotopes of different nuclides. Thus, the dissolution ports 222A, 222B can supply and recover different dissolution liquids SL. However, the dissolution ports 222A, 222B may recover radioisotopes of the same nuclide. The dissolution ports 222A, 222B are provided adjacent to each other in the X-axis direction. In addition, the dissolution ports 222A, 222B have a surface extending parallel to the XZ plane as an opposing surface facing the sealing surface 230a of the support device 230. The center lines SCL, SCL of the opposing surfaces of the dissolution ports 222A, 222B extend parallel to the Y-axis direction while being spaced apart from each other in the X-axis direction. The center lines SCL, SCL of the dissolution ports 222A, 222B are set at the same height as the irradiation axis BL. The dissolution ports 222A, 222B may be detachable from the dissolution device 220. That is, the dissolution ports 222A, 222B may be detachably attached to the mounting table 223. This allows the dissolution port 222 to be replaced according to the nuclide of the radioisotope.

16 and 17, the configuration of the dissolution port 222A will be described in detail. Note that the dissolution port 222B has a similar configuration to the dissolution port 222A, and therefore a description thereof will be omitted. The dissolution port 222A has an opposing surface 222a against which the sealing surface 230a of the support device 230 is pressed. The dissolution port 222A also has a flow path 224 and an adsorption structure 226.

The flow path 224 allows the dissolving liquid SL to flow. The flow path 224 is formed inside the member of the dissolving port 222A and opens at the opposing surface 222a. The flow path 224 allows the dissolving liquid SL to flow out from the opening and also sucks the dissolving liquid SL from the opening. Note that a flow path forming member 227 protrudes from the position of the center line SCL of the opposing surface 222a toward the negative side in the Y-axis direction. The flow path forming member 227 is a member that is inserted into the internal space 233 of the support device 230 to form a flow path for the dissolving liquid SL in the internal space 233. The flow paths 224 open at positions adjacent to each other in the circumferential direction of the flow path forming member 227. Note that the dissolving port 222A has two flow paths 224, but the number is not particularly limited.

The suction structure 226 is a mechanism that sucks the sealing surface 230a in contact with the opposing surface 222a. The suction structure 226 has an annular groove portion 226a centered on the center line SCL. The suction structure 226 also has a vacuum exhaust path 226b formed in the melting port 222A. The vacuum exhaust path 226b opens at the position of the groove portion 226a.

12 and 13, the support device 230 is a device that supports the solid target 10. The support device 230 is connected to the irradiation port 212 and also to the melting ports 222A and 222B. Therefore, the support device 230 functions as a movable unit of the target irradiation device 210. The support device 230 also functions as a movable unit of the melting device 220. In this embodiment, the target exchanger 240 can be fitted with multiple support devices 230 as described below. Therefore, the target irradiation system 200 can be equipped with multiple support devices 230 depending on the application. In this embodiment, the target irradiation system 200 is equipped with two support devices 230A and 230B.

The configuration of the support device 230 will be described in detail with reference to FIG. 15. As shown in FIG. 15, the support device 230 is a member having an approximately cylindrical shape. The center line CL of the support device 230 extends parallel to the Y-axis direction. The support device 230 includes a first member 231 and a second member 232. The support device 230 is divided into the first member 231 and the second member 232 at a midpoint in the longitudinal direction, i.e., in the Y-axis direction. The first member 231 is disposed on the positive side in the Y-axis direction, i.e., the upstream side in the irradiation direction of the charged particle beam B. The second member 232 is disposed on the negative side in the Y-axis direction, i.e., the downstream side in the irradiation direction of the charged particle beam B.

The support device 230 supports the solid target 10 by sandwiching the solid target 10 between the first member 231 and the second member 232. The support device 230 supports the solid target 10 so that it is inclined with respect to the center line CL. The inclination direction of the solid target 10 is not particularly limited. Here, the solid target 10 is inclined so as to move upward (to the positive side in the Z-axis direction) as it moves from the positive side to the negative side in the Y-axis direction. The first member 231 has a support surface 231a at the end on the negative side in the Y-axis direction. The second member 232 has a support surface 232a at the end on the positive side in the Y-axis direction. The support surface 231a of the first member 231 and the support surface 232a of the second member 232 face each other in parallel. In addition, the support surfaces 231a and 232a are inclined in the same manner as the inclination direction of the solid target 10 described above. The support surfaces 231 a and 232 a are provided with seal portions each having an O-ring near the end portion on the outer circumferential side of the solid target 10 .

The first member 231 has the above-mentioned sealing surface 230a at the end on the positive side in the Y-axis direction. Therefore, the first member 231 functions as a member connected to the irradiation port 212 and connected to the dissolving ports 222A and 222B. A seal portion having an O-ring is provided on the sealing surface 230a. The first member 231 has an internal space 233 extending parallel to the Y-axis direction at the position of the center line CL. The internal space 233 extends from the sealing surface 230a to the support surface 231a so as to penetrate. As a result, the solid target 10 is exposed to the internal space 233. The internal space 233 functions as a transport path of the target irradiation device 210 that guides the charged particle beam B to the solid target 10. The internal space 233 also functions as a dissolving tank of the dissolving device 220 that circulates the dissolving liquid SL. Since the first member 231 is a member that allows the charged particle beam B to pass through and the dissolving liquid SL to flow through, it is preferable to use, as the material for the first member 231, a material that is resistant to chemicals, radiation, and heat, such as Nb or ceramic.

When the support device 230 is connected to the irradiation port 212, the sealing surface 230a of the first member 231 is pressed against the irradiation port 212. In addition, the internal space 233 and the internal space 213 are in communication. The support device 230 is positioned so that the center line CL coincides with the irradiation axis BL. In this state, the position where the irradiation axis BL and the surface 10a of the solid target 10 intersect becomes the irradiation position RP.

The second member 232 functions as a cooling structure for cooling the solid target 10. The second member 232 has a groove 234 at the position of the support surface 232a. In the internal space of the groove 234, the back surface 10b of the solid target 10 is exposed. Therefore, the cooling medium W supplied to the groove 234 comes into contact with the solid target 10. The second member 232 has cooling channels 236 and 237 extending in the Y-axis direction. The cooling channels 236 and 237 are connected to the groove 234. The cooling channel 236 supplies the cooling medium W to the groove 234. The cooling channel 237 recovers the cooling medium W from the groove 234. Since the second member 232 is a member that cools the solid target 10, it is preferable that a rust-resistant material such as SUS is used as the material of the second member 232.

16, when the support device 230 is connected to the dissolution port 222A, the sealing surface 230a of the first member 231 is pressed against the opposing surface 222a of the dissolution port 222A. The support device 230 is arranged so that the center line CL coincides with the center line SCL of the dissolution port 222A. A part of the sealing surface 230a faces the groove portion 226a of the adsorption structure 226. As a result, the sealing surface 230a is adsorbed to the groove portion 226a that is evacuated. In addition, the flow path forming member 227 is inserted into the internal space 233. As a result, a flow path for the dissolution liquid SL is formed in the internal space 233. The internal space 233 is in communication with the opening of the flow path 224. The dissolution liquid SL supplied from the flow path 224 comes into contact with the surface 10a of the solid target 10. The dissolution liquid SL in which the radioisotope is dissolved is collected from the flow path 224.

Next, the target exchanger 240 will be described. As shown in Figures 12 and 13, the target exchanger 240 functions as a transport device that transports the solid target 10. The target exchanger 240 supports the solid target 10 via the support device 230. The target exchanger 240 is equipped with a holder 241 to which multiple support devices 230 can be attached. Therefore, the target exchanger 240 can support multiple solid targets 10. In addition, the holder 241 can slide in the X-axis direction with multiple support devices 230 attached. Therefore, the holder 241 can transport the solid target 10 together with the multiple support devices 230 in the X-axis direction.

An example of a specific structure of the target exchanger 240 will be described with reference to Figure 14. As shown in Figure 14, the target exchanger 240 includes a base plate 242, a first slide plate 243, a second slide plate 244, a first cylinder 246, a second cylinder 247, and a third cylinder 248.

The base plate 242 is a member that serves as a base for mounting the first and second slide plates 243, 244. A guide rail 242a (see FIG. 12) extending in the Y-axis direction is provided on the upper surface of the base plate 242. The base plate 242 is connected perpendicularly to a fixing plate 249 for mounting and fixing the target exchanger 240 to the cyclotron.

The first slide plate 243 is a plate-like member having a rectangular outer shape in a plan view. A guide rail 251 extending along the X-axis direction is provided on the edge of the first slide plate 243 on the positive side in the Y-axis direction. A first cylinder 246 is attached to the side surface of the first slide plate 243 on the negative side in the Y-axis direction. The first cylinder 246 advances and retreats the drive shaft in the Y-axis direction, causing the holder 241 to move back and forth in the Y-axis direction together with the first slide plate 243. A second cylinder 247 is mounted on the upper surface of the first slide plate 243. The drive shaft of the second cylinder 247 can advance and retreat in the X-axis direction.

A third cylinder 248 is mounted on the upper surface of the first slide plate 243. The drive shaft of the third cylinder 248 can advance and retreat in the Y-axis direction. The drive shaft of the second cylinder 247 is connected to the third cylinder 248. Therefore, when the second cylinder 247 advances and retreats the drive shaft in the X-axis direction, the third cylinder 248 moves back and forth in the X-axis direction together with the holder 241 with which the drive shaft is engaged (details will be described later).

A mounting plate 252 extending in the Y-axis direction is attached to the upper surface of the third cylinder 248. An attacker 253 is attached to the end of the mounting plate 252 on the positive side in the Y-axis direction. When this attacker 253 comes into contact with a microswitch 259 provided on the second slide plate 244 described later, the position of the second slide plate 244 in the X-axis direction is detected.

The second slide plate 244 has a rectangular parallelepiped base 256 and a holder 241 erected on the base 256. A liner 255 with a U-shaped cross section extending in the X-axis direction is attached to the underside of the base 256. The holder 241 is rectangular when viewed from the front. The holder 241 has four holding holes 257 for holding the support devices 230, and the approximately cylindrical support devices 230 are fitted and held in these holding holes 257. The four holding holes 257 are arranged in parallel along the X-axis direction. This allows the holder 241 to hold a maximum of four support devices 230. In this embodiment, the holder 241 holds two support devices 230A and 230B, but can hold two more support devices 230 in addition.

Four microswitches 259 are attached to the front surface of the base 256 of the second slide plate 244 at the same pitch as the retaining holes 257. The position of the second slide plate 244 in the X-axis direction is detected when the attacker 253 abuts against these microswitches 259. In addition, an engagement hole 261 is provided below each microswitch 259. The engagement hole 261 is approximately the same size as the diameter of the drive shaft of the third cylinder 248, and is configured so that the drive shaft can engage with this engagement hole 261. As a result, the holder 241 moves back and forth in the X-axis direction when driven by the second cylinder 247.

As a result, the target exchanger 240 can transport the supported solid target 10 together with the support device 230 in the X-axis direction. The target exchanger 240 transports the support device 230 to a position facing the irradiation port 212 or the dissolution ports 222A, 222B. At this time, the target exchanger 240 is provided with a mechanism for pressing the support device 230 against the irradiation port 212 or the dissolution ports 222A, 222B. Specifically, as shown in FIG. 12 and FIG. 13, the target exchanger 240 is provided with push-out mechanisms 270A, 270B. The push-out mechanisms 270A, 270B are provided with a support member 271 connected to the first slide plate 243, a cylinder 272 that advances and retreats the drive shaft in the Y-axis direction, and a push-out member 273 that pushes out the support device 230. The push-out member 273 is provided on the drive shaft of the cylinder 272. As a result, the cylinder 272 moves the push-out member 273 to the positive side in the Y-axis direction, thereby pressing the support device 230 toward the melting device 220. As shown in Fig. 13, the push-out mechanism 270A is provided at a position facing the support device 230A. The push-out mechanism 270B is provided at a position facing the support device 230B. For example, when the holder 241 places the support device 230A at a position facing the dissolution port 222B (see Fig. 20), the push-out mechanism 270A presses the support device 230A against the dissolution port 222B.

The control unit 260 controls the operation of the target exchanger 240 by sending control signals to each drive unit (cylinder) of the target exchanger 240. An example of the control content by the control unit 260 will be described with reference to Figures 13 and 18 to 23. However, the operation of the target irradiation system 200 is not limited to the following example, and the number of solid targets 10 and the number of nuclides may be changed as appropriate.

Figure 13 and Figures 18 to 23 show an example of the operation when one radioisotope is recovered using two solid targets 10. First, as shown in Figure 13, two support devices 230A and 230B are held in the holder 241. The support device 230A is held in the first holding hole 257 seen from the positive side in the X-axis direction. The support device 230B is held in the second holding hole 257 seen from the positive side in the X-axis direction. The control unit 260 controls the second cylinder 247 (see Figure 14) of the target exchanger 240 to place the holder 241 in a position facing the fixed unit 211. At this time, the most positive holding hole 257 in the X-axis direction of the holder 241, i.e., the support device 230A, is placed in a position facing the irradiation port 212. This position is called the "initial position". In the following description, the control content is expressed as "the control unit 260 places the support device 230A at a position facing the irradiation port 212." Similar expressions are used for the control content and other control contents with the same meaning.

Next, as shown in FIG. 18, the control unit 260 controls the first cylinder 246 of the target exchanger 240 to move the first slide plate 243 (see FIG. 12) toward the positive side in the Y-axis direction, thereby pressing the support device 230A against the irradiation port 212. At this time, the support device 230B also moves toward the positive side in the Y-axis direction, but the support device 230B is not pressed against other members in particular. In the following description, the control content is expressed as "the control unit 260 presses the support device 230A against the irradiation port 212." Similar expressions are used for the control content and control content with the same meaning. The control unit 260 controls the target irradiation device 210 to irradiate the solid target of the support device 230A with the charged particle beam B. When the irradiation is completed, the control unit 260 releases the support device 230A from pressing against the irradiation port 212.

Next, as shown in FIG. 19, the control unit 260 places the support device 230A at a position facing the dissolution port 222B. Also, as shown in FIG. 20, the control unit 260 controls the first cylinder 246 of the target exchanger 240 to move the first slide plate 243 (see FIG. 12) to the positive side in the Y-axis direction, thereby placing the support device 230A in front of the dissolution port 222B. Furthermore, the control unit 260 presses the support device 230A against the dissolution port 222B by extending the cylinder 272 of the push-out mechanism 270A. At this time, the support device 230B also moves to the positive side in the Y-axis direction, but the support device 230B is not pressed against any other member. In the following description, the control content is expressed as "the control unit 260 presses the support device 230A against the dissolution port 222B". Similar expressions are used for the control content and control content with the same meaning. The control unit 260 controls the dissolving device 220 to supply the dissolving liquid SL to the supporting device 230A and collect the dissolving liquid SL in which the radioisotope of the solid target 10 has been dissolved. When the collection is completed, the control unit 260 releases the support device 230A from pressing against the dissolving port 222B. Then, the control unit 260 returns the positions of the supporting devices 230A and 230B to their initial positions.

21, the control unit 260 places the support device 230B in a position facing the irradiation port 212 and presses the support device 230B against the irradiation port 212. The control unit 260 controls the target irradiation device 210 to irradiate the solid target of the support device 230B with the charged particle beam B. When the irradiation is completed, the control unit 260 releases the support device 230B from the pressure against the irradiation port 212.

22, the control unit 260 places the support device 230B in a position opposite the dissolution port 222B and presses the support device 230B against the dissolution port 222B. The control unit 260 controls the dissolution device 220 to supply dissolution liquid SL to the support device 230B and recovers the dissolution liquid SL in which the radioisotopes of the solid target 10 have been dissolved. When the recovery is complete, the control unit 260 releases the support device 230B from pressing against the dissolution port 222B. The control unit 260 then returns the positions of the support devices 230A and 230B to their initial positions. This completes the recovery of radioisotopes using the two solid targets 10.

Next, an example of the operation for recovering two radioisotopes using two solid targets 10 will be described. Operations common to the above-mentioned operations will be described using the common drawings.

The control unit 260 irradiates the solid target 10 of the support device 230A with the charged particle beam B by executing the operation shown in FIG. 18. Next, as shown in FIG. 23, the control unit 260 places the support device 230A at a position opposite the dissolution port 222A and presses the support device 230A against the dissolution port 222A. The control unit 260 controls the dissolution device 220 to supply the dissolution liquid SL to the support device 230A and recover the dissolution liquid SL in which the radioisotope of the solid target 10 has been dissolved. When the recovery is completed, the control unit 260 releases the support device 230A from pressing against the dissolution port 222A. Then, the control unit 260 returns the positions of the support devices 230A and 230B to their initial positions.

Next, the control unit 260 irradiates the solid target 10 of the support device 230B with the charged particle beam B by performing the operation shown in FIG. 21. Next, the control unit 260 recovers the radioisotopes of the solid target 10 of the support device 230B by performing the operation shown in FIG. 22. At this time, the dissolution port 222B uses a dissolution liquid SL different from that used in the dissolution port 222A. As a result, the radioisotopes of the solid target 10 of the support device 230B are recovered with a dissolution liquid SL different from that used for the support device 230A. Then, the control unit 260 returns the positions of the support devices 230A and 230B to their initial positions. With the above, the recovery of the radioisotopes using the two solid targets 10 is completed.

It is also possible to recover one type of radioisotope using one solid target 10. In this case, the support device 230B is omitted from Figures 18 to 20, and only the support device 230A is used to perform the operations shown in Figures 18 to 20.

As described above, the target irradiation system 200 further includes a target exchanger 240 that transports the solid targets 10, and the target exchanger 240 is capable of supporting multiple solid targets 10. In this case, the target exchanger 240 can transport multiple solid targets 10 to the irradiation position and the melting position without removing the solid targets 10 along the way. This reduces the impact of exposure to radiation due to the removal work.

For example, after radioisotopes are collected from the solid target 10 of the support device 230A as shown in Figures 18 and 23, processing is performed on the solid target 10 of the support device 230B as shown in Figures 21 and 22 without any particular replacement (removal) of the solid target 10. In this way, once the solid targets 10 are installed on multiple support devices 230, the target irradiation system 200 can automatically perform the switching, irradiation, dissolution, and recovery processes of the solid targets 10 multiple times. This significantly reduces the amount of radiation exposure associated with the replacement of the solid targets 10.

The target irradiation system 200 further includes a support device 230 that supports the solid target 10, the target irradiation device 210 includes an irradiation port 212 from which the charged particle beam B is emitted, the melting device 220 includes melting ports 222A and 222B that supply and collect the melting liquid SL, and the support device 230 may be connected to the irradiation port 212 and also to the melting ports 222A and 222B. In this case, the support device 230 can be used as both a part of the target irradiation device 210 and a part of the melting device 220.

The dissolving device 220 may be provided with multiple dissolving ports 222A, 222B for supplying and recovering the dissolving liquid SL. In this case, the dissolving process of multiple radioisotopes can be performed without replacing the dissolving ports 222A, 222B.

2...Cyclotron, 3,200...Target irradiation system, 4...Shielding shield (support part), 10...Solid target, 11...Metal layer, 20,210...Target irradiation device, 21,220...Melting device, 22...Transport device, 50...Control part, 70...Storage part, 71...Exhaust part, 100...Self-shielded cyclotron system, 212...Irradiation port, 222A, 222B...Melting port, 230, 230A, 230B...Support device (target irradiation device, melting device), 240...Target exchanger (transport device).

Claims (9)

A target irradiation system for generating radioisotopes of a metal layer by irradiating a solid target having a metal layer with a charged particle beam emitted from a particle accelerator, the target irradiation system comprising:
a target irradiation device that holds the solid target at an irradiation position of the charged particle beam and enables the solid target to be irradiated with the charged particle beam;
a dissolving device that dissolves, with a strong acid , the radioisotope attached to the solid target after the irradiation of the charged particle beam by the target irradiation device is completed;
A housing for covering the melting device;
a shielding shield that houses the particle accelerator, the target irradiation device, the melting device, and the container, and blocks radiation emitted from the particle accelerator, the target irradiation device, and the melting device;
an exhaust unit that exhausts gas within the accommodation unit to the outside of the shielding shield so as not to come into contact with at least one of the particle accelerator and the target irradiation device. A support portion for supporting the target irradiation device is further provided.
The melting apparatus is supported by the support portion.
The target illumination system of claim 1 . The solid target may be released from the target irradiation device and may be transported to the melting device.
3. A target illumination system according to claim 1 or 2. a transport device that transports the solid target from the target irradiation device to the melting device;
A control unit,
The target irradiation system according to any one of claims 1 to 3, wherein the control unit controls the transport device to transport the solid target held by the target irradiation device to the melting device after the metal layer is irradiated with the charged particle beam. A transport device for transporting the solid target is further provided,
The target irradiation system of claim 1 , wherein the transport device is capable of supporting a plurality of the solid targets. a support device for supporting the solid target;
the target irradiation device includes an irradiation port through which the charged particle beam is emitted;
The dissolving device includes a dissolving port for supplying and recovering a dissolving liquid,
The target illumination system of claim 1 , wherein the support device is coupled to the illumination port and is coupled to the dissolution port. The target irradiation system according to any one of claims 1 to 6, wherein the melting device is provided with a plurality of melting ports for supplying and recovering the melting liquid. The target irradiation system according to any one of claims 1 to 7, wherein the target irradiation device and the melting device are arranged in the same room in a building. 1. A method for recovering radioisotopes from a solid target, comprising recovering radioisotopes from a metal layer attached to the solid target, the method comprising the steps of:
a target irradiation device disposed in a shielded room in a building irradiates the solid target with a charged particle beam to generate the radioisotope in the solid target;
transporting the solid target, which has been irradiated with the charged particle beam, to a melting device disposed in the shielding chamber by a transport device capable of transporting the solid target;
The radioisotope attached to the solid target is dissolved with a strong acid by the dissolving device;
exhausting the gas in a container that covers the melting apparatus to the outside of a shield that blocks radiation emitted from the particle accelerator, the target irradiation device , and the melting apparatus, without the gas coming into contact with at least one of the particle accelerator and the target irradiation device ;
the shielding shield accommodates the particle accelerator, the target irradiation device, the melting device, and the accommodation section therein;
A method for the recovery of radioisotopes from solid targets.

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