Target irradiation system and method for recovering radioactive isotopes

Abstract

The present invention provides a target irradiation system that allows the target to be removed from the irradiation device and the radioactive isotope to be quickly dissolved in a dissolution device, and a method for recovering radioactive isotopes from a solid target. [Solution] The transport device 22 transports the solid target 10 from the target irradiation device 20, where the charged particle beam B is irradiated onto the solid target 10, to the dissolution device 21, which recovers the radioactive isotopes. Here, the target irradiation device 20 and the dissolution device 21 are located in a cyclotron chamber 152 provided in the building 150. Therefore, both the process of irradiating the solid target 10 with a charged particle beam and the process of recovering the radioactive isotopes by dissolution are performed in the cyclotron chamber 152. Thus, the solid target 10 can be removed from the target irradiation device 20 and the radioactive isotopes can be quickly dissolved in the dissolution device 21.

Description

[Technical Field]

[0001] The present invention relates to a target irradiation system and a method for recovering radioactive isotopes from a solid target. [Background technology]

[0002] As shown in Patent Document 1, a self-shielded cyclotron system is known that houses a cyclotron and has a self-shielding mechanism to suppress the emission of radiation from the cyclotron 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 scans (positron emission tomography) and other applications in hospitals. For example, in Patent Document 2, a target to which solid radioisotopes are attached is transported to a dissolution device, and the radioisotopes are dissolved in the dissolution device to recover the RI. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-105293 [Patent Document 2] Japanese Patent Publication No. 2014-115229 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] At this point, the target is activated after irradiation with charged particle beams. Therefore, it is necessary to remove the target from the irradiation device and quickly dissolve the radioactive isotopes in a dissolution device.

[0005] The present invention aims to provide a target irradiation system that allows a target to be removed from an irradiation device and radioactive isotopes to be quickly dissolved in a dissolution device, and a method for recovering radioactive isotopes from a solid target. [Means for solving the problem]

[0006] The target irradiation system according to the present invention is a target irradiation system that generates radioactive isotopes in a metal layer by irradiating a solid target having a metal layer with a charged particle beam emitted from a particle accelerator, and comprises: a target irradiation device located in a room provided in a building, which 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; and a dissolution device located in the room, which dissolves the radioactive isotopes adhering to the solid target after irradiation with the charged particle beam by the target irradiation device.

[0007] 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, enabling irradiation of the solid target with the charged particle beam. As a result, radioactive isotopes are formed in the areas of the metal layer of the solid target that have been irradiated with the charged particle beam. The dissolution device dissolves the radioactive isotopes adhering to the solid target after irradiation with the charged particle beam by the target irradiation device. This makes it possible to recover the radioactive isotopes by recovering the dissolved solution. Here, the target irradiation device and the dissolution device are located 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 dissolution are performed indoors. Consequently, the solid target can be removed from the target irradiation device and the radioactive isotopes can be quickly dissolved in the dissolution device.

[0008] The target irradiation system may further include a support section that supports the target irradiation device relative to the floor of the room, and the dissolution device may be supported relative to the floor by the support section. In this case, since the target irradiation device and the dissolution device are supported by a common support section, they can be placed in close proximity to each other.

[0009] The target irradiation system may further include a transport device for transporting the solid target, once released from the target irradiation device, to the dissolution device. In this case, the solid target can be transported quickly from the target irradiation device to the dissolution device.

[0010] The target irradiation system is installed in a room and houses a particle accelerator and a target irradiation device inside, further comprising a shielding shield to block radiation emitted from the particle accelerator and the target irradiation device, and the dissolution device may be installed inside the shielding shield. In this case, the shielding shield can block radiation when transporting the solid target from the target irradiation device to the dissolution device.

[0011] The target irradiation system further comprises a transport device for transporting a solid target from the target irradiation device to the dissolution device, and a control unit. The control unit may control the transport device so that, after irradiation of the metal layer with charged particle beams, the solid target held in the target irradiation device is transported to the dissolution device. This allows the transport of the solid target by the transport device to be performed automatically by the control unit. This further reduces radiation exposure to workers. In addition, the automatic transport of the solid target by the control unit can shorten the working time.

[0012] The target irradiation system is installed in a room and houses a particle accelerator and a target irradiation device inside. It further includes a shielding shield to block radiation emitted from the particle accelerator and the target irradiation device. The shielding shield may also include a housing section that covers the dissolution device and an exhaust section that exhausts the gas inside the housing section to the outside of the shielding shield. In this case, if the dissolution liquid of the dissolution device vaporizes, the housing section prevents the gas from diffusing into the shielding shield. The gas inside the housing section is also discharged to the outside of the shielding shield by the exhaust section. This prevents other equipment inside the shielding shield from being corroded by the gas.

[0013] The target irradiation system further includes a transport device for transporting 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 requiring the removal of the solid targets along the way. This reduces the effects of radiation exposure due to the removal process.

[0014] The target irradiation system further comprises a support device for supporting a solid target, the target irradiation device has an irradiation port from which a charged particle beam is emitted, the dissolution device has a dissolution port for supplying and recovering the dissolution solution, and the support device may be connected to the irradiation port and / or the dissolution port. In this case, the support device can be used as both a part of the target irradiation device and a part of the dissolution device.

[0015] The dissolution apparatus may be equipped with multiple dissolution ports for supplying and recovering the dissolution solution. In this case, the dissolution process for multiple radioactive isotopes can be performed without the need to replace the dissolution ports.

[0016] The target irradiation system is a target irradiation system that generates radioactive isotopes in a metal layer by irradiating a solid target having a metal layer with a charged particle beam emitted from a particle accelerator. The system comprises a target irradiation device that holds the solid target at the irradiation position of the charged particle beam, enabling irradiation of the solid target with the charged particle beam, and a dissolution device that dissolves the radioactive isotopes adhering to the solid target after irradiation with the charged particle beam by the target irradiation device. The target irradiation device and the dissolution device are located in the same room within the building. This target irradiation system can achieve the same effects and capabilities as the target irradiation system described above.

[0017] The method for recovering radioactive isotopes from a solid target is a method for recovering radioactive isotopes from a metal layer attached to a solid target having a metal layer. The method involves irradiating the solid target with a charged particle beam using a target irradiation device located in a shielded room within a building to generate radioactive isotopes on the solid target, transporting the solid target after irradiation with the charged particle beam using a transport device capable of transporting the solid target to a dissolution device located in the shielded room, and dissolving the radioactive isotopes attached to the solid target using the dissolution device. With this recovery method, the steps of irradiating the solid target with a charged particle beam, transporting the solid target, and recovering the radioactive isotopes by dissolution are all performed within the shielded room. Therefore, the solid target can be removed from the target irradiation device and the radioactive isotopes can be quickly dissolved in the dissolution device. Furthermore, radiation can be shielded at each step. [Effects of the Invention]

[0018] According to the present invention, a target irradiation system is provided that allows the target to be removed from the irradiation device and the radioactive isotope to be quickly dissolved in a dissolution device, and a method for recovering radioactive isotopes from a solid target is also provided. [Brief explanation of the drawing]

[0019] [Figure 1] It is a schematic configuration diagram showing a self - shielded cyclotron system including a target irradiation system according to an embodiment of the present invention. [Figure 2] It is a perspective view of a solid target. [Figure 3] It is an enlarged view of a target irradiation system. [Figure 4] It is a flowchart showing the processing content of a control unit. [Figure 5] It is an enlarged view showing the operation of a target irradiation system. [Figure 6] It is an enlarged view showing the operation of a target irradiation system. [Figure 7] It is an enlarged view showing the operation of a target irradiation system. [Figure 8] It is an enlarged view showing the operation of a target irradiation system. [Figure 9] It is an enlarged view showing the operation of a target irradiation system. [Figure 10] It is an enlarged view showing a self - shielded cyclotron including a target irradiation system according to a modified example. [Figure 11] It is a conceptual configuration diagram showing a target irradiation system according to a modified example. [Figure 12] It is a schematic configuration diagram showing a target irradiation system according to a modified example. [Figure 13] It is a schematic diagram showing the main part of the target irradiation system shown in FIG. 12. [Figure 14] It is a perspective view showing an example of the specific structure of a target exchanger. [Figure 15] It is a cross - sectional view showing a state where a support device is pressed against an irradiation port. [Figure 16] It is a cross - sectional view showing a state where a support device is pressed against a dissolution port. [Figure 17] It is a front view of a dissolution port. [Figure 18] It is a schematic diagram showing the operation of a target irradiation system. [Figure 19] It is a schematic diagram showing the operation of a target irradiation system. [Figure 20] This is a schematic diagram illustrating the operation of the target irradiation system. [Figure 21] This is a schematic diagram illustrating the operation of the target irradiation system. [Figure 22] This is a schematic diagram illustrating the operation of the target irradiation system. [Figure 23] This is a schematic diagram illustrating the operation of the target irradiation system. [Modes for carrying out the invention]

[0020] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.

[0021] As shown in Figure 1, the self-shielded cyclotron system 100 is a system installed inside the building 150. The self-shielded cyclotron system 100 according to this embodiment is a system that produces radioactive isotopes (hereinafter sometimes referred to as RI) using charged particle beams. The self-shielded cyclotron system 100 can be used, for example, as a PET cyclotron, and the RI produced by this system is used, for example, in the production of radiopharmaceuticals (including radiopharmaceuticals) which are radioactive isotope-labeled compounds (RI compounds). Examples of radioactive isotope-labeled compounds used in PET scans (positron emission tomography) in hospitals, etc., include: 18 F-FLT (fluorothymidine), 18 F-FMISO (fluorosonidazole), 11 Examples include C-Lacropride, etc.

[0022] The self-shielded cyclotron system 100 comprises 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 the building 150 in the cyclotron chamber 152 inside the building 150. The cyclotron chamber 152 is a room covered with concrete (shielding walls). Therefore, by using the self-shielded cyclotron system 100, users can obtain radioactive isotopes on-site within the building.

[0023] Cyclotron 2 is an accelerator that emits charged particle beams. 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. Cyclotron 2 has a pair of magnetic poles, a vacuum box, and an annular yoke surrounding these pair of magnetic poles and the vacuum box. Part of the pair of magnetic poles face each other within the vacuum box with a predetermined distance between their main surfaces. Charged particles are multiple-accelerated within the gap between these pairs of magnetic poles. Examples of charged particles include protons and heavy particles (heavy ions). In this embodiment, Cyclotron 2 is equipped with a plurality of ports 2a for emitting charged particle beams. A target irradiation device 20, described later, is formed in one of the plurality of ports 2a. Cyclotron 2 adjusts the trajectory of the charged particle beam in the acceleration space and extracts the charged particle beam from a desired port 2a.

[0024] The shielding shield 4 is installed inside the room (inside the cyclotron chamber 152) and houses the cyclotron 2 and the target irradiation device 20 described later, shielding it from radiation emitted from the cyclotron 2 and the target irradiation device 20. The shielding shield 4 is located inside the building and houses the cyclotron 2, suppressing the emission of radiation from the cyclotron 2 into the cyclotron chamber 152. By covering the cyclotron 2 from all directions, the shielding shield 4 can shield radiation from all directions. In this embodiment, the shielding shield 4 has a hexahedral box structure, but its shape is not particularly limited. The shielding shield 4 separates the internal space of the building 150 (cyclotron chamber 152) 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 where other equipment is installed or where workers can pass through. Therefore, the self-shielded cyclotron system 100 of this embodiment differs from a system where the cyclotron 2 is simply placed inside a building, and the surrounding walls that make up the room in the building do not constitute the shielding shield 4. The walls of the shielding shield 4 are made of materials such as polyethylene, iron, lead, and heavy concrete. Inside the shielding shield 4, in addition to the cyclotron 2, a vacuum pump and wiring for operating the cyclotron 2 are also placed. Components of the target irradiation system 3 are also placed inside the shielding shield 4. Therefore, the shielding shield 4 functions as a support for the target irradiation device 20 described later against the floor 151 of the cyclotron room 152. The dissolution device 21 described later is supported against the floor 151 by the shielding shield 4, which functions as a support. With the above configuration, the target irradiation device 20 and the dissolution device 21 described later are located in the same room (inside the cyclotron room 152) provided in the building 150.

[0025] The target irradiation system 3 irradiates a solid target 10 with a charged particle beam and dissolves and recovers the radioisotope generated by the irradiation. The target irradiation system 3 is formed near the outer periphery of the cyclotron 2 and is disposed within the shielding shield 4. The solution containing the radioisotope obtained by the target irradiation system 3 is sent via the transport pipe 161 to an apparatus 160 such as a purification apparatus for purifying the radioisotope in the solution or a synthesis apparatus for synthesizing drugs.

[0026] Referring to FIG. 2, the solid target 10 will be described. The solid target 10 includes a target substrate 13 and a metal layer 11. Specifically, as shown in FIG. 2, the solid target 10 has a metal layer 11 as a target material formed on a target substrate 13 composed of a metal plate. Note that the metal layer 11 is not limited to a layer of a highly pure metal and may be a layer of a metal oxide. By setting the target substrate 13 in the apparatus and irradiating the metal layer 11 with the charged particle beam B, a trace amount of radioisotope 12 is generated in the irradiated portion. As a result, the radioisotope 12 is contained in the metal layer 11. As the material of the target substrate 13, a material that is not dissolved by the solution is adopted. For example, Au, Pt, etc. are adopted. Although the target substrate 13 shown in FIG. 2 is formed in a disc shape, the shape and thickness are not particularly limited. As the material of the metal layer 11 which is the target material, for example, 64 Ni, 89 Y, 100 Mo, 68 Zn, etc. may be mentioned. As the radioisotope 12 generated corresponding to the metal layer 11, 64 Cu, 89 Zr, 99m Tc, 68Examples include Ga. The metal layer 11 is formed by plating the surface 10a of the target substrate 13. Alternatively, a plate-shaped metal layer may be attached to the target substrate 13, rather than being plated. The metal layer 11 shown in Figure 2 is formed in a circular shape at the center of the target substrate 13, but its shape and position are not particularly limited. When the metal layer 11 is irradiated with charged particle beam B, cooling water or the like is supplied to the back 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 of charged particle beam B to be absorbed by the cooling water or the like.

[0027] Next, with reference to Figure 3, the details of the configuration of the target irradiation system 3 will be described. The target irradiation system 3 irradiates a solid target 10 having a metal layer 11 with a charged particle beam emitted from the cyclotron 2 to generate radioactive isotopes in the metal layer 11. The target irradiation system 3 comprises a target irradiation device 20, a dissolution device 21, a transport device 22, and a control unit 50.

[0028] The target irradiation device 20 is located inside a room (cyclotron room 152) in the building 150 and is a device that holds the solid target 10 at the irradiation position for the charged particle beam B, enabling irradiation of the solid target 10 with the charged particle beam B. The target irradiation device 20 holds the solid target 10, which has a metal layer 11, at the irradiation position for the charged particle beam B. The target irradiation device 20 also releases the solid target 10 once the irradiation of the charged particle beam B to the solid target 10 is complete. Specifically, the target irradiation device 20 comprises 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 within a shielding shield 4.

[0029] The fixed unit 23 is a cylindrical member fixed to the outer periphery of the cyclotron 2. The fixed unit 23 is provided so as to extend along the irradiation axis BL of the charged particle beam B emitted from the cyclotron 2 and protrude from the outer periphery of the cyclotron 2. The fixed unit 23 has an internal space 26 for allowing the charged particle beam B to pass through at a position corresponding to the irradiation axis BL of the charged particle beam B. The internal space 26 is formed to extend along the irradiation axis BL with the irradiation axis BL as its centerline. The fixed unit 23 and the internal space 26 are arranged to be inclined downward with respect to the horizontal direction.

[0030] The fixed unit 23 has a horizontally extending surface at its lower end, which serves as an opposing surface 23a facing the upper surface of the movable unit 24. The fixed unit 23 holds the solid target 10 at the position of the opposing surface 23a. A sealing member, such as an O-ring, is provided on the opposing surface 23a. The opposing surface 23a also functions as a sealing surface for the solid target 10 by contacting the solid target 10 via the sealing member. In this embodiment, the location where the internal space 26 opens on the opposing surface 23a (and further, the position of the irradiation axis BL within that location) corresponds to the irradiation position RP. Therefore, when the target irradiation device 20 holds the solid target 10, it holds the solid target 10 such that the metal layer 11 is positioned at the opening of the internal space 26.

[0031] The fixed unit 23 is equipped with a vacuum foil 25 at an intermediate position in the internal space 26. The vacuum foil 25 maintains a vacuum in the region of the internal space 26 upstream of the vacuum foil 25.

[0032] The fixed unit 23 has a channel 27 for blowing a gas such as helium onto the charged particle beam B and vacuum foil 25 positioned at the irradiation location. The channel 27 has a main channel 27a and branch channels 27b and 27c that branch off from the main channel 27a. Branch channel 27b extends toward the vacuum foil 25 and blows gas onto the vacuum foil 25. Branch channel 27c extends toward the irradiation position RP of the solid target 10 and blows gas onto the held solid target 10.

[0033] The movable unit 24 moves up and down relative to the fixed unit 23. When the solid target 10 is placed on the transport tray 60, the movable unit 24 is positioned at a location separated downward from the fixed unit 23. When the solid target 10 is held 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 Figure 5).

[0034] The movable unit 24 has a cylindrical shape that extends in the vertical direction. The movable unit 24 is connected to a drive mechanism 28 that moves in the vertical direction at a part 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 circumference of the transport tray 60, which will be described later. As a result, the small-diameter portion 29 passes through the through hole on the inner circumference side of the transport tray 60, comes into contact with the solid target 10, and presses the solid target 10 against the fixed unit 23 above.

[0035] The movable unit 24 has a surface that extends horizontally on the upper end side of the small-diameter portion 29, which serves as an opposing surface 24a facing 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 also functions as a sealing surface for the solid target 10 by contacting the solid target 10 via the sealing member. When the target irradiation device 20 holds the solid target 10, the opposing surface 23a and the opposing surface 24a sandwich the solid target 10 (see Figure 5).

[0036] The movable unit 24 has an internal space 31 that opens on 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.

[0037] The dissolution apparatus 21 is located inside the chamber (cyclotron chamber 152) and is used to dissolve radioactive isotopes adhering to the solid target 10 after irradiation with charged particle beam B by the target irradiation apparatus 20. The dissolution apparatus 21 dissolves the metal layer 11 containing radioactive isotopes in the solid target 10. The dissolution apparatus 21 comprises a fixed unit 40 and a movable unit 41. The dissolution apparatus 21 holds the solid target 10 by sandwiching it between the fixed unit 40 and the movable unit 41. With the solid target 10 held, the dissolution apparatus 21 supplies a dissolving solution to at least the metal layer 11, dissolves the metal of the metal layer 11 containing radioactive isotopes in the dissolving solution, and recovers the dissolving solution together with the radioactive isotopes. Hydrochloric acid, nitric acid, etc., are used as the dissolving solution. The fixed unit 40 and the movable unit 41 are housed within the shielding shield 4.

[0038] The fixed unit 40 is positioned away from the fixed unit 23 of the target irradiation device 20, on the opposite side of the cyclotron 2. The fixed unit 40 comprises a cylindrical main body portion 48 extending in the vertical direction, and a support portion 49 that supports the main body portion 48 on its outer circumference. The main body portion 48 has a surface that extends horizontally at its lower end, which serves as an opposing surface 40a facing 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 also functions as a sealing surface for the solid target 10 by contacting the solid target 10 via the sealing member. The solid target 10 is held at the position of the opposing surface 40a.

[0039] The main body 48 has an internal space 42 that opens at the opposing surface 40a. The internal space 42 is a dissolution tank for storing a dissolving solution for dissolving the metal layer 11 of the solid target 10. A supply / suction pipe 43 for supplying the dissolving solution and a suction pipe 44 for sucking the dissolving solution and the gas inside the internal space 42 are connected to the internal space 42. The diameter of the internal space 42 that opens at the opposing 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 opposing surface 40a itself is not particularly limited, but in this embodiment it is smaller than the diameter of the solid target 10.

[0040] The support portion 49 is a cylindrical member having an end face 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 its central position 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.

[0041] 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 location separated downward from the fixed unit 40. When the metal layer 11 of the solid target 10 is melted in the melting apparatus 21, the movable unit 41 is positioned to sandwich the solid target 10 between itself and the fixed unit 40 (see Figure 9).

[0042] The movable unit 41 comprises a main body portion 46 and a receiving tray portion 47 provided on the upper end side of the main body portion 46. The main body portion 46 has a cylindrical shape that extends in the vertical direction. The main body portion 46 is connected to a drive mechanism (not shown) that moves in the vertical direction at a part of its outer circumferential surface. A groove structure for supporting the receiving tray portion 47 is formed at the upper end of the main body portion 46.

[0043] The receiving tray portion 47 comprises a bottom wall portion 47a that extends horizontally at the upper end of the main body portion 46, and a side wall portion 47b that rises upward from the outer peripheral edge of the bottom wall portion 47a. The bottom wall portion 47a has a surface that extends horizontally as an opposing surface 41a that faces the opposing surface 40a of the fixing unit 40. The opposing surface 41a is in contact with the solid target 10. When the dissolving device 21 holds the solid target 10, the opposing surface 40a and the opposing surface 41a sandwich the solid target 10 (see Figure 9). The inner diameter of the side wall portion 47b is larger than the diameter of the solid target 10. Also, when holding the solid target 10, the upper end of the side wall portion 47b is positioned higher than the solid target 10. Therefore, if the dissolving liquid leaks from the internal space 42 while the metal layer 11 of the solid target 10 is being dissolved, the receiving tray portion 47 receives the dissolving liquid. Furthermore, the lower surface of the bottom wall portion 47a has a recessed and recessed structure for fitting with the groove structure of the main body portion 46.

[0044] In the dissolution apparatus 21, the main body 48 and the receiving tray 47, which come into contact with the dissolution liquid, are configured as replaceable disposable parts. Specifically, the main body 48 is detachably attached to the support 49, and the receiving tray 47 is detachably attached to the main body 46. Here, "detachable" means that even after being attached, the attachment method allows the operator to easily remove it during normal maintenance work. For example, detachable attachment structures include structures attached by bolting, and structures attached by fitting and engaging with sufficient strength to prevent them from coming loose during dissolution. For example, fixing structures such as welding or brazing do not qualify as detachable. The replaceable main body 48 and receiving tray 47 can be made of materials with high acid resistance, such as Teflon®.

[0045] The transport device 22 is a device that transports the solid target 10, which has been released from being held by the target irradiation device 20, to the dissolution device 21. The transport device 22 transports the solid target 10 from the target irradiation device 20 to the dissolution device 21. The transport device 22 is located inside the shielding shield 4. The transport device 22 comprises a transport tray 60 on which the solid target 10 is placed and transport drive unit 61 that drives the transport tray 60. The transport tray 60 is an annular member having a support portion on its upper surface for supporting the solid target 10. The transport tray 60 has a groove formed around its entire circumference on the inner edge of its upper surface, and the outer edge of the lower surface of the solid target 10 rests in this groove. The transport drive unit 61 is composed of a combination of a drive source and a drive force transmission mechanism, which are not shown. The transport drive unit 61 transports the transport tray 60 to the dissolution apparatus 21 by moving it horizontally from the position of the target irradiation device 20 when transporting the solid target 10 after charged particle beam irradiation to the dissolution apparatus 21. The transport drive unit 61 transports the transport tray 60 from the area between the fixed unit 23 and the movable unit 24 of the target irradiation device 20 to the area between the fixed unit 40 and the movable unit 41 of the dissolution apparatus 21. The transport drive unit 61 may be configured using known drive sources such as rotary motors and linear motors, and a drive force transmission mechanism such as gears and rods. The transport drive unit 61 may be configured in any way that avoids interference with other components and can perform the desired operation. The position of the transport tray 60 at each stage will be explained in detail later when describing the operation.

[0046] The control unit 50 controls the self-shielded cyclotron system 100. The control unit 50 consists of a CPU, RAM, ROM, and 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 ROM, and controls each component within the self-shielded cyclotron system 100. The control unit 50 does not have to be composed of a single processing unit, but may be composed of multiple processing units. The control unit 50 may be located inside the shielding shield 4 or outside the shielding shield 4.

[0047] The control unit 50 comprises an irradiation control unit 51, a holding control unit 52, a dissolution control unit 53, and a transport control unit 54. The irradiation control unit 51 mainly controls the cyclotron 2 and controls the operation related to the irradiation of charged particle beam B by the cyclotron 2. The holding control unit 52 mainly controls the target irradiation device 20 and controls the operation related to the holding of the solid target 10 by the target irradiation device 20. The dissolution control unit 53 mainly controls the dissolution device 21 and controls the operation related to dissolving the metal layer 11 of the solid target 10. The transport control unit 54 mainly controls the transport device 22 and controls the operation related to the transport of the solid target 10. After irradiation of the metal layer 11 with charged particle beam B, the transport control unit 54 controls the transport device 22 to transport the solid target 10 held in the target irradiation device 20 to the dissolution device 21.

[0048] Next, the operation of the target irradiation system 3 will be explained along with the details of the control processing by the control unit 50, with reference to Figures 3 to 9. Figure 4 is a flowchart showing the details of the control processing by the control unit 50. Figures 4 to 9 show the state of the target irradiation system 3 at each stage of operation. For the sake of explanation, the control unit 50 and the transport drive unit 61 are omitted from Figures 4 to 9. Also, symbols not used in the explanation may be omitted as appropriate.

[0049] As shown in Figure 4, the control unit 50 performs a process to set the solid target 10 in the target irradiation system 3 (step S10). In step S10, the control unit 50 positions the target irradiation device 20, the dissolution device 21, and the transport device 22 in their initial positions. The control unit 50 drives the drive units of each component to bring the target irradiation system 3 to the state shown in Figure 3. In this state, the movable unit 24 is positioned at a position separated downward from the fixed unit 23. The movable unit 41 is positioned at a position separated downward from the fixed unit 40. The transport tray 60 is positioned at a position separated downward from the fixed unit 23 and at a reference height. Here, "reference height" is a predetermined height position in the height direction that is between the fixed unit 23 and the movable unit 24, and between the fixed unit 40 and the movable unit 41. At this height position, the transport tray 60 does not interfere with each of the units 23, 24, 40, and 41 even when moved horizontally. The control unit 50 may notify the operator, via a monitor or other means, that the solid target 10 is ready to be set. When the control unit 50 detects that the operator has placed the solid target 10 on the transport tray 60, it recognizes that the setting of the solid target 10 is complete. The control unit 50 may detect that the setting of the solid target 10 is complete through detection by a sensor or through input from the operator.

[0050] Next, the control unit 50 performs a process to hold the solid target 10 at the irradiation position RP of the charged particle beam B (step S20: Figure 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 Figure 5, the solid target 10 is sandwiched between the fixed unit 23 and the movable unit 24 at the irradiation position RP. During the process of the movable unit 24 moving upward, the solid target 10 placed on the transport tray 60 is supported by the movable unit 24, which has passed through the through-hole of the transport tray 60 from below. At this time, the transport tray 60 may rise while being supported by the movable unit 24. Alternatively, the transport tray 60 may be driven to rise together with the movable unit 24.

[0051] Next, the control unit 50 performs the process of irradiating the solid target 10 with charged particle beam B (step S30: Figure 4). In S30, the irradiation control unit 51 of the control unit 50 irradiates the solid target 10 with charged particle beam B by controlling the cyclotron 2. At this time, the holding control unit 52 controls the flow path system so that helium gas or the like is blown from the flow path 27 of the fixing unit 23 onto 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 discharge pipe 33 to cool the solid target 10 by flowing a cooling medium into the internal space 31.

[0052] Once the process in S30 is complete, the holding control unit 52 of the control unit 50 controls the drive mechanism 28 of the movable unit 24, thereby moving the movable unit 24 downward. As a result, the movable unit 24 returns 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 on it.

[0053] Next, the control unit 50 performs the process of transporting the solid target 10 from the target irradiation device 20 to the dissolution 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 move the transport tray 60 horizontally from the target irradiation device 20 to the position of the dissolution 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 its position at the reference height in the height direction. As a result, the solid target 10 is positioned so that it faces the opposing surface 40a with the internal space 42 open on the lower side.

[0054] Next, the control unit 50 performs the process of setting the solid target 10 into the dissolution device 21 (step S50: Figure 4). In S50, as shown in Figure 8, the dissolution control unit 53 of the control unit 50 controls the piping system of the suction tube 44 to adsorb the solid target 10 onto the opposing surface 40a via the internal space 42. Before adsorbing the solid target 10, the solid target 10 is pressed against the opposing surface 40a of the main body 48 by raising the transport tray 60. This seals the internal space by crushing the O-ring (not shown) provided between the solid target 10 and the main body 48. After this, the transport control unit 54 controls the transport drive unit 61 (see Figure 3) to move the transport tray 60 to the position on the target irradiation device 20 side. This prevents the transport tray 60 from interfering with the movable unit 41.

[0055] 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 Figure 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 from above by the main body 48.

[0056] Next, the control unit 50 performs a process to recover the radioactive isotopes contained in the metal layer 11 of the solid target 10 by dissolving the metal layer 11 in the dissolution device 21 (step S60: Figure 4). In S60, the dissolution control unit 53 of the control unit 50 controls the pipeline system of the supply / suction pipe 43 to supply the dissolution liquid SL from the supply / suction pipe 43 to the internal space 42. The dissolution control unit 53 also controls the pipeline system of the suction pipe 44 to collect the dissolution liquid SL containing the dissolved radioactive isotopes by suctioning it through the supply / suction pipe 43. With this, the control process shown in Figure 4 is completed. After the recovery of the radioactive isotopes is completed, the operator removes the solid target 10 together with the main body 48 and the receiving tray 47 and takes it outside the shielding shield 4.

[0057] As shown in Figure 1, the dissolved radioactive isotope solution SL is discharged outside the shielding shield 4 and sent to equipment 160, such as a purification unit for purifying the radioactive isotope in the solution SL or a synthesis unit for synthesizing pharmaceuticals. The purification unit and synthesis unit may be located within the same building 150 or in a different building (facility). When transporting the solution SL to a synthesis unit, etc., within the same building 150, the solution SL is sent to the synthesis unit, etc., via a transport pipe 161 connected to a supply / suction pipe 43. Since radiation is emitted from the solution SL, the transport pipe 161 is covered with a shielding shield or passed through the shielding wall (floor or wall) of building 150. When transporting the solution SL to a different building, the recovered 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 the entire shielding box is transported by automobile or the like.

[0058] Next, the operation and effects of the target irradiation system 3 according to this embodiment will be described.

[0059] The target irradiation system 3 according to this embodiment is a target irradiation system 3 that generates radioactive isotopes in a metal layer 11 by irradiating a solid target 10 having a metal layer 11 with a charged particle beam B emitted from a cyclotron 2, and comprises a target irradiation device 20 located in a cyclotron chamber 152 provided in a building 150, which holds the solid target 10 at the irradiation position of the charged particle beam B and enables irradiation of the solid target 10 with the charged particle beam B, and a dissolution device 21 located in the cyclotron chamber 152, which dissolves the radioactive isotopes adhering to the solid target 10 after irradiation with the charged particle beam B by the target irradiation device 20 has been completed.

[0060] 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, enabling irradiation of the solid target 10 with the charged particle beam B. As a result, radioactive isotopes are formed in the areas of the metal layer 11 of the solid target 10 that have been irradiated with the charged particle beam B. The dissolution device 21 dissolves the radioactive isotopes adhering to the solid target 10 after irradiation with the charged particle beam B by the target irradiation device 20. This makes it possible to recover the radioactive isotopes by recovering the dissolved solution. The target irradiation device 20 and the dissolution device 21 are located in the 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 dissolution are performed in the cyclotron chamber 152. Consequently, the solid target 10 can be removed from the target irradiation device 20 and the radioactive isotopes can be quickly dissolved in the dissolution device 21.

[0061] The target irradiation system 3 further includes a shielding shield 4 as a support for the target irradiation device 20 relative to the floor 151 of the cyclotron chamber 152, and the dissolution device 21 is supported relative to the floor 151 by the support. In this case, since the target irradiation device 20 and the dissolution device 21 are supported by a common support, they can be placed in close proximity to each other.

[0062] The target irradiation system 3 further includes a transport device 22 for transporting the solid target 10, which has been released from the target irradiation device 20, to the dissolution device 21. In this case, the solid target 10 can be quickly transported from the target irradiation device 20 to the dissolution device 21.

[0063] The target irradiation system 3 is located within the cyclotron chamber 152 and houses the cyclotron 2 and the target irradiation device 20. It further includes a shielding shield 4 that shields against radiation emitted from the cyclotron 2 and the target irradiation device 20, and the dissolution device 21 is located within the shielding shield 4. In this case, the shielding shield 4 can shield against radiation when transporting the solid target 10 from the target irradiation device 20 to the dissolution device 21.

[0064] The target irradiation system 3 further includes a transport device 22 for transporting the solid target 10 from the target irradiation device 20 to the dissolution 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 dissolution device 21 after irradiation of the metal layer 11 with charged particle beam B. As a result, the transport of the solid target 10 by the transport device 22 is performed automatically by the control unit 50. This further reduces radiation exposure to workers. In addition, the automatic transport of the solid target 10 by the control unit 50 can shorten the working time.

[0065] The target irradiation system 3 is a target irradiation system 3 that generates radioactive isotopes in a metal layer 11 by irradiating a solid target 10 having a metal layer 11 with a charged particle beam B emitted from a cyclotron 2. The system comprises a target irradiation device 20 that holds the solid target 10 at the irradiation position of the charged particle beam B, enabling irradiation of the solid target 10 with the charged particle beam B, and a dissolution device 21 that dissolves the radioactive isotopes adhering to the solid target 10 after irradiation with the charged particle beam B by the target irradiation device 20. The target irradiation device 20 and the dissolution device 21 are located in the same cyclotron room 152 provided in the building 150. With this target irradiation system 3, the same operations and effects as described above can be obtained.

[0066] The method for recovering radioactive isotopes from a solid target 10 is a method for recovering radioactive isotopes from a metal layer 11 attached to a solid target 10 having a metal layer 11. The method involves irradiating the solid target 10 with a charged particle beam B using a target irradiation device 20 located in a shielded room provided in a building 150 to generate radioactive isotopes on the solid target 10, transporting the solid target 10 after irradiation with the charged particle beam B is completed using a transport device 22 capable of transporting the solid target 10 to a dissolution device 21 located in the shielded room, and dissolving the radioactive isotopes attached to the solid target 10 using the dissolution device 21. With this recovery method, the steps of irradiating the solid target 10 with the charged particle beam B, transporting the solid target 10, and recovering the radioactive isotopes by dissolution are all performed in the shielded room. Therefore, the solid target can be removed from the target irradiation device 20 and the radioactive isotopes can be quickly dissolved in the dissolution device 21. Furthermore, radiation can be shielded at each stage of the process.

[0067] In the self-shielded cyclotron system 100 according to this embodiment, the target irradiation device 20 holds the target having a metal layer 11 at the 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 areas of the metal layer 11 of the solid target 10 that have been irradiated with the charged particle beam B. The dissolution device 21 is equipped with a dissolution device that dissolves the metal layer 11 containing the radioactive isotopes in the solid target 10. This makes it possible to recover the radioactive isotopes by recovering the dissolution solution. The transport device 22 transports the solid target 10 from the target irradiation device 20, where the charged particle beam B is irradiated onto the solid target 10, to the dissolution device 21, where the radioactive isotopes are recovered. Here, the target irradiation device 20, the dissolution device 21, and the transport device 22 are located inside the shielding shield 4. Therefore, the process of irradiating the solid target 10 with charged particle beam B, the process of recovering the radioactive isotope by dissolution, and the process of transporting the target between the two processes are all carried out within the shielding shield 4. Consequently, in each process, the radiation emitted from the solid target 10 after irradiation with charged particle beam is blocked by the self-shielding. As a result, the safety of radiation exposure when obtaining radioactive isotopes can be further improved.

[0068] 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 dissolution device 21 after irradiation of the metal layer 11 with charged particle beam B. This allows the transport of the solid target 10 by the transport device 22 to be performed automatically by the control unit 50. This further improves safety against radiation exposure. Furthermore, the automatic transport of the solid target 10 by the control unit 50 can reduce working time.

[0069] The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention, as described below.

[0070] For example, a configuration like that shown in Figure 10 may be adopted. The self-shielded cyclotron system shown in Figure 10 may include a housing section 70 that covers the dissolution device 21 within the shielding shield 4, and an exhaust section 71 that exhausts the gas inside the housing section 70 to the outside of the shielding shield 4. The housing section 70 covers only the dissolution device 21 and does not cover the target irradiation device 20. An opening 70a may be formed in the housing section 70 where the transport tray passes through. This opening 70a may be closed when the transport tray is not passing through. The exhaust section 71 may have an exhaust pipe that connects from the housing section 70 through the shielding shield 4 to the outside of the shielding shield 4. This exhaust section 71 may be equipped with a pump or the like in the exhaust pipe.

[0071] As a result, if the dissolving solution in the dissolving device 21 vaporizes, the containment section 70 prevents the gas from diffusing into the shielding shield 4. Furthermore, the gas in the containment section 70 is discharged to the outside of the shielding shield 4 by the exhaust section 71. This prevents other equipment inside the shielding shield 4 from being corroded by the gas.

[0072] Furthermore, the configuration of the target irradiation system shown in the figures of the embodiments described above is merely an example, and the shape and arrangement may be changed as appropriate, as long as they remain within the scope of the present invention. For example, the transport device may use, for instance, an arm-shaped gripping part for gripping the target instead of a transport tray.

[0073] Furthermore, the transport of the target by the transport device was performed automatically by the control unit. Alternatively, the drive of the transport device itself may be performed manually by an operator. In such a case as well, since the target is housed within a self-shielding structure, safety against radiation exposure can be further improved.

[0074] A target irradiation system 3 as shown in Figure 11(a) may also be used. In the example shown in Figure 11(a), the target irradiation device 20 and the dissolution device 21 may be located in an irradiation room 153 separate from the cyclotron room 152 of the building 150. In this case, the charged particle beam emitted from the cyclotron 2 is transported from the cyclotron room 152 to the target irradiation device 20 in the irradiation room 153 via the transport line 155. At this time, the target irradiation device 20 and the dissolution device 21 are supported by a support part 156 against the floor 151 of the irradiation room 153.

[0075] Alternatively, a target irradiation system 3 as shown in Figure 11(b) may be used. In the example shown in Figure 11(b), the cyclotron 2, target irradiation device 20, and dissolution device 21 are located in the same cyclotron chamber 152. In this case, unlike the configuration shown in Figure 1, the shielding shield 4 may be omitted.

[0076] In the embodiments described above, a cyclotron was given as an example of a particle accelerator, but it is not limited to a cyclotron. For example, a linear accelerator may be used as the particle accelerator.

[0077] The target irradiation system 200 shown in Figure 12 may be used. The target irradiation system 200 comprises a fixed unit 211 of the target irradiation device 210, a fixed unit 221 of the dissolution device 220, a support device 230, a target exchanger 240, and a control unit 260.

[0078] To explain the target irradiation system 200, we will set up an XYZ coordinate system. 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 considered the positive side of 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 considered the positive side of the Y-axis direction. The up and down direction is the Z-axis direction. The upper side is considered the positive side of the Z-axis direction.

[0079] As shown in Figure 13, the fixed unit 211 of the target irradiation device 210 is provided with 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 centerline. In this embodiment, the irradiation axis BL of the charged particle beam B extends parallel to the Y-axis direction. Furthermore, 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.

[0080] The fixed unit 211 is equipped with an irradiation port 212 for emitting a charged particle beam B. The irradiation port 212 has a surface that extends parallel to the XZ plane as a facing surface opposite to the sealing surface 230a of the support device 230. The irradiation port 212 has an opening through which an internal space 213 opens. The charged particle beam B is emitted from this opening.

[0081] The fixed unit 221 of the dissolution apparatus 220 is positioned at a location spaced apart from the fixed unit 211 of the target irradiation apparatus 210 toward the positive side in the X-axis direction. The fixed unit 221 is equipped with a plurality of dissolution ports 222A, 222B for supplying and recovering the dissolution solution SL. The dissolution ports 222A, 222B may recover radioactive isotopes of different nuclides. Therefore, the dissolution ports 222A, 222B can supply and recover different dissolution solutions SL. However, the dissolution ports 222A, 222B may recover radioactive isotopes of the same nuclide. The dissolution ports 222A, 222B are arranged adjacent to each other in the X-axis direction. In addition, the dissolution ports 222A, 222B have surfaces that extend parallel to the XZ plane as opposing surfaces facing the sealing surface 230a of the support apparatus 230. The centerlines SCL, SCL of the opposing surfaces of the dissolution ports 222A and 222B extend parallel to each other in the Y-axis direction, spaced apart in the X-axis direction. Furthermore, the centerlines SCL, SCL of the dissolution ports 222A and 222B are set at the same height as the irradiation axis BL. The dissolution ports 222A and 222B may be detachable from the dissolution apparatus 220. That is, the dissolution ports 222A and 222B may be detachably attached to the mounting base 223. This allows the dissolution ports 222 to be replaced according to the radioactive isotope nuclide.

[0082] The configuration of the dissolution port 222A will be described in detail with reference to Figures 16 and 17. Note that the dissolution port 222B has a similar configuration to the dissolution port 222A, and therefore its description 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 includes a flow path 224 and an adsorption structure 226.

[0083] The flow path 224 allows the dissolving liquid SL to flow through it. The flow path 224 is formed inside the member of the dissolution port 222A and opens on the opposing surface 222a. The flow path 224 allows the dissolving liquid SL to flow out through the opening and also draws the dissolving liquid SL in through the opening. A flow path forming member 227 protrudes from the position of the center line SCL of the opposing surface 222a, projecting 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, thereby forming 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. The dissolution port 222A has two flow paths 224, but the number is not particularly limited.

[0084] The adsorption structure 226 is a mechanism that attracts the sealing surface 230a when it is in contact with the opposing surface 222a. The adsorption structure 226 has an annular groove 226a centered on the center line SCL. The adsorption structure 226 also has a vacuum exhaust passage 226b formed within the dissolution port 222A. The vacuum exhaust passage 226b opens at the position of the groove 226a.

[0085] As shown in Figures 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 dissolution 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 dissolution device 220. In this embodiment, as will be described later, the target exchanger 240 can be fitted with multiple support devices 230. 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.

[0086] The configuration of the support device 230 will be described in detail with reference to Figure 15. As shown in Figure 15, the support device 230 is a member having a substantially cylindrical shape. The center line CL of the support device 230 extends parallel to the Y-axis direction. The support device 230 comprises 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 an intermediate position in the longitudinal direction, i.e., in the Y-axis direction. The first member 231 is positioned on the positive side in the Y-axis direction, i.e., on the upstream side in the irradiation direction of the charged particle beam B. The second member 232 is positioned on the negative side in the Y-axis direction, i.e., on the downstream side in the irradiation direction of the charged particle beam B.

[0087] The support device 230 supports the solid target 10 by sandwiching it between the first member 231 and the second member 232. The support device 230 supports the solid target 10 so as to be 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 it moves from the positive side in the Y-axis direction towards the negative side, it moves upward (towards the positive side in the Z-axis direction). The first member 231 has a support surface 231a at its negative end in the Y-axis direction. The second member 232 has a support surface 232a at its positive end 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 a parallel state. Furthermore, the support surfaces 231a and 232a are inclined in the same way as the inclination direction of the solid target 10 described above. The support surfaces 231a and 232a are provided with sealing portions equipped with O-rings near the outer edges of the solid target 10.

[0088] The first member 231 has the aforementioned sealing surface 230a at its positive end in the Y-axis direction. Therefore, the first member 231 functions as a member connected to the irradiation port 212 and also to the dissolution ports 222A and 222B. The sealing surface 230a is provided with a sealing portion having an O-ring. 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 so as to penetrate from the sealing surface 230a to the support surface 231a. As a result, the solid target 10 is exposed to the internal space 233. The internal space 233 functions as a transport path for 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 dissolution tank for the dissolution device 220 that circulates the dissolution liquid SL. Since the first member 231 is a member that allows charged particle beam B to pass through and dissolving liquid SL to flow through it, it is preferable that the material of the first member 231 be Nb, ceramic, or other material with chemical resistance, radiation resistance, and heat resistance.

[0089] 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 spaces 233 and 213 are in communication. The support device 230 is positioned so that its 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.

[0090] 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. The back surface 10b of the solid target 10 is exposed in the internal space of the groove 234. 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 communicate with 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 component for cooling the solid target 10, it is preferable that a corrosion-resistant material such as SUS be used as the material for the second member 232.

[0091] Next, as shown in Figure 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 positioned so that its centerline CL coincides with the centerline SCL of the dissolution port 222A. A portion of the sealing surface 230a faces the groove 226a of the adsorption structure 226. As a result, the sealing surface 230a is adsorbed onto the vacuum-sealed groove 226a. In addition, a 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 within 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 containing the dissolved radioactive isotope is recovered from the flow path 224.

[0092] Next, the target exchanger 240 will be described. As shown in Figures 12 and 13, the target exchanger 240 functions as a transport device for transporting solid targets 10. The target exchanger 240 supports the solid targets 10 via support devices 230. The target exchanger 240 includes 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 is slidable in the X-axis direction with multiple support devices 230 attached. Therefore, the holder 241 can transport the solid targets 10 in the X-axis direction along with the multiple support devices 230.

[0093] Referring to Figure 14, an example of the specific structure of the target exchanger 240 will be described. As shown in Figure 14, the target exchanger 240 comprises 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.

[0094] The base plate 242 is a base component for mounting the first and second slide plates 243 and 244. A guide rail 242a (see Figure 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 the fixing plate 249 for attaching and fixing the target exchanger 240 to the cyclotron.

[0095] The first slide plate 243 is a plate-shaped member having a rectangular outline in plan view. A guide rail 251 extending along the X-axis is provided on the positive edge of the first slide plate 243 in the Y-axis direction. A first cylinder 246 is attached to the negative side surface of the first slide plate 243 in the Y-axis direction. As the first cylinder 246 moves its drive shaft back and forth in the Y-axis direction, the holder 241 reciprocates 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 is movable back and forth in the X-axis direction.

[0096] A third cylinder 248 is mounted on the upper surface of the first slide plate 243. The drive shaft of the third cylinder 248 is movable 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 moves its drive shaft in the X-axis direction, the third cylinder 248 reciprocates in the X-axis direction together with the holder 241 (details described later) to which the drive shaft is engaged.

[0097] 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 positive end of the mounting plate 252 in the Y-axis direction. When this attacker 253 contacts 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.

[0098] 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 lower surface of the base 256. The holder 241 is rectangular in front view. The holder 241 has four holding holes 257 for holding support devices 230, and a substantially cylindrical support device 230 is fitted into each of these holding holes 257 for holding. The four holding holes 257 are arranged side by side along the X-axis direction. As a result, the holder 241 can hold up to four support devices 230. In this embodiment, the holder 241 holds two support devices 230A and 230B, but it can hold two additional support devices 230.

[0099] Four microswitches 259 are mounted on 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 contacts these microswitches 259. Engagement holes 261 are provided below each microswitch 259. The engagement holes 261 are approximately the same size as the diameter of the drive shaft of the third cylinder 248, and the drive shaft is configured to engage with these engagement holes 261. As a result, the holder 241 reciprocates in the X-axis direction when driven by the second cylinder 247.

[0100] As described above, 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 equipped with a mechanism for pressing the support device 230 against the irradiation port 212 or the dissolution ports 222A, 222B. Specifically, as shown in Figures 12 and 13, the target exchanger 240 is equipped with extrusion mechanisms 270A, 270B. The extrusion mechanisms 270A, 270B include a support member 271 connected to the first slide plate 243, a cylinder 272 that moves the drive shaft back and forth in the Y-axis direction, and an extrusion member 273 that pushes out the support device 230. The extrusion member 273 is provided on the drive shaft of the cylinder 272. As a result, the cylinder 272 moves the extrusion member 273 to the positive side in the Y-axis direction, pressing the support device 230 toward the melting device 220. As shown in Figure 13, the extrusion mechanism 270A is positioned opposite the support device 230A. The extrusion mechanism 270B is positioned opposite the support device 230B. For example, if the holder 241 is positioned so that the support device 230A is opposite the melting port 222B (see Figure 20), the extrusion mechanism 270A presses the support device 230A toward the melting port 222B.

[0101] The control unit 260 controls the operation of the target exchanger 240 by transmitting 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.

[0102] Figures 13 and 18-23 show an example of the operation when recovering a single radioactive isotope using two solid targets 10. First, as shown in Figure 13, two support devices 230A and 230B are held in the holder 241. Support device 230A is held in the first holding hole 257 when viewed from the positive side in the X-axis direction. Support device 230B is held in the second holding hole 257 when viewed from the positive side in the X-axis direction. The control unit 260 controls the second cylinder 247 of the target exchanger 240 (see Figure 14) to position the holder 241 opposite the fixing unit 211. At this time, the most positive holding hole 257 of the holder 241 in the X-axis direction, i.e., support device 230A, is positioned opposite the irradiation port 212. This position is called the "initial position". In the following explanation, the control content will be expressed as "the control unit 260 positions the support device 230A opposite the irradiation port 212." The same expression will be used for this control content and for control content of the same nature.

[0103] Next, as shown in Figure 18, the control unit 260 controls the first cylinder 246 of the target exchanger 240 to move the first slide plate 243 (see Figure 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 any other components. In the following description, this control action will be expressed as "the control unit 260 presses the support device 230A against the irradiation port 212." The same expression will be used for this control action and control actions of the same nature. The control unit 260 controls the target irradiation device 210 to irradiate the solid target of the support device 230A with charged particle beam B. Once the irradiation is complete, the control unit 260 releases the pressure of the support device 230A against the irradiation port 212.

[0104] Next, as shown in Figure 19, the control unit 260 positions the support device 230A opposite the dissolution port 222B. Also, as shown in Figure 20, the control unit 260 controls the first cylinder 246 of the target exchanger 240 to move the first slide plate 243 (see Figure 12) toward the positive side in the Y-axis direction, thereby positioning the support device 230A in front of the dissolution port 222B. Furthermore, the control unit 260 extends the cylinder 272 of the extrusion mechanism 270A to press the support device 230A against the dissolution port 222B. 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 any other components. In the following description, this control action will be expressed as "the control unit 260 presses the support device 230A against the dissolution port 222B." The same expression will be used for this control action and control actions of the same nature. The control unit 260 controls the dissolution device 220 to supply the dissolution solution SL to the support device 230A and recovers the dissolution solution SL in which the radioactive isotopes of the solid target 10 have been dissolved. Once the recovery is complete, the control unit 260 releases the pressure of the support device 230A against the dissolution port 222B. Then, the control unit 260 returns the positions of the support devices 230A and 230B to their initial positions.

[0105] Next, as shown in Figure 21, the control unit 260 positions the support device 230B opposite 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. Once the irradiation is complete, the control unit 260 releases the pressure of the support device 230B against the irradiation port 212.

[0106] Next, as shown in Figure 22, the control unit 260 positions the support device 230B 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 the dissolution solution SL to the support device 230B and recovers the dissolution solution SL in which the radioactive isotopes of the solid target 10 have been dissolved. Once the recovery is complete, the control unit 260 releases the pressure of the support device 230B against the dissolution port 222B. Then, the control unit 260 returns the positions of the support devices 230A and 230B to their initial positions. Thus, the recovery of radioactive isotopes using the two solid targets 10 is completed.

[0107] Next, we will describe an example of the operation when recovering two radioactive isotopes using two solid targets 10. Note that operations common to the above-described operation will be explained using common diagrams.

[0108] The control unit 260 irradiates the solid target 10 of the support device 230A with charged particle beam B by performing the operation shown in Figure 18. Next, as shown in Figure 23, the control unit 260 positions the support device 230A 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 solution SL to the support device 230A and recovers the dissolution solution SL in which the radioactive isotopes of the solid target 10 have been dissolved. Once the recovery is complete, the control unit 260 releases the pressure of the support device 230A against the dissolution port 222A. Then, the control unit 260 returns the positions of the support devices 230A and 230B to their initial positions.

[0109] Next, the control unit 260 irradiates the solid target 10 of the support device 230B with charged particle beam B by performing the operation shown in Figure 21. Then, by performing the operation shown in Figure 22, the radioactive isotopes of the solid target 10 of the support device 230B are recovered. At this time, the dissolution port 222B uses a different dissolving solution SL than the one used in dissolution port 222A. As a result, the radioactive isotopes of the solid target 10 of the support device 230B are recovered using a different dissolving solution SL than 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. Thus, the recovery of radioactive isotopes using the two solid targets 10 is completed.

[0110] It is also possible to recover a single radioactive isotope of one nuclide using a single solid target 10. In this case, the support device 230B is omitted from Figures 18 to 20, and the operation shown in Figures 18 to 20 is performed using only the support device 230A.

[0111] Based on the above, the target irradiation system 200 further comprises a target exchanger 240 for transporting 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 requiring the removal of the solid targets 10 along the way. This reduces the effects of radiation exposure due to the removal process.

[0112] For example, after the recovery of radioactive isotopes from the solid target 10 of support device 230A as shown in Figures 18 and 23, processing is performed on the solid target 10 of support device 230B as shown in Figures 21 and 22, without any particular replacement (removal) work of the solid target 10. In this way, once the solid targets 10 are installed in 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 solid targets 10.

[0113] The target irradiation system 200 further comprises a support device 230 for supporting a solid target 10, the target irradiation device 210 comprises an irradiation port 212 from which a charged particle beam B is emitted, the dissolution device 220 comprises dissolution ports 222A and 222B for supplying and recovering the dissolution solution SL, and the support device 230 may be connected to the irradiation port 212 and also to the dissolution ports 222A and 222B. In this case, the support device 230 can be used as part of both the target irradiation device 210 and the dissolution device 220.

[0114] The dissolution apparatus 220 may be equipped with multiple dissolution ports 222A, 222B for supplying and recovering the dissolution solution SL. In this case, the dissolution process for multiple radioactive isotopes can be performed without the need to replace the dissolution ports 222A, 222B.

[0115] [Form 1] A target irradiation system for generating radioactive isotopes of a metal layer by irradiating a solid target having a metal layer with a charged particle beam emitted from a particle accelerator, A target irradiation device is provided in a room within a building, which holds the solid target at the irradiation position of the charged particle beam, enabling irradiation of the solid target with the charged particle beam. The system includes a dissolution apparatus located in the aforementioned room for dissolving the radioactive isotopes adhering to the solid target after irradiation with the charged particle beam by the target irradiation apparatus. Target irradiation system. [Form 2] The room further comprises a support portion for supporting the target irradiation device relative to the floor of the room, The dissolving apparatus is supported by the support portion relative to the floor. A target irradiation system as described in Form 1. [Form 3] The system further includes a transport device for transporting the solid target, which has been released from being held by the target irradiation device, to the dissolution device. A target irradiation system according to form 1 or 2. [Form 4] The chamber is provided with a shielding shield that houses the particle accelerator and the target irradiation device and shields the radiation emitted from the particle accelerator and the target irradiation device, The dissolving apparatus is provided within the shielding shield. A target irradiation system as described in any one of the three forms. [Form 5] A transport device for transporting the solid target from the target irradiation device to the dissolution device, The control unit further comprises, The target irradiation system according to any one of embodiments 1 to 4, wherein the control unit controls the transport device to transport the solid target held in the target irradiation device to the dissolution device after irradiation of the metal layer with the charged particle beam. [Form 6] The chamber is provided with a shielding shield that houses the particle accelerator and the target irradiation device and shields the radiation emitted from the particle accelerator and the target irradiation device, A housing section that covers the melting device within the shielding shield, A target irradiation system according to any one of embodiments 1 to 5, comprising an exhaust unit for exhausting the gas inside the containment unit to the outside of the shielding shield. [Form 7] The system further comprises a conveying device for conveying the solid target, The transport device is capable of supporting a plurality of solid targets, and is a target irradiation system according to any one of embodiments 1 to 6. [Form 8] The system further comprises a support device for supporting the solid target, The target irradiation device includes an irradiation port from which the charged particle beam is emitted, The dissolution apparatus is equipped with a dissolution port for supplying and recovering the dissolution solution. The support device is connected to the irradiation port and to the dissolution port, the target irradiation system according to any one of embodiments 1 to 7. [Form 9] The target irradiation system according to any one of embodiments 1 to 8, wherein the dissolution apparatus comprises a plurality of dissolution ports for supplying and recovering the dissolution solution. [Form 10] A target irradiation system for generating radioactive isotopes of a metal layer by irradiating a solid target having a metal layer with a charged particle beam emitted from a particle accelerator, A target irradiation device that 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, The device comprises a dissolution apparatus for dissolving the radioactive isotopes adhering to the solid target after irradiation with the charged particle beam by the target irradiation apparatus, The target irradiation device and the dissolution device are located in the same room within the building. Target irradiation system. [Form 11] A method for recovering radioactive isotopes from a solid target having a metal layer, wherein the radioactive isotopes of the metal layer adhering to the solid target are recovered from the metal layer. A target irradiation device located in a shielded room within the building irradiates the solid target with a charged particle beam to generate the radioactive isotope in the solid target. The solid target, after irradiation with the charged particle beam has been completed, is transported by a transport device capable of transporting the solid target to a dissolution device located in the shielded chamber. The aforementioned dissolution apparatus dissolves the radioactive isotope attached to the solid target. A method for recovering radioactive isotopes from solid targets. [Form 21] A target irradiation system that generates radioactive isotopes by irradiating them with charged particle beams emitted from an accelerator, A target irradiation device that holds a solid target at the irradiation position of the charged particle beam, enabling irradiation of the solid target with the charged particle beam, A dissolution apparatus for dissolving the radioactive isotopes adhering to the solid target after irradiation with the charged particle beam by the target irradiation apparatus using a strong acid, Equipped with, A target irradiation system characterized by sliding the irradiated solid target into the dissolution apparatus. [Form 22] The device further comprises a support for the target irradiation device, The dissolution apparatus is supported by the support part. A target irradiation system as described in form 21. [Form 23] A transport device for transporting the solid target from the target irradiation device to the dissolution device, The control unit further comprises, The target irradiation system according to embodiment 21 or 22, wherein the control unit controls the transport device to transport the solid target held in the target irradiation device to the dissolution device after irradiation of the metal layer of the solid target with the charged particle beam. [Form 24] The system further comprises a conveying device for conveying the solid target, The transport device is capable of supporting a plurality of solid targets, and is a target irradiation system according to any one of embodiments 21 to 23. [Form 25] The system further comprises a support device for supporting the solid target, The target irradiation device includes an irradiation port from which the charged particle beam is emitted, The dissolution apparatus is equipped with a dissolution port for supplying and recovering the dissolution solution. The support device is connected to the irradiation port and to the dissolution port, the target irradiation system according to any one of embodiments 21 to 24. [Form 26] The target irradiation system according to any one of embodiments 21 to 25, wherein the dissolution apparatus comprises a plurality of dissolution ports for supplying and recovering the dissolution solution. [Form 27] The target irradiation system according to any one of embodiments 21 to 26, wherein the target irradiation device and the dissolution device are located in the same room within the building. [Form 28] A method for recovering radioactive isotopes from a solid target having a metal layer, wherein the radioactive isotopes are recovered from the solid target having a metal layer. The solid target, after irradiation with charged particle beams has been completed, is transported to the dissolution apparatus by sliding it using a transport device capable of transporting the solid target. The aforementioned dissolution apparatus dissolves the radioactive isotope attached to the solid target with a strong acid. A method for recovering radioactive isotopes from solid targets. [Explanation of Symbols]

[0116] 2...Cyclotron, 3,200...Target irradiation system, 4...Shielding shield (support unit), 10...Solid target, 11...Metal layer, 20,210...Target irradiation device, 21,220...Dissolution device, 22...Transport device, 50...Control unit, 70...Housing unit, 71...Exhaust unit, 100...Self-shielded cyclotron system, 212...Irradiation port, 222A,222B...Dissolution port, 230,230A,230B...Support device (target irradiation device, dissolution device), 240...Target exchanger (transport device).

Claims

1. A target irradiation system for generating radioactive isotopes of a metal layer by irradiating a solid target having a metal layer with a charged particle beam emitted from a particle accelerator, A target irradiation device having an irradiation port from which the charged particle beam is emitted, and irradiating the solid target with the charged particle beam, A dissolution apparatus having a dissolution port for supplying and recovering the dissolution solution, for dissolving the radioactive isotope adhering to the solid target after irradiation with the charged particle beam by the target irradiation apparatus, A support device for supporting the solid target, Equipped with, A target irradiation system comprising: pressing the support device against the irradiation port when irradiating the solid target of the support device with the charged particle beam; and pressing the support device against the dissolution port when dissolving the solid target of the support device.

2. The target irradiation system according to claim 1, wherein when the charged particle beam is irradiated onto the solid target of the support device, the support device is moved along the irradiation axis of the charged particle beam and pressed against the irradiation port.

3. The support device has a sealing surface, The target irradiation system according to claim 1, wherein at least one of the irradiation port and the dissolution port has an opposing surface against which the sealing surface is pressed.

4. The support device has a sealing surface, The aforementioned dissolution port is The opposing surface against which the sealing surface is pressed, A suction structure that attracts the sealing surface in contact with the opposing surface, A target irradiation system according to claim 1, comprising:

5. Further comprising a conveying device for conveying the solid target, The target irradiation system according to claim 1, wherein the transport device comprises a plurality of the support devices.

6. The target irradiation system according to any one of claims 1 to 5, wherein the target irradiation device and the dissolution device are located in the same room provided in the building.

7. A method for recovering radioactive isotopes adhering to a solid target having a metal layer, the method for recovering radioactive isotopes from a solid target, The support device that supports the solid target after irradiation with charged particle beams is transported to the dissolution device. A method for recovering radioactive isotopes, comprising pressing the support device against the dissolving device to dissolve the radioactive isotopes attached to the solid target.

Images