Conversion from radium-226 to actinium-225 without the use of a converter.

Abstract

A high-energy electron beam with an average effective beam output of approximately 20kW to 250kW at a beam energy of approximately 25 to 100 MeV. 226 By direct electron beam impact that collides with Ra 226 Ra 225 A converter-free method for converting to Ac is disclosed. Unlike other electron-based bombardment methods, this method does not use a converter to decelerate electrons and convert their kinetic energy into bremsstrahlung photons, and targets 226 Ra 225 Ra(This is, 225 This is done by generating virtual photons that are converted to Ac (which decays into Ac).

Description

Technical Field

[0001] Description Cross - Reference to Related Applications This application claims priority to U.S. Patent Application No. 63 / 523992, filed on June 29, 2023, the disclosure of which is incorporated herein by reference.

[0002] Technical Field The present invention relates to 226 the production of virtual photon electromagnetic radiation that converts both Ra 225 into Ac 225 and Ra 225 into Fr by the impact of a high - energy electron beam on the radium isotope, for 226 the preparation of Ac from a Ra target. This photonuclear reaction is carried out without using a bremsstrahlung converter intervening between the electron beam and the target 225 Ra. 226 This is done without using a bremsstrahlung converter intervening between the electron beam and the target Ra.

Background Art

[0003] severely limited 225 the supply of Ac (having a half - life T 1 / 2 = 9.92 days) and the huge global demand for this isotope is an important factor in nuclear medicine. 225 The demand for Ac stems from the use of this isotope in targeted alpha therapy (TAT). The radioisotope 225 Ac and its daughter 213 Bi (T 1 / 2 = 45.61 minutes) are used in pharmaceuticals for the treatment of several cancers such as prostate cancer, brain cancer, and neuroendocrine cancer.

[0004] In one of the conventional production methods, 225 Ac is 225 produced via the β 1 / 2 decay of Ra (T - = 14.9 days), and 225 Ra itself is 226 high - purity Ra (T1 / 2 (1600) Produced by a (γ,n) reaction in the target. Photons are produced by solid converters of high atomic number (high Z) materials such as tantalum via a bremsstrahlung (braking-radiation) mechanism, which can result from the deceleration of very high-energy accelerating electrons by collisions with the converter material. The bremsstrahlung produced therein are very high-energy photons, which are the target 226 Collided with Ra 226 Ra is another radioactive isotope 225 Convert to Ra, this 225 Ra is β - Collapse 225 It collapses into Ac.

[0005] However, the typical photon spectrum produced using the converter is broadly dispersed with respect to energy (see Figure 1), and also to some extent with respect to emission angle (see Figure 2). Furthermore, approximately 80% of the photon flux spectrum is 226 Ra neutron separation energy (for example, S n ) is below (S n (=6.39 MeV), while rendering those photons meaningless, can catastrophically overheat the target and the surrounding material. Such overheating would require enhanced cooling, and consequently, an enhanced radioactive waste removal system.

[0006] Conventionally, two tantalum disk converters were used to enhance cooling and heat removal. These are shown in Figures 1 and 2 to illustrate the difficulties associated with using converters. The use of multiple converters was proposed by Diamond et al., J Appl Phys 129:104901 (March 09, 2021).

[0007] Furthermore, when using a converter, 226 By photon bombardment (irradiation) of the Ra target 225An important precursor of Ra, namely, 225 Fr(T 1 / 2 The proton removal channel that generates (=3.95m) is not feasible. This defect is due to the (γ,p) reaction cross-section having a peak value of σ. max This is due to the expected very low yield resulting from the extremely low photon flux level at energies with (30 MeV) = 0.2 mb.

[0008] Alternatively, if no converter is used, the super-relativistic velocity (energy >> M) o ) electron transfer and high Z

[0009]

number

[0010] Absorption probabilities can be converted into (γ, n) and (γ, p) cross-sections, which can be measured experimentally using several methods. One of these methods is the activation and delayed counting method. This method has been used in numerous measurements across various beam-target systems in the past. These have been reported in [Gerab et al., Phys Rev C, 48(1):105-108 (1993); Martins et al., Phys. Rev. C, 16:613 (1977); and Shotter et al., Nucl Phys A330:325 (1979)]. 238 Research on accelerated electrons incident on U is, 226 (e - , n) and (e - , via p) 225 Ra / 225 This is particularly interesting because the reaction here appears similar to the reaction involving the production of Ac.

[0011] Two target nuclear systems, namely, 238 U and 226 The similarity in nuclear structure between Ra and Ra suggests using the same optical model potential (OPM) parameters for distortion wave Born approximation (DWBA) calculations as a reaction model for both systems when interacting with E1 and E2 virtual photons generated from hyperrelativistic electrons. As shown in Figure 3, adopted from the above paper by Gerab et al. and replotted using the JANIS database [JANIS Database (NEA)-JANIS (oecd-nea.org)], at a beam energy of 40 MeV, 238 The cross-sectional area required to remove neutrons from a U nucleus is approximately 2.5 mb. 226 Ra is (e - ,n) It is thought that similar values ​​of the reaction cross-section will be observed. However, in the case of absorption of virtual photons, the proton must pass through the Coulomb barrier of the radium nucleus, so (e- , p) The value of the reaction cross-section is considered to be slightly low.

[0012] As will be described in detail below, the present invention uses an electron beam having an average power of about 20 to 250 kW, and is encapsulated 226 Direct impact on Ra target 225 This invention aims to develop a converter-free method for generating Ac. 226 A well-established and validated nuclear decay (CD) mechanism is used when impacting a thin Ra target. [Overview of the Initiative]

[0013] The present invention 226 Due to virtual photon filtering by Ra 225 The generation of Ac, and subsequently 225 Ra and 225 Removal of spontaneously occurring neutrons or protons that generate Fr, then, 225 Ra and 225 This occurs after the β-minus decay of Fr. 225 The aim is to form Ac. High-purity photons are produced using a high-intensity electron beam current with an energy of approximately 25 to 100 MeV. 226 It is generated from the direct impact of a target containing Ra. In this practical form, the virtual photon causes Coulomb dissociation (CD) of the target, 226 By removing neutrons or protons from the Ra target, respectively, 225 Ra and 225 Following the spontaneous beta-minus decay of Fr 225 Ac can be produced. The average electron beam intensity is approximately 20-250 kW of effective beam power at approximately 25-100 MeV. The high efficiency is a result of using a focused, single-energy electron beam.

[0014] By photons 225Conventional methods for Ac production use beam converters to convert electron beam energy into bremsstrahlung photons, but approximately 81% are produced below the neutron rejection threshold. Such conventional methods employ high-Z material converters to produce photons emitted at large angles. This type of production reduces the number of photons in the target. As a result, the production yield is low. Furthermore, the efficiency of these methods is very low, as is the complexity of designing such mechanisms.

[0015] In this embodiment, there is no actual beam converter. 226 Ra is directly bombarded with electrons of approximately 25 to 100 MeV. In some cases, thin layers (approximately 120 to 200 μm) of well-known high-Z materials such as gold (Au), tantalum (Ta), or tungsten (W) present on the inner wall of the housing lid generate bremsstrahlung photons [Gerab et al., Phys Rev C, 48(1):105-108 (1993)].

[0016] More specifically, the present invention relates to electron beam shock by high-energy electrons, comprising the following steps: 226 Ra 225 The aim is to devise a method for converting to Ac. The terms "bombardment" and "irradiation" are used interchangeably herein. It is contained within a hermetically sealed capsule. 226 Ra is bombarded with an electron beam having an average electron intensity of approximately 20 to 250 kW at an effective beam power of approximately 25 to 100 MeV electrons.

[0017] The capsule is an electron beam 226 The capsule has a lid 232 that the electron beam passes through before colliding with Ra. 226 The inner surface of the capsule, which passes through before colliding with Ra, may include a high-Z material coating with a thickness of approximately 120 to 220 μm (μ), however, this high-Z material coating is not thick enough to provide the amount of bremsstrahlung radiation necessary to trigger the conversion reaction.

[0018] When the impact is 226 sufficient to remove neutrons or protons from Ra to form 225 Ra or 225 Fr respectively for a period of time. The formed 225 Ra and 225 Fr 225 decay to Ac and they are typically recovered from the irradiated target material and typically also separated from the remaining 226 Ra as well as the formed 225 Ra or 225 Fr. 225 Ra and 225 Fr can be separated by an elution process.

[0019] Furthermore, 226 all 227 Ac by-products, which are decay products of 227 Ra (half-life = 42 ± 0.5 minutes) produced by a low-probability neutron capture reaction in Ra, can be eliminated by discarding the first fraction of actinium eluted several hours after the end of the impact. 227 A waiting time of several hours is sufficient for most of the

[0020] 226 The impact on 225 Ra does not directly form 225 Ac, but the intermediate 226 Fr has a half-life of only about 3.95 hours and thus, if an actinium product is obtained, is generally not present in the 225 Ra or 225 Ra reaction mixture. Similarly, although to a lesser extent, as shown in Figure 4, the formed 225 Ra also decays more slowly to 226 Ac. 225 Considering the disappearance of some intermediate products formed from 226 Ra and the acquisition of the desired 225 Ac, this method is described as a method of converting

Brief Description of the Drawings

[0021] [Figure 1] This graph shows the bremsstrahlung photon flux profile produced by two tantalum disk converters, indicating that no photons with an energy below 6.4 MeV have the energy necessary to produce 225Ra / 225Ac. [Figure 2] The image above shows the MCNP-simulated spatial distribution of photons generated by the two disk-type converters, indicating that the majority of photons do not hit the target, with the target shown as a black rectangular box in the center of the circle. [Figure 3] This graph shows the virtual photon-induced reaction cross-section on a 238U target (thickness = 150 μg / cm2), measured using (e-,n) activation reactions with electron beam energies of 12–60 MeV, as reported in [Gerab et al., Phys Rev C, 48(1):105-108 (1993)]. The plot was generated using the JANIS EXFOR database [Nuclear Energy Agency (NEA)-JANIS(oecd-nea.org)]. [Figure 4] This graph shows the relative activity of 225Ac versus 225Ra over the storage period, as calculated in Maslov et al., Radiochemistry, 48(2):195-197 (2006). [Figure 5] This is a schematic diagram of an exemplary system 100 for producing isotopes such as 225Ac. [Figure 6] This is a schematic diagram of the target capsule housing showing five 226Ra target containment capsules. The electron beam enters through a window in the housing, and an electron-absorbing tantalum beam stop captures the flow of electrons that enter the air-filled housing. [Figure 7] This is a block diagram of a beamline according to an exemplary embodiment. [Modes for carrying out the invention]

[0022] The present invention contemplates a method for converting 226 Ra to 226 Ra by electron beam bombardment that collides electrons of high energy from about 25 to about 100 MeV with a 225 Ra target. In this reaction, 226 Ra is converted to 225 Ac by losing neutrons, which decays naturally to 225 Ac by beta minus decay with a half-life of 14.9 days. 226 Ra is also converted to 225 Fr by losing protons by electron beam bombardment, and then is converted to 225 Ac with a half-life of 3.95 hours.

[0023] Contrary to conventional electron-based bombardment methods, this method is performed by generating virtual photons instead of using a converter that converts electron beam energy to bremsstrahlung photons. In the contemplated method, the estimated 225 Ac yield when using the disclosed systems and methods is approximately three times higher than the yield obtained from 226 Ra bremsstrahlung bombardment using a converter. This superior feature of the converter-free concept makes the need for higher accelerator beam power less critical, since a similar yield can be achieved using about one-third of the power required when using a converter.

[0024] The contemplated method is basically a neutron or proton removal process. Conventionally, neutron removal processes for generating isotopes, particularly radioactive isotopes, involve irradiating a target positioned along the common axis of a linear electron accelerator (linac) or Rodotron®. However, the conventional method results in a low yield of the desired isotope and also produces backstream radiation that is harmful to equipment over a range along the beamline's range.

[0025] Referring to FIG. 5, isotopes, particularly 225An exemplary system 100 for producing Ac is shown. In detail, the system 100 for producing isotopes may comprise an accelerator 110 connected to a first beamline 130. The beamline 130 collides with a target holder 150. The target holder 150 produces isotopes of a target, for example, 226 This could be a device for holding Ra, etc., for irradiation. The target holder 150 can further be connected to a target cooling system 160 (also called a process cooling system) and a hot cell 170.

[0026] The accelerator 110, beamline 130, and target holder 150 can be shielded within the accelerator vault 180. In an exemplary embodiment, the accelerator vault 180 can be further divided into a first irradiation zone 182 that houses the accelerator 110 and beamline 130, and a second irradiation zone 186 that houses the target holder 150.

[0027] In an exemplary embodiment, the accelerator chamber 180, along with the interior walls used to form radiation zones 182 and 186, as well as any other rooms in the building, can be constructed of high-density (HD) concrete blocks supplied by Veritas Medical Solutions (Harleysville, Pennsylvania, USA). HD concrete is superior per unit volume to conventional density concrete in shielding against gamma rays, which are the primary source of prompt radiation produced in the process.

[0028] In detail, prompt radiation refers to radiation emitted instantaneously during the operation of accelerator 110 and is distinct from residual or induced radiation caused by activated components in accelerator chamber 180 or beamline 130. Other materials such as steel or lead could also be used for accelerator chambers, but these materials are more expensive and less efficient than HD concrete in blocking prompt neutrons generated during the process.

[0029] The accelerator 110 was held within the target holder 150. 226 Accelerated electrons are generated for irradiating Ra. In an exemplary embodiment, the electron accelerator 110 can supply an average power of about 20 to about 250 kW with electrons of about 25 to about 100 MeV. Preferably, the average power is about 60 to about 200 kW, and more preferably about 80 to about 125 kW. Preferably, the electrons are about 25 to about 55 MeV.

[0030] To irradiate the target holder 150, each electron beam can be bent to an angle directed toward the target holder 150 using a dedicated beamline (shown in Figure 7). In an exemplary embodiment, beamline 130 bends the electron beam 90 degrees toward the target holder 150. The present invention is not limited to 90 degrees, but may include other angles that result in beamlines irradiating the target holder 150 from different directions or angles. As a result, the target holder 150 does not have to be located on a common axis with the accelerator 110. In one exemplary embodiment, the accelerator 110 is offset from the target holder 150, as shown in Figure 5. In another exemplary embodiment, the accelerator 110 may be located on a common axis with the target holder 150.

[0031] Furthermore, the accelerator 110, beamline 130, target cooling system 160, hot cell 170, and 225 A control system can be provided that integrates the individual control systems of other system components for generating radioactive isotopes such as Ac. For example, by using this integrated control system, the timing of beam pulse generation in the accelerator 110 can be adjusted so that the beam pulses reach the target holder 150 at desired intervals.

[0032] As illustrated in more detail in Figure 7, the beamline 130 can receive electron beams from the accelerator 110 during operation. The beamline 130 can then bend each beam to hit a desired spot in the target holder 150 and avoid backflow radiation. After bending, the beamline 130 directs the beam to a desired spot in the target holder 150, analyzes the beam's energy, or allows the beam to pass straight through to a waiting beam analyzer and dump.

[0033] According to an exemplary embodiment, a Rhodotron® electron beam (e - The beam accelerator can be used as accelerator 110. Unlike conventional linear accelerators (e.g., linacs), the Rhodotron® E beam accelerator is a pulsed-wave electron beam accelerator that combines high power and high energy. - The high power and high energy characteristics of beam accelerators were previously impossible to achieve using linacs. 225 It helps improve the efficiency of Ac production. Furthermore, Rhodotron(registered trademark) e - Beam accelerators are smaller in size, which allows for the installation of accelerators in a smaller area within isotope production facilities.

[0034] Preferred Rhodotron(registered trademark)e - The beam accelerator can provide electron beams with diameters of 7 mm (full width at half maximum; FWHM) or 12 mm (FWHM). Gaussian beams with a standard deviation of 3 sigma correspond to diameters of 8.9 mm and 15 mm, respectively. In all simulations used for this disclosure, the target size was 25 mm in diameter and 0.060198 mm thick (RaBr2).

[0035] Figure 6 shows the target capsule enclosure system 200. The target capsule enclosure system 200 may be included in or part of the target holder 150 in Figure 1.

[0036] The target capsule housing system 200 includes a housing 210 designed to house one or more target capsules 220. The housing 210 consists of walls 212, which are provided with windows 214 through which an electron beam 216, such as an electron beam generated by the accelerator 110 and beamline 130 in Figure 5, passes and irradiates one or more target capsules 220.

[0037] As shown in one embodiment, the target capsule housing system 200 includes five target capsules 221-225. However, in other embodiments, the target capsule housing system 200 may include more or fewer target capsules 220.

[0038] Each of the one or more target capsules 220 may be identical. If the target capsule housing system 200 includes multiple target capsules 220, each target capsule 220 may be positioned along a common axis with the path of an electron beam designed to collide with the target capsule 220.

[0039] In an exemplary embodiment, as shown in Figure 6, the long axis of one or more target capsules 220 is positioned perpendicular to the axis through which the electron beam 216 passes. In other embodiments, the electron beam 216 passes through the “short side” or “short axis” of one or more target capsules 220. In other embodiments, the long axis of one or more target capsules 220 may be positioned on the same axis as the electron beam 216.

[0040] Many geometric shapes can be used for the one or more target capsules 220. Exemplary examples include: 226Examples include cylindrical capsules with generally rounded ends, comprising a lid 232 (for example, the tantalum layer is on the inner surface of the capsule) whose inner surface is coated with a thin layer of tantalum 234, and the Ra target 230 is made of RaBr2, RaCl2, or Ra(NO3)2 salt and is located on the inner surface of the capsule base.

[0041] Another embodiment is, 26R A conical or frustoconical capsule is used, in which the target 230 is located on the inner wall of the capsule, while the inner surface of the lid 232 is coated solely with tantalum. The conical capsule provides a large surface area for heat transfer to the cooling fluid (a water-based liquid or a chemically inert gas) and simultaneously disperses and diffuses the volumetric heating induced by the electron beam. The direction of the coolant flow may be perpendicular or parallel to the electron beam.

[0042] 226 Ra metal is preferably electroplated or liquid deposited as a salt on the inner surface of the target capsule and then dried. Solid radium salt particles are preferably used as targets and are preferably prepared in situ by drying a solution of a water-soluble radium salt such as a nitrate or halide.

[0043] The one or more target capsules 220 are generally referred to as “capsules” in this specification for ease of expression, not because they have the shape of a pharmaceutical capsule. This is similar to how capsules used in space travel are not shaped like pharmaceutical capsules, but rather like truncated cones.

[0044] The term “lid” is also used herein for convenience, and such a cover is typically located at the top of the chamber when viewed along the longest vertical axis of the chamber, and covers the top opening at that location. In the present invention, the capsule lid 232 may be located at the first end opposite the second end of the capsule, in which case the first end and the second end are generally aligned along the common axis of the capsule.

[0045] In a preferred embodiment, as shown in Figure 6, the common axis along which the first and second capsule ends are aligned is the "minor axis" of the capsule, parallel to the direction of the electron beam. The "minor axis" is a different axis from the illustrated "major axis" of the capsule and is typically perpendicular to the axis of the electron beam. In other embodiments, the common axis along which the first and second ends are aligned is the "major axis" of the capsule. In other words, the capsule can be provided in shapes having different lengths, heights, and thicknesses. Furthermore, the lid can be aligned along any of these axes.

[0046] Here, the "lid" of the capsule is, in most cases, a part of the capsule whose inner surface is coated with a tantalum layer upon which the electron beam impacts.

[0047] Here, the term “lid” is typically used to close and airtight seal the target containment capsule, although other sealing devices in other locations may also be used to seal the capsule. The lid 232 and its sealing of the capsule help prevent radon gas and radium (and any other radioactive material) from leaking out of the capsule after a long irradiation period and heating.

[0048] The one or more target capsules 220 are, in part, preferably made of aluminum (e.g., aluminum walls 236) due to their weldability (e.g., ability to be joined in an airtight seal). Furthermore, aluminum also has good mechanical properties (yield strength / ultimate strength), as well as high thermal conductivity and a high melting point, albeit to a lesser degree. The latter two properties are not so important because the conduction length scale (wall thickness) is small enough that volume generation is minimized.

[0049] Diamond et al., J Appl Phys 129:104901 (March 09, 2021), reported that by placing 0.5 mm of aluminum on both sides of a radium target, excellent protection against target damage during irradiation and handling is obtained with almost no reduction in bremsstrahlung intensity, even when multiple segments are used. Aluminum is a good choice for target coating because it is used in high-power electron beams with little degradation due to processes such as oxidation by radiolysis products of water.

[0050] Other materials with similar properties include silicon carbide (SiC), titanium, and Inconel® 718, as well as aluminum alloys, titanium alloys, and stainless steel alloys. Volume heating is also minimal with low-Z materials.

[0051] Regardless of the shape or material of the configuration, the target capsule lid 232 may have its inner surface coated with a high-Z material, such as tantalum (Ta) 234, as an example. The thickness of the exemplary Ta coating 234 is about 120 to about 220 μm (μ). Preferably, the thickness of the high-Z material coating 234 is about 150 to about 190 μm, and more preferably about 160 to about 180 μm. The high-Z material coating is preferably spray-applied onto the metal surface of the capsule lid, which becomes the inner surface of the capsule lid after it is closed.

[0052] Tantalum is used as a converter for generating bremsstrahlung photons in radium electron beam shocks at thicknesses of approximately 1 to 3 mm [Diamond et al., J Appl Phys 129:104901 (March 09, 2021)]. Such tantalum thicknesses are up to approximately 20 times the thickness used herein.

[0053] The one or more target capsules 220 may include an air gap 238. The air gap 238 is made of a high-Z material coating 234 and 226Surrounding and / or in contact with the Ra target 230. The air gap 238 is 226 It can function as a heat sink to dissipate heat during the activation of Ra target 230.

[0054] The target capsule housing system 200 further includes a beam stop 240 positioned behind one or more target capsules 220. The beam stop 240 is preferably made of a well-known gamma radiation shielding material. Exemplary beam stop materials include high-density (HD) concrete blocks and stainless steel supplied by Veritas Medical Solutions (Harleysville, Pennsylvania, USA). The beam stop 240 is positioned along the incident path of the electron beam 216 (e.g., on the same axis).

[0055] Furthermore, since the impact process may cause the target capsule housing system 200 to heat up, the target capsule housing system 200 preferably includes a space 250 for a cooling medium or heat sink. In some embodiments, the cooling space 250 is composed of gas. In a preferred embodiment, the cooling space 250 is filled with air. In other embodiments, the cooling space 250 is filled with a liquid coolant such as water.

[0056] target 226 After the electronic shock to the Ra containment capsule ends, the hermetically sealed target capsule is opened, and the generated 225 Ac, starting materials 226Ra is separated from the remainder and various reaction products and daughter nuclides. These separation methods are well known in the art and include elution processes such as the use of diglycolamide (DGA) materials dispersed on porous inert resins or silica carriers, as described in U.S. Patents 7,087,206, 7,157,022, and 7,553,461. The so-called UTEVA® (uranium and tetravalent actinide) (dipentylpentylphosphonate) resins are both available from Eichrom Technologies, Inc.

[0057] As an example, radium was found to have a radioactivity of 10 μCi in a solution of 0.1 M HCl by EZAG / Georgia (Atlanta, Georgia, USA). 226 It is supplied by Ra. Activation (i.e., formation of radioisotope products) can be carried out over 30 hours at the LEAF of ANL or the IBA in Belgium. LEAF is a good source for this activation due to the redundancy of its beamlines and the presence of a universal target station and hot cell.

[0058] Typically generated 225 Ac is subsequently recovered. Recovery is typically carried out as an aqueous salt solution of a pharmaceutically acceptable anion, such as a nitrate or a chloride or bromide halide. DGA resin, available from Eichrom Industries, Inc. (Lyle, Illinois, USA), is useful for separating aqueous actinium salts from radium salts.

[0059] 225 Examples of commercially available products containing Ac include those approved by the FDA. 225 Aqueous solutions of Ac nitrate are available from Oak Ridge National Laboratory. 225 Ac is typically diluted with a pharmaceutically acceptable aqueous diluent for use.

[0060] Figure 7 shows an integrated control system 300 that may be provided to integrate the individual control systems of the accelerator 110 with the baseline 130 described with reference to Figure 5 in order to generate an electron beam, such as electron beam 216, as described with reference to Figure 6.

[0061] The integrated control system 300 includes a beamline subsystem 305, which may include a first beam optics system 310 that receives an electron beam from the accelerator 110.

[0062] The beam optics system 310 can be used to correct and guide the electron beam received from the accelerator 110. The beam optics system 310 can be coupled with a diagnostic component 320 that can be used to analyze the current or position of the electron beam. The diagnostic component 320 can further be connected to a second beam optics system 330 used to focus the electron beam.

[0063] The second beam optics system 330 can be connected to a third beam optics system 340 for further correction and guidance of the electron beam. This allows the third beam optics system 340 to be connected to a fourth beam optics system 350, which includes an achromatic bending system.

[0064] In an exemplary embodiment, an achromatic bending system facilitates the bending of an electron beam. For example, to bend the electron beam path by 270°, three magnets are used in the achromatic bending system. The first and third magnets each provide a 70° bend, and the second magnet provides a 130° bend, thus providing a complete 270° bend.

[0065] From the fourth beam optics system 350, the electron beam can proceed along one of three paths. If the electron beam meets one or more predetermined generation criteria, the electron beam can be bent by the fourth beam optics system 350 toward the second diagnostic component 360 for further analysis of the electron beam's current or position.

[0066] The second diagnostic component 360 can be connected to a fifth beam optics system 370 for correction and guidance, and the fifth beam optics system 370 can be further connected to a sixth beam optics system 380 for focusing. The sixth beam optics system 380 directs the electron beam to a target (for example, housed in the target holder 150 described above with reference to Figure 5). 226 Before being sent to Ra), it can be connected to a third diagnostic component 390 for further analysis of the electron beam's current and position.

[0067] Alternatively, if the electron beam does not meet predetermined criteria for generation, the fourth beam optics system 350 may send the electron beam to a fourth diagnostic component 392. In some embodiments, the fourth diagnostic component 392 includes beam dumping or beam stopping. However, if the electron beam is not used for generation, the fourth beam optics system 350 may send the electron beam to a fifth diagnostic component 394, such as a spectrometer, for further analysis.

[0068] In an exemplary embodiment, the electron beam can be incident on and exit from the fourth beam optics system 350 in substantially the same plane. In other words, the achromatic bending system of the fourth beam optics system 350 does not affect the vertical elevation angle of the electron beam.

[0069] However, in other embodiments, the electron beam can exit the fourth beam optics system 350 in a plane different from the plane in which the electron beam enters the fourth beam optics system 350. In other words, depending on the circumstances, the achromatic bending system of the fourth beam optics system 350 can affect the vertical elevation angle of the electron beam.

[0070] It will be understood that the beamline subsystem 305 may include other variations, such as the addition or omission of certain components. Such variations are within the scope of the present disclosure.

[0071] Electron activation and delayed counting methods are, 225 This is very suitable for investigating the total production cross-section of Ac. Several electron accelerator facilities (domestic and international) can provide electron beams at energies of approximately 40 MeV. For example, the Low Energy Accelerator Facility (LEAF) at Argonne National Laboratory (ANL) is very convenient. Furthermore, IBA in Belgium can also facilitate this task. Other accelerator facilities, such as ELBE in Dresden, Germany, or the IBA TT300-HE Rhodotron® facility at NorthStar Medical Radioisotope, LLC in Beloit, Wisconsin, USA, can also be negotiated and utilized.

[0072] As an example, 225Ac yield measurement is obtained by striking a target containing a homogenized mixture of 100 μg of RaBr2 and 1 mg of Al2O3 (functioning as a packing agent), located in an activation vacuum chamber, which is situated within a hollow cylinder (e.g., a capsule structure) with a diameter of 8 mm and a height of 5 mm, and having generally rounded ends, and covered with a 0.1 mm thick aluminum lid 232. The activation process (e.g., striking the target 230 in the target holder 150) is carried out for approximately 30 hours. Subsequently, the radioactivity of the activation product can be determined using a gamma-ray detector by performing offline measurements.

[0073] The electron beam current is monitored for total charge using methods and equipment well known to those skilled in the art. One example of exemplary equipment is the Faraday cup. Another exemplary equipment is a current transformer (sometimes called a current converter), such as the ACCT device sold by Bergoz Instrumention, headquartered in Saint-Genis-Pouilly, France.

[0074] 225 The total Ac production cross-section (from both the neutron-removed channel and the proton-removed channel) is: 221 Fr collapse (T 1 / 2 218.0 keV (I) generated from (= 4.801 min) γ Measurement of gamma ray radioactivity (=11.44%) and 213 Bi's collapse (T 1 / 2 =45.59 minutes, β - 440.45 keV (I) derived from BR: 97.86%) γ This can be directly obtained by measuring the gamma-ray radioactivity of =25.9%, and both of these during the counting period. 225 Ac is in a permanent equilibrium state.

[0075] The counting period is typically less than one hour on the 18th day after the end of the impact process. See Figure 4. 225The expected maximum relative radioactivity of Ac is shown to occur on day 18 [Maslov et al., Radiochemistry, 48(2):195-197 (2006)]. For detection, an HPGe detector with standard lead shielding is used.

[0076] 226 Ra(e - ,n) 225 Ra and 226 Ra(e - , p) 225 Fr -β decay→ 225 Although measurement results for the Ra cross-section have not been reported, similar beam-target systems in the same electron energy range have been proposed, namely, 238 U(e - ,n) 237 The measurement data by Gerab et al. in U, as described above, 225 This indicates that the yield of Ac is reasonable. 225 The yield of Ra is 100 mg 226 This was calculated using Ra, which corresponds to approximately 2.7E+20 radium atoms.

[0077] The total production cross-section at an electron beam energy of 39 MeV (intermediate target energy) is (2 × 2.5) milliburns (mb), 1E-27 square centimeters (cm), as shown in Figure 3. 2 )) is equal to, in this case, 226 Ra(e - ,n) 225 Ra and 226 Ra(e - , p) 225 The total of Fr is 238 U(e - ,n) 237 It is approximately twice the value of the U cross-sectional area. For a beam spot with a full width at half maximum (FWHM) of 7 mm and a beam current of 3.125 mA, the value is 4.9E+16e - / (cm 2 [e - / (cm 2 [A second is a unit of flux for the number of incident electrons per unit area per unit time.]

[0078] Next, the reaction rate is such that a portion of it will decay during production with a decay constant of 5.38E-7 (1 / sec). 225 Ra / sec is equal to 4E+10[ 225 Ra / second is the number of units generated per unit time. 225 This is the number of Ra atoms, and here it is the number of Ra atoms. 225 The important collapse into Ac 225 Used to provide the production rate of Ra isotope; 1 / second is the decay constant unit, i.e., the probability that one decay occurs per unit time. 6.5 days after impact, produced 225 The total number of Ra atoms is 2E+16, which was estimated using the simulated photon flux shown in Figure 1 for a tantalum converter (two disks). 225 It is compared to the 3E+15 atoms of Ra.

[0079] High-intensity electron beam shock (e.g., irradiation) 225 Considering the collapse of AC, 225 The process is carried out for a sufficient amount of time to generate the desired amount of Ac. Typical impact (e.g., irradiation) times are 4 to about 30 days, preferably about 10 to about 25 days.

[0080] Each patent, patent application, and paper cited herein is incorporated herein by reference. The use of the articles “a” or “an” is intended to include one or more.

[0081] The above description and examples are illustrative and should not be considered limiting. Furthermore, other variations within the spirit and scope of the invention are possible and will be readily conceivable to those skilled in the art. [Explanation of Symbols]

[0082] 100 Systems 110 Accelerator 130 First beamline 150 Target Holders 160 Target Cooling Systems 170 Hot Cells 182 First irradiation zone 186 Second irradiation zone 200 Target Capsule Housing System 220 Target Capsules 210 cabinets 212 Wall 214 windows 216 Electron beam 221-225 Target Capsules 230 226 Ra target 232 Lid 234 Ta coating 236 Aluminum Wall 238 Air Gap 240 Beam Stop 250 Cooling space 300 Control Systems 305 Beamline Subsystem 310 First beam optics 320 diagnostic components 330 Second beam optics 340 Third beam optics 350 Fourth beam optics 360 Second diagnostic component 370 The fifth beam optical system 380 The sixth beam optical system 390 Third diagnostic component 392 Fourth diagnostic component 394 Fifth diagnostic component

Claims

1. Without using a converter, by electron beam shock with high-energy electrons 226 Ra 225 A method for converting to AC, a) An electron beam having an average effective beam output of approximately 20 kW to approximately 250 kW at a beam energy of approximately 25 to approximately 100 MeV, located inside a hermetically sealed capsule. 226 A process of striking a target made of Ra, wherein the capsule and the electron beam 226 It has a capsule lid that passes before the electron beam collides with Ra, and the capsule lid is such that the electron beam 226 The process may include having a high-Z material coating with a thickness of about 120 to about 220 μm (μ) on the inner surface of the capsule that passes before impacting the Ra target, b) The above 226 Removing neutrons and / or protons from Ra targets on a commercial scale 225 A step of maintaining the impact for a period of time sufficient to form Ac A method that includes this.

2. The formed 225 The method according to claim 1, wherein Ac is recovered.

3. The method according to claim 1, wherein the aforementioned high-Z material coating is present.

4. The method according to claim 1, wherein the capsule is made of aluminum or titanium.

5. The method according to claim 4, wherein the capsule is provided in the form of a hollow cylinder, a hollow cone, or a hollow frustum having generally rounded ends.

6. The method according to claim 5, wherein the capsule lid is positioned at its end along an axis of the capsule that is different from the long axis of the capsule.

7. The method according to claim 5, wherein the capsule lid is positioned at the end of the capsule along the long axis of the capsule.

8. The method according to claim 1, wherein the period for impact is maintained for approximately 4 to 30 days.

9. The method according to claim 1, wherein the average electron beam output is approximately 60 to approximately 200 kW.

10. The method according to claim 1, wherein the beam energy is for electrons at approximately 25 to approximately 65 MeV.

11. Without using a converter, by high-energy electrons 226 By bombarding the Ra target with an electron beam of 226 the Ra target 225 is converted to Ac, a method comprising a) An electron beam with an average effective beam output of approximately 60 kW to approximately 200 kW at a beam energy of approximately 25 to approximately 65 MeV, located inside a hermetically sealed capsule. 226 A process of striking a target made of Ra, wherein the capsule is such that the electron beam 226 It has a capsule lid that passes before the electron beam collides with Ra, and the capsule lid is such that the electron beam 226 The process may include having a high-Z material coating with a thickness of about 120 to about 220 μm (μ) on the inner surface of the capsule that passes before impacting the Ra target, b) A period of approximately 4 days to approximately 30 days as described above 226 Maintaining Ra target impact on a commercial scale 225 The process of forming Ac and A method that includes this.

12. The aforementioned 226 The method according to claim 11, wherein the Ra target exists as a halide or nitrate.

13. The formed 225 The method according to claim 11, wherein Ac is recovered.

14. The method according to claim 11, wherein the capsule is made of aluminum.

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