Method and apparatus for producing lead-212 isotopes

Abstract

An apparatus for producing Pb-212 is disclosed. The apparatus includes a radiation box including a radiation source comprising a porous non-reactive material. The radiation box receives at least one of Th-228 and Ra-224, wherein the at least one of Th-228 and Ra-224 decays to Rn-220 within the radiation box. The apparatus further includes a carrier gas supply connected to the radiation box. The carrier gas supply directs an inert gas into the radiation box, and the inert gas transports the Rn-220 out of the radiation box through a carrier gas outlet port of the radiation box. The apparatus also includes one or more Rn-220 targets connected to the carrier gas outlet port. The carrier gas transports the Rn-220 from the radiation box to the one or more Rn-220 targets, and the Rn-220 decays to Pb-212 within the one or more Rn-220 targets. The Pb-212 is directed into a Pb-212 collection container.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 241,610, filed on September 8, 2021. Technical Field

[0003] Generally, the present invention relates to methods and apparatus for generating / producing and capturing / separating lead-212 (Pb-212) isotopes.

[0004] Description of related technologies

[0005] Alpha particle therapy offers opportunities for the treatment of many cancers. However, the production of alpha particle emission isotopes is a highly complex process, fraught with numerous technical and regulatory hurdles. The production of alpha particle emission isotopes is also very expensive and difficult to scale up, which has prevented alpha particle therapy from being commercialized and made available to patients to date. Generally, high-energy accelerators or reactors are required for complex and cumbersome bombardment, radiation, and conventional chemical separation processes to produce alpha emission isotopes for use as radiolabeled drug products for human injection. Pb-212 is an alpha emission isotope with energy distributions and chemical properties suitable for radiolabeling. This makes Pb-212 a very promising contender for TAT (targeted alpha therapy) for treating a variety of cancers. Pb-212 isotopes can be produced from the parent isotope Th-228, which can be obtained from reactors or nuclear waste from industrial or government nuclear power plants.

[0006] Previous methods and systems for producing Pb-212 isotopes relied on the chemical separation of radium-224 (Ra-224) from Th-228 as the feedstock / parent isotope. Ra-224 has a half-life of 3.66 days. Due to the short half-life of Ra-224, previous systems required frequent replenishment of the Ra-224 feedstock / isotope source into the generator to produce Pb-212, and the Pb-212 activity was limited to a maximum of 30 mCi due to transport index and transport issues. The replenishment and extraction of Ra-224 from Th-228 were repetitive processes used in the chemical separation methods previously employed for Pb-212 production. Furthermore, previous methods posed a high risk of radiation exposure during the purification of Ra-224 from Th-228 and the loading of Ra-224 into the current Pb-212 generator. These methods repeatedly extract Ra-224 from Th-228 and supplement Ra-224 into Pb-212 generators, thus increasing the risk of radiation exposure during Ra-224 transportation, production, and replacement.

[0007] Existing Ra-224 / Pb-212 generator technologies are only suitable for small-scale R&D and clinical trials. However, from a financial, regulatory, manufacturing safety, and patient safety perspective, scaling up and commercializing these previous methods is not feasible. Furthermore, because previous methods rely on the chemical separation of Ra-224 from Th-228, there is a risk that Th-228 and Ra-224 will penetrate into the final Pb-212 product. This separation is a limiting step in existing methods because the presence of any parent isotope in the Pb-212 drug product poses radiation and health hazards to patients receiving the drug product due to the long half-lives and energy distributions of Th-228 and Ra-224.

[0008] The method disclosed herein employs a radically different approach from the aforementioned prior chemical separation methods. Furthermore, the method disclosed herein offers several advantages over existing methods for generating Pb-212 via radiation. Weaknesses and drawbacks of current methods for generating Pb-212 via radiation include, for example, using Ra-224 as a feedstock / parent isotope loaded onto a radioactive source, which faces the same problems as the aforementioned chemical separation methods, using solid organic phase target materials such as urea or other organic materials to capture and trap Rn-220, and using residual solvents as the final target for capturing and trapping Rn220. This solid organic material also needs to be dissolved in acid and chemically separated to extract Pb-212 generated from the decay of Rn-220. These prior methods require high-performance liquid chromatography (HPLC) quality control to verify the absence of residual or cross-contamination of urea or any other organic material used in the separation and extraction of Pb-212. Any residual organic material used in the separation may exceed the maximum tolerated dose or limit (MTD / L), indicating toxicity to patients.

[0009] Rn-220 capture can also be accomplished using organic liquid media (residual solvents) such as methanol or hexanol. This method requires further distillation, evaporation, filtration, and chemical separation of Pb-212 produced from the decay of Rn-220 in the organic liquid media to ensure the separation and extraction of Pb-212 isotopes free of methanol, hexanol, or any common residual solvents. This separation is difficult to scale up and is cumbersome. Furthermore, the process requires gas chromatography (GC) testing for any residual organic compounds before releasing the Pb-212 product to patients, which is unsuitable for large-scale production or environments not easily adaptable to small-scale laboratory settings. The presence of residual solvents in the final drug product is hazardous for patient administration and treatment and is considered a limiting step in current therapeutic Pb-212 drug products.

[0010] Besides the aforementioned Rn-220 capture problem, another significant issue with existing radioactive technologies in Pb-212 production is the method of loading the parent isotope or raw material onto the radioactive source and the materials used to construct the source. Materials used in existing methods to construct the radioactive source include resins, salts, or materials that are radioactively decomposed when large quantities of Th-228 or Ra-224 are loaded into previously used sources. All existing methods lack a safe and efficient method for introducing the raw material / parent isotope into the radioactive source. In current methods, the operator must first manually introduce the raw material / parent isotope into the source and then manually place the source within the radiation chamber. This is a dangerous and cumbersome process that cannot be performed when handling commercial and highly reactive production systems.

[0011] Due to the shortcomings of existing Pb-212 production methods, there is a need for an effective and safe method to produce and extract Pb-212 to address the deficiencies of existing methods and systems. Summary of the Invention

[0012] This disclosure provides an apparatus and method for producing Pb-212 using thorium-228 (Th-228) feedstock / parent isotope (half-life of 1.92 years). For example, according to certain exemplary embodiments, this disclosure relates to an apparatus for producing Pb-212. In some embodiments, the apparatus may include a Th-228 supply container, a radiation chamber, a carrier gas supply, a radiation chamber and radiation source loading device, a heating block, and an Rn-220 target system. According to certain exemplary embodiments, the Th-228 supply container and the carrier gas supply may be connected to the radiation chamber. In some embodiments, the radiation chamber may be connected to the Rn-220 target system.

[0013] In one embodiment, this disclosure provides a method for producing the Pb-212 isotope. The method includes introducing Th-228 into a radiation chamber, wherein the radiation chamber includes a radioactive source comprising a high surface area material. The method further includes introducing a carrier gas into the radiation chamber via a carrier gas supply, wherein the carrier gas is an inert gas and flows through the radiation chamber. Th-228 decays into Rn-220 within the radiation chamber, and the carrier gas delivers the Rn-220 generated from the decay of Th-228 in the radiation chamber to one or more Rn-220 targets via a multi-way valve connected to a carrier gas outlet port of the radiation chamber. The method further includes separating the Rn-220 from the carrier gas within the one or more Rn-220 targets, discharging the carrier gas from the one or more Rn-220 targets via a carrier gas exhaust port, introducing liquid into the one or more Rn-220 targets via a liquid supply, and causing the Rn-220 to undergo radioactive decay into the Pb-212 isotope within the one or more Rn-220 targets. The liquid contains Pb-212 isotopes produced by the radioactive decay of Rn-220 within one or more Rn-220 targets. The method further includes guiding the liquid containing the Pb-212 isotopes from one or more Rn-220 targets to a Pb-212 collection container and separating the Pb-212 isotopes from the liquid.

[0014] In another embodiment, this disclosure provides an apparatus for producing Pb-212, comprising a radiation chamber including a radiation source comprising a porous non-reactive material, and the radiation chamber receiving at least one of Th-228 and Ra-224 at an inlet, wherein at least one of Th-228 and Ra-224 decays into Rn-220 within the radiation chamber. The apparatus further includes a carrier gas supply connected to the radiation chamber, wherein the carrier gas supply introduces an inert gas into the radiation chamber, and the inert gas delivers Rn-220 out of the radiation chamber through a carrier gas outlet port connected to a multi-way valve. The apparatus further includes one or more Rn-220 targets connected to the carrier gas outlet port via a multi-way valve, wherein the carrier gas delivers Rn-220 from the radiation chamber to the one or more Rn-220 targets, and wherein the Rn-220 decays into Pb-212 within the one or more Rn-220 targets. A liquid supply is connected to the one or more Rn-220 targets. The liquid supply introduces liquid into the Rn-220 target, bringing the liquid into contact with the carrier gas that delivers Rn-220 to the target. Pb-212 generated from the decay of Rn-220 is transferred to the liquid through this contact between the carrier gas and the liquid. A Pb-212 collection container is connected to the Rn-220 target system, and the generated Pb-212 is introduced into the Pb-212 collection container.

[0015] In yet another embodiment, this disclosure includes a radiation chamber comprising a radiation source including fins made of a non-reactive porous material, wherein Th-228 in a solvent is introduced into the radiation chamber and adsorbed onto the fins of the radiation source. A shielding structure is positioned around the radiation source, wherein the shielding structure is operable to absorb radiation generated by the radioactive decay of Th-228 in the radiation chamber. The radiation chamber includes a carrier gas supply port operable to provide an inlet for carrier gas introduced into the radiation chamber. The radiation chamber also includes a carrier gas outlet port operable to provide an outlet for carrier gas from the radiation chamber. The radiation chamber further includes an evaporation outlet port operable to provide an outlet for evaporated solvent. The radiation chamber further includes a heat source operable to provide heat to the radiation chamber to evaporate the solvent.

[0016] This disclosure provides an apparatus and method for producing Pb-212 that requires less frequent feedstock / parent isotope replenishment, achieves high yields due to the radioactive source design, provides safe and efficient loading of the radioactive source-containing radiation chamber, a safe and efficient Rn-220 transfer method via a carrier gas, a safe and efficient Rn-220 capture method potentially including cryogenic effects, and oscillations between targets that capture Rn-220 and hold it during its decay into Po-216 and ultimately into Pb-212. Furthermore, in some embodiments, this novel technique can be operated using GMP operating software. The disclosed method and system are well-shielded, easy to maintain, can be scaled up using high activity, and provide a higher level of safety for the operator than previous systems. The disclosed method and system also provide 100% theoretical radionuclear purity because no Th-228 or Ra-224 residues or remnants are present in the final Rn-220 / Pb-212 collection target. Furthermore, in some exemplary embodiments, the disclosed methods and systems differ from previous radioactive methods for producing Pb-212 by not using solid organic extraction / collection of Rn-220 using organic materials (such as urea) or liquid-phase capture of Rn-220 to decay into Pb-212 using residual solvents (such as methanol or hexanol). Moreover, the final product obtained by separating Pb-212 without the use of organic solvents or residual solvents as disclosed herein is safer for pharmaceutical use and requires less stringent and extensive testing to ensure safety. Another advantage of the methods and systems disclosed herein includes a higher yield of Pb-212 because the conversion of Rn-220 to Pb-212 occurs in aqueous solution rather than on solid organic extraction resins or residual solvents as in previous methods.

[0017] These listed advantages are illustrative only and are not intended to be an exhaustive list of the advantages of the methods and systems disclosed herein. Other advantages will be apparent to those skilled in the art who will benefit from this disclosure. This disclosure may include one or more of the following features, or a combination thereof. Attached Figure Description

[0018] The disclosed subject matter will now be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:

[0019] Figure 1 A block diagram of an apparatus for producing and separating Pb-212 according to exemplary embodiments of the present disclosure is depicted.

[0020] Figure 2 A perspective view of an apparatus for producing and separating Pb-212 according to an exemplary embodiment of the present disclosure is depicted.

[0021] Figure 3 This is a close-up perspective view of a radiation source inside a radiation chamber according to an exemplary embodiment of the present disclosure.

[0022] Figure 4 This is a close-up perspective view of a radioactive source according to an exemplary embodiment of the present disclosure;

[0023] Figure 5 This is a perspective view of an apparatus for producing and separating Pb-212 according to an exemplary embodiment of the present disclosure.

[0024] Figure 6 This is a close-up perspective view of a radiation source inside a radiation chamber according to an exemplary embodiment of the present disclosure.

[0025] Figure 7 A schematic diagram of the decay chain of thorium-228 (Th-228) is provided.

[0026] Figure 8 A flowchart of a method for producing Pb-212 according to an exemplary embodiment of the present disclosure is provided.

[0027] While the subject matter of this disclosure is readily adaptable to various modifications and alternatives, specific embodiments thereof have been illustrated by way of example in the accompanying drawings and are described in detail herein. It should be understood, however, that the description of particular embodiments herein is not intended to limit the subject matter of this disclosure to the specific forms disclosed, but rather, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter of this disclosure as defined by the appended claims. Detailed Implementation

[0028] The following detailed description illustrates embodiments of this disclosure: these embodiments are described in sufficient detail to enable those skilled in the art to practice them without excessive experimentation. However, it should be understood that the embodiments and examples described herein are for illustrative purposes only and are not intended to be limiting. Although specific embodiments of the invention will now be described with reference to the accompanying drawings, it should be understood that these embodiments are merely illustrative and represent only a small fraction of the many possible specific embodiments that may embody the principles of the invention. Various changes and modifications that will be apparent to those skilled in the art are considered to fall within the spirit, scope, and concept of the invention as further defined in the appended claims.

[0029] As used herein, the term "connected" or "connection" includes both direct and indirect connections between components. Regarding components that direct fluid from one component to another, the term "connected" or "connection" includes connections via pipes or other conduits to provide fluid communication between components.

[0030] For the purposes of this disclosure, an information processing system may include means and collections of means operable to compute, classify, process, transmit, receive, retrieve, initiate, switch, store, display, exhibit, detect, record, reproduce, process, or utilize information, intelligence, or data in various forms for commercial, scientific, control, entertainment, or other purposes. For example, an information processing system may be a server, personal computer, laptop computer, smartphone, PDA, consumer electronics device, network storage device, or other suitable device, and its size, shape, performance, functionality, and price may vary. An information processing system may include memory, one or more processing resources, such as a processor (e.g., a central processing unit (CPU) or hardware or software control logic). Additional components of an information processing system may include one or more storage devices, one or more communication ports for communicating with external devices, and various input and output (I / O) devices, such as a keyboard, mouse, and video display. An information processing system may also include one or more buses operable to transmit communication between various hardware components.

[0031] Furthermore, in the accompanying drawings and description, the same reference numerals are intended to denote the same elements.

[0032] refer to Figure 1This diagram illustrates a block diagram of an apparatus 100 for producing Pb-212 according to exemplary embodiments of the present disclosure. The apparatus includes a Th-228 supply container 101 connected to a radiation chamber 102. An N2 supply 103 is connected to the radiation chamber 102, and the outlet of the radiation chamber 102 is connected to a solution collection container 104. Additionally, one or more Rn-220 collection targets 105a, 105b are connected to the radiation chamber 102. In some embodiments, the apparatus 100 may further include an acidic solution supply 106 and a Pb-212 collection container 107. In some embodiments, one or more Rn-220 targets may include a first Rn-220 target container 105a and a second Rn-220 target container 105b, such as... Figure 1 As shown. Figure 1 The functions of each component are combined below. Figure 2 To provide a more detailed explanation.

[0033] In some exemplary embodiments, Figure 1 The apparatus can be controlled by an information processing system 110. For example, the information processing system 110 can be a computerized automated system utilizing software-based control (such as GMP software). GMP software as used herein refers to "Good Manufacturing Practice" software, i.e., manufacturing automation software that follows a set of standards called "Good Manufacturing Practices". The structure and operation of GMP software are well known to those skilled in the art who benefit from this disclosure, and therefore will not be discussed in detail here. For example, in some exemplary embodiments, one or more pumps or valves located between each unit can be controlled by the information processing system 110 that implements the automated system. Furthermore, in some exemplary embodiments, the temperature of each unit and / or the temperature of materials contained in or transported between each unit can be monitored and / or controlled by the information processing system 110 that implements the automated system. Compared to previous methods of producing and separating Pb-212, this automated system reduces the need for human interaction with the apparatus and improves operator safety due to the reduced need for human intervention.

[0034] Figure 2 yes Figure 1 The block diagram shows a perspective view of the device. Figure 2 The exemplary embodiment shown includes a Th-228 supply 201, a radiation chamber 202, an N2 carrier gas supply 203, an N2 outlet port 208 for supplying Rn-220 to an Rn-220 collection target 205, a radiation chamber evaporation outlet port 204a connected to a Peltier system 204b (e.g., any commercially available electric cooler employing the Peltier effect, as known to those skilled in the art who benefit from this disclosure), a Pb-212 collection container 207, and a control system 210. Figure 2As shown, the system further includes various valves and pipes for guiding and / or regulating material flow between the various system components. In some exemplary embodiments, the control system 210 may include an information processing system 110, as described above, operable to utilize process control software connected to various sensors (e.g., flow meters, thermocouples, pressure sensors, etc.) via Figure 2 The device controls valves and pumps. The structure and operation of such process control software, and the way they control various sensors (e.g., flow meters, thermocouples, pressure sensors, etc.), will be apparent to those skilled in the art who benefit from the teachings herein, and therefore will not be discussed in detail. For example, control system 210 is operable to monitor the temperature of Rn-220 target 205 and, if the monitored temperature deviates from a desired setpoint, to increase or decrease the cooling of Rn-220 target 205. Furthermore, in some embodiments, control system 210 may house raw material containers, such as containers for the various solutions, acids, and gases described herein, and is operable to supply those materials to... Figure 2 The apparatus comprises various modules. In some exemplary embodiments, a user can regulate the supply, reception, and flow of material through the apparatus by manually controlling valves (not labeled) placed in the piping and conduits throughout the apparatus. In some embodiments, the control system 210 may be communicatively connected to these valves and may selectively and automatically open and close the valves based on predetermined parameters. In still other embodiments, the control system 210 may provide a user interface through which a user can regulate the valves. An exemplary embodiment includes a Th-228 supply 201 connected to a radiation chamber 202. Th-228 may be disposed in and introduced into the radiation chamber 202 from the Th-228 supply 201. In some embodiments, the Th-228 supply 201 may be disposed within the radiation chamber 202. The Th-228 supply 201 provides a method for supplying Th-228 to the radiation chamber 202. In an exemplary embodiment, the radiation chamber 202 has a first distal end 202a and a second distal end 202b. The first distal end 202a of the radiation chamber 202 is fluidly connected to an N2 carrier gas supply 203 (which supplies N2 carrier gas or other inert carrier gas flow to the radiation chamber 202). Although referred to throughout this disclosure as N2 carrier gas, any inert gas can be used as the carrier gas. The second distal end 202b of the radiation chamber 202 is connected to an Rn-220 target 205 via an N2 carrier gas outlet 208. According to some exemplary embodiments, the radiation chamber 202 includes a radiation source (e.g., Figure 5 Radioactive source 506 and Figure 6 The radioactive source 600 and the heat source (e.g., as described in detail in the text) are described in detail in the text. Figure 5 (Heat source 507), for a more detailed description, refer to [reference needed]. Figure 3 , 45 and 6. As described in more detail below, Th-228 is supplied to the radiation chamber 202 via Th-228 supply 201, and a residence time for Th-228 is provided at the radiation source while it undergoes radioactive decay into Rn-220. N2 carrier gas supply 203 provides a flow of N2 carrier gas through the radiation chamber 202, and the N2 carrier gas delivers any Rn-220 generated by the decay of Th-228 in the radiation chamber 202 to the Rn-220 target 205 via N2 carrier gas outlet 208. According to certain exemplary embodiments, the Rn-220 target 205 may have an N2 carrier gas inlet port 205c, a liquid inlet and outlet port 205d, and an N2 carrier gas outlet port 205e. The Rn-220 target 205 serves as a container for separating Rn-220 from the N2 carrier gas and as a residence space for Rn-220 to undergo radioactive decay into Pb-212, as described in more detail below. Liquid supply 206 may be connected to Rn-220 target 205 to provide liquid (e.g., an acidic solution) to dissolve Pb-212 produced by the radioactive decay of Rn-220 in Rn-220 target 205. In some exemplary embodiments, the same liquid supply line 206 may provide an outlet line for the liquid solution containing Pb-212, and Rn-220 target 205 may be connected to Pb-212 collection container 207 via a multi-way valve 209, which is operable to control the inflow and outflow of Rn-220 target 205.

[0035] Th-228 supply 201 is connected to radiation chamber 202 and provides a method for transferring Th-228 into radiation chamber 202. In some embodiments, Th-228 may be dissolved in a liquid before being transferred to radiation chamber 202. In some embodiments, Th-228 may be dissolved in nitric acid (HNO3) or another acid before being transferred to radiation chamber 202. In other embodiments, Th-228 may be purchased in solution form, and vials of Th-228 may be loaded into… Figure 2In the illustrated apparatus, the Th-228 solution is thus transferred to the radiation chamber 202. After being loaded into the apparatus, a portion of the Th-228 solution can be transferred to the radiation chamber 202, as described in more detail below. As those skilled in the art will understand, with the benefit of this disclosure, handling radioactive material such as Th-228 solution involves certain risks, and any accident in the process can lead to undesirable consequences. Therefore, to mitigate such risks, in some exemplary embodiments, the radiation chamber 202 may store Th-228 to extend the operating cycle, thereby avoiding the need for repeated handling of Th-228 and minimizing the risks associated with the process. For example, in some exemplary embodiments, the radiation chamber 202 may store a supply of Th-228 sufficient for one year. In some embodiments, the radiation chamber 202 may store 1000 millicuries (mCi) of Th-228. In some embodiments, Th-228 can be loaded into the system from vials containing Th-228 via Th-228 supply 201. The Th-228 supply 201 can be any suitable system for transferring a quantity of dissolved Th-228 from vials or other storage containers or media to the radiation chamber 202, as will be understood by those skilled in the art who will benefit from this disclosure. For example, the Th-228 supply 201 can be an auto-injector driver, vacuum system, or pressurization system that interfaces with and is controlled by the control system 210. For example, in some embodiments, Th-228 can be loaded into the device monthly, every two months, semi-annually, or annually, which reduces the risk of handling radioactive material. Th-228 can be dissolved in an acid for loading, such as HCl or 3M HNO3, or any desired molar concentration of acid that can dissolve Th-228 or any isotope in its decay chain (e.g., Ra-224).

[0036] In other embodiments, Th-228 or Ra-224 may be pre-loaded into a radioactive source (e.g., radioactive source 506) and then incorporated into the radioactive source. Figure 2 and Figure 5In a device, for example, Th-228 or Ra-224 in solution can be loaded into a radioactive source, and the solvent (acid) can be evaporated at a centralized remote facility. The radioactive source loaded with Th-228 or Ra-224 is then radiation shielded according to DOT regulations and transported to a Pb-212 production facility housing the device described herein for incorporation into said facility and production of Pb-212 as described herein, as will be understood by those skilled in the art who will benefit from this disclosure. In such embodiments, the radioactive source can be periodically replaced with a newly loaded radioactive source containing Th-228 or Ra-224 after a set amount of time or once the activity of Th-228 or Ra-224 in the previous radioactive source has decreased to a predetermined level. In some embodiments, the used radioactive source can be transported back to a centralized Th-228 and Ra-224 loading facility for cleaning and reloading of Th-228 or Ra-224.

[0037] In another embodiment, the Ra-224 solution may be periodically loaded into the Th-228 supply 201. For example, once or twice a week, because Ra-224 has a shorter half-life compared to Th-228. In such an embodiment, Ra-228 may be dissolved in an acid, such as 3M HNO3 or HCl. After loading, the Th-228 or Ra-224 solution may be heated to evaporate the liquid and deposit Th-228 or Ra-224 onto the radioactive source within the radiation chamber 202, as described below.

[0038] Figure 3 and Figure 4 A close-up perspective view of a radiation source 300 within a radiation chamber 202 is shown. When introduced into the radiation source 300, Th-228 is dispersed onto fluid distribution fins 301 via the evaporation of a carrier solution, as described below. The fluid distribution fins 301 are high-surface-area components made of any desired material to which Th-228 can adsorb. In some exemplary embodiments, the high-surface-area material may be a porous material having a porosity required for a particular application. For example, in some non-limiting exemplary embodiments, the porosity of the material constituting the fluid distribution fins 301 may be between approximately 2 μm and approximately 200 μm. As will be understood by those skilled in the art who will benefit from this disclosure, other porosities may be used as needed without departing from the scope of this disclosure. In some embodiments, the material of the fluid distribution fins 301 may have a large surface area. For example, in some embodiments, the surface area of ​​the fluid distribution fins 301 may be greater than approximately 10,000 m². 2The fluid distribution fins 301 can be composed of any desired material, including but not limited to metals, ceramic lattices, or foams. In some embodiments, the high surface area material can be porous titanium, silica, tungsten, zirconium, platinum, gold, iridium, rhenium, ceramics, or combinations thereof. In some embodiments, the fluid distribution fins 301 can have a fin structure comprising a plurality of fins constituting the high surface area material. The radiation source 300 may also include a fluid distribution plate 309 to provide attachment points for the fluid distribution fins 301 and to provide additional surface area for Th-228 deposition. The fluid distribution plate 309 can be made of a high surface area material. For example, in some non-limiting exemplary embodiments, the porosity of the material constituting the fluid distribution plate 309 can be between about 2 μm and about 200 μm. In some embodiments, the fluid distribution plate 309 can be made of the same material as the fluid distribution fins 301. In other embodiments, the fluid distribution plate 309 may be made of a different material than the fluid distribution fins 301. For example, if the fluid distribution fins 301 are made of porous titanium, the fluid distribution plate may be made of porous zirconium.

[0039] The fluid distribution fin 301 retains the Th-228 as it undergoes radioactive decay. Figure 7 The decay path of Th-228 is depicted 700. Specifically, Th-228 first decays into Ra-224, as... Figure 7 As shown, Ra-224 is also adsorbed onto the fluid distribution fins 301. Ra-224 then decays into Rn-220 (which is not adsorbed onto the fluid distribution fins 301). After decaying into Rn-220, Rn-220 can be transported out of the radioactive source 300 by the N2 carrier gas flow supplied to the radioactive source 300 through the N2 carrier gas outlet port 308. As further described herein, the N2 carrier gas can transport Rn-220 to the Rn-220 target 205, where Rn-220 undergoes radioactive decay into Pb-212.

[0040] The radiation chamber 202 may also include a heat source 302 located below the radiation source 300. In some embodiments, the heat source 302 may be located outside the radiation source 300 and in contact with the radiation source 300. In some exemplary embodiments, the heat source 302 may be an electrically controlled heat plate or a heating element, and may be controlled by the information processing system of the control system 210. The heat source 302 provides heat to evaporate the solvent of Th-228 supplied from the Th-228 supply 201. As the liquid portion of the solution evaporates, Th-228 remains on the fluid distribution fins 301.

[0041] The evaporated liquid can exit the radiation source 300 through the evaporation outlet port 304. In some exemplary embodiments, the evaporation outlet port 304 may be disposed on the top surface of the radiation source 300. In some exemplary embodiments, the evaporation outlet port 304 may be connected to a solution collection container (e.g., Figure 5 The condenser flask 525 is connected to and connected to a heat exchanger (e.g., a Peltier cooler 204b) to cool the evaporated solution, which can be collected in a solution collection container. In other embodiments, the heat exchanger may be located in a pipeline between the evaporation outlet port 304 and the solution collection container. In some exemplary embodiments, the heat exchanger may be an electrically powered Peltier effect cooling device that cools the evaporated solution for collection as a liquid. A Peltier effect cooling device is an electrically powered cooler that utilizes the Peltier effect to convert electrical energy into thermal motion, thereby cooling one side of the device and transferring heat to the other side. Such coolers are well known to those skilled in the art who benefit from this disclosure. The embodiments described above with the evaporation outlet port 304 and the Peltier effect cooler... Figure 2 As shown in the image.

[0042] Figure 4 A close-up perspective view of the internal components of an embodiment of the radioactive source 300 described herein is provided. The radioactive source 300 shown includes fluid distribution fins 401 and a fluid distribution plate 409. The fluid distribution fins 401 may correspond to... Figure 3 The component referred to as radiation source 301 can be made of any high surface area material described herein. Fluid distribution fins 401 have a fin structure with multiple closely spaced fins to provide multiple paths for the N2 carrier gas flow through radiation source 300. Fluid distribution plate 409 holds fluid distribution fins 401 in place and provides surface area for Th-228 deposition in addition to the surface area provided by fluid distribution fins 401.

[0043] Return to Figure 2The radiation source (e.g., radiation source 300) within the radiation chamber 202 is supplied by an N2 carrier gas supply 203. The N2 carrier gas supply 203 provides N2 carrier gas that delivers Rn-220 from the radiation source (e.g., radiation source 300) within the radiation chamber 202 through an N2 carrier gas outlet port 208 to the Rn-220 target 205. In certain embodiments, the N2 supply rate can be automatically controlled. For example, in some exemplary embodiments, the N2 supply rate can be controlled by mass flow rate, using a mass flow meter to control the flow rate of the N2 carrier gas at a desired level, and the inlet valve is controlled by the control system 210. The N2 supply to the radiation chamber 202 can be shut off by operating the inlet valve, and one or more manual valves can be connected after the inlet valve in case of inlet valve failure. In some embodiments, the flow rate can be controlled by an information processing system incorporated into the control system 210. For example, in some exemplary embodiments, it may be necessary to flow the N2 carrier gas at a rate suitable for the fixture. This rate can be adjusted by a mass flow system based on the size and number of collection targets and other variables embedded in the system. In a particular embodiment, the N2 supply rate can be controlled at approximately 200 mL / min. The mass flow-controlled N2 carrier gas supply 203 may include an N2 carrier gas supply line, an inlet valve, and a mass flow meter, as referenced. Figure 5 More detailed description. The inlet valve and mass flow meter are operable to control the mass flow rate of N2 carrier gas flowing through the N2 carrier gas supply line using control methods that are obvious to those skilled in the art who benefit from the teachings of this document. For example, the inlet valve and mass flow meter can be combined in a simple feedback control loop scheme. Figure 2 In an exemplary embodiment, the inlet valve and mass flow meter may be connected to the control system 210. N2 carrier gas flows into the radiation chamber 202, carrying away any Rn-220 generated by the decay of Th-228 and / or Ra-224 in the radiation chamber 202, and delivering the Rn-220 to the Rn-220 target 205.

[0044] As described above, the Rn-220 target 205 may consist of one or more containers for collecting Rn-220. For example, in a particular embodiment, the Rn-220 target 205 may include a first container 205a and a second container 205b for collecting Rn-220. In another embodiment, the Rn-220 target 205 may be a single container. In some embodiments, the Rn-220 target 205, whether one, two, or multiple containers, may be filled with a cooled acidic solution. The acidic solution may be any suitable acidic solution, such as hydrochloric acid (HCl). The acidic solution may be cooled to a temperature in the range of approximately -72°C to -95°C. In another embodiment, the acid may be HNO3. In other embodiments, the Rn-220 target 205 may be filled with an uncooled acidic solution at ambient temperature. In another embodiment, the Rn-220 target 205 may include one or more containers containing zeolite, metal zeolite-type chalcogenides (e.g., germanium, tin, zinc, or combinations thereof, chalcogenides having a zeolite-like structure), or tin-rich germanium surface targets. In some embodiments, the container containing the surface target may also be filled with a cooled or uncooled acidic solution, such as an aqueous buffer solution. In other embodiments, the Rn-220 target 205 containing the surface target may include nozzles to spray acid or other aqueous solutions onto the walls of the target container. In embodiments where the Rn-220 target 205 comprises zeolite, metal zeolite-type chalcogenides, or tin-rich germanium surface targets, the Rn-220 target may not be filled with liquid.

[0045] In one embodiment, the Rn-220 target 205 may operate as described below. The first and second Rn-220 targets 205 may include containers containing an acidic solution. The acidic solution may include HCl, HNO3, or any other aqueous, non-organic acid or buffer solution. For ease of explanation, an HCl solution is described below; however, this description is applicable to any aqueous acid solution, and the methods and systems described herein are not limited to the use of an HCl solution. In some embodiments, the first and second Rn-220 targets 205 may be supplied by an automated liquid supply 206. In one particular embodiment, the HCl solution supplied from the liquid supply 206 may be a 20% HCl solution. In another embodiment, the HCl solution may have a concentration of 22.5%. In other embodiments, the HCl concentration may be between 10% and 50%. In some embodiments, the HCl concentration may be between 15% and 30%. In a particular embodiment, the HCl concentration may be between 20% and 25%. In a particular embodiment, the HCl concentration may be between 22% and 27%. In one particular embodiment, the HCl concentration may be 25%. In another embodiment, Rn-220 target 205 can be supplied by a 3M HNO3 solution.

[0046] The first and second Rn-220 targets 205 may also include a temperature control unit / system (such as...) Figure 5 The cooling bath 522 shown is used to cool the HCl solution to a temperature below -72°C and above -95°C, and to maintain the HCl solution at that temperature. In one particular embodiment, the temperature control system can cool the HCl solution to -85°C and maintain the HCl solution at that temperature. In another embodiment, the HCl solution can be cooled to -82°C. In yet another embodiment, the temperature control unit can cool the HNO3 solution to approximately -41°C. In some embodiments, the temperature control unit can be operated to cool the liquid in the Rn-220 target 205 to a temperature above the freezing point of the liquid to increase the solubility of Rn-220 in the liquid.

[0047] When N2 carrier gas containing Rn-220 comes into contact with a cooled HCl solution, Rn-220 freezes because it has a freezing point of -72°C. In some embodiments, the target material may include zeolite or zeolite-like chalcogenide materials that absorb Rn-220 instead of freezing it in the cold acidic solution. In other embodiments, the Rn-220 target 205 may contain a liquid acidic solution at or below ambient temperature, which dissolves the Rn-220 supplied to the Rn-220 target. The N2 carrier gas may then exit the first or second Rn-220 target 205 that does not contain Rn-220. The Rn-220 remaining in the Rn-220 target container decays into Po-216 (which dissolves in the HCl solution). Po-216 dissolves in the HCl solution and then rapidly decays into Pb-212. Because Rn-220 has a half-life of 55.6 seconds and freezes upon contact with acidic solutions, the supply of N2 carrier gas containing Rn-220 can be switched approximately once per minute between the first Rn-220 target 205a and the second Rn-220 target 205b to replenish the Rn-220 supply. However, in some embodiments, only a single Rn-220 target 205 may be used. In other embodiments, the N2 carrier gas flow can be switched between Rn-220 targets 205 at longer intervals (such as 2 or 3 minutes). In yet another embodiment, the N2 carrier gas flow can be switched between Rn-220 targets 205 every 10 minutes. Since Rn-220 has a half-life of 55.6 seconds, 10 minutes provides approximately 10 Rn-220 half-lives, which provides sufficient time for Rn-220 to decay almost completely into Pb-212. While one container waits for 10 minutes, the Rn-220 stream flows to the second Rn-220 target container for another 10 minutes. At the end of the 10 minutes, the outlet valve of the second Rn-220 target container opens, venting N2 gas and preparing for the next cycle. At this time, the outlet valve on the first Rn-220 target closes for 10 minutes. This oscillating cycle continues until the desired amount of Pb-212 is collected in each Rn-220 target container. This oscillating cycle, the residence time (i.e., the time between capture and release), the volume that each container can hold, and the number of containers can be varied according to process requirements.In some exemplary embodiments, the automatic filling system of the device controlled by control system 210 can alternately perform the following operations: filling a first Rn-220 target 205, waiting 10 minutes for 10 Rn-220 half-lives to pass, during which time filling a second Rn-220 target 205, returning to filling the first Rn-220 target 205 after 10 minutes since the last filling of the first Rn-220 target 205, and then returning to filling the second Rn-220 target 205 after 10 minutes since the last filling of the second Rn-220 container, alternating between filling containers and waiting, until control system 210 determines that the Rn-220 target 205 contains the desired amount of Pb-212 based on the flow rate, Rn-220 target 205 volume, number of oscillations, and waiting time. At this point, the resulting Pb-212 solution can be emptied from one of the Rn-220 target containers (e.g., 205a). In some embodiments, the process can be automated and can be performed by a control system 210 that can be implemented using an information processing system. For example, the automated control system may include a multi-way valve 209 controlled by the control system 210, operable to switch between filling the first and second Rn-220 targets 205a, 205b upon receiving a command from the control system 210. Pb-212 dissolved in the HCl solution can then be removed from the Rn-220 target container as needed. Separation of Pb-212 from the HCl solution can be accomplished by methods known to those skilled in the art who benefit from this disclosure.

[0048] In other embodiments, one or more Rn-220 targets can be filled based on a known flow rate of the carrier gas (e.g., measured by a mass flow meter on the carrier gas supply 203) and a pressure measured in each Rn-220 target (e.g., by a pressure sensor located within each Rn-220 target). After the Rn-220 targets have been filled to a predetermined pressure or a predetermined amount of carrier gas based on the mass flow rate of the carrier gas supply, the control system 210 may instruct a multi-way valve to begin filling a second Rn-220 target, followed by a third Rn-220 target, and so on. Any number of Rn-220 targets can be used depending on the production needs of the apparatus.

[0049] As a non-limiting exemplary example, an Rn-220 target 205 with a volume of 200 mL can be filled at a rate of 20 mL / min, requiring 10 minutes to fill. Once the first Rn-220 container (e.g., 205a) is filled, the device begins filling a second Rn-220 container (e.g., 205b) at a rate of 20 mL / min, also requiring 10 minutes to fill. During this time, 10 Rn-220 half-lives pass through the first Rn-220 target 205. When one or two Rn-220 targets 205 are emptied (e.g., as required based on a decision by control system 210), the system will stop filling the Rn-220 target 205 with N2 carrier gas until the emptied container is filled with acid, and then the process continues. Depending on the size of the radioactive source 300 and the flow rate of the N2 carrier gas, three, four, or more Rn-220 target containers 205 can be combined. Figure 1 In the apparatus, sequential alternating filling is used. In some embodiments, the Rn-220 targets may have different volumes from each other. It will be apparent to those skilled in the art that any volume, time, temperature, and flow rate described herein are illustrative and non-limiting. For example, larger or smaller containers, longer or shorter filling times, and higher or lower flow rates may be used depending on the needs of Pb-212 production.

[0050] In another embodiment, as described above, the Rn-220 target 205 may contain uncooled acid or an aqueous solution. In such an uncooled system, Rn-220 dissolves directly into the solution and therefore must undergo 10 half-lives to provide sufficient time for the Rn-220 isotope to completely decay before being transferred to the next Rn-220 target 205 in series.

[0051] In another embodiment, system 200 may include two or more Rn-220 targets 205. For example, the system may include three, four, five or more Rn-220 targets. In such a system, the supply of Rn-220 containing N2 carrier gas can be periodically circulated among the Rn-220 targets while Pb-212 is extracted from other unsupplyed Rn-220 targets.

[0052] In embodiments where the solution within the Rn-220 target 205 is cooled to below the freezing point of Rn-220, for example, when the solution is cooled to -82°C, this helps Rn-220 remain in the liquid phase while decaying into Pb-212. At this temperature, Rn-220 remains in the liquid phase within the refrigerated acid and will leave the Rn-220 target 205 by evaporation or gas diffusion, regardless of whether it is oscillatingly filled with Rn-220 containing N2 carrier gas from the Rn-220 target 205. During oscillating filling, while one target is filled with N2 carrier gas to deliver Rn-220, another container stores Rn-220 and N2 gas until the temperature of the container contents (i.e., the liquid and gas contained within the Rn-220 target 205) reaches a temperature as low as or lower than the freezing point of Rn-220. At this temperature, Rn-220 is in liquid form (e.g., when cooled with refrigerating acid to or below the freezing point of Rn-220 but above the freezing point of the acid, Rn-220 forms a miscible liquid with the acid), and when the outlet valve is opened, only N2 gas will leave the Rn-220 target 205. This oscillating filling process can continue until the desired amount of Pb-212 is obtained.

[0053] Regardless of whether the solution in the Rn-220 target 205 is cooled, when Rn-220 decays, it decays into Po-216 with a half-life of only 0.145 seconds, and then into Pb-212. The energy of Po-216 decaying into Pb-212 is extremely high, resulting in a significant velocity of Pb-212 ions. This is well known to those skilled in the art and is referred to as the recoil effect. These velocities are high enough that, in previous methods using solid Rn-220 targets (such as ion exchange resins and urea), some Pb-212 atoms become embedded in the surface of the solid Rn-220 target material, thereby reducing the Pb-212 yield. In the liquid-filled Rn-220 target container described herein, the decay of Po-216 into Pb-212 occurs in the liquid medium. The liquid solution modulates the velocity of the Pb-212 atoms, resulting in a higher Pb-212 yield than before.

[0054] In the above embodiments, the Rn-220 target 205 contains a solid Rn-220 target surface (such as zeolite, metal zeolite-type chalcogenides, or tin-rich germanium material), and the Rn-220 target 205 may contain nozzles to spray acid or buffer solutions (such as the HCl solution described above) onto the walls of the Rn-220 target 205. A spray nozzle located at the top of the Rn-220 target 205 may be configured to spray a small amount of liquid solution (such as HCl solution) onto the side surface of the Rn-220 target 205, forming a thin film of liquid solution on the side surface of the Rn-220 target 205. Such a spray nozzle may include atomizing or fine mist nozzles suitable for any such application, as will be apparent to those skilled in the art who benefit from this disclosure, and may be supplied by, for example, a pump from the control system 210. The thin liquid film provides sufficient liquid to any Pb-212 atoms generated, thereby mitigating the recoil effect and loss of Pb-212 onto the surface of the Rn-220 target 205.

[0055] In some embodiments, the Rn-220 target 205 may include a distributor or bubbler device and a conical target material. When the Rn-220 target is supplied with N2 carrier gas and filled with acid, the distributor or bubbler device is operable to generate a plurality of small N2 carrier gas bubbles, thereby increasing the surface area of ​​the N2 carrier gas in the Rn-220 target and enhancing the transfer of Rn-220 from the N2 carrier gas to the solvent (acid) within the Rn-220 target. The Rn-220 target 205 may include an inlet port for supplying the N2 carrier gas to Rn-220 and an outlet port for releasing N2 free of Rn-220. The piping and valve arrangement may be operated by software that provides an arrangement sequence such that oscillations occur between the Rn-220 targets 205 to capture Rn-220 and provide sufficient time for Rn-220 to completely decay into Pb-212 in the aforementioned medium (e.g., in an aqueous solution or a spray solution through a nozzle). In some embodiments, the software may be implemented using an information processing system of the control system 210.

[0056] Figure 5 This is an exploded perspective view of an apparatus for producing and separating Pb-212 according to certain exemplary embodiments. In some embodiments, Figure 5 The device can be used in conjunction with the method described in this article. Figure 1 block diagram and Figure 2 The apparatus described in the exemplary embodiment operates in essentially the same manner. Figure 5 The device includes a control unit 501, which may include or be in communication with an information processing system (not shown), and is operable to control... Figure 5 The device's flow rate, temperature, valve circulation, and other aspects are monitored. The distribution system 502 can be connected to the control system 501 and is operable to distribute the aqueous solution to... Figure 5The device is used in various units. For example, the dispensing system 502 can be operated to dispense an aqueous solution, such as an HCl solution, into RN-220 targets 520 and 521. The dispensing system can also dispense a fractional Pb-212 solution from RN-220 targets 520 or 521 independently or upon receiving instructions from the control system 501. In some embodiments, the dispensing system 502 may be contained within the same housing as the control system 501. As will be understood by those skilled in the art who will benefit from this disclosure, the control system 1 may be connected to any one or more sensors, control valves, coolers, heaters described herein, and is operable to process information obtained from such sensors and provide control output signals to control valves, heaters, coolers, alarms, etc.

[0057] The N2 carrier gas supply 503 may include a mass flow meter and a mass flow inlet valve 504 to control the N2 carrier gas flow to the radiation source 506. The radiation source 506 may also be connected to a Th-228 supply 526, which may be connected to or otherwise controlled by a control system 501 to deliver Th-228 dissolved in an aqueous solution to the radiation source 506. The radiation source 506 may comprise a high surface area material, such as a composite material. Figure 3 , 4 As described in section 6, residence of Th-228 is provided within the radioactive source 506. The radioactive source 506 may also include a heat source 507, as described herein, to provide heat for evaporating any solvent used to deliver Th-228 to the radioactive source 506. This evaporated solvent may exit the radioactive source 506 and flow through an evaporation outlet valve port 511, a Peltier cooler 517 (which operates to condense the evaporated solvent), and into a condenser flask 525.

[0058] As described above, the Th-228 contained in the radioactive source 506 undergoes radioactive decay within the source 506, continuously decaying into Rn-220. To shield against radiation emitted by the radioactive decay of Th-228, the radioactive source 506 is enclosed within a lead shield 528, which is of sufficient thickness to block radiation generated by the radioactive decay of Th-228 and the radioactive decay of isotopes produced by this decay. Furthermore, the lead shield 528 is located within a stainless steel shield 527, which provides additional radiation shielding and a corrosion-resistant outer casing for the radioactive source 506.

[0059] Since Rn-220 is generated from the decay of Th-228, it is delivered from the radioactive source 506 by a flow of N2 carrier gas through an N2 carrier gas outlet valve 514, an ultra-high purity gas filter 515, and an inlet valve 516 to Rn-220 targets 520 and 521. The gas filter 515 can remove impurities, such as small particles or Th-228 particles detached from the high surface area material of the radioactive source 506, from the Rn-220 flow containing N2 carrier gas. The inlet valve 516 can be connected to the control system 501 and can be operated to direct the N2 carrier gas flow to Rn-220 target 520 or Rn-220 target 521. As described herein, in some embodiments, the inlet valve 516 can be operated to periodically circulate the N2 carrier gas flow between Rn-220 target 520 and Rn-220 target 521.

[0060] Liquid supply 518 is fluidly connected to Rn-220 targets 520 and 521 via a multi-way valve 519. Liquid supply 518 may be connected to and / or controlled by a control system 501 and is operable to provide a liquid supply (such as a water-soluble HCl solution as described herein) to Rn-220 targets 520 and / or Rn-220 targets 521. Multi-way valve 519 is operable to periodically circulate the liquid supply flow between Rn-220 targets 520 and Rn-220 targets 521. Rn-220 targets 520 and 521 are located within a cooling bath 522. Cooling bath 522 may be any temperature control unit / system, cooler, or heat exchanger known in the art and is operable to cool Rn-220 targets 520 and 521 and their contents to a temperature sufficient to freeze the Rn-220 supplied to Rn-220 targets 520 and 521. For example, in a particular embodiment, cooling bath 522 is operable to cool the contents of Rn-220 targets 520 and 521 to -82°C. The temperature of the cooling bath may depend on and be related to the freezing point of the acid type and its molar concentration. Cooling bath 522 is located within a lead shield of cooling bath 529. The lead shield for cooling bath 529 may be of sufficient thickness to block radiation generated by the decay of Rn-220 within Rn-220 targets 520 and 521 into Pb-212. As described above, after the Rn-220 collected in Rn-220 or Rn-220 target 520 or Rn-220 target 521 has decayed into Pb-212, an aqueous solution containing Pb-212 may be removed from Rn-220 or Rn-220 target 520 or Rn-220 target 521, through a multi-way valve 519, and into Pb-212 collection container 523. Rn-220 target 520 or Rn-220 target 521 is also connected to rinse bottle 524. Rinse bottle 524 can collect any liquid supplied through Rn-220 target 520 or Rn-220 target 521 for use in... Figure 5 The target container is flushed before Rn-220 is introduced during operation of the apparatus shown.

[0061] Figure 5 The device also includes a PTFE sealed chamber 530. The PTFE sealed chamber 530 may be made of PTFE or any other impermeable, non-reactive polymer or material. The PTFE sealed chamber 530 is configured to be sealed and contains the radioactive source 506. In some embodiments, the PTFE sealed chamber 530 may have an air inlet and an outlet, wherein the outlet is connected to an exhaust system. Even if the radioactive source 506 leaks, the PTFE sealed chamber 530 can contain the leak and ensure that any leaked Rn-220 / carrier gas is discharged through the exhaust system. Such an exhaust system may include a charcoal or other high surface area material filter operable to adsorb any Rn-220 in the event of a leak in the radioactive source 506. The exhaust system may also be connected to an air compression system (ACS) that collects the radioactive gas, compresses it, and releases it according to the active half-life.

[0062] at last, Figure 5 The device has safety ball valves 505, 508, 509, 510, 512, and 513 on each of its supply and outlet lines. These safety ball valves are operable to shut off flow in the line, thereby isolating the pipe. Figure 5 These are components of the device. Isolating these components can be used for maintenance, such as cleaning or replacing parts. In some embodiments, safety ball valves 505, 508, 509, 510, 512, and 513 are operable to receive signals from the control system 501 indicating that the device is open or closed, and are operable to return to a safe position if communication from the control system 501 is lost (e.g., "fail-safe" operation).

[0063] According to some embodiments, Figure 6 Provided as described in this article Figure 5 A close-up schematic diagram of the radioactive source 506. Figure 6 The radioactive source 600 has an upper plate 601 and a lower plate 602, which includes fluid distribution fins 603 and a fluid distribution plate 604 and has inlet and outlet ports for supplying N2 carrier gas, Th-228, and solvent evaporation. The upper plate 601 and lower plate 602 can be joined together in a manner sufficient to form a seal between the two plates, sufficient to prevent N2 carrier gas or any evaporated solvent from leaving between the plates. For example, the upper plate 601 and lower plate 602 can be welded together at chamfered joints 618 and 619. Other methods of joining the upper plate 601 and lower plate 602 will be apparent to those skilled in the art who benefit from this disclosure.

[0064] The fluid distribution fins 603 and fluid distribution plate 604 can be made of any high surface area (i.e., porous) material described herein. The fluid distribution fins 603 may comprise a plurality of closely spaced fins to provide a flow path for N2 carrier gas through the high surface area material fins of the fluid distribution fins 603. As described herein, these fins made of high surface area material absorb Th-228 introduced into the radioactive source and provide residence for Th-228 until it decays into Rn-220, at which point it is transported out of the radioactive source by the N2 carrier gas.

[0065] The lower plate 602 has a carrier gas inlet port 605 operable to provide a carrier gas inlet, an inlet closure safety and transport plug 606, an outlet port 607 operable to provide an outlet for carrier gas from the radioactive source, an outlet closure safety and transport plug 608, maintenance plugs 609 and 610, a focusing outlet chamber 615, a main chamber 616, and an inlet carrier gas distribution chamber 617. The upper plate 601 has a carrier gas blade 613, an exhaust chamber 614, an exhaust port 612 operable to provide an outlet for evaporated solvent, and an exhaust closure safety and transport plug 611. The main chamber 616 provides a housing for the fluid distribution plate 604 and the fluid distribution fins 603. The upper plate 601 and the lower plate 602 can be made of any non-reactive metal (such as titanium, zirconium, gold, platinum, iridium, tungsten) and a non-reactive alloy (such as Monel alloy or ferrochrome alloy).

[0066] During the operation, Th-228 in the solution can be introduced into... Figure 6 In the radioactive source. For example, through N2 carrier gas inlet port 605. As mentioned above, the introduction of Th-228 into the radioactive source occurs only periodically, for example, once a year. After the Th-228 solution is introduced, it can be, for example, through... Figure 5 The heat source 507 provides heat to the radiation source 506 to evaporate any solvent. The evaporated solvent can flow out of the radiation source through the exhaust chamber 614 and the exhaust port 612.

[0067] Next, the N2 carrier gas flow is introduced into the radiation source 506 through the N2 carrier gas inlet port 605. In some embodiments, the N2 carrier gas flow can be introduced into the radiation source while the fluid distribution fins are still “wet,” for example, before all the solvent carrying Th-228 has evaporated. In other embodiments, the N2 carrier gas flow can be introduced into the radiation source 606 after the fluid distribution fins have “dried,” for example, after all or substantially all of the solvent carrying Th-228 has evaporated. The N2 carrier gas flow is guided across the fins of the fluid distribution fins 603 by the inlet carrier gas distribution chamber 617, the fluid distribution plate 604, and the carrier gas blades 613, and flows to the focusing outlet chamber 615 before leaving the radiation source through the outlet port 607. The carrier gas blades 613 are operable to guide and distribute the incoming N2 carrier gas flow across the fluid distribution fins 603 and the fluid distribution plate 604 to ensure a uniform and homogeneous distribution of the gas flow through the radiation source 506. As described above, the N2 carrier gas flow through the fluid distribution fin 603 transports the Rn-220 formed by the radioactive decay of Th-228 absorbed onto the material of the fluid distribution fin 603 from the radioactive source.

[0068] Figure 6 Safety plugs 606, 608, and 611 of the radioactive source 600 are operable to isolate the interior of the radioactive source from the external environment. Because Th-228 has a half-life of 1.91 years, after Th-228 is introduced into the radioactive source 600, the interior of the source 600 can remain radioactive for a considerable period (e.g., 10 half-lives of Th-228). Therefore, it is important to be able to isolate the interior of the radioactive source, for example, if the source needs to be moved or maintenance is required, to ensure that radioactive material does not escape from the source.

[0069] As described above, in some embodiments, Figure 1 , 2 The device and 5 can be operated by an automatic control system. In some exemplary embodiments, the automatic control system can be implemented using an information processing system. Such a system can be based on a device placed... Figure 1 An automated system uses one or more sensors located throughout the device to automatically control multiple different system variables, such as flow rate, time, and temperature. For example, an automated system can automatically control multiple different system variables by executing... Figure 8 Method 1000 is used to operate the apparatus disclosed herein to produce Pb-212. First, in step 1001, Th-228 is introduced into a radiation chamber 202 containing a radioactive source 300, which includes the components described above. Figure 1-6The high surface area material is described above. Next, in step 1002, a carrier gas comprising nitrogen is supplied to the radiation chamber 202. As described above, the automated system can control the flow rate of the carrier gas based on a measured mass flow rate. Next, in step 1003, after flowing through the radiation chamber 202, the carrier gas is introduced into a pre-cooled hydrochloric acid solution or any other acid or aqueous solution. Finally, in step 1004, Pb-212 is separated from the hydrochloric acid solution. As described above, the pre-cooled hydrochloric acid solution may have a temperature of -72°C or lower and may contain a target operable to collect Rn-220.

[0070] The specific embodiments disclosed above are merely illustrative, as the disclosed subject matter can be modified and practiced in different but equivalent ways that will be apparent to those skilled in the art who have benefited from the teachings herein. Furthermore, no limitation is intended to be made on the details of the constructions or designs shown herein other than those described in the following claims. Therefore, it is apparent that the specific embodiments disclosed above can be changed or modified, and all such changes are considered to be within the scope and spirit of the subject matter of this disclosure. Therefore, the protection sought herein is set forth in the following claims.

Claims

1. A method for producing Pb-212 isotopes, comprising: introducing Th-228 into a radio box, wherein the radio box comprises a radio source comprising a high surface area material; introducing a carrier gas into the radio box through a carrier gas supply, wherein the carrier gas is an inert gas, the carrier gas flows through the radio box, the Th-228 decays into Rn-220 within the radio box, the Rn-220 produced by the decay of the Th-228 in the radio box is transported to one or more Rn-220 targets through a multi-way valve connected to a carrier gas outlet port of the radio box; separating the Rn-220 from the carrier gas in the one or more Rn-220 targets; directing the carrier gas out of the one or more Rn-220 targets through a carrier gas exhaust port; directing a liquid into the one or more Rn-220 targets through a liquid supply; subjecting the Rn-220 to radioactive decay into Pb-212 isotopes within the one or more Rn-220 targets, wherein the liquid dissolves the Pb-212 isotopes produced by the radioactive decay of Rn-220 within the one or more Rn-220 targets; directing the liquid containing the Pb-212 isotopes from the one or more Rn-220 targets to a Pb-212 collection vessel; and separating the Pb-212 isotopes from the liquid, wherein separating the Rn-220 from the carrier gas in the one or more Rn-220 targets comprises contacting the carrier gas with the liquid within the one or more Rn-220 targets until the Rn-220 has transferred from the carrier gas to the liquid, the liquid is an acidic solution selected from the group consisting of HC1 or HN03, and the liquid is cooled to a temperature of -72 °C or lower by a cooling unit connected to the one or more Rn-220 targets.

2. The method of claim 1, wherein the carrier gas is nitrogen gas.

3. The method of claim 1, wherein the flow of the carrier gas through the radio box is controlled based on mass flow.

4. The method of claim 1, further comprising: directing the carrier gas to a first Rn-220 target through the multi-way valve connected to the carrier gas outlet port of the radio box for a first time period; opening a first carrier gas exhaust port on the first Rn-220 target after the first time period ends; and directing the carrier gas to a second Rn-220 target through the multi-way valve connected to the carrier gas outlet port of the radio box for a second time period after the first time period ends.

5. The method of claim 1, wherein the high surface area material comprises a porous metal or a porous ceramic material having a surface area between about 1 m 2 and 100,000 m 2 .

6. The method of claim 5, wherein the porous metal comprises titanium, zirconium, gold, platinum, iridium, tungsten, or a combination thereof.

7. The method of claim 1, wherein the one or more Rn-220 targets comprise a zeolite or a metal chalcogenide having a zeolite-like structure.

8. A method for producing Pb-212 isotopes, comprising: introducing Ra-224 into a radio box, wherein the radio box comprises a radio source comprising a high surface area material; introducing a carrier gas into the radio box through a carrier gas supply, wherein the carrier gas is an inert gas, the carrier gas flows through the radio box, the Ra-224 decays into Rn-220 within the radio box, the Rn-220 produced by the decay of the Ra-224 in the radio box is transported by a multi-way valve connected to a carrier gas outlet port of the radio box to one or more Rn-220 targets; separating the Rn-220 from the carrier gas in the one or more Rn-220 targets; conducting the carrier gas out of the one or more Rn-220 targets through a carrier gas exhaust port; conducting a liquid into the one or more Rn-220 targets through a liquid supply; subjecting the Rn-220 to radioactive decay into Pb-212 isotopes within the one or more Rn-220 targets, wherein the liquid dissolves the Pb-212 isotopes produced by the radioactive decay of Rn-220 within the one or more Rn-220 targets; conducting the liquid containing the Pb-212 isotopes from the one or more Rn-220 targets to a Pb-212 collection vessel; and separating the Pb-212 isotopes from the liquid, wherein separating the Rn-220 from the carrier gas in the one or more Rn-220 targets comprises contacting the carrier gas with the liquid within the one or more Rn-220 targets until the Rn-220 has transferred from the carrier gas to the liquid, the liquid is an acidic solution selected from the group consisting of HC1 or HN03, and the liquid is cooled to a temperature of -72°C or lower by a cooling unit connected to the one or more Rn-220 targets.

9. The method of claim 8, wherein the carrier gas is nitrogen.

10. The method of claim 8, wherein the flow of the carrier gas through the radio box is controlled based on mass flow.

11. The method of claim 8, further comprising: conducting the carrier gas to a first Rn-220 target through the multi-way valve connected to the carrier gas outlet port of the radio box for a first time period; opening a first carrier gas exhaust port on the first Rn-220 target after the first time period ends; and conducting the carrier gas to a second Rn-220 target through the multi-way valve connected to the carrier gas outlet port of the radio box for a second time period after the first time period ends.

12. The method of claim 8, wherein the high surface area material comprises a porous metal or a porous ceramic material having a surface area between about 1 m 2 and 100,000 m 2 .

13. The method of claim 12, wherein the porous metal comprises titanium, zirconium, gold, platinum, iridium, tungsten, or a combination thereof.

14. The method of claim 8, wherein the one or more Rn-220 targets comprise a zeolite or a metal chalcogenide having a zeolite-like structure.

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