Irradiation targets for the generation of radioactive isotopes and dismantling equipment for their decomposition

Abstract

1. An irradiation target system comprising: an irradiation target having at least one annular plate defining a central opening, the irradiation target including an elongated body, a flange portion extending beyond a first end of the plurality of plates, and a tab portion; and a target demolition tool having a bottom plate, a gripper assembly attached to the bottom plate, and a twister assembly including a housing defining a target hole configured to receive the target therein and a slide portion slidably and non-rotatably mounted to the housing at a bottom end of the target hole.

Description

Technical Field

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 344,391, filed May 20, 2022, and U.S. Provisional Patent Application No. 63,212,177, filed Jun. 18, 2021, the entire disclosures of which are incorporated herein by reference.

[0002] The invention to be disclosed hereinafter generally relates to a titanium-molybdate 99 material suitable for use in a technetium-99m generator (Mo-99 / Tc-99m generator), and more specifically, to an irradiation target used in the production of such a titanium-molybdate 99 material and a disassembling device for disassembling the irradiation target.

Background Art

[0003] Technetium-99m (Tc-99m) is the most commonly used radioisotope in nuclear medicine (e.g., medical diagnostic imaging). Tc-99m (m indicates metastability) is typically injected into a patient and used to image organs within the patient's body when used with specific equipment. However, Tc-99m has a half-life of only 6 (six) hours. Thus, an easily accessible source of Tc-99m is of particular interest and / or particular need, at least in the field of nuclear medicine.

[0004] Given Tc-99m's short half-life, it is typically obtained where and / or when needed (e.g., in pharmacies, hospitals, etc.) via Mo-99 / Tc-99m generators. A Mo-99 / Tc-99m generator is a device used to extract the metastable isotope of technetium (i.e., Tc-99m) from a source of decaying molybdenum-99 (Mo-99) by passing physiological saline through a Mo-99 material. Mo-99 is unstable and decays to Tc-99m with a half-life of 66 hours. Mo-99 is typically produced from the irradiation of a highly enriched uranium target (93% uranium-235) in a high-neutron flux reactor and, after subsequent processing steps, is shipped to a Mo-99 / Tc-99m generator manufacturing site to reduce the Mo-99 to a usable form. Mo-99 / Tc-99m generators are then distributed from such centralized locations to hospitals or pharmacies throughout the country. Because Mo-99 has a short half-life and the number of manufacturing locations is limited, it is desirable to minimize the time required to reduce the irradiated Mo-99 material to a usable form.

[0005] Therefore, there remains at least a need for a process to produce titanium-molybdate 99 material suitable for use in Tc-99m generators in a timely manner. [Overview of the project] [Means for solving the problem]

[0006] One embodiment of the present invention provides an irradiation target system for the generation of radioactive isotopes, the irradiation target system comprising an irradiation target comprising a plurality of annular plates defining a central opening, and a first elongated central member on which the plurality of annular plates are maintained by passing through the central opening of the plurality of annular plates, comprising an elongated body, a flange portion extending laterally therefrom at a first end, and a tab portion extending axially therefrom at a second end, wherein the flange portion of the first elongated central member extends axially outward beyond the first end of the plurality of plates, and the tab portion extends axially outward beyond the second end of the plurality of plates. The present invention relates to an irradiation target including a first elongated central member extending in a certain direction, and a target dismantling device comprising a bottom plate, a gripper assembly attached to the bottom plate, a twister assembly rotatably fixed to the bottom plate, the twister assembly comprising a housing that defines a target hole configured to receive the irradiation target, and a sliding portion slidably and non-rotatably mounted in the housing at the bottom end of the target hole, the sliding portion being substantially circular and defining a first hole having a maximum diameter smaller than the outer diameter of a plurality of annular plates of the irradiation target.

[0007] The attached drawings are incorporated into this specification and constitute part of it, illustrating one or more embodiments of the invention and serving to explain the principle of the invention in conjunction with the description.

[0008] The invention is described more fully below with reference to the accompanying drawings, which show some, but not all, embodiments of the invention. Naturally, the invention may be embodied in many different forms and should not be construed as being limited to the embodiments described herein, rather these embodiments are provided to satisfy the legal requirements to which this disclosure is applicable. [Brief explanation of the drawing]

[0009] [Figure 1A]This is a perspective view of a retaining clip that forms a rigid backbone of an irradiation target according to one embodiment of the present invention. [Figure 1B] This is a front view of a retaining clip that forms the rigid backbone of an irradiation target according to one embodiment of the present invention. [Figure 2] This is a side perspective view of an irradiation target according to one embodiment of the present invention. [Figure 3] Figure 2 shows the assembly process of the irradiation target. [Figure 4] This is a perspective view of the irradiation target shown in Figure 2, loaded into the corresponding target canister with one end cap removed. [Figure 5] Figure 4 is a side view of the target canister with both end caps attached. [Figure 6A] This is a perspective view of a demolition tool according to one embodiment of the present invention. [Figure 6B] This is a top view of a demolition device according to one embodiment of the present invention. [Figure 6C] This is a front view of a demolition tool according to one embodiment of the present invention. [Figure 6D] This is a left side view of a demolition tool according to one embodiment of the present invention. [Figure 7A] Figures 6A to 6D are perspective views of the twister assembly of the demolition tool. [Figure 7B] Figures 6A to 6D are top views of the twister assembly of the dismantling tool. [Figure 7C] Figures 6A to 6D are rear views of the twister assembly of the dismantling tool. [Figure 7D] Figures 6A to 6D are left side views of the twister assembly of the dismantling tool. [Figure 8] Figures 7A to 7D are top views of the sliding portion of the twister assembly. [Modes for carrying out the invention]

[0010] The repeated use of reference numerals in this specification and in the drawings is intended to represent the same or similar features and elements of the invention disclosed.

[0011] The invention is described more fully below with reference to the accompanying drawings, which show some, but not all, embodiments of the invention. Naturally, the invention may be embodied in many different forms and should not be construed as being limited to the embodiments described herein, rather these embodiments are provided to satisfy the legal requirements to which this disclosure is applicable.

[0012] When used herein, terms such as "vertical," "horizontal," "top," "bottom," "up," or "down," which refer to the orientation or position of the irradiation target dismantling device with respect to its orientation, refer to the orientation and relative position of the irradiation target dismantling device as shown in Figures 6A and 6B, but are not limited to these. Therefore, for example, the terms "vertical" and "top" refer to the vertical orientation and the relatively upward position in the perspective views of Figures 6A and 6B, and should also be understood in this context for irradiation target dismantling devices that may be arranged in different orientations.

[0013] Furthermore, the term “or” as used in this application or the attached claims is intended to mean inclusive, not exclusive. That is, unless otherwise specified or evident from the context, the expression “X utilizes A or B” is intended to mean any of the natural inclusive arrangements. That is, the expression “X utilizes A or B” is satisfied by any of the following examples: X utilizes A, X utilizes B, or X utilizes both A and B. In addition, the articles “a” and “an” as used in this application and the attached claims should generally be interpreted as “one or plural” unless otherwise specified or evident from the context. Throughout the specification and claims, the following terms take the meanings explicitly assigned herein, at least unless the context indicates otherwise. The meanings identified below are not necessarily limiting to the terms, but merely provide illustrative examples of the terms. The meanings of "a," "an," and "the" may include multiple references, and the meaning of "in" may include "inside" and "on." As used herein, the phrase "in one embodiment" does not necessarily refer to the same embodiment, although it may.

[0014] Referring next to Figures 1A, 1B, and 2, the irradiation target 100 according to the present invention includes a plurality of thin annular plates 110 held on a rigid spine 120 formed by a pair of retaining clips 121a and 121b, which are slidably housed within an outer canister 102. Preferably, the plurality of thin annular plates 110 and the retaining clips 121a and 121b are all formed from the same material capable of generating isotope molybdenum-99 (Mo-99) after undergoing a neutron capture process in a reactor, such as a fission-type reactor. In preferred embodiments, this material is Mo-98. However, it should be noted that in alternative embodiments, the plate 110 and retaining clips 121a and 121b may be formed from materials such as, but are not limited to, molybdenum-lanthanum (Mo-La), titanium-zirconium-molybdenum (Ti-Zr-Mo), molybdenum-hafnium carbide (MoHf-C), molybdenum-tungsten (Mo-W), nickel-cobalt-chromium-molybdenum (Mo-MP35N), and uranium-molybdenum (U-Mo).

[0015] As shown in Figure 2, the rigid spine 120 is formed by a first retaining clip 121a and a second retaining clip 121b, the two clips being identical in structure. Thus, each clip includes a substantially planar elongated body 122, a flange portion at the first end of the elongated body, and a tab portion 126 at the second end of the elongated body 122. Note that in Figures 1A and 1B, the tab portion 126 of the retaining clip 121 is shown in an unbent position. Prior to the assembly of the spine 120, the tab portion 126 of each retaining clip 121 extends axially outward from the end of the corresponding elongated body 122. Preferably, the elongated body 122 of each clip includes a rib portion 123 extending the length of the elongated body 122, excluding the tab portion 126, thereby providing rigidity to the clip 121 while allowing the tab portion 126 to bend easily. Similarly, the presence of the rib portion 123 on the flange portion 124 of the retaining clip 121 increases its rigidity.

[0016] In the examined embodiment, the elongated body 122 of the retaining clip 121 has a length slightly greater than the overall length of the plurality of thin annular plates 110 of the irradiation target 100. The maximum width of the elongated body 122 allows the ends of the retaining clip 121, including the tab portion 126, to slide through the holes 111 defined by the plurality of thin plates 110 during the assembly process, as will be considered in more detail below.

[0017] Most of the mass of the irradiation target 100 is in the plurality of thin plates 110 that are slidably received on the rigid backbone 120. Preferably, each thin plate 110 is a thin annular disk, although alternative shapes other than circular are possible. The reduced thickness of each annular plate 110 provides an increased surface area for a given amount of target material. The increased surface area of each thin plate 110 facilitates the process of dissolving the plates after they have been irradiated in a nuclear fission reactor as part of the process of producing Ti-Mo-99. Additionally, as a preferred embodiment, each thin plate 110 defines a central hole 112 such that each thin plate 110 is slidably positioned on the rigid backbone 120.

[0018] In this embodiment, a target canister 102 is utilized to insert the irradiation target 100 into the nuclear fission reactor during the irradiation process. As best seen in FIGS. 4 and 5, each target canister 102 includes a substantially cylindrical body portion that defines an inner hole 103. The hole 103 is sealed by an end cap 105 so that the thin plates 110 of the irradiation target remain in a dry environment during the irradiation process in the corresponding reactor. Maintaining the thin plates 110 of the target dry during the irradiation process prevents the formation of an oxide layer thereon, and the formation of an oxide layer can interfere with the effort to dissolve the thin plates in a subsequent chemical process in order to reduce the Mo-99 to a usable form.

[0019] Next, with reference to Figure 3, the assembly process of the irradiation target 100 will be discussed. First, a plurality of thin plates 110, preferably annular plates, are positioned in the semi-cylindrical recess 142 of the alignment jig 140. The alignment jig 140 may be formed by a 3D printing process, and the plurality of plates are tightly packed into the semi-cylindrical recess 142 so that their central holes 112 are aligned. The front end of the first retaining clip 121a, having a tab portion 126a, is inserted into the central holes 111 of the plurality of plates 110 that are tightly packed into the alignment jig 140. The first retaining clip 121a may be aligned with the central holes 111 by providing a semi-circular recess 144 in the end wall of the alignment jig 140. The first retaining clip 121a is inserted until the bottom surface of its flange portion 124a abuts against the plurality of annular plates 110. After the first retaining clip 121a is fully inserted into the multiple annular plates 110, the tab portion 126a extends outward beyond the end of the stack of annular plates.

[0020] Next, the tab portion 126b of the second retaining clip 121b is inserted into the end of the central hole 111 from which the flange portion 124a of the first retaining clip 121a extends. As shown in Figure 2, the elongated bodies 122a and 122b of the first retaining clip 121a and the second retaining clip 121b are positioned within the central holes of the multiple annular plates 110, so that they fit together snugly. Similar to the first retaining clip 121a, the second retaining clip 121b is slidably inserted into the hole of the annular plate 110 until the bottom surface of its flange portion 124b abuts against the outer surface of the outermost annular plate 110. In this position, the tab portion 126b of the second retaining clip 121b extends axially outward beyond the flange portion 124a of the first retaining clip 121a. As shown in Figure 2, the tab portions 126a and 126b of the first retaining clip 121a and the second retaining clip 121b are bent over the flange portions 124a and 124b of the other retaining clip, thereby holding the multiple annular plates 110 between the flange portion 124a of the first retaining clip 121a and the flange portion 124b of the second retaining clip 121b.

[0021] Following irradiation of the target canister 102 and removal of the multiple annular plates 110 therefrom, the rigid spine 120 is removed to allow further processing of the annular plates 110. Next, referring to Figures 6A to 6D, the multiple annular plates 110 may be slidably removed from the rigid spine 120 for processing by preferably using an irradiation target dismantling tool 150 to remove the flange portion 124 from one end of the rigid spine 120 of the corresponding irradiation target 100. As shown, preferably, the dismantling tool 150 includes a top plate 153 supported above a bottom plate 152 by a plurality of posts 151. As best seen in Figures 6C and 6D, a twist assembly 170 is fixed to the bottom surface of the top plate 153 of the dismantling tool 150. A sliding portion 172 is slidably supported within the housing 176 of the twist assembly and is movable between a plurality of positions, as will be discussed in more detail below. As best seen in Figure 6A, a removable drawer 156 is positioned directly beneath the twister assembly 170 and held in place on the bottom plate 152 by multiple rails 154. The drawer 156 is configured to accommodate the open annular plate 110 and a portion of the rigid spine 120 that fall from the twister assembly 170 when the irradiation target 100 is dismantled.

[0022] Continuing to refer to Figures 6A to 6D, the dismantling tool 150 includes a gripper assembly 157 fixed to the top surface of the top plate 153. Preferably, the gripper assembly 157 is pneumatically actuated and includes a gripper mounting block 159 and a pair of gripper arms 161 movably supported by the gripper mounting block 159. Each gripper arm 161 includes a gripper 158 positioned thereon, and the gripper arms 161 are configured to move opposing grippers 158 toward each other and toward each other as desired. A loading tube 166 is vertically supported by the top plate 153 and defines a cylindrical target hole 167 therein, configured to slidably receive the irradiation target 100 after it has been irradiated and removed from the target canister 102. The length of the target hole 167 is selected so that when the irradiation target 100 is placed therein, the flange portion 124 of the rigid spine 120 of the target extends upward beyond the top surface of the loading tube 166, allowing the flange portion 124 to be secured in place by the gripper 158. Similarly, an electric motor 190 is held on the upper surface of the top plate 153 and is mechanically coupled to the electric motor 190, configured to selectively drive a corresponding drive gear 192 located directly below the top plate 153.

[0023] Referring further to Figures 7A to 7D, the twister assembly 170 is shown in more detail. As shown, a portion of the twister assembly housing 176 forms a portion of the loading tube 166 mentioned earlier, so that the bottom end of the loaded irradiation target 100 extends below the top plate 153 and into the twister assembly 170. Note that the housing 176 of the twister assembly 170 is rotatable relative to the top plate 153 and is supported from the top plate 153 by an internal bushing (not shown). The top surface 184 of the sliding portion 172 defines the bottom end of the target hole 167 of the loading tube 166 and may be used to selectively support the corresponding irradiation target 100 thereon, as will be discussed in more detail below. The sliding portion 172 includes a handle 171 at its first end, which allows the user to slide the sliding portion 172 laterally relative to the housing 176, and therefore laterally relative to the loading tube 166. A sturdy locking mechanism 178 is located at the opposite end of the sliding portion 172 to prevent the user from inadvertently removing the sliding portion 172 from the twister assembly 170.

[0024] A twisted gear 177 extends radially outward from the outer surface of a rotatable housing 176, and the twisted gear 177 is rotatably engaged by a drive gear 192 of an electric motor 190, as best seen in Figure 6D. Thus, the electric motor 190 may be used to selectively rotate the twisted gear 177 and, therefore, the housing 176, via the drive gear 192. Referring further to Figure 6, the sliding portion 172 defines a catch hole 180, a drop hole 182, and a jaw hole 172 extending between them. The catch hole 180, the drop hole 182, and the jaw hole 174 are axially aligned along the longitudinal central axis of the sliding portion 172. As shown, the catch hole 180 and drop hole 182 of the slide portion 172 are substantially circular, with the maximum diameter of the catch hole 180 being slightly smaller than the outer diameter of the corresponding post-irradiation target 200, indicated by a dotted line with a circumference of 200, while the outer diameter of the drop hole 182 is slightly larger than the maximum diameter of the corresponding post-irradiation target, also indicated by a dotted line with a circumference of 200. Thus, the catch hole 182 is configured to prevent the post-irradiation target 200 from passing through the slide portion 172, so that the post-irradiation target is supported on the slide portion 172, while the drop hole 182 is configured to allow the post-irradiation target to pass through it. Note that the diameter of the catch hole 180 is greater than the lateral length of the flange portion 124 of the spine so that the flange portion can pass through the catch hole 180 regardless of the orientation of the target 100. Similarly, the jaw hole 174 is formed by a pair of parallel side walls 174a and 174b configured to slidably receive the flange portion 202 of the corresponding target 202 between them, indicated by the dotted line.

[0025] After the irradiation target 100 is removed from the reactor, it is removed from the outer canister 102 by removing one of the end caps 105, as shown in Figure 4. Before inserting the post-irradiated target 100 into the dismantling tool 150, the sliding portion 172 of the twister assembly 170 is positioned so that the catch hole 180 is positioned at the bottom end of the loading tube 166, as is best seen in Figure 8. A ball and spring retaining assembly 196, as is best seen in Figures 7A and 7D, engages with a corresponding slot 198 formed on the edge of the sliding portion 172 to hold the sliding portion 172 in the desired position. The post-irradiated target 100 is slidably inserted into the target hole 167 of the dismantling tool 150 until a plurality of thin plates 110 rest on a portion of the top surface 184 of the sliding portion 172 surrounding the catch hole 180. Preferably, all inner surfaces of the dismantling instrument 150 that come into contact with the target 100 after irradiation are made of titanium to avoid material interfaces colliding with the target and to avoid the possibility of introducing foreign matter into the target 100 that could affect the final medical product. Next, the housing 176 of the twister assembly 170 is rotated until the parallel side walls 174a and 174b of the jaw holes 174 are parallel to the gripping surfaces of the grippers 158. The grippers 158 are then pushed inward until they engage with the exposed flange portion 124 of the irradiation target 100, thereby preventing rotation of the upper part of the rigid spine 120. The engagement of the exposed flange portion with the grippers 158 also ensures that the flange portion 124 located at the bottom end of the target 100 after irradiation is axially aligned with the jaw holes 174 as shown in Figure 8.

[0026] The sliding portion 172 is then moved to a second position where the bottom flange portion 124 of the post-irradiation target 100 is slidably received within the jaw hole 174. Here again, a ball and spring retainer 196 holds the sliding portion 172 in the desired position. An electric motor 190 is now energized, which rotates the housing 176 via the rotation of the twister gear 177 by the drive gear 192. The rotation of the housing 176 of the twister assembly 170 relative to the bottom plate 152 of the dismantling tool 150 causes the rotation of the bottom flange portion 124 of the post-irradiation target 100 relative to the top flange portion 124. Typically after a sufficient rotation of 4 to 6 turns of the housing 176, the rigid spine 120 mechanically breaks, and the loosened portion of the broken spine falls through the jaw hole 174 into the lower drawer 156. With the bottom flange 124 removed, the sliding portion 172 is moved to a third position where the drop hole 182 is positioned beneath the irradiated target 100. As shown in Figure 8, the diameter of the drop hole 182 is larger than the diameter of the plate 110 of the irradiated target, allowing the thin plate 110 to fall through the drop hole 182 into the lower drawer 156. The top flange 124 of the irradiated target 100 can also fall into the drawer 156 by releasing the gripper 158. At this point, the dismantled irradiated target is ready for further processing.

[0027] These and other modifications and variations of the invention may be practiced by those skilled in the art without departing from the spirit and scope of the invention as described in more detail in the appended claims. In addition, it should be understood that the various embodiments may be interchangeable in whole or in part. Furthermore, those skilled in the art will understand that the above description is merely an example and is not intended to limit the invention to such inventions as described further in the appended claims. Accordingly, the spirit and scope of the appended claims should not be limited to the illustrative descriptions of the form contained herein.

Claims

1. In irradiation target systems for the production of radioactive isotopes, It is an irradiation target, Multiple annular plates defining the central opening, An irradiation target comprising a first elongated central member on which the plurality of annular plates are maintained by passing through the central opening of the plurality of annular plates, the first elongated central member comprising an elongated body, a flange portion extending laterally thereto at a first end, and a tab portion extending axially therefrom at a second end, wherein the flange portion of the first elongated central member extends axially outward beyond the first end of the plurality of annular plates, and the tab portion extends axially outward beyond the second end of the plurality of annular plates, A target dismantling device, Bottom plate and The gripper assembly attached to the bottom plate, An irradiation target system for the generation of radioactive isotopes, comprising a target dismantling device comprising a twister assembly rotatably fixed to the bottom plate, the twister assembly comprising a housing defining a target hole configured to receive the irradiation target inside, and a sliding portion slidably and non-rotatably mounted on the housing at the bottom end of the target hole, the sliding portion being substantially circular and defining a first hole having a maximum diameter smaller than the outer diameter of the plurality of annular plates of the irradiation target.

2. The irradiation target system according to claim 1, wherein the plurality of annular plates and the first elongated central member are all formed of a material that generates molybdenum-99 (Mo-99) through neutron capture.

3. The irradiation target system according to claim 1, wherein the first elongated central member further comprises a rib portion extending outward from the main body portion and along the longitudinal central axis of the main body portion.

4. The irradiation target system according to claim 1, further comprising a second elongated central member including a flange portion extending laterally from a first end and a tab portion extending axially from a second end, wherein the tab portion of the first elongated central member is adjacent to the flange portion of the second elongated central member.

5. The irradiation target system according to claim 4, wherein the tab portion of the first elongated central member is bent over the flange portion of the second elongated central member.

6. The irradiation target system according to claim 4, wherein each of the plurality of annular plates and the first elongated central member and the second elongated central member are made of molybdenum-98 (Mo-98).

7. The irradiation target system according to claim 4, wherein when the irradiation target is placed in the target hole, the gripper assembly is configured to engage with the flange portion of the first elongated central member so that the irradiation target is non-rotatable relative to the twister assembly.

8. The irradiation target system according to claim 7, wherein the sliding portion of the twister assembly further defines a second hole defined by two parallel side walls, and the second hole is configured to slidably receive the flange portion of the second elongated member.

9. The irradiation target system according to claim 8, wherein the sliding portion is slidable between a first position in which the first hole is located at the bottom of the irradiation target and a second position in which the second hole is located at the bottom of the irradiation target.

10. The irradiation target system according to claim 9, wherein the sliding portion is substantially circular and further defines a third hole having a minimum diameter greater than the outer diameter of at least one of the plurality of annular plates, and the third hole is slidable to a third position where it is located at the bottom of the target hole.

11. In irradiation target systems for the production of radioactive isotopes, It is an irradiation target, Multiple annular plates defining the central opening, An irradiation target comprising a first elongated central member on which the plurality of annular plates are supported by passing through the central opening of the plurality of annular plates, the first elongated central member comprising an elongated body, a flange portion extending laterally thereto at a first end, and a tab portion disposed at a second end thereof, wherein the flange portion abuts against the first end faces of the plurality of annular plates and extends axially outward therefrom, and the tab portion extends outward beyond the second end faces of the plurality of annular plates, A target dismantling device, Bottom plate and The gripper assembly attached to the bottom plate, An irradiation target system for the generation of radioactive isotopes, comprising a target dismantling device comprising a twister assembly fixed to the bottom plate, the twister assembly comprising a rotatable housing that defines a target hole configured to receive the irradiation target inside, and a sliding portion that is slidably and non-rotatably installed on the housing at the bottom end of the target hole.

12. The irradiation target system according to claim 11, wherein the plurality of annular plates and the first elongated central member are all formed of a material that generates molybdenum-99 (Mo-99) through neutron capture.

13. The irradiation target system according to claim 11, further comprising a second elongated central member including a flange portion extending laterally from a first end and a tab portion extending axially from a second end, wherein the tab portion of the first elongated central member is adjacent to the flange portion of the second elongated central member.

14. The irradiation target system according to claim 13, wherein the tab portion of the first elongated central member is bent over the flange portion of the second elongated central member.

15. The irradiation target system according to claim 13, wherein each of the plurality of annular plates and the first elongated central member and the second elongated central member are made of molybdenum-98 (Mo-98).

16. The irradiation target system according to claim 13, wherein when the irradiation target is placed in the target hole, the gripper assembly is configured to engage with the flange portion of the first elongated central member so that the irradiation target is non-rotatable relative to the twister assembly.

17. The irradiation target system according to claim 13, wherein the sliding portion is substantially circular and defines a first hole having a maximum diameter smaller than the outer diameter of the plurality of annular plates of the irradiation target, the sliding portion further defines a second hole defined by two parallel side walls, the second hole is configured to slidably receive the flange portion of the second elongated central member.

18. The irradiation target system according to claim 17, wherein the first elongated central member further comprises a rib portion extending outward from the main body portion and along the longitudinal central axis of the main body portion.

19. The irradiation target system according to claim 17, wherein the sliding portion is slidable between a first position in which the first hole is located at the bottom of the irradiation target and a second position in which the second hole is located at the bottom of the irradiation target hole.

20. The irradiation target system according to claim 19, wherein the sliding portion is substantially circular and further defines a third hole having a minimum diameter greater than the outer diameter of at least one of the plurality of annular plates of the irradiation target, and the third hole is slidable to a third position in which it is located at the bottom of the target hole.

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