HIGH POWER POINT SOURCE CONVERTER TARGET ASSEMBLY FOR PRODUCING BRICHIBLE RADIATION FOR PHOTONuclear REACTIONS USING ELECTRON LINEAR ACCELERATORS OR ELECTRON ACCELERATORS HAVING A

Abstract

The invention relates to a device for producing radionuclides, in particular diagnostic and therapeutic radionuclides, on the basis of the principle of photo-nuclear radiation, comprising an electron accelerator (1), which generates an electron beam (2) with temporal structural features for the linear electron accelerator (1), a converter target assembly (21), which is arranged between the electron accelerator (1) and the converter target assembly (21), the invention relates to a converter target assembly (21) for generating radionuclides, comprising a converter target (20) for converting the electron beam (2) into bremsstrahlung photons (15), a plurality of production targets (17) irradiated by the bremsstrahlung photons (15) in order to generate the radionuclides, the converter target assembly (21) comprising a sealed housing (9) enclosing a cavity (19) accommodating the converter target (20), comprising an entrance window with a window disk (23) for the electron beam (2) and an exit window for the bremsstrahlung photons (15), comprising cooling medium ports (10) which are part of a cooling circuit (11) for establishing a cooling flow through the cavity (19) in order to cool the converter target (20) and the window disk (23), the converter target (20) comprises a plurality of rotatable converter discs (12), the electron beams (2) are arranged off-center with respect to the respective converter discs (12), and wherein the respective converter discs (12) are designed to rotate during operation of the device such that the converter discs (12) are arranged on the converter target (20) over time. The focus of the electron beam (2) is dispersed onto an annular region (14) of the converter disk (12) in multiple rotations.

Description

[0001] This invention relates to an apparatus for producing radionuclides based on the principle of photonuclear radiation, particularly for producing diagnostic and therapeutic radionuclides. The invention also relates to a converter target component for use in this apparatus. Furthermore, the invention relates to a method for operating the apparatus and a method for producing radionuclides.

[0002] Photonuclear reactions have been identified as highly suitable for the production of radionuclides for diagnostic and therapeutic purposes in nuclear medicine. High-energy photons (8 MeV) can induce nuclear reactions of the (γ,n), (γ,2n), (γ,p), and (γ,pn) types. Photonuclear reactions exhibit significant cross-sections in the giant dipole resonance (GDR) region, and in some cases, these cross-sections are not significantly larger than those of charged particles (e.g., protons, deuterons, etc.). 3 He and 4 He-induced reaction cross-sections are much smaller. Due to the penetrating power of high-energy photons compared to charged particles, the total yield of radionuclides from high-energy photons can be very high, as the missing cross-section compared to charged particle reactions can be overcompensated by thicker targets. Typically, the photonuclear reaction cross-section is roughly proportional to the number of atoms.

[0003] Promising candidates for high-demand radionuclides that can be produced using photonucleation are 100 The product of the Mo(γ,n) reaction 99 Mo (for 99 Mo / 99m Tc radionuclide generator) or 66 The positron emitter produced in the Zn(γ,np) reaction for use in positron emission tomography (PET) imaging. 64 Cu. Furthermore, it can be used in photonuclear reactions. Significant activity produced in 111 In.

[0004] Promising candidates for radionuclides used in radionuclide therapy, which are currently difficult to obtain but in high demand and can be produced in large quantities, are alpha particle emitters. 225 Ac (from photonuclear reaction) 226 Formed in Ra(γ,n) 225 Ra decay), β-minus emitter 67 Cu (in the reaction) 68 (Generated in Zn(γ, p)) and 47 Sc (in the reaction) 48 (Generated in Ti (γ, p)). Furthermore, in photonuclear reactions... 150 The β-negative emitter 149Pm, produced in Nd(γ,n) with a half-life of 53.1 h, exhibits promising chemical and decay properties as a therapeutic radionuclide. Additionally, commonly used β-negative emitters...90 Y or 177 Lu can be in 91 Zr(γ, p) or 178 Hf(γ,p) is produced in the reaction.

[0005] The object of this invention is to provide an apparatus that allows for the industrial-scale production of rare but in-demand radionuclides, particularly for the diagnosis and treatment of radionuclides, for example, 225 Ac or 99 Mo. The device has low installation and operating costs, high reliability, high safety margin, and minimal raw material consumption during operation. Furthermore, a target component for the converter used in this device should be provided. Appropriate operating methods and methods for producing radionuclides should be given.

[0006] According to the present invention, the first aforementioned objective is satisfied by the device according to claim 1.

[0007] This invention provides an apparatus for producing radionuclides based on the principle of photonuclear radiation, particularly for producing diagnostic and therapeutic radionuclides, comprising:

[0008] • An electron accelerator generates an electron beam, and if necessary, a beam transmission line.

[0009] • A converter target assembly having a converter target for converting the electron beam into bremsstrahlung photons;

[0010] • Multiple production targets, through bremsstrahlung photon radiation, thereby producing the aforementioned radionuclides,

[0011] The converter target component includes a sealed housing.

[0012] • A cavity surrounding and housing the converter target.

[0013] • Includes an entrance window for the electron beam and an exit window for the bremsstrahlung photons.

[0014] • Includes cooling medium ports, which are part of a cooling circuit used to establish a cooling flow through the cavity, thereby cooling the converter target and the entrance window.

[0015] in,

[0016] The converter target includes multiple rotatable converter disks.

[0017] • The electron beam is positioned off-center relative to the corresponding converter disk.

[0018] And therein, the corresponding converter disk is designed to rotate during the operation of the device, thereby dispersing or distributing the focus of the electron beam over time on the annular area of ​​the converter disk.

[0019] In one aspect of the invention, the electron accelerator is selected such that it produces an electron beam with the temporal structure characteristics of a linear electron accelerator. Such a linear electron accelerator typically produces a pulsed electron beam, wherein the pulsed electron beam has a pulse time (“beam-on time”) in the microsecond range and a period time (“beam-off time”) in the millisecond range or longer. In other words, the “temporal structure characteristics of a linear electron accelerator” within the scope of this invention should be understood as a pulsed temporal structure, wherein the total period time is significantly longer than the actual pulse time, providing a significant “pulse”-like beam structure.

[0020] This invention is based on the consideration that if an electron beam with high energy and high power is directed onto a suitable point source, high-power converter target to generate bremsstrahlung radiation, which is then used to irradiate a suitable production target, high-yield radionuclides of the aforementioned type can be produced according to the principle of photonuclear radiation. A key element enabling the converter target to withstand the thermal load associated with the high-intensity electron beam while maintaining the point source characteristics of the emitted photon radiation is the distribution of beam energy over a relatively large area of ​​the converter target by rotating multiple stacked converter disks during radiation, while removing excess heat through a flow of cooling medium, particularly cooling gas or liquid, in direct contact with the surfaces of the converter disks. The impact or focus of the electron beam is essentially fixed in space, although some small oscillations (compared to the target size) are permitted or even forced, while the corresponding converter disks move relative to this fixed point.

[0021] The converter target component according to claim 21 and the corresponding method as defined in claim 23, etc., satisfy other objectives.

[0022] Further features, embodiments, objectives, and related advantages are associated with the common pending independent and dependent claims and the corresponding description in conjunction with the accompanying drawings.

[0023] In light of the above and following descriptions, the following non-limiting examples may be considered, many of which are considered inventive in themselves.

[0024] 1. Equipment for producing radionuclides based on the principle of photonuclear radiation, especially for producing diagnostic and therapeutic radionuclides, including:

[0025] • An electron accelerator (1) generates an electron beam (2) and, if necessary, a beam transmission line (3).

[0026] • Converter target assembly (21) having a converter target (20) for converting the electron beam (2) into bremsstrahlung photons (15).

[0027] • Production target (17), irradiated by the bremsstrahlung photons (15), thereby producing the radionuclide,

[0028] The converter target component (21) includes a sealed housing (9).

[0029] • A cavity (19) surrounds and accommodates the converter target (20).

[0030] • Includes an entrance window holder (8) having a window disk (23) for mounting the electron beam (2) and an exit window (22) for the bremsstrahlung photons (15).

[0031] • Includes cooling medium ports (10), which are part of a cooling circuit (11) for establishing a cooling flow through the cavity (19) to cool the converter target (20) and the entrance window holder (8) with its mounted window disk (23).

[0032] in,

[0033] • The converter target (20) includes a plurality of rotatable converter disks (12).

[0034] • The electron beam (2) is positioned off-center relative to the corresponding converter disk (12).

[0035] And therein, the corresponding converter disk (12) is designed to rotate during operation of the device, thereby dispersing the focus of the electron beam (2) over time so that a series of radiation points form a ring-shaped region (14) of uniform radiation of the converter disk (12) during multiple radiation cycles and multiple rotations of the converter disk.

[0036] 2. The device according to Example 1, wherein the electron accelerator (1) is designed to generate electron energies exceeding 20 MeV.

[0037] 3. The device according to Example 1 or 2, wherein the electron accelerator (1) is designed to generate a beam power of more than 20 kW.

[0038] 4. The device according to any one of the foregoing examples, wherein the electron accelerator (1) generates a pulsed electron beam (2).

[0039] 5. The device according to Example 4, wherein the pulsed electron beam (2) has a pulse time of microseconds and a period time in the range of milliseconds or longer.

[0040] 6. The device according to Example 4 or 5, wherein the electron accelerator (1) is a linear accelerator or an electron cyclotron (microtron) or other type of accelerator having a similar beam structure as described in Examples 3 and 5.

[0041] 7. The device according to Examples 4 to 5, wherein the electron accelerator (1) is a superconducting linear accelerator.

[0042] 8. The device according to any one of Examples 4 to 7 includes a control unit (24) that keeps the rotational speed of the corresponding converter disk (12) synchronized with the time structure of the electron accelerator.

[0043] The control unit preferably includes suitable sensors, actuators, and controllers for the task.

[0044] 9. The device according to Example 8, wherein the area on the corresponding converter disk exposed to a single beam pulse describes a near-circular region, wherein the ratio of the rotation time of the converter disk to the periodic time of the electron beam is preferably such that the beam point rotates or moves at least one point diameter. According to this aspect of the invention, the system is designed and engineered such that the heat load deposited on the converter disk is limited to an acceptable amount for the converter material. To facilitate this, in a preferred embodiment, a segment of the converter disk exposed to the corresponding beam pulse within the time interval of the corresponding period is moved such that it is not further exposed in subsequent pulses, or in other words, the segment is moved or shifted far enough that subsequent electron pulses radiate a different segment. A concept according to one aspect of the invention allows a cooled portion of the converter disk to be exposed to each pulse, and thus, in multiple radiation cycles, the series of radiation points forms a ring-shaped region of more uniform or less uniform radiation from the converter disk. Depending on the deposition energy per unit surface area on the converter disk, even slight overlap of deposition points in subsequent beam pulses can be considered permissible.

[0045] In another aspect of the invention, the converter disk can rotate about two or more axes of rotation, each more or less parallel to the beam direction. The rotational speeds around these different axes may vary, resulting in a wider annular region of the radiation area on the converter disk. In particular, the design in the preferred embodiment can be extended by additional rotation or linear movement of the main axis of rotation of the converter disk, rather than providing only a single axis. In this way, the photon field can remain stationary while radiating an additional region of the converter disk (compared to a single-axis design).

[0046] 10. The device according to Example 8 or 9, characterized in that the rotational speed of the corresponding converter disk (12) is set in the range of several hundred to several thousand revolutions per minute.

[0047] 11. The device according to any one of the preceding claims, characterized in that the entrance window holder (8) includes a rotatable window disk (23), the electron beam (2) is disposed off-center relative to the window disk (23), and wherein the window disk (23) is designed to rotate during operation of the device, thereby dispersing the focus of the electron beam (2) onto a plurality of radiation points of the window disk (23) over time.

[0048] This is another key embodiment of the invention, similar to the converter disk, allowing for effective heat distribution over a larger area of ​​the incident window. In one aspect of the invention, slight overlap of deposition points of subsequent pulses is considered permissible based on the deposition energy per unit surface area on the window disk (23).

[0049] The window disk 23 is preferably mounted in / on / in the hollow shaft 30. The rotation of the hollow shaft (30) is preferably facilitated by a rotation drive (26).

[0050] 12. The device according to Example 11, wherein the entrance window retainer (8) is coupled to the rotation drive (26).

[0051] The rotary drive can be a stepper motor mounted outside the housing, wherein the hollow vacuum feedthrough is driven by gears.

[0052] 13. The device according to Example 11 or 12, characterized in that the entrance window retainer (8) comprises a window disk (23), which, in a preferred embodiment, is a beryllium foil, preferably with a thickness between 50 and 500 micrometers, or any other high-strength material with a low atomic number. In an alternative embodiment, the window disk (23) may be made of Havar. TM It is manufactured, preferably with a thickness between 50 and 250 micrometers.

[0053] 14. The device according to any one of Examples 11 to 13, characterized in that the entrance window retainer (8) is mounted on / in / at a hollow shaft, which is part of a rotating vacuum feedthrough. In a preferred embodiment, the entrance window retainer (8) and the mounted window disk (23) or rotating vacuum feedthrough are sealed relative to the beam transmission line (3) by a suitable feedthrough technique to separate the vacuum of the accelerator section from the gaseous or liquid cooling medium, preferably by a magnetohydrodynamic seal (31).

[0054] 15. The device according to Example 14, wherein the entrance window retainer (8) and the mounted window disk (23) are sealed relative to the beam transmission line (3) by a magnetohydrodynamic seal. Alternatively, the seal may be achieved by any other feedthrough technique to separate the vacuum of the accelerator section from the gaseous or liquid cooling medium.

[0055] Due to the required thinness of the incident vacuum window and the mechanical and thermal stresses it is exposed to, a diameter of 40 mm is preferably considered. The commercially available hollow shaft magnetohydrodynamic sealed vacuum feedthrough allows a maximum rotational speed of 3,100 rpm. Gear drives on the hollow shaft are commercially available.

[0056] 16. The device according to any one of Examples 11 to 15, wherein the control unit (25) keeps the rotational speed of the entrance window retainer (8) and the mounted window disk (23) synchronized with the time structure of the electron accelerator.

[0057] 17. The device according to Example 16, wherein the area on the corresponding converter disk (12) exposed to a single beam pulse describes a near-circular region, wherein the ratio of the rotation time of the converter disk (12) to the period time is preferably selected such that the beam point on the converter disk rotates by at least one spot diameter to allow exposure to the cooling portion of the converter disk (12), and a series of radiation points in multiple radiation cycles and rotations of the converter disk form an annular region of uniform radiation from the converter disk (12).

[0058] 18. The device according to Example 16 or 17, wherein the rotational speed of the window disk (23) is set in the range of several hundred to several thousand revolutions per minute.

[0059] 19. The device according to any one of the foregoing examples, wherein the beam transmission line (3) includes beam optics (5a-c) that allow the electron beam (2) to be focused or defocused to different FWHMs.

[0060] 20. The device according to Example 19, characterized in that an FWHM of at least 2 mm is provided.

[0061] 21. The device according to any one of the foregoing examples, wherein the beam transmission line (3) includes a beam oscillator (6, 7) that allows the focus of the electron beam (2) to move periodically over the incident window foil (23) and the corresponding converter disk (12).

[0062] 22. The device according to Example 21, wherein the swing amplitude is within millimeters on the converter disk (12).

[0063] 23. The device according to Example 21 or 22, characterized in that the oscillation frequency is 10 1 -10 6 Within the Hz range.

[0064] 24. The device according to any of the foregoing examples, wherein the bundle transmission line (3) includes a slammer valve (4) triggered by a downstream pressure sensor to protect the electron accelerator (1) from vacuum leakage in the converter target assembly (21).

[0065] 25. The device according to any one of the foregoing examples, wherein the converter target (20) comprises a plurality of converter disks (12).

[0066] 26. The device according to Example 25, wherein the converter disk (12) is stacked on a common shaft (13).

[0067] Preferably, the converter disks are stacked or placed one after another (concentrically) on the shaft with gaps between them to allow the flow of cooling medium to cool any disks on either side. On the other hand, the gaps are small enough to keep the converter compact and not disrupt the fundamental point-source characteristics of the emitted photon radiation.

[0068] 27. The device according to any of the foregoing examples, wherein the corresponding converter disk (12) is coupled to the rotary drive (27).

[0069] The rotary drive is preferably mounted in a concealed position outside the housing. The converter disk is preferably driven by a stepper motor via gear drive and rotary feedthrough.

[0070] 28. The device according to any one of the foregoing examples, wherein the converter disk (12) is configured to form a Tesla pump.

[0071] 29. The device according to any one of the foregoing examples, wherein the converter disk (12) is made primarily of tantalum or tungsten.

[0072] 30. The device according to any one of the foregoing examples, wherein the corresponding converter disk (12) has a plurality of radially aligned slots or recesses on its outer circumference.

[0073] 31. The device according to any one of the foregoing examples, wherein the exit window comprises a flattening filter (22) that absorbs most of the photons with photon energy ≤ 8 MeV and preferably absorbs and / or slows down the remaining electrons.

[0074] In one aspect of the invention, in a preferred embodiment, water is used as the cooling medium. In this embodiment, the water itself will act as a homogenizer.

[0075] 32. The device according to Example 33, wherein the leveler (22) comprises a water-cooled aluminum column.

[0076] 33. The device according to any of the foregoing examples, wherein the exit window of the equalizer (22) includes a neutron absorber (16).

[0077] In one aspect of the invention, in a preferred embodiment, water is used as the cooling medium. In this embodiment, boric acid may be added to the cooling water to enhance neutron absorption.

[0078] 34. The device according to any one of the foregoing examples, characterized in that the cooling medium is a liquid, preferably water. In one aspect of the invention, a gas can be used as the cooling medium, preferably gaseous helium.

[0079] 35. The device according to any of the foregoing examples, wherein a large, preferably water-cooled beam stop (18) is arranged behind the production target (17).

[0080] 36. The device according to any one of the foregoing examples, wherein the origin region of the emitted bremsstrahlung photons is fixed in space.

[0081] 37. The apparatus according to any one of the foregoing examples, wherein the production target (17) is primarily made of one of the following isotopes: 226 Ra、 178 Hf, 150 Nd, 112 Sn、 100 Mo、 91 Zr、 66 Zn, 68 Zn, 48 Ti、 48 Ca.

[0082] 38. A converter target component (21) for use in the device according to any one of the preceding claims, characterized in that it comprises a sealed housing (9), said housing (9)

[0083] • A cavity (19) surrounding and accommodating the converter target (20);

[0084] • Includes an entrance window holder (8) with an entrance window disk (23) for mounting the electron beam (2) and an exit window (22) for bremsstrahlung photons.

[0085] • Includes cooling medium ports (10) designed to connect to a cooling circuit (11) for establishing a cooling flow through the cavity (19) to cool the converter target (20) and the entrance window holder (8) with their mounted entrance window disk (23).

[0086] The converter target (20) comprises a plurality of rotatable converter disks (12), wherein each converter disk (12) is designed to rotate during operation of the device, thereby dispersing the focus of the incident electron beam (2) over time through multiple radiation cycles and rotation of the converter disks. A series of radiation points form a ring-shaped region of uniform radiation from the converter disks (12).

[0087] 39. The converter target assembly (21) according to Example 38, wherein the incident window holder (8) includes a rotatable window disk (23), wherein the window disk (23) is designed to rotate during operation of the device, thereby dispersing the focus of the incident electron beam (2) over time into multiple radiation cycles. A series of radiation points form an annular region of uniform radiation from the window disk (23).

[0088] 40. The method of operating the device according to any one of the foregoing examples, characterized in that at least the following radionuclides are produced: 225 Ra、 224 Ra、 225 Ac、 213 Bi、 212 Pb, 177 Lu、 149 Nd, 149 Pm, 111 Sn、 111 In、 90 Y、 99 Mo、 99 mTc, 67 Cu、 64 Cu、 47 Ca, 47 Sc.

[0089] 41. A method for producing a radionuclide, wherein an electron beam (2) is directed onto a converter target (20) having a plurality of rotating converter disks (12), particularly around one or more axes, such that the focus of the electron beam (2) is dispersed over time after a plurality of radiation cycles. The beam points on the converter disks are rotated by at least one point diameter to allow the cooling portions of the converter disks (12) to be exposed, and after a plurality of radiation cycles and rotation of the converter disks, the series of radiation points form an annular region of uniform radiation of the converter disks (12). Slight overlap of the deposition points is permissible depending on the deposition energy per unit surface area on the converter disks (12). The resulting bremsstrahlung photon beam is used to irradiate a production target (17), wherein the converter target (20) is cooled by a cooling medium, particularly gaseous helium, or preferably liquid water.

[0090] 42. The method according to Example 41, wherein the converter target (20) is arranged within a housing (9), and wherein the electron beam (2) is guided through a rotating entrance window holder (8) of the housing (9) having an mounted entrance window disk (23), such that after multiple radiation cycles, the series of radiation points form an annular region of uniform radiation from the entrance window disk (23).

[0091] The present invention will now be described in detail with reference to the accompanying drawings.

[0092] Figure 1 The components of the photonuclear radiation setup are shown schematically.

[0093] Figure 2 A schematic diagram of a rotating hollow shaft vacuum feedthrough with a magnetohydrodynamic seal is shown. A vacuum window disk is mounted on the upstream side of the shaft. The feed axis is offset from the center of the shaft.

[0094] Figure 3 A comparison of the temporal structure of electron beams produced by a linear accelerator and a rhodotron with similar beam power is shown.

[0095] Figure 4 An exemplary illustration is shown of a series of beam points deposited on a rotating converter disk (e.g., 0.5 mm thick tungsten), where the temporal structure of the electron beam has a beam-on period in the microsecond range and a beam-off period in the millisecond range. The converter disk rotates on a common axis with an angular velocity that displaces the applied beam points by at least one point diameter. This allows for maximum available cooling time before previously irradiated beam points are irradiated again. Over time, the annular portion of the converter disk is irradiated.

[0096] Figure 5A proposed scheme for radiation from a rotating, e.g., beryllium (Be), vacuum window foil, and rotating converter disk, observed in the beam axis direction, is shown. The window disk and converter disk have minimal area overlap and rotate in opposite directions. The tangential velocities of the two disks are similar to avoid excessive shear forces on the cooling medium (e.g., water).

[0097] Figure 6 A design diagram of a Tesla pump-type rotating disk converter is shown.

[0098] Figure 7 The method for additional linear movement of the spindle is illustrated. In the figure, gray dots represent exemplary beam pulses. The blue line describes the center position of the beam pulse on the disk. In subfigure a), a single-axis design is shown. Here, the center point line is of radius R. C A circle. Due to the mismatch between the rotation frequency and the beam repetition rate, the radius is R. C + R Beam and R C –R Beam The band between the virtual circles (the dashed gray lines in the figure) is radiated after several rotations. An additional vertical movement of the principal axis is introduced in subfigure b). This will cause the centerline point to fluctuate vertically, expanding the radiating area. The path of the centerline describes the area around the average radius R. C The amplitude is A lin The diagram depicts an oscillating motion. It shows a path of approximately three rotations. The frequencies of rotation and linear motion must be carefully adjusted. Otherwise, a stable trajectory will be achieved, and radiation will only occur within a portion of the entire area between the virtual boundaries (dotted gray lines).

[0099] According to the present invention, the key to the industrial realization of the photonuclear reaction for the production of medical radionuclides is the following components:

[0100] 1.) A high-power electron accelerator with available electron energies exceeding approximately 20 MeV and beam power exceeding approximately 20 kW.

[0101] 2.) A high-power converter target that converts an electron beam into brazing radiation photons, which absorb power emitted by a high-intensity electron beam. The higher the photon flux in the GDR region, the higher the achievable specific activity (i.e., for use in...). 99 Mo production), or for production targets, a smaller amount of target material is required, primarily valuable isotope-enriched materials (i.e., materials used for...). 67 Cu production 68 Zn) or dangerous highly radioactive materials (i.e. 226 Ra), preferably used for 225 Ac production.

[0102] 3.) Designed to withstand high-energy, high-intensity photon flux in production targets, while safely encapsulating hazardous and / or radioactive target materials (such as... 226 Ra).

[0103] 4.) An automated chemical procedure to extract the desired radionuclides in the quality and quantity required for medical applications.

[0104] Ad 1): In the past, several electron accelerator designs were primarily intended to generate bremsstrahlung radiation up to 10 MeV for sterilizing medical devices or curing polymers. Currently, commercially available accelerators have beam energies of 30-40 MeV and beam powers of over 100 kW.

[0105] Ad 2): No high-power, point-source converter target has been developed capable of converting electron beams exceeding 20 MeV and beam power exceeding 100 kW into Brenzin radiation. This fact effectively prevents the large-scale production of medical radionuclides using photonuclear reactions. The description of such a converter target is the main subject of this application.

[0106] Ad 3): Because the target material can be encapsulated in thicker, stronger, and higher-temperature materials, existing methods can be adapted to the task.

[0107] Ad 4): For many of the aforementioned radionuclides, chemical separation procedures have been developed to separate the desired product from the target material, or these procedures can be adapted to existing procedures.

[0108] Based on the above assessment, designing and constructing a high-power converter to generate bremsstrahlung for photonuclear reactions is essential. Basic and preferred components, their functions, and technical implementations are detailed in the appendix. Figure 1 As shown, the description is as follows.

[0109] Figure 1The preferred components of a photonuclear radiation device comprising a high-power electron beam 2 provided by a conventional (discontinuous wave) linear electron accelerator or an electron accelerator with a similar beam time structure (i.e., a microtron) 1, a vacuum beamline 3, a fast-acting vacuum valve 4 (breakdown valve) arranged within the beamline 3, multiple beam optics (5a-c) for focusing or defocusing the beam 2 to different full width at half maximum (FWHM), a rotating vacuum window holder 8 including a rotatable vacuum window disk 23, a rotation drive 26 for the vacuum window with an associated control unit 25, a housing 9 for rotating the converter target 20, incident and exit ports 10 provided for providing a cooling medium flowing through the housing 9, and a converter target 20 having multiple (shown here: one) rotating converter disks 12 surrounded by the housing 9. Further indications include the beam points 14 (trajectories over time) distributed on the rotating converter disk 12, the shaft 13 of the converter disk 12 coupled to the rotation drive 27 associated with the control unit 24, the exit cone 15 of bremsstrahlung photons, the equalizer and neutron absorber 16, the production target 17, and a large number of high-density beam stoppers 18.

[0110] from Figure 1 As will become clear from the following detailed description, the vacuum window holder 8, arranged in subject 9 and having a vacuum window disk 23 mounted thereon, serves as the entrance or entrance window for the electron beam 2, which enters the cavity 19 enclosed by the housing 9. The electron beam 2 strikes the converter target 20 located in the cavity 19 and generates bremsstrahlung photons 15. The homogenizer 22 and neutron absorber 16, arranged in the housing 9, serve as exit or exit windows 22 for the photon cone 15 exiting the cavity on the other side. The photon cone 15 is centered on an extension of the electron beam axis. The cavity 19 is sealed to the external environment in a liquid-tight manner by the housing 9. That is, the entrance window 8 and the homogenizer exit window 22 provide a liquid-tight barrier, but are largely transparent to electron radiation or photon radiation, respectively. The cooling medium within the cavity 19, particularly the flow of cooling water, flows through the inner surface of the cavity 19, providing cooling for the converter target 20 and the vacuum window holder 8, which includes the rotating vacuum window disk 23. The cooling flow enters and exits the cavity 19 through cooling medium injection and exit ports 10 arranged on the housing wall. The housing wall can also be cooled by the flow of coolant, especially cooling water, through suitable channels.

[0111] The cooling flow through cavity 19 is part of cooling circuit 11, which is only schematically shown in... Figure 1 As shown in the diagram. Advantageously, liquid water is used as the cooling medium. The pressure of the coolant within cavity 19 is preferably within the range of atmospheric pressure, so as to maintain the differential pressure between the entrance window 8 and the equalizer exit window 22 within a manageable range.

[0112] The following will explain in more detail that the rotating shaft 13 of the converter disk 12 is arranged off-center (parallel) relative to the axis of the electron beam 2.

[0113] Furthermore, the entrance window holder 8 of the electron beam 2 preferably includes a rotatable window disk 23, the axis of rotation of which is also arranged off-center (parallel movement) relative to the axis of the electron beam 2.

[0114] The unit includes a housing 9 having a cooled incident port and an exit port 10, a vacuum window holder 8 having a mounted vacuum window disk 23 for the entry of the electron beam 2, a homogenizer 22 and a neutron absorber 16 at the exit of the photon cone 15, and an integrated converter target 20, which, if necessary, has an associated rotational drive for the vacuum window holder 8. The vacuum window holder 8 includes the vacuum window disk 23 and / or the converter target 20 – which may be referred to as the converter target unit or converter target assembly 21.

[0115] Instead of a single equalizer 22 and neutron absorber 16, there can be two (or more) separate filters, one for flattening (see below) and one for neutron absorption. While it is convenient to integrate these functions into a single exit window 22 of the housing 9, it is also possible to have an exit window 22 for high-energy photons plus several additional filters of the type described above, which can be integrated into a single component or implemented as separate parts. For example, there could be a simple exit window 22 that seals the housing 9 relative to the external environment, followed by equalizers and neutron absorbers in any order (viewed from the direction of photon transmission), or even just one or even one.

[0116] When using coolant, especially flowing water, the coolant itself acts as a homogenizer, primarily absorbing low-energy bremsstrahlung (< 8 MeV) radiation that does not affect the photonucleation process. Furthermore, adding boric acid to the coolant will improve its neutron absorption characteristics.

[0117] More specifically, industrial radionuclide production equipment employing photonuclear reactions preferably includes:

[0118] • High-power linear electron accelerators or electron accelerators with a similar time structure to beams.

[0119] • A vacuum-evacuated beam transport line that carries the extracted electron beam in a vacuum.

[0120] • Preferably, a fast-acting valve with a downstream pressure sensor (breakdown valve) is used to protect the accelerator from vacuum leakage.

[0121] • Preferably, the beam optics allow the beam to be focused or defocused to different FWHMs, for example in the form of a quadrupole triplet.

[0122] • Preferably, a beam optics element that allows the beam to move rapidly at high frequency in the x-axis and y-axis directions is called a “beam oscillator”.

[0123] • Vacuum window, which separates the vacuum of the accelerator and beamline from the converter target components.

[0124] • Housing containing the converter target component.

[0125] • Configuration and connection of cooling gas and / or coolant.

[0126] • A cooling converter target assembly that (ideally) completely stops an electron beam and converts it into bremsstrahlung photons of various energies. The converter target preferably comprises several disks to reduce individual heat loads and is optimally arranged for effective cooling.

[0127] • By rotating the converter disk, preferably in sync with the time structure of the beam, the incident beam packet is evenly distributed over a large area of ​​the converter disk.

[0128] Preferably, a homogenizer absorbs most of the low-energy photons that only affect the heating of the production target without inducing photonuclear reactions. This task can be accomplished simultaneously using a coolant as the cooling medium.

[0129] • Preferably, the neutron filter is used for low-energy and high-energy photoneutrons, which can promote the generation of unwanted byproducts, thereby increasing the radionuclide purity of the desired product.

[0130] • The cooling assembly holds a stack of at least one, preferably multiple, production targets and is preferably used for remotely adding or retrieving production targets.

[0131] • A beryllium (optional) cooling block for generating photons.

[0132] • A large, cooled beam stopper with an auxiliary (optional) radiating position for gem coloring.

[0133] • A cooling loop with a pump, reservoir, heat exchanger and filter is preferred for cooling the target components of the converter.

[0134] Figure 2A rotating vacuum window assembly is schematically shown. An electron beam 2 strikes an off-center beryllium vacuum window disk 23. The beryllium vacuum window disk is mounted in an annular retainer 8 connected to a rotating hollow shaft vacuum feed 30. Alternatively, the retainer 8 can be an integral part of the hollow shaft 30. On the left, the rotating vacuum window assembly is connected to the beam transmission line 3. On the right, a cavity 19 exists. The hollow shaft 30, with a magnetohydrodynamic seal 31 and a bearing 32, separates the vacuum of the accelerator 1 and the beam transmission line 3 from the coolant in the housing 9. If a coolant is used, any suitable technique can be used to separate the coolant from the beamline vacuum. The hollow shaft is driven by a rotation drive 26 and a corresponding control unit 25 (in... Figure 1 (Illustrated schematically) drive.

[0135] Preferred embodiments of the various components and underlying concepts are described in more detail in the following paragraphs.

[0136] 1) Electron beam accelerator and specifications

[0137] Electron accelerators suitable for inducing photonuclear reactions must meet several requirements, including electron beam energy, beam intensity (beam power), beam temporal structure, and beam spatial width. Currently, several commercially available accelerators can provide electron beams with energies greater than 20 MeV and beam power greater than 20 kW, which are prerequisites for the profitable production of radionuclides in medical applications.

[0138] The linear accelerator has electron energies ranging from 35 to above 100 MeV and maximum beam power ranging from 35 to 120 kW. Peak current intensity can reach 200 to 300 mA, and at variable repetition frequencies, such as 800 Hz, the average beam current produced is up to 4 mA. The length of a pulse can reach 16 μs[1a]. By using beam optics, the electron beam can be shaped into different FWHMs. The beam profile can be selected as non-Gaussian (i.e., flat-top profile).

[0139] A Rotor tube accelerator with an electron energy of 40 MeV and a maximum beam power of 125 kW is commercially available. Rotor tube accelerators operate at frequencies from 10 to 50 Hz, duty cycles from 1 to 12.5%, pulse lengths up to 2.5 ms, and have a maximum peak current of 25 mA and an average beam current of 3.125 mA [1b]. By using beam optics, the electron beam can be shaped into different FWHMs. The beam profile can be selected as non-Gaussian (i.e., flat-top profile).

[0140] Compared to a Rotor tube, a conventional linear accelerator has advantages when operating with a point-source converter target. Due to the different beam structure, the beam pulse is much shorter than that of a Rotor tube. Therefore, the beam power cannot be significantly dispersed over a larger area of ​​the vacuum window and the rapidly moving parts of the converter assembly. However, due to the short beam pulse, the energy deposited in one pulse converts to approximately the same area energy density (per cm² of vacuum window or converter disk assembly). 2 (Energy density of deposited components). Specifically, for a flat-top beam profile with a diameter of 5 mm (transmitted by a 40 MeV, 800 Hz, 15 kW linear accelerator), the energy density deposited in a 0.5 mm thick tungsten converter disk is approximately 10⁻¹⁵ J / cm². 2 Similar to the energy density of a Rodov tube (40MeV, 50Hz, 15kW) beampass pulse transmission, this beampass pulse has a duration of 2.5 ms, a flat-top beam profile with a diameter of 5 mm, and is dispersed over approximately 1 / 3 of the area of ​​a rotating 0.5 mm thick transducer disk with a radius of 15 cm (approximately 10 J / cm²). 2 Therefore, the peak temperature of each beam pulse caused by the passage of a strong electron beam is similar. Figure 3 This situation is illustrated with an example.

[0141] More specifically, Figure 3 A comparison of the temporal structures of electron beams generated by a linear accelerator and a Rhodo tube is shown. In this example, it is assumed that the linear accelerator generates beam pulses with a duration of 15 μs and a peak current of 200 mA at a pulse repetition rate of 800 pps. This results in an average beam current of 2.4 mA and a duty cycle of 1.2%. The Rhodo tube operates at a frequency of 50 Hz and generates beam pulses with a duration of 2.5 ms at a peak current of 25 mA. This results in an average beam current of 3.125 mA and a duty cycle of 12.5%.

[0142] 2) Quick-acting valve (breakdown valve)

[0143] To protect the accelerator and beamline from damage to the vacuum window and the transport of material into the accelerator cavity, a fast-acting valve is installed. This valve is triggered by a pressure sensor located downstream of the beamline, in front of the vacuum window. In the event of vacuum window failure, the fast-acting valve physically closes the cross-sectional area of ​​the beamline within milliseconds before the intruding shock wave reaches the accelerator.

[0144] 3) The rotating vacuum window and converter target and beam structure are synchronized.

[0145] In the proposed method, a fixed beam point is directed towards a rotating disk (vacuum window and converter target). To distribute the heat load on the disk, the rotation time of these components is synchronized with the beam structure. Specifically, the beam structure of a linear electron accelerator is characterized by very short, microsecond-level beam-on pulses followed by millisecond-level beam-off periods. The beam-on period is characterized by very high beam currents in the hundreds of milliamperes, but lasting for a very short time period, while the millisecond-level beam-off period allows the vacuum window and converter disk to rotate in such a manner that the previously cooled lower area of ​​the vacuum window or converter disk is radiated. This means that the window disk and converter disk must rotate at least one beam diameter during the beam-off period to expose a newly cooled portion of the window disk or converter disk to the next beam pulse. In this way, the rotational speed of the window disk and converter disk can be drastically reduced from thousands of revolutions per minute (RPM) required for the Rotor tube time structure of the beam to hundreds of RPM for the conventional linear accelerator time structure of the beam. As an example, in Figure 4 The text describes a radiation pattern.

[0146] More specifically, Figure 4 An exemplary illustration of the pattern produced by applying short beam pulses of microseconds at a frequency of several hundred Hz to a rotating disk is shown. Assuming the beam pulses are applied to a conversion disk with a radius of 15 cm, a repetition frequency of 800 Hz, and a beam diameter of 5 mm, a maximum of 188 locations can be generated if the disk is rotated at 255 revolutions per minute. This results in a maximum cooling time of 235 milliseconds for a single deposition point, significantly longer than the 60 milliseconds cooling time for a third-circumference portion using a Rhodo tube. Depending on the beam diameter, the rotation speed can be adjusted to a faster speed to prevent overheating of adjacent deposition points. Alternatively, the rotation speed can be slightly reduced if the overlap of deposition points is acceptable, i.e., due to the Gaussian beam profile. The typically reduced rotation speed (several hundred rpm compared to thousands of rpm when using Rhodo tube radiation) allows the use of a liquid cooling medium, such as water.

[0147] 4) Vacuum window

[0148] The electron beam from the accelerator must pass through a vacuum window that separates the accelerator vacuum from the converter's cooling circuit. This window must withstand the electron beam intensity without compromising its mechanical stability. Therefore, the window must be composed of a material with a high melting point, good mechanical strength, and a low atomic number to allow the electron beam to pass through with minimal energy decay. Furthermore, the vacuum window material should be chemically relatively inert and should not react with the components or trace components of the cooling circuit. Suitable materials for the vacuum window include beryllium or some high-strength alloys (such as Havar). TM The foil is made of electron beams. Due to the energy of the intense electron beam deposition, the vacuum window and the target material of the converter must be cooled. Blackbody radiation is far from sufficient to dissipate the deposited energy.

[0149] Vacuum windows made of beryllium foil with a thickness > 0.1 mm were considered. The energy deposited in the foil depends on the foil thickness, but for a window with a thickness of 100 μm, the energy does not exceed 80 watts.

[0150] Assuming a beam diameter of 5 mm (flat-top profile), the temperature rise of a beam pulse from a conventional linear electron accelerator (40 MeV, 800 Hz, 125 kW) passing through a 0.1 mm thick beryllium window is calculated to be only 1.5°C. To further reduce the temperature change, the incident vacuum window can be rotated (see...). Figure 6 That is, the vacuum window is coupled to the rotary drive. For example, a 4 cm diameter beryllium foil is mounted on a hollow shaft, which is part of a rotary vacuum feedthrough, preferably sealed with magnetohydrodynamics. A commercially available 4 cm rotary vacuum feedthrough can rotate at a maximum speed of approximately 3100 rpm. With this in mind, the beam impacts the periphery of the 4 cm diameter disk at a distance of 0.5 cm from the periphery, creating an annular impact zone with a diameter of 3 cm.

[0151] Assuming a 5mm deposition point, approximately 18 points can be applied on a rotating vacuum window disk. With a beam break period of 1.25 milliseconds, the vacuum window disk needs to rotate at approximately 2600 rpm. This rotation speed can be reduced if smaller beam diameters or overlapping deposition points can be tolerated. This aspect becomes important when considering liquid cooling. The resulting cooling period before a new beam point is applied is approximately 20 milliseconds, which should be long enough for the applied beam point to cool completely. Smaller beam diameters or overlapping deposition points can be tolerated due to the relatively low temperature rise per beam point and the higher mechanical strength provided by the thicker beryllium window.

[0152] More specifically, Figure 6 A schematic diagram shows a 4 cm diameter beryllium foil mounted on a hollow shaft of a rotating vacuum feeder. One side is cooled by flowing helium or water.

[0153] A rotation speed of 2,600 rpm was chosen. This resulted in approximately 18 deposition spots, each irradiated for microseconds, followed by a 1.25 ms beam interruption period during which the disk rotated by a diameter of the large confinement point. This allowed the same point to have a 20 ms cooling time before being irradiated again.

[0154] More specifically, Figure 5The proposed radiation scheme for a rotating beryllium foil vacuum window is shown. The foil rotates in the opposite direction (counterclockwise) to the rotation of the converter disk. A radiation scheme with a beam structure of 800 Hz and a duty cycle of 1.2% is employed to maximize the cooling cycle of the radiation section. By minimizing the area overlap between the window disk and the converter disk (viewed from the beam axis) as much as possible, and by rotating the window disk and the converter disk in opposite directions, the shear force on the cooling medium (especially water) is minimized due to the similar tangential velocities of the rotating window disk and the converter disk.

[0155] 5) Electron-to-photon converter, housing and cooling

[0156] Then, the electron beam bombards the converter material. The converter must be a material with a high melting point and good mechanical stability. Furthermore, the material must be composed of a high atomic number and high density to effectively convert the electron beam into bremsstrahlung. High atomic number and high density are optimal point source sources for bremsstrahlung. Due to maintenance and radioactive waste management reasons, the converter material can only be slightly activated by the electron beam. In addition, the converter material should be chemically relatively inert and should not react with components or trace components of the cooling circuit. The thickness of the converter must be adjusted to the range of electrons in the converter material. A good converter material is 4–5 mm thick tungsten or tantalum.

[0157] The interaction between electrons and converter materials can be described by a variety of physical processes and is quite complex. For the production of radionuclides in photonic nuclear reactions, bremsstrahlung photons with energies exceeding approximately 8 MeV are important. However, to account for the energy deposited in the converter material, all physical processes must be included. The arrangement of the converter material relative to the target material to be radiated is crucial. Bremsstrahlung photons greater than 8 MeV are primarily emitted forward (beam direction) in a cone-shaped configuration with a certain aperture angle.

[0158] Due to the intense energy deposited by the electron beam, the target material of the vacuum window and converter must be cooled. Blackbody radiation is far from sufficient to dissipate the deposited energy. Therefore, the vacuum window and converter must be cooled by a gas or liquid. In our consideration, we propose cooling by flowing helium. Helium has the advantages of low atomic number, high viscosity, and inability to be activated or attenuated by bremsstrahlung photons. When water is used as the coolant, oxygen isotopes undergo photonuclear reactions. Most notably, in… 16 O(γ, n) 15 The O reaction produces isotopes with relatively short lifespans. 15 O, with a half-life of 122.24 s. Other conceivable reaction products are... 13 N (T) 1 / 2 = 9.97 m), 11 C (T) 1 / 2= 20.364 m) or 14 C (T) 1 / 2 = 5730 a). remove 14 In addition, these products have a short lifespan and can be filtered from cooling water. 15 (excluding O).

[0159] The same principles applied to the construction of the vacuum window assembly can be applied to the converter target. As mentioned above, the converter must be a high-Z, high-melting-point material with good thermal conductivity. It must provide mechanical stability for rapid rotation and can only be slightly activated. In our consideration, we chose tantalum as the converter material because of its high melting point of 3017°C and machinability. Furthermore, natural tantalum consists of only two isotopes: [missing information - likely a specific element or component]. 181 Ta and natural abundance of 0.01201% 180m Ta. In 181 In the (γ, n) or (γ, 2n) reaction on Ta, 180 Ta or 179 Ta has a half-life of 665 days to a stable state. 179 Hf. The latter decays through electron capture without emitting gamma rays. 180 Ta has a half-life of 8.15 h, but its decay leads to a stable 180W or stable 180 The (γ, pxn) reaction on Ta is forming stable Hf isotopes. Neutron capture reactions produce... 182 Ta estimates that it only slightly activates the Ta converter material.

[0160] In addition, tungsten has a high melting point of 3422°C, making it a potentially good conversion material. Furthermore, natural tungsten is composed of five isotopes: one with a natural abundance of 0.12. 180 W, with a natural abundance of 26.50%. 182 W, with a natural abundance of 14.31%. 183 W, with a natural abundance of 30.64%. 184 W and natural abundance of 28.43% 186 W. In 180 In the (γ, n) or (γ, 2n) reaction on W, 179 Ta has a half-life of 665 days, and its decay becomes stable. 179 Hf, or the formation of a relatively short lifetime. 178 W (T1 / 2 = 22 d), its decay becomes 178 Ta. In 182 W and 183 The (γ, n) or (γ, 2n) reaction on W will produce a product with a half-life of 121 and 2d, respectively.181 W decays through electron capture, forming stable forms under the emission of X-rays and extremely low-energy gamma rays. 181 Ta. In 186 The (γ, n) reaction on W will produce a product with a half-life of 75.1 days. 185 W, which forms a stable 185Re through β-negative emission (0.4 MeV) and 125 keV gamma-ray attenuation with a low branching ratio. Further research is needed in... 183 W and 184 A 114.43-day half-life is formed in the (γ, p) or (γ, pn) reaction on W. 182 Ta, even with prolonged decay periods, can still significantly contribute to the total dose rate. (n, γ) reactions on various W isotopes are of less interest. In general, W possesses many advantageous properties as a converter material, but its activation performance is expected to be much higher than that of Ta.

[0161] The converter target component should be very compact to allow for high photon flux with minimal opening angle. The ideal thickness for gamma-ray formation in the 8 to 30 MeV energy window is between 4 and 5 mm.

[0162] To deposit approximately 45 kW of energy onto a 4.5 mm thick W converter plate, the converter target is divided into multiple disks. The energy of beam pulses, each a few microseconds in length, is distributed across the circumference of a rotating disk with an assumed radius of 15 cm. As described above, the disk rotation speed is preferably synchronized with the beam's temporal structure, such that the rotation speed for a beam diameter of 5 mm and a deposition radius of 15 cm is > 255 rpm.

[0163] The number of discs can be increased while adjusting the total thickness to the optimal value between 4.5-5mm.

[0164] The maximum temperature reached depends on the electron beam's free-flowing mass (FWHM). The energy deposited in the actual converter is approximately 45 kW. To dissipate this heat, if the helium outlet temperature is 200 °C higher than the inlet temperature, a helium flow rate of approximately 250 L / s at standard temperature and pressure (STP) is required. This relatively high flow rate for He can be provided by a commercially available medium-sized pump. Alternatively, cooling can be achieved using water flow. The energy deposited in the window, converter disk, and cooling water is approximately 50 kW. Assuming an inlet temperature of 20 °C and an outlet temperature of 80 °C, a minimum cooling water flow rate of 200 ml / s (12 L / min) is required, which can be easily achieved with a commercially available water pump. Furthermore, the rotating converter disk acts as a Tesla pump to support the cooling flow.

[0165] The converter disks are stacked on a common axis separated by small gaps (on the sub-millimeter scale). The number and thickness of the disks are optimized according to the electron beam energy to achieve maximum bremsstrahlung conversion efficiency. As described above, the disk rotation speed is preferably at least one diameter of the point at which the deposited beam point moves during the beam break cycle. Depending on the diameter of the converter disks and the beam point diameter, rotational speeds ranging from several hundred to several thousand rpm can be obtained. The disks are enclosed in a water-cooled housing with small gaps between the disks and the walls. To cool the disks heated by the aforementioned particle beam, a cooling gas (e.g., helium) circulates through the gaps between the disks. Due to the low rotational speed, water can also be used as the cooling medium. In this case, water cooling of the housing is no longer required. Orifices are provided cocentrically with the axis to facilitate axial gas or liquid flow along the axis. The housing includes openings to allow gas or liquid to circulate from the outer edge of the disks. This configuration describes a cohesion-type pump, also known as a Tesla pump, originally described in U.S. Patent 1,061,206, which is incorporated herein by reference.

[0166] The gas or liquid flow between the discs describes the helical flow (vortex) generated by the interaction of the gas or liquid, its adhesion to the discs, and its internal viscosity. Due to rotation, the contact time between the gas or liquid and the disc surface is prolonged, optimizing heat transfer for the coolant. In a pump configuration, the shaft is externally driven, and the gas or liquid flows from the outer edge of the axial disc.

[0167] The outward flow of cooling gas or liquid allows the trays to be cooled uniformly. Furthermore, as the number of trays increases, the total surface area available for cooling increases. Although the total heat load of the system remains constant in this configuration, the load per tray can be reduced.

[0168] More specifically, Figure 6 A schematic diagram of a Tesla converter design is shown. On the left, the complete disk assembly with one shaft and multiple disks is shown, with the particle beam (blue) impacting the outer edge of the disks (the heated area, corresponding to the circular trajectory of the electron beam). On the right, a coolant flow diagram on a single disk of a pump-configured converter is depicted.

[0169] 6) Reduce energy density

[0170] Further reductions in energy density within the converter disk can be achieved through additional movement of the spindle or additional movement (oscillation) of the electron beam. While the first method preserves the basic point-like characteristics of the emitted photon beam, oscillation of the electron beam results in a reduction in photon density at the production target location. Figure 7 This illustrates a method for additional linear movement of the main shaft (or the vertical oscillation of the beam). In the figure, gray dots represent exemplary beam pulses. The blue line describes the center position of the beam pulse on the disk. In subfigure a), a single-axis design is shown. Here, the center point line is of radius R. CA circle. Due to misadjustment of the rotation frequency and beam repetition rate, the radius is R. C + R Beam and R C – R Beam The band between the virtual circles (the dashed gray lines in the diagram) is radiated after several rotations. The radiated area is derived from the following formula.

[0171] .

[0172] In subgraph b), an additional vertical motion (or vertical oscillation of the beam) is introduced along the principal axis. This will cause the centerline point to fluctuate vertically, expanding the radiation area. The path of the centerline describes the area around the average radius R. C The amplitude is A lin The diagram depicts an oscillating motion. It shows a path of approximately three rotations. The frequencies of rotation and linear motion must be carefully adjusted. Otherwise, a stable trajectory is achieved, and radiation occurs only on a portion of the entire region between the virtual boundaries (dotted gray lines). The radiation region is quantized by the following formula.

[0173] .

[0174] Linear actuation of the main shaft (or vertical oscillation of the beam) is the simplest extension of the method. Circular motion of the main shaft can certainly be achieved.

[0175] 7) Production Targets

[0176] The target material must be placed within the emitted photon cone to be effectively radiated. If the quantity of the target material is limited, i.e. 226 Ra, or materials with high isotopic enrichment, such as, but not limited to, 48 Ca, 48 Ti、 68 Zn, 100 Mo、 112 Sn or 150 For Nd, the target needs to be placed as close as possible to the converter. Due to the compact geometry of the converter, the highest possible photon flux density is achieved. In the (γ,n) reaction, [the following occurs]. 100 Mo produced 99 Mo causes "carrier-added" 99 Mo cannot interact with the target material. 100 Mo chemical separation. To produce an easy-to-use product from this material. 99m Tc radionuclide generator 99 The specific activity of Mo should exceed approximately 5 Ci / g. This can only be achieved through high enrichment with high photon flux density. 100This is achieved through the radiation of Mo, where photons are emitted from a point-like converter source. Because photons with energies of 8 MeV or higher have high penetrating power, stacked target materials can be irradiated simultaneously. During irradiation, the target material absorbs the photons, and the energy is deposited within the target. Therefore, the target must be cooled, for example, by flowing cooling water. The advantage of high photon energy is that it allows for the safe encapsulation of difficult-to-handle target materials, such as those that are radioactive, toxic, or chemically reactive, within suitable materials for irradiation. This avoids damage to the target material from entering the cooling water circuit. Furthermore, it is possible to simultaneously irradiate multiple production targets with the same photon beam, thus enabling the simultaneous production of multiple radionuclides. For example, relatively thin... 226 Ra will be loaded at the location closest to the converter components, where the photon flux is highest, followed by, for example, [other components]. 112 Sn or 150 Nd is a target material that allows for high production rates, but is relatively expensive as an enrichment material, followed by large quantities. 68 Zn or 48 The target material is Ti, where chemical separation and recovery procedures already exist when processing large quantities of the target material. Preferably, a setup is provided for remote loading, unloading, and transfer of the target material to the processing hot chamber.

[0177] 8) Large beam stopper

[0178] Since most of the high-energy photons will penetrate all target materials, they must be stopped by a large number of, preferably water-cooled, beam stoppers made of lead. According to Table 1, the energy deposited in the beam stoppers is about 68 kW [2]. For shielding purposes, it is conceivable that the electron beam, converter and production target be arranged vertically, using the ground as additional shielding around the large number of beam stoppers. Otherwise, additional shielding (i.e., concrete) must be installed to reduce the gamma dose to an acceptable level.

[0179] Within a large number of beam stoppers, radiation on synthetic gemstones can be anticipated. High-energy gamma radiation induces defects in the crystal lattice of the artificially produced gemstones, which act as color centers, thus enabling permanent coloring of synthetic gemstones such as topaz.

[0180] 9) Cooling circuit

[0181] Due to the low rotational speed, water is preferred as the coolant, which greatly simplifies the construction of a suitable cooling circuit. The required water flow rate is moderate, and most components are readily available. Therefore, the technical simplicity far surpasses that of particle beam activation. Assuming an inlet temperature of 20°C and an outlet temperature of 80°C, a minimum cooling flow rate of 200 ml / s (12 L / min) is required, which can be easily achieved with commercially available water pumps. Furthermore, the rotating converter disk acts as a Tesla pump to support the cooling flow. The building air conditioning unit contains a chiller capable of removing 100 kW or more of heat.

[0182] Alternatively, helium can be chosen as the cooling medium due to its low atomic number and density, chemical inertness, and reasonable heat capacity. Furthermore, it does not react with high-energy bremsstrahlung photons. Assuming a temperature increase of 200°C, approximately 250 L / s of He at STP is required to remove energy deposited in the converter target component. Helium is expected to enter the converter component at room temperature. Helium preferentially circulates in the gas loop. Therefore, the cooling loop preferably includes a high-flow pump, a high-flow heat exchanger, a storage tank, filters for trace components (e.g., oxygen, water vapor, and particles), and a supply for filling and purging circuitry with helium. The pressure in the He tank (high-pressure side) can be regulated via a butterfly valve connected to a pressure sensor. Several components of the cooling loop can be sourced from the automotive industry, such as high-flow interchillers or radial compressors.

[0183] Calculating the yield of radionuclides (example):

[0184] Using the point-source high-power converter target component described above and the production target exposed to the resulting photon field, assuming an electron energy of 40 MeV and a beam power of 125 kW, the following yield can be obtained:

[0185] Depend on 226 Ra production 225 Ra:

[0186] Given a target thickness of 100 mg / cm² and a target diameter of 2 cm, the calculated radiation production rate is 10.65 GBq. 225 Ra / day. This is equivalent to approximately 5 GBq after a 14-15 day growth period. 225 Ac. To limit the number of chemical separation procedures, it is advantageous to choose a longer radiation time, such as 2 weeks. After a waiting period of several days, the first batch... 225 Ac can separate from the radiation target. With an optimal waiting period of approximately 17 days, due to... 225 Ac has a half-life of 14.9 days. 225 It is produced in the decay of Ra, hence the so-called second and third chances.225 Ac can be separated from the radiation target. Assuming this production protocol and a patient dose of 10 MBq, then one 226 Ra targets produce a dose for approximately 500 patients per day.

[0187] Depend on 100 Mo production 99 Mo:

[0188] When the target thickness is 1 g / cm² and the target diameter is 2 cm, the calculated value is approximately 650 GBq. 99 The production rate is Mo / day. This is equivalent to approximately 17.5 Ci / day / target. At 1 g / cm², the target thickness is still relatively thin.

[0189] The calculated yields demonstrate that photonuclear reactions are a feasible method for producing medical radionuclides. The aforementioned point-source high-power converter target component is capable of absorbing massive beam power up to 125 kW and can utilize line accelerators to achieve the production of conventional radionuclides.

[0190] References:

[0191] The following references are incorporated herein by reference:

[0192] [1a] MEVEX The accelerator technology company. High Power Linacs for Isotope Production. http: / / www.mevex.com / Brochures / Brochure_High_Energy.pdf [Accessed May 17, 2019]

[0193] [1b] Ion Beam Applications, IBA Industrial, Rhodotron® TT300-HE HighEnergy Electron Generator, www.iba-industrial.com [Accessed June 26, 2018]

[0194] [2] M. Vagheian, "A Point Source High Power Converter Target toProduce Bremsstrahlung for Photonuclear Reaction", PhD thesis, University ofBern, Switzerland, February 25, 2022.

[0195] Reference tag list

[0196] 1. Electron beam source (electron accelerator)

[0197] 2 electron beam

[0198] 3. Electron beam transmission line (vacuum tube)

[0199] 4. Vacuum valve (breakdown valve)

[0200] 5a-c beam optical element (quadrupole triple)

[0201] 8. Entrance window retainer for vacuum windows

[0202] 9 shells

[0203] 10 Cooling medium ports (injection port and outlet port)

[0204] 11. Cooling Loop (Cooling Circuit)

[0205] 12-channel converter disk

[0206] 13-spindle

[0207] 14. Projected focal points (time tracking)

[0208] A cone (photon field) of 15 bremsstrahlung photons.

[0209] 16 Neutron Absorbers

[0210] 17 Production Targets

[0211] 18-beam stopper

[0212] 19 cavities

[0213] 20 converter target

[0214] 21 Converter Target Components

[0215] 22-Average Calculator / Exit Window

[0216] 23 Vacuum Window Disk

[0217] 24 Vacuum Window Control Unit

[0218] 25 Converter Disk Control Unit

[0219] 26 Vacuum Window Rotation Drive

[0220] 27 Converter Disk Rotation Drive

[0221] 30 hollow shaft

[0222] 31 Magnetohydrodynamic Seal

[0223] 32 bearing

[0224] 33-spindle

Claims

1. Equipment for producing radionuclides based on the principle of photonuclear radiation, especially for producing diagnostic and therapeutic radionuclides, characterized in that, include: • Electron accelerator (1) generates an electron beam (2) with time structure characteristics for use in the linear electron accelerator (1). • Converter target assembly (21) having a converter target (20) for converting the electron beam (2) into bremsstrahlung photons (15). • Multiple production targets (17) are irradiated by the bremsstrahlung photons (15), thereby producing the radionuclides. The converter target component (21) includes a sealed housing (9). • A cavity (19) surrounds and accommodates the converter target (20). • Includes an entrance window having a window disk (23) for the electron beam (2) and an exit window for the bremsstrahlung photons (15). • Includes cooling medium ports (10), which are part of a cooling circuit (11) for establishing a cooling flow through the cavity (19) to cool the converter target (20) and the window disk (23). in, • The converter target (20) includes a plurality of rotatable converter disks (12). • The electron beam (2) is positioned off-center relative to the corresponding converter disk (12). And therein, the corresponding converter disk (12) is designed to rotate during the operation of the device, thereby dispersing the focus of the electron beam (2) onto the annular region (14) of the converter disk (12) over time in multiple rotations.

2. The device according to claim 1, characterized in that, The electron accelerator (1) generates a pulsed electron beam (2), wherein the pulsed electron beam (2) has a pulse time in the range of microseconds and a period time in the range of milliseconds or longer.

3. The device according to claim 1 or 2, characterized in that, Includes a control unit (24) that keeps the rotational speed of the corresponding converter disk (12) synchronized with the periodic time structure of the electron beam.

4. The device according to claim 3, characterized in that, The area on the corresponding converter disk (12) exposed to a single beam pulse describes a near-circular region, wherein the ratio of the rotation time of the converter disk (12) to the periodic time of the electron beam (2) is preferably such that the beam point on the converter disk rotates at least about one point diameter between subsequent pulses.

5. The device according to any one of the preceding claims, characterized in that, The rotational speed of the corresponding converter disk (12) is set in the range of several hundred to several thousand revolutions per minute.

6. The device according to any one of the preceding claims, characterized in that, The window disk (23) is rotatable and held or supported by an entrance window holder (8), the electron beam (2) is disposed off-center relative to the window disk (23), and the window disk (23) is designed to rotate during operation of the device, thereby dispersing the focus of the electron beam (2) onto multiple radiation points of the window disk (23) over a period of time.

7. The device according to claim 6, characterized in that, The incident window retainer (8) includes or retains a preferably circular window disk (23), preferably beryllium foil or any other high-strength material with a low atomic number, wherein the incident window retainer (8) is mounted on / in / at a hollow shaft (30) or is part of the hollow shaft (30), which is part of a rotating vacuum feedthrough.

8. The device according to claim 7, characterized in that, The incident window retainer (8) and the mounted window disk (23) or the rotating vacuum feeder relative to the bundle transmission line (3) are sealed by a magnetohydrodynamic seal (31).

9. The device according to any one of claims 6 to 8, characterized in that, The control unit (25) keeps the rotational speed of the entrance window holder (8) and the mounted window disk (23) synchronized with the time structure of the electron beam period.

10. The device according to claim 9, characterized in that, The area on the window disk (23) exposed to a single beam pulse describes a near-circular region, wherein the ratio of the rotation time of the window disk (23) to the beam period time is preferably selected such that, in multiple radiation cycles, the series of radiation points form a ring-shaped region of uniform radiation from the window disk (23).

11. The device according to any one of claims 6 to 10, characterized in that, The rotational speed of the window disk (23) is set in the range of several hundred revolutions per minute to several thousand revolutions per minute.

12. The device according to any one of claims 6 to 11, characterized in that, When viewed along the beam axis, the overlap between the window disk and the rotating converter disk is minimal.

13. The device according to any one of claims 6 to 12, characterized in that, The rotation direction of the window disk (23) is opposite to the rotation direction of the rotating converter disk.

14. The device according to any one of the preceding claims, characterized in that, The beam transmission line (3) includes beam optics (5a-c) that allow the electron beam (2) to be focused or defocused to different FWHMs ("full width half maximum") and set at least 2 mm of FWHM.

15. The device according to any one of the preceding claims, characterized in that, The converter target (20) includes a plurality of preferably circular converter disks (12).

16. The device according to claim 15, characterized in that, The converter disk (12) is stacked on a common axis (13).

17. The device according to any one of the preceding claims, characterized in that, The corresponding converter disk (12) is coupled to the rotary drive (27).

18. The device according to any one of the preceding claims, characterized in that, The converter disk (12) is arranged to form a Tesla pump.

19. The device according to any one of the preceding claims, characterized in that, The cooling medium is a coolant, especially water.

20. The device according to any one of the preceding claims, characterized in that, Apart from some optional oscillations or some movement of the amplitude of the common axis (13) within the millimeter range, the origin region of the emitted bremsstrahlung photons (15) is fixed in space.

21. A converter target component (21) for use in the device according to any one of the preceding claims, characterized in that, Includes a sealed housing (9), said housing (9) • A cavity (19) surrounding and accommodating the converter target (20); • Includes an entrance window holder (8) having an entrance window disk (23) for the electron beam (2) and an exit window (22) for bremsstrahlung photons. • Includes cooling medium ports (10) designed to connect to a cooling circuit (11) for establishing a cooling flow through the cavity (19) to cool the converter target (20) and the entrance window holder (8) with their mounted entrance window disk (23). The converter target (20) includes a plurality of rotatable converter disks (12), and each of the converter disks (12) is designed to rotate during operation of the device, thereby dispersing the focus of the incident electron beam (2) into a series of nearly circular beam points over time, after multiple radiation cycles and rotation of the converter disks, the beam points forming a uniformly radiating annular region on the converter disks (12).

22. The converter target component (21) according to claim 21, characterized in that, The incident window holder (8) includes a rotatable window disk (23), wherein the window disk (23) is designed to rotate during operation of the device, thereby dispersing the focus of the incident electron beam (2) into a series of nearly circular beam points over time, through multiple radiation cycles and rotation of the window disk, the beam points forming a uniformly radiating annular region on the window disk (23).

23. A method for producing a radionuclide, characterized in that, An electron beam (2) is directed onto a converter target (20) having multiple rotating converter disks (12) such that, over time, the focus of the electron beam (2) is dispersed onto the annular region of the respective converter disk (12), thereby generating a beam of bremsstrahlung photons (15) for radiating a production target (17), wherein the converter target (20) is cooled by the flow of a cooling medium, particularly gaseous helium or liquid water.

24. The method according to claim 23, characterized in that, The converter target (20) is arranged inside the housing (9), and wherein the electron beam (2) is guided through the housing (9) by a rotating entrance window holder (8) having an installed entrance window disk (23), such that over time, after multiple radiation cycles, the focus of the electron beam (2) is dispersed into a series of nearly circular beam points, which form a uniformly radiating annular region on the entrance window disk (23).

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