Continuous target system and method for radioisotope production.

Abstract

In some embodiments, provided herein are apparatuses and methods useful for producing radioisotopes. In some embodiments, a system for producing radioisotopes includes a high-energy photon source configured to emit photons, a first target positioned behind the photon source and configured to be illuminated by the photons, and a second target positioned behind the first target and configured to be illuminated by the photons, the second target being a different material than the first target.

Description

[Technical Field]

[0001] Priority claims This disclosure claims priority to and the benefit of U.S. Provisional Application No. 63 / 383,622, filed November 14, 2022, the contents of which are incorporated herein by reference in their entirety.

[0002] TECHNICAL FIELD The present disclosure relates generally to radioisotope production, and more particularly to systems and methods for radioisotope production. [Background technology]

[0003] The production of radioisotopes is valuable for many applications, such as the medical industry. Currently, most radioisotope production systems operate by irradiating a target with a radioactive source, such as a nuclear reactor or accelerator. As expected, such equipment and the ultimate production of the radioisotope are expensive and complex. In some current systems, the "source radiation" (i.e., the radiation produced by the radioactive source) is typically underutilized (i.e., not used as effectively and / or efficiently as possible). For example, once the radiation penetrates or passes through the target, it is no longer used in the production of radioisotopes. Because the systems and the actual production are expensive, there is a need to develop improved systems and methods that are more cost-effective and / or efficient. [Brief explanation of the drawings]

[0004] Disclosed herein are embodiments of systems, apparatus, and methods for producing radioisotopes. This description includes the following drawings:

[0005] [Figure 1] FIG. 1 is a block diagram of a system 100 for producing a radioisotope 118 using a continuous target, according to some embodiments.

[0006] [Figure 2]FIG. 2 is a block diagram of a system 200 for producing a radioisotope 218 using a continuous target, according to some embodiments.

[0007] [Figure 3A] FIG. 3A illustrates an example of a continuous target arrangement according to some embodiments. [Figure 3B] FIG. 3B illustrates an example of a continuous target arrangement according to some embodiments. [Figure 3C] FIG. 3C illustrates an example of a continuous target arrangement according to some embodiments.

[0008] [Figure 4] FIG. 4 shows examples of the types of materials and radioisotopes that may be produced using a continuous target 400, according to some embodiments.

[0009] [Figure 5] FIG. 5 is a flowchart illustrating example operations for producing a radioisotope, according to some embodiments.

[0010] Elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the size and / or relative location of some elements in the figures may be exaggerated relative to other elements to aid in understanding various embodiments of the present disclosure. Also, common and well-understood elements that are useful or necessary in commercially feasible embodiments are often not shown to reduce an obscured view of these various embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Generally speaking, in various embodiments, provided herein are systems, devices, and methods useful for producing radioisotopes. In some embodiments, a system for producing a radioisotope includes a high-energy photon source configured to emit photons, a first target positioned behind the photon source and configured to be illuminated by the photons, and a second target positioned behind the first target and configured to be illuminated by the photons, the second target being a different material than the first target.

[0012] As mentioned above, radioisotopes are used in a variety of fields. One such field is medicine. For example, radioisotopes can be used in medical imaging and therapy. Despite the wide range of uses for radioisotopes, the equipment required to produce them and the actual production of radioisotopes are expensive and complex.

[0013] A typical high-energy photon system for producing radioisotopes includes a single target that is irradiated. Irradiating the target converts a small portion of the target's atomic nuclei into a radioactive form that can be collected. As the radiation passes through the target, it loses energy and intensity. Once the radiation has passed through the target, it is no longer used to produce radioisotopes. Although the radiation that has passed through the target is not used to produce radioisotopes, it may still be useful for irradiating additional targets (e.g., to produce different radioisotopes), whether they are the same as the previous target or targets with different properties.

[0014] Described herein are systems, methods, and apparatus that aim to at least minimize, if not eliminate, some of the shortcomings of current systems. In one embodiment, a system for producing radioisotopes includes multiple targets arranged serially (i.e., in a target stack). For example, the targets can be arranged one behind the other. In such a system, radiation can be applied to not only the first target but also subsequent targets, making more efficient use of the energy of the radiation source. Simply put, arranging targets serially makes more efficient use of the generated radiation than systems including only a single target. This allows for the production of a larger number of radioisotopes than when using a single target, improving the overall efficiency of the system. Figure 1 shows an overview of such a system.

[0015] FIG. 1 is a block diagram of a system 100 for producing radioisotopes 118 using a continuous target, according to some embodiments. The system 100 includes an electron beam source 102, a converter 114, and a target. The electron beam source 102 is configured to emit an electron beam 104 and can be of any suitable type. For example, the electron beam source 102 can be a linear accelerator, a microtron, a roadtron, or the like. The converter 114 is configured to receive the radiation 104 and emit photons 116. The converter can be of any type suitable for emitting photons. For example, the converter 114 can be a converter plate or series of plates (e.g., a bremsstrahlung converter), a gas, a liquid, a solid, or the like. In one embodiment, the photons 116 emitted by the converter 114 are high-energy photons (i.e., photons with an energy of 10 MeV or greater). Accordingly, the radiation source 102 and the converter 114 can be selected to achieve the production of such photons.

[0016] Located after the converter 114 (i.e., downstream with respect to the emission of radiation 104 and / or photons 116) is a target (i.e., target stack). As shown in Figure 1, there are N targets in the target stack: 1) first target 106, 2) second target 108, ... N) Nth target 110. As indicated by the Nth target 110, the system may be adapted for use with any suitable number of targets.

[0017] Further, as shown in FIG. 1 , each subsequent target is located behind (i.e., downstream with respect to the flow of radiation 104 and / or photons 116) the previous target. For example, as shown in FIG. 1 , the second target 108 is located behind the first target 106 and ahead of the Nth target 110. As each target in the target stack is illuminated by photons, a photonuclear reaction occurs in at least some of the target's atomic nuclei. The photonuclear reaction causes the removal of protons, neutrons, and / or other particles from the atomic nuclei, resulting in the production of radioisotopes 118 within the target. In embodiments in which the targets are of different types (i.e., different materials), each target may produce a different radioisotope 118.

[0018] Although not shown in FIG. 1 , in some embodiments, system 100 also includes a collection device. The collection device is configured to remove the target stack and / or individual targets or target materials from the system. In such embodiments, one or more of the targets can be removed before radioisotopes 118 are collected from the targets. For example, in some embodiments, one or more of the targets can be independently removed from system 100. That is, in such embodiments, one or more of the targets can be removed (i.e., collected) from system 100 without removing or otherwise disturbing the other targets. This allows, for example, one or more targets to be removed without interrupting radioisotope production at the other targets. The collection device can be of any suitable type and can include a mechanical device (e.g., a lever, arm, clamp, etc.) for removing solid targets from the target stack or a mechanical device (e.g., a valve, tube, etc.) for removing fluid (i.e., gaseous or liquid) targets. Briefly, targets and / or entire target materials can be removed from the system via the collection device. Additionally, in some embodiments, the system 100 can be designed such that one or more of the targets are individually removable from the system 100 .

[0019] The description in FIG. 1 provides an overview of a system for producing radioisotopes that includes a radiation source and a converter, while the description in FIG. 2 provides an overview of a system for producing radioisotopes that includes a photon source.

[0020] FIG. 2 is a block diagram of a system 200 for producing radioisotopes using continuous targets, according to some embodiments. The system 200 includes a radiation source 202 and a target. The radiation source 202 is configured to emit radiation 204. In some embodiments, the radiation source 202 can directly emit photons (e.g., high-energy photons). In such embodiments, the radiation source 202 can be, for example, a laser backscattering system (e.g., a Compton laser backscattering system). Alternatively, the radiation source 202 can emit an electron beam. In such embodiments, the radiation source 202 can be, for example, a linear accelerator, a microtron, a roadtron, or the like. In such embodiments, one or more targets in the target stack can function as a converter and emit photons as a result of an incident electron beam.

[0021] Located behind the radiation source 202 (i.e., downstream with respect to the emission of photons 204) is a target (i.e., target stack). As shown in Figure 2, there are a total of N targets: 1) first target 206, 2) second target 208, ... N) Nth target 212. As shown by Nth target 210, the system can be adapted for use with any suitable number of targets.

[0022] Further, as shown in FIG. 2 , each subsequent target is positioned behind (i.e., downstream with respect to the flow of photons 204) the previous target. For example, as shown in FIG. 2 , the second target 208 is positioned behind the first target 206 and ahead of the Nth target 210. As each target in the target stack is illuminated by photons, a photonuclear reaction occurs in at least some of the target's atomic nuclei. The photonuclear reaction causes the removal of protons, neutrons, and / or other particles from the atomic nuclei, resulting in the production of radioisotopes 218 within the target. In embodiments in which the targets are of different types (i.e., different materials), each target may produce a different radioisotope 218. Unlike the system shown in FIG. 1 , system 200 does not include a converter. Instead, the first target 206 (and possibly one or more of the subsequent targets) can function as a converter by generating photons when illuminated. Thus, the first target 206 can produce both photons (e.g., high-energy photons) and radioisotopes 218. In such embodiments, it may be beneficial to use as the target material for the first target 206 a material that has a high proportion of components with high atomic numbers (eg, heavy metals).

[0023] Although not shown in FIG. 2 , in some embodiments, system 200 also includes a collection device. The collection device is configured to remove the target stack and / or individual targets from the system. In such embodiments, one or more of the targets can be removed before radioisotopes 218 are collected from the targets. For example, in some embodiments, one or more of the targets can be independently removed from system 100. That is, in such embodiments, one or more of the targets can be removed (i.e., recovered) from system 100 without removing or otherwise disturbing the other targets. This allows, for example, removal of one or more targets without interrupting radioisotope production at the other targets. The collection device can be of any suitable type and can include a mechanical device (e.g., a lever, arm, clamp, etc.) for removing solid targets from the target stack or a mechanical device (e.g., a valve, tube, etc.) for removing fluid (i.e., gaseous or liquid) targets. Briefly, targets and / or the entire target material can be removed from the system via the collection device. Additionally, in some embodiments, the system 200 can be designed such that one or more of the targets are individually removable from the system 200 .

[0024] The description in Figures 1 and 2 provides an overview of the system for producing radioisotopes, while the description in Figures 3A-3C provides more details about the placement of the target.

[0025] 3A-3C illustrate example sequential target arrangements according to some embodiments. FIG. 3A illustrates a stacked configuration of targets. As shown in FIG. 3A, target stack 300 includes five targets: 1) first target 302; 2) second target 304; 3) third target 306; 4) fourth target 308; and 5) fifth target 310. While the example shown in FIG. 3A includes five targets, embodiments are not so limited. For example, target stack 300 can include more or fewer than five targets. Each target (except for first target 302 and last target 310) is positioned between the targets before and after it. For example, third target 306 is positioned between second target 304 and fourth target 308. As previously mentioned, with respect to direction, the terms "rear" and "forward" (and similar terms) are used to refer to the flow of photons and / or radiation within the system.

[0026] FIG. 3B illustrates a nested target configuration. As shown in FIG. 3B, target stack 320 includes four targets: 1) first target 322; 2) second target 324; 3) third target 326; and 4) fourth target 328. While the example shown in FIG. 3B includes four targets, embodiments are not so limited. For example, target stack 320 can include more or fewer than four targets. Each target (except for first target 322 and last target 328) is positioned between the targets before and after it. For example, second target 324 is positioned between first target 322 and third target 326. Unlike the stacked configuration shown in FIG. 3A, previous targets do not completely cover the next target in target stack 320. That is, a portion of each subsequent target is not completely behind the previous target. For example, referring again to the second target 324, a portion of the second target 324 is not behind / covered by the first target 322 and therefore may be exposed to photons that have not yet contacted and / or penetrated any of the other targets in the target stack 320. Furthermore, it should be noted that the target stack 320 (or any other target stack described herein) may take any suitable shape. For example, the target stack 320 may be rectangular, spherical, circular, cylindrical, etc. As an example, FIG. 3B may show a cross-section of a cylindrical target stack.

[0027] FIG. 3C illustrates a pyramidal configuration of targets. As shown in FIG. 3C, target stack 340 includes five targets: 1) first target 342; 2) second target 344; 3) third target 346; 4) fourth target 348; and 5) fifth target 350. While the example shown in FIG. 3C includes five targets, embodiments are not so limited. For example, target stack 340 can include more or fewer than five targets. Each target (except for first target 342 and last target 350) is positioned between the targets before and after it. For example, second target 344 is positioned between first target 342 and third target 346. Unlike the stacked configuration shown in FIG. 3A, previous targets do not completely cover the next target in target stack 340. That is, a portion of each subsequent target is not completely behind the previous target. For example, with reference to the second target 344, a portion of the second target 344 is not behind / covered by the first target 342 and therefore may be exposed to photons that have not yet contacted and / or passed through any of the other targets in the target stack 340.

[0028] Although not shown in the examples provided in FIGS. 3A-3C , in some embodiments, a target stack can include one or more cooling elements. One or more cooling elements can be positioned around (above, below, between, etc.) one or more of the targets in the target stack to help dissipate heat generated by irradiation of the target stack. The cooling element can include liquid and / or gas channels to allow a cooling fluid to contact (directly and / or indirectly) one or more of the targets in the target stack. The cooling element can be part of a larger cooling system, such as a bath cooling system, an industrial blower system, a high-pressure gas system, etc. For example, the cooling element can include passages for fluid flow between the targets. Furthermore, although each target in FIGS. 3A-3C is depicted as touching adjacent targets, this need not be the case (e.g., gaps can exist between targets, targets can be contained within a housing for irradiation, etc.). Furthermore, in some embodiments, one or more of the targets can be individually removable from the target stack.

[0029] The descriptions of Figures 1-3 provide an overview of a system for producing radioisotopes and an example of a serial target arrangement, while the description of Figure 4 provides additional details regarding a specific series of targets.

[0030] FIG. 4 illustrates an example of the types of materials and radioisotopes that may be produced using a target stack 400, according to some embodiments. As shown in FIG. 4, the target stack 400 includes five targets: 1) a first target 404; 2) a second target 406; 3) a third target 408; 4) a fourth target 410; and 5) a fifth target 412. While the targets are arranged in a stacked configuration, this is not required, and the stacked configuration is used merely as an example. As shown in FIG. 4, the first target 404 is neon (e.g., naturally occurring neon), the second target 406 is copper (e.g., naturally occurring copper), the third target 408 is ruthenium-96 (e.g., enriched ruthenium-96), the fourth target 410 is zinc-68 (e.g., enriched zinc-68), and the fifth target 412 is selenium-74 (e.g., enriched selenium-74). 4, neon, copper, ruthenium, zinc, and selenium are shown as targets, but this need not be the case - any suitable number and type of targets can be used to produce the desired radioisotopes.

[0031] The target stack 400 is irradiated with photons 402 (e.g., high-energy photons). Each target in the target stack produces a different radioisotope upon irradiation. For example, as shown in Figure 4, upon irradiation, the first target 404 (i.e., neon) produces fluorine-18, the second target (i.e., copper) produces copper-64, the third target 408 (i.e., ruthenium-96) produces technetium-95, the fourth target (i.e., zinc-68) produces copper-67, and the fifth target 412 (i.e., selenium-74) produces arsenic-73.

[0032] The targets in the target stack 400 can be arranged in any suitable order. By way of example only, the targets can be arranged based on the half-life of the radioisotope produced by the target material. Such an arrangement can optimize utilization of the radiation source, particularly if the time interval between collection cycles is optimized based on the type of target. In this example, the target producing the shortest half-life radioisotope can be arranged first, followed by the target producing the second longest half-life radioisotope, and so on, until the target producing the longest half-life radioisotope is finally arranged. Furthermore, while the targets in the target stack 400 shown in FIG. 4 are depicted as having similar thicknesses, shapes, etc., this is not required. For example, different targets may have different surface areas, densities, shapes, thicknesses, etc.

[0033] Although the targets in FIG. 4 are arranged in order of the half-life of the radioisotopes produced, any suitable arrangement can be used. As another example, the targets can be arranged in order of photon absorption. For example, the targets can be arranged so that the first target has the lowest photon absorption, the second target has the second lowest photon absorption, and so on. As a third example, the targets can be arranged based on thickness and / or surface area. For example, thinner targets with larger surface areas can be placed earlier in the target stack. As a fourth example, the targets can be arranged based on type. For example, gas targets can be placed before liquid targets, which can be placed before solid targets. While some examples of target arrangements are provided herein, it should be recognized that there are many more possible target arrangements based on the desired results, and all such arrangements are contemplated herein.

[0034] While the description of Figures 1-4 provides additional details regarding a system for producing radioisotopes using a continuous target, the description of Figure 5 describes an example operation of such a system. Although the operations shown in Figure 5 are shown as occurring sequentially, this need not be the case. For example, in practice, one or more of the processes shown in Figure 5 may occur simultaneously. Furthermore, in practice, one or more of the processes shown in Figure 5 may occur in a different order than that shown in Figure 5.

[0035] 5 is a flowchart illustrating example operations for producing a radioisotope, according to some embodiments. The flow begins at block 502.

[0036] In block 502, high-energy photons are emitted. For example, the high-energy photons may be emitted by one or more of the converter and / or targets. For example, as described with respect to FIG. 1, an electron beam source may emit radiation that irradiates the converter. Irradiation of the converter generates photons that are emitted from the converter. In such an embodiment, the photons emitted by the converter are high-energy photons, and the converter (which may be in conjunction with an electron beam source) may be a source of high-energy photons. As another example, as described with respect to FIG. 2, a radiation source may emit photon radiation and / or electron radiation that irradiates one or more targets in a target stack. In such an embodiment, irradiation of one or more targets results in a photonuclear reaction in the nuclei of the one or more targets. Regardless of the source of the high-energy photons, the high-energy photons are emitted to the target stack. Flow continues at block 504.

[0037] At block 504, a first target is irradiated. For example, the first target may be irradiated with high-energy photons. As described herein, a group of targets are arranged in series to form a target stack. The target stack includes two or more targets. When the first target is irradiated with high-energy photons, a photonuclear reaction occurs within the first target. This photonuclear reaction causes a nuclear reaction within the atomic nuclei of the first target, producing a first radioisotope. It should be noted that the photonuclear reaction may produce multiple different radioisotopes within the first target. However, for ease of discussion, the photonuclear reaction will generally be described as producing a single type of radioisotope. Flow continues at block 506.

[0038] At block 506, a second target is irradiated. For example, the second target may be irradiated with high-energy photons. As previously described, the targets are arranged in a target stack containing two or more targets. When the second target is irradiated with high-energy photons, a photonuclear reaction occurs within the second target. This photonuclear reaction causes a nuclear reaction within the atomic nuclei of the second target, producing a second radioisotope. It should be noted that the photonuclear reaction may produce multiple different radioisotopes within the second target. However, for ease of discussion, the photonuclear reaction is generally described as producing a single type of radioisotope. Flow optionally continues to block 508. If optional blocks 508 and 510 are skipped, flow continues to block 512.

[0039] At block 508, the first target is recovered. For example, the first target may be recovered via a recovery device. During the recovery process, the first target and / or material from the first target is removed by the recovery device. The recovery device may be of any suitable type and may include a mechanical device (e.g., a lever, arm, clamp, etc.) for removing a solid target from the target stack or a mechanical device (e.g., a valve, tube, etc.) for removing a fluid (i.e., gas or liquid) target. In embodiments that include recovery of the first target, the first target may be recovered before the first radioisotope is collected from the first target. Flow continues to block 510.

[0040] At block 510, the second target is collected. For example, the second target can be collected via a collection device. During the collection process, the second target and / or material from the second target is removed by the collection device. The collection device can be of any suitable type and can include a mechanical device (e.g., a lever, arm, clamp, etc.) for removing a solid target from the target stack or a mechanical device (e.g., a valve, tube, etc.) for removing a fluid (i.e., gas or liquid) target. In embodiments that include collection of the second target, the second target can be collected before the second radioisotope is collected from the second target. The flow continues to block 510. At block 510, the first radioisotope is collected. For example, the first target can be irradiated with high-energy photons and then the first radioisotope can be collected from the first target. As used herein, the term “harvest” refers to any process intended to generate a useful radioisotope product from a target (e.g., by separation, purification, or fabrication (e.g., in a form and / or shape)). The first radioisotope may be collected from the first target by any suitable means. For example, depending on the type of first radioisotope and the type of first target, the first radioisotope may be collected from the first target by a chemical process (e.g., ion exchange) and / or a physical process (e.g., sublimation). Simply stated, the first radioisotope may be collected from the first target using any suitable method for processing a radioisotope from a target. Furthermore, in some embodiments, the first target is recovered from the system before the first radioisotope is collected, as shown in optional block 506. For example, the first target may be recovered by physical removal and / or isolation from the target stack before the first radioisotope is collected from the first target. Flow continues at block 512.

[0041] At block 512, the first radioisotope is collected. For example, the first radioisotope may be collected from the first target after the first target is irradiated with high-energy photons. As used herein, the term "harvest" refers to any process intended to generate a useful radioisotope product from the target (e.g., by separation, purification, or fabrication (e.g., in a form and / or shape)). The first radioisotope may be collected from the first target by any suitable means. For example, depending on the type of first radioisotope and the type of first target, the first radioisotope may be collected from the first target by a chemical process (e.g., ion exchange) and / or a physical process (e.g., sublimation). Briefly, the first radioisotope may be collected from the first target using any suitable method for processing radioisotopes from a target. Further, in some embodiments, the first target is recovered from the system before the first radioisotope is collected, as shown in optional block 508. For example, the first target may be recovered by physical removal and / or isolation from the target stack before the first radioisotope is collected from the first target. Flow continues to block 514.

[0042] At block 514, the second radioisotope is collected. For example, the second radioisotope may be collected from the second target after the second target is irradiated with high-energy photons. As used herein, the term "harvest" refers to any process intended to generate a useful radioisotope product from a target (e.g., by separation, purification, or fabrication (e.g., in a form and / or shape)). The second radioisotope may be collected from the second target by any suitable means. For example, depending on the type of second radioisotope and the type of second target, the second radioisotope may be collected from the second target by a chemical process (e.g., ion exchange) and / or a physical process (e.g., sublimation). Briefly, the second radioisotope may be collected from the second target using any suitable method for removing a radioisotope from a target. Additionally, in some embodiments, the second target is recovered from the system before the second radioisotope is collected, as shown in optional block 508. For example, the second target may be recovered by physical removal and / or isolation from the target stack before the second radioisotope is collected from the first target.

[0043] In some embodiments, a system for producing a radioisotope includes a high-energy photon source configured to emit photons, a first target located behind the photon source and configured to be illuminated by the photons, and a second target located behind the first target and configured to be illuminated by the photons, the second target being a different material than the first target.

[0044] In some embodiments, an apparatus, and corresponding method performed by the apparatus, includes emitting photons with a high-energy photon source; illuminating a first target with the photons, the first target being located behind the high-energy photon source; illuminating a second target with the photons, the second target being located behind the first target and being of a different material than the first target; collecting a first radioisotope produced in the first target; and collecting a second radioisotope produced in the second target.

[0045] In some embodiments, a system for producing radioisotopes in multiple targets includes a high-energy photon source configured to emit photons, and a plurality of targets arranged consecutively in a target stack behind the high-energy photon source, each of the plurality of targets configured to be illuminated by the photons, and at least one of the plurality of targets being a different material than other targets of the plurality of targets.

[0046] Those skilled in the art will recognize that various other modifications, variations, and combinations can be made to the above-described embodiments without departing from the scope of the present disclosure, and that such modifications, variations, and combinations should be considered within the scope of the inventive concept.

Claims

1. a high energy photon source configured to emit photons; a first target located behind the photon source and configured to be illuminated by the photons; a second target located behind the first target and configured to be illuminated by the photons, the second target being a different material than the first target; 1. A system for producing a radioisotope, comprising:

2. 10. The system of claim 1, further comprising a third target located behind the first target, configured to be illuminated by the photons, the third target being a different material than one or more of the first target and the second target.

3. The system of claim 1 , wherein the first target has a first thickness and the second target has a second thickness, the first thickness being different from the second thickness.

4. The system of claim 1 , wherein the first target and the second target are arranged in one of a nested configuration, a stacked configuration, and a pyramidal configuration.

5. The system of claim 1 , further comprising a cooling element configured to dissipate heat from one or both of the first target and the second target.

6. 10. The system of claim 1, wherein the photon source is a converter plate, the converter plate configured to emit the photons in response to an electron beam.

7. The system of claim 1 , wherein the first target and the second target are independently retrievable.

8. 2. The system of claim 1, wherein a first radioisotope is generated in the first target and a second radioisotope is generated in the second target, the first radioisotope having a first half-life and the second radioisotope having a second half-life, the second half-life being longer than the first half-life.

9. emitting photons with a high energy photon source; illuminating a first target with the photons, the first target being located behind the high-energy photon source; illuminating a second target with the photons, the second target being located behind the first target and being of a different material than the first target; collecting a first radioisotope produced in the first target; collecting a second radioisotope produced in the second target; and A method for producing a radioisotope, comprising:

10. 10. The method of claim 9, further comprising illuminating a third target with the photons, the third target being located behind the second target and being of a different material than one or more of the first target and the second target.

11. 10. The method of claim 9, wherein the first target has a first thickness and the second target has a second thickness, the first thickness being different from the second thickness.

12. 10. The method of claim 9, wherein the first target and the second target are arranged in one of a nested configuration, a stacked configuration, and a pyramidal configuration.

13. The method of claim 9 , wherein a cooling element is configured to dissipate heat from one or both of the first target and the second target.

14. 10. The method of claim 9, wherein the photon source is a converter plate, the converter plate configured to emit the photons in response to an electron beam.

15. 10. The method of claim 9, wherein the first target and the second target are independently retrievable.

16. 16. The method of claim 15, wherein the first radioisotope has a first half-life and the second radioisotope has a second half-life, the second half-life being longer than the first half-life.

17. a high energy photon source configured to emit photons; a plurality of targets disposed in a target stack behind the high-energy photon source, each of the plurality of targets configured to be illuminated by the photons, and at least one of the plurality of targets being a different material than other targets of the plurality of targets; A system for producing radioisotopes in multiple targets, comprising:

18. 20. The system of claim 17, wherein the multiple targets are arranged in one of a nested configuration, a stacked configuration, and a pyramidal configuration.

19. further comprising a plurality of cooling elements; The system of claim 1 , wherein one of the plurality of cooling elements is positioned between adjacent targets of the plurality of targets.

20. 20. The system of claim 17, wherein each target of the plurality of targets is individually removable.

Images