Isotope production target chamber including a cavity formed from a single sheet of metal foil

A target chamber and a method for manufacturing the target chamber for a radioisotope production system is provided. The target chamber includes a cavity formed from a single sheet of metal foil enclosed by a cover. The cavity configured to contain a starting liquid and receive a particle beam that is incident upon the starting liquid thereby generating radioisotopes.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates generally to isotope production systems, and more particularly to a target chamber of the isotope production system that includes a cavity formed from sheet metal.

Radioisotopes (also called radionuclides) have several applications for medical therapy, imaging, and research, as well as other applications that are not medically related. Systems that produce radioisotopes typically include a particle accelerator that generates a particle beam. The particle accelerator directs the beam toward a target material in a target chamber. In some cases, the target material is a liquid (also referred to as a starting liquid), such as enriched water. Radioisotopes are generated through a nuclear reaction when the particle beam is incident upon the starting liquid in the target chamber.

Conventionally, the target chamber is formed by milling or machining a block of metal, such as niobium, to form a cavity to contain the starting liquid. However, the milling process is inefficient, producing waste and low manufacturing yield rates based on tolerance requirements, such as for thickness, for transferring thermal heat from the target chamber to an external system.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment, a target chamber for a radioisotope production system is provided. The target chamber includes a cavity formed from a single sheet of metal foil enclosed by a cover. The cavity configured to contain a starting liquid and receive a particle beam that is incident upon the starting liquid thereby generating radioisotopes.

Optionally, the cavity is formed by mechanically punching, hydroforming or hydraulic forming a cavity form factor into the single sheet of metal foil.

In an embodiment, a method for manufacturing a target chamber is provided. The method includes, receiving a single sheet of metal foil, and punching the single sheet of metal foil to form a cavity. The cavity is configured to contain a starting liquid and receive a particle beam that is incident upon the starting liquid thereby generating radioisotopes. The method also includes coupling a cover to a lip of the cavity to enclose the cavity.

In an embodiment an isotope production system is provided. The isotope production system includes a particle accelerator configured to produce a particle beam, a target chamber having a cavity configured to receive the particle beam. The cavity formed from a single sheet of metal foil enclosed by a cover and configured to contain a starting liquid. The cavity is located so that the particle beam is incident upon the starting liquid thereby generating radioisotopes.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. To the extent that the figures illustrate diagrams of the blocks of various embodiments, the blocks are not necessarily indicative of the division between hardware or structures. Thus, for example, one or more of the blocks may be implemented in a single piece of hardware or multiple pieces of hardware. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings.

As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated, such as by stating “only a single” element or step. Furthermore, references to “one embodiment” are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.

Also, as used herein, the term “fluid” generally means any flowable medium such as liquid, gas, vapor, supercritical fluid, or combinations thereof. The term “liquid” can include a liquid medium in which a gas is dissolved and/or a bubble is present. As used herein, the term “vapor” generally means any fluid that can move and expand without restriction except for a physical boundary such as a surface or wall, and thus can include a gas phase, a gas phase in combination with a liquid phase such as a droplet (e.g., steam), supercritical fluid, or the like.

Generally, various embodiments provide a target apparatus for isotope production systems that includes a cavity within a target chamber. The target chamber includes a cavity for the bombardment of a media or starting liquid (e.g., enriched H218O water,18O2gas, enriched H216O water, or the like). A particle beam is bombarding the starting liquid resulting in an increase in pressure and thermal energy (e.g., heat) within the cavity. A cooling system may be coupled externally to the cavity to absorb thermal energy away from the cavity.

The cavity may be made of a thin sheet metal having a uniform thickness and/or a thickness within a predetermined tolerance. The thin sheet metal may comprise niobium, tantalum, stainless steel, aluminum, or the like. The cavity may be mechanically punched or formed (e.g., using hydroforming, using hydraulic forming) into the sheet metal. At least one technical effect of various embodiments include improved heat transfer from the cavity to the cooling system due to the thin wall thickness of the cavity. At least one technical effect of various embodiment include a reduction in waste material from forming the cavity compared to conventional methods of milling and/or machining the cavity from a metal block.

A target apparatus formed in accordance with various embodiments may be used in different types and configurations of isotope production systems. For example,FIG. 1is a block diagram of an isotope production system100that includes a particle accelerator102(e.g., isochronous cyclotron) having several sub-systems including an ion source system104, an electrical field system106, a magnetic field system108, and a vacuum system110. When the particle accelerator102is a type of cyclotron, charged particles may be placed within or injected into the particle accelerator102through the ion source system104. The magnetic field system108and electrical field system106generate respective fields that cooperate with one another in producing a particle beam112of the charged particles. Although in one embodiment the particle accelerator102may be a cyclotron, other embodiments may use different types of particle accelerators to provide particle beams.

Also shown inFIG. 1, the system100has an extraction system115and a target system114that includes one or more target apparatus116having respective target materials (not shown). The target system114may be positioned immediately adjacent to or spaced apart from the particle accelerator102. The target apparatus116may be, for example, the target apparatus200described in greater detail below. To generate radioisotopes, the particle beam112is directed by the particle accelerator102through the extraction system115along a beam transport path or beam passage117and into the target system114so that the particle beam112is incident upon the target material located at a corresponding production or target chamber120within the corresponding target apparatus116. When the target material is irradiated with the particle beam112, the target material may generate radioisotopes through nuclear reactions. Thermal energy may also be generated within the target chamber120.

As shown, the system100may have multiple target apparatuses116A-C with respective target chambers120A-C where target materials are located. A shifting device or system (not shown) may be used to shift the target chambers120A-C with respect to the particle beam112so that the particle beam112is incident upon a different target material for different production sessions. Alternatively, the particle accelerator102and the extraction system115may not direct the particle beam112along only one path, but may direct the particle beam112along a unique path for each different target chamber120A-C. Furthermore, the beam passage117may be substantially linear from the particle accelerator102to the target chamber120or, alternatively, the beam passage117may curve or turn at one or more points therealong. For example, magnets (not shown) positioned alongside the beam passage117may be configured to redirect the particle beam112along a different path.

Examples of isotope production systems and/or cyclotrons having one or more of the sub-systems are described in U.S. Pat. Nos. 6,392,246; 6,417,634; 6,433,495; and 7,122,966 and in U.S. Patent Application Publication Nos. 2005/0283199 and 2012/0321026. Additional examples are also provided in U.S. Pat. Nos. 5,521,469; 6,057,655; 7,466,085; and 7,476,883. Furthermore, isotope production systems and/or cyclotrons that may be used with embodiments described herein are also described in U.S. Patent Application No. 2013/0169194. The target apparatus and methods described herein may be used with these exemplary isotope production systems and/or cyclotrons as well as others.

The system100is configured to produce radioisotopes (also called radionuclides) that may be used in medical imaging, research, and therapy, but also for other applications that are not medically related, such as scientific research or analysis. When used for medical purposes, such as in Nuclear Medicine (NM) imaging or Positron Emission Tomography (PET) imaging applications, the radioisotopes may also be called tracers. By way of example, the system100may generate protons to make isotopes in liquid form, such as18F−isotopes.13N isotopes may also be generated by the system100. The target material may be a starting liquid used to make these isotopes. The starting liquid may be, for example, enriched water such as H218O water or H216O.

In some embodiments, the system100uses1H−technology and brings the charged particles to a low energy (e.g., about 9.6 MeV) with a beam current of approximately 10-1000 μA or, more particularly, approximately 10-500 μA. In particular embodiments, the system100uses1H−technology and brings the charged particles to a low energy (e.g., about 9.6 MeV) with a beam current of approximately 10-200 μA or, more particularly, approximately 10-70 μA. In such embodiments, the negative hydrogen ions are accelerated and guided through the particle accelerator102and into the extraction system115. The negative hydrogen ions may then hit a stripping foil (not shown inFIG. 1) of the extraction system115thereby removing the pair of electrons and making the particle a positive ion,1H+. However, embodiments described herein may be applicable to other types of particle accelerators and cyclotrons. For example, in alternative embodiments, the charged particles may be positive ions, such as1H+,2H−, and3He+. In such alternative embodiments, the extraction system115may include an electrostatic deflector that creates an electric field that guides the particle beam toward the target chamber120. Furthermore, in other embodiments, the beam current may be, for example, up to approximately 200 μA. The beam current could also be up to approximately 2000 μA or more.

The system100may also be configured to accelerate the charged particles to a predetermined energy level. For example, some embodiments described herein accelerate the charged particles to an energy of approximately 18 MeV or less. In other embodiments, the system100accelerates the charged particles to an energy of approximately 16.5 MeV or less. However, embodiments describe herein may also have an energy above 16.5 MeV. For example, embodiments may have an energy above 100 MeV, 500 MeV or more.

The system100may produce the isotopes in approximate amounts or batches, such as individual doses for use in medical imaging or therapy. Accordingly, isotopes having different levels of activity may be provided.

The system100may include a cooling system122that transports a cooling or working fluid to various components of the different systems in order to absorb heat generated by the respective components. The system100may also include a control system118that may be used by a technician to control the operation of the various systems and components. The control system118may include one or more user-interfaces that are located proximate to or remotely from the particle accelerator102and the target system114. Although not shown inFIG. 1, the system100may also include one or more radiation and/or magnetic shields for the particle accelerator102and the target system114.

FIG. 2is an exploded perspective view of the target apparatus200illustrating various components that may be assembled together to form the target apparatus200. However, the components shown and described herein are only exemplary and the target apparatus may be constructed according to other configurations. For example, some of the components may be combined into a single structure in other embodiments. As shown, the target apparatus200includes a beam conduit208and a target housing202that is configured to be coupled to the beam conduit208. The beam conduit208may enclose a beam passage, such as the beam passage117(FIG. 1). As shown, the target housing202may include a plurality of housing portions204-206. The housing portion204may be referred to as a leading housing portion that couples to the beam conduit208, the housing portion205may be referred to as a target body, and the housing portion206may be referred to as a trailing housing portion. Although not shown, the target apparatus200may fluidly couple to a fluidic system that delivers and removes a working fluid(s) for cooling and controlling production of the radioisotopes and also to a fluidic system that delivers and removes the liquid that carries the radioisotopes.

The target apparatus200may also include mounting members210,212(FIG. 3) and a cover plate214(FIG. 3). The housing portions204-206, the mounting members210,212, and the cover plate214may comprise a common material or be fabricated from different materials. For example, the housing portions204-206, the mounting members210,212, and the cover plate214may comprise metal or metal alloys that include aluminum, steel, tungsten, nickel, copper, iron, niobium, or the like. In some embodiments, the materials of the various components may be selected based upon the thermal conductivity of the material and/or the ability of the materials to shield radiation. The components may be molded, die-cast, and/or machined to include the operative features disclosed herein such as the various openings, recesses, or passages shown inFIG. 2.

For example, the housing portions204-206may include passages240-246that extend through the respective components. The target body205includes a cavity226that may extend entirely through a thickness of the target body205. In other embodiments, the cavity226extends only a limited depth into the target body205. The cavity226may have a window227that provides access to the cavity226. The target apparatus200may also include nozzles or valves235,232that are configured to be inserted into respective openings231,233of the housing portions204and/or206. Connections (e.g., nozzle, valve)234,236may also be inserted into respective openings of the target body205.

The target apparatus200can also include a variety of sealing members220and fasteners222. The sealing members220are configured to seal interfaces between the components to maintain a predetermined pressure within the target apparatus200(e.g., such as the fluid circuit formed by the passages240-246), to prevent contamination from the ambient environment, and/or to prevent fluid from escaping into the ambient environment. The fasteners222may be configured to secure the components of the target apparatus200to each other. Also shown, the target apparatus200includes at least one cavity cover member224. The particle beam is configured to be incident upon the cavity cover member224.

As shown inFIG. 3, when the target apparatus200is fully constructed, the target body205is sandwiched between the housing portions204,206so that the cavity226(FIG. 2) is enclosed with the cavity cover member224to form a target chamber230(FIG. 4). The beam conduit208is secured to the housing portion204. The beam conduit208is configured to receive the particle beam and permit the particle beam to be incident upon the target chamber230. Also, when the target housing202is constructed, the passages240-246(FIG. 2) may form a fluid circuit that is a part of the cooling system122. The passages240-246direct a working fluid (e.g., cooling fluid such as water) through the target housing202to absorb thermal energy and transfer the thermal energy away from the target housing202. Incoming fluid may enter through the nozzle235and exit through the nozzle232. In other embodiments, the incoming fluid may enter through the nozzle232and exit through the connection234.

FIG. 4is a cross-section of the target body205taken along the lines4-4inFIG. 3. As described above, the target chamber230is formed within the target housing202(FIG. 2) when the target body205is stacked with respect to the housing portions204and206. However, in alternative embodiments, the target chamber230may be formed by other methods. The target chamber230is disposed within the target housing202and is defined by the cavity226with an interior surface254, which is in contact with a starting liquid SL, and an interior surface258, which defines a head space256. The cavity226may be configured to contain or hold a starting liquid SL and a vapor V (shown as wavy lines), which may be formed within the cavity226. The starting liquid SL may be injected into the cavity226through the connection236to a level260that has access to the target chamber230through the interior surface254at a port250. The level260separates the interior surfaces254and258. It should be noted that the level260of the starting liquid SL may change during the production session (e.g., during operation of the target apparatus200). The target chamber230is located so that the particle beam may be incident upon the starting liquid SL at a strike point2523.

The target apparatus200may be oriented with respect to axes290,291and292. In some embodiments, the axis291may also be referred to as a gravitational force axis since the axis291is aligned with gravity. As indicated by an arrow G, gravity can facilitate pulling liquid within the cavity226in one general direction. Also, gas or the vapor V within the cavity226may generally rise above the starting liquid SL in a direction that is opposite that of the arrow G.

The target apparatus200may also include a gas line (not shown) connected to the connection234. The connection234may constitute or be part of a pressure regulator that regulates the flow of a working gas (e.g., helium) into and out of a head space256of the target chamber230received by the gas line through a port262. The working gas may be configured to raise and/or lower the boiling temperature of the starting liquid SL.

During operation of the target apparatus200, the particle beam is incident upon the starting liquid SL at the strike point252. The particle beam may be constantly or intermittently applied to the starting liquid SL during a production session. When the particle beam is incident upon the starting liquid SL, radioisotopes are generated within the starting liquid SL. Thermal energy (e.g., heat) is also deposited within the starting liquid SL. The increased amount of heat may cause at least a portion of the starting liquid SL to transform into the vapor V. As the vapor V is generated within the target chamber230, the pressure within the production chamber230increases. As such, the vapor V is forced into the head space256.

As the vapor V is within the head space256, the vapor V becomes in contact with the interior surface258. The cavity226comprises a body material that is thermally conductive. In other words, the body material is configured to absorb thermal energy generated within the cavity226and permit the thermal energy to transfer away from the cavity226. In an exemplary embodiment, the target apparatus200is configured to remove thermal energy away from the interior surface258to facilitate transformation of possible vapor V into a condensed liquid, which returns to the starting liquid. For example, the passages240and246are located adjacent or thermally coupled to an external surface502(FIG. 5) of the cavity226and extend in a perpendicular manner with respect to the axes290,291and292. Optionally, the passages240and246may be coupled to a portion of the external surface502that corresponds to a surface area represented by the interior surface258. A working fluid (e.g., gas or liquid, such as water) is configured to flow through the passages240and246. The flow rate of the working fluid may be a part of and controlled by the cooling system122. The working fluid may absorb thermal energy from the cavity226and transfer the thermal energy away from the target body205thereby reducing the heat experienced by the interior surface258. In at least one embodiment, a heat sink having fins may be located adjacent or thermally coupled to the external surface502of the cavity226or within the passages240,246. A working fluid may flow through the fins of the heat sink to remove thermal energy. Accordingly, some embodiments may include an active cooling mechanism that actively cools the cavity226. Optionally, the target housing202may include a condensing chamber and a fluid channel that are also disposed within the target housing202as described in U.S. Patent Publication 2012/0321026, titled “TARGET APPARATUS AND ISOTOPE PRODUCTION SYSTEM AND METHODS USING THE SAME,” which is hereby expressly incorporated herein by reference in its entirety.

FIGS. 5-6are peripheral views of the cavity226from the target chamber230shown inFIG. 4.FIG. 5is a peripheral view of a base506of the cavity226shown concurrently with the axes290,291and292ofFIG. 4. The cavity226is formed from a single sheet504of a metal foil by mechanically punching, hydroforming (e.g., using pressurized water), hydraulic forming (e.g., using pressurized oil or other fluids), or the like, a cavity form into the metal foil. The metal foil may comprise a metal and/or metal alloy that includes at least one of niobium, tantalum, aluminum or stainless steel, and have a thickness702(FIG. 7) of zero point five millimeters. It should be noted that the thickness702of the metal foil may be greater than or less than zero point five millimeters. For example, the thickness702of the metal foil may be in a range of one to five millimeters.

The external surface502of the cavity226is shown having curved edges510,512. Each curved edge510,512is interposed between sections of the cavity226(e.g., the base506, a lip508, a transition section514) that may be aligned with one of the axes290,291and292. The sections of the cavity226may correspond to one or more structural features of the cavity226, such as, the transition section514that may correspond to a depth604(FIG. 6) of the cavity226. Each curved edge510,512may be configured to transition a corresponding section of the cavity226to another section. For example, the curved edge512is interposed between the lip508, which is aligned with the axis291, and the transition section514, which is perpendicular to the lip508and aligned with the axis292. The curved edge510is interposed between the transition section514and the base506.

FIG. 6is a peripheral view of an interior surface602of the cavity226shown concurrently with the axes290,291and292ofFIG. 4. A difference in the positions of the lip508and the base506along the axis292creates an upper606and lower608limits of the interior surface602of the cavity226defining the depth604of the cavity226. In at least one embodiment, the depth604of the cavity226may be ten millimeters. It should be noted that in other embodiments the depth604may be greater than or less than ten millimeters. For example, the depth604of the cavity226may be in a range of one to twenty-five millimeters (e.g., in at least one embodiment the depth604is one millimeter, in at least one embodiment the depth604is twenty-five millimeters). It should be noted in other embodiments, the depth604may be greater than twenty-five millimeters. The interior surface602is bounded laterally by the transition section514allowing the cavity226to contain the starting liquid SL. The interior surface602is shown having an elliptical shape. In other embodiments, the interior surface602may have other shapes that do not include corners (e.g., two converging surfaces meet at an angle), such as, an oval, a circle, or other shapes. Additionally or alternatively, the interior surface602may include shapes that have corners, such as, a rectangle, a square, a triangle, or the like.

In at least one embodiment, the interior surface602of the cavity226is enclosed by the cavity cover member224(FIG. 2). The cover member224may be coupled to the lip508. Optionally, the cover member224may comprise the same metal as the single sheet504.

FIG. 7illustrates a cross section700(FIG. 7) of the cavity226along the axis291. The cross section700shows the thickness702of the single sheet504of metal foil that is formed into the cavity226. Optionally, the thickness702of the single sheet504may be in a range of one to five millimeters. (e.g., in at least one embodiment the thickness702may be one millimeter, and at least one embodiment the thickness702may be five millimeters). It should be noted in other embodiments the thickness705may be less than one millimeter (e.g., zero point five millimeters) or greater than five millimeters. Additionally or alternatively, the thickness702of the single sheet504may be uniform throughout the cavity226, for example, the thickness702is approximately (e.g., within a predetermined tolerance) the same throughout the cavity226. For example, the transition section514, the base506, the lip508and the curved edges510and512may have approximately the same thickness702within the predetermined tolerance.

FIG. 8illustrates a flowchart of a method800for manufacturing a target chamber. The method800, for example, may employ structures or aspects of various embodiments (e.g., systems and/or methods) discussed herein. In various embodiments, certain steps (or operations) may be omitted or added, certain steps may be combined, certain steps may be performed simultaneously, certain steps may be performed concurrently, certain steps may be split into multiple steps, certain steps may be performed in a different order, or certain steps or series of steps may be re-performed in an iterative fashion. In various embodiments, portions, aspects, and/or variations of the method800may be used as one or more algorithms to direct hardware to perform one or more operations described herein. It should be noted, other methods may be used, in accordance with embodiments herein.

One or more methods may (i) receiving a single sheet of metal foil; (ii) punching the single sheet of metal foil to form a cavity, and (iii) coupling a cover to a lip of the cavity to enclose the cavity.

Beginning at802, the method800receives the single sheet504of metal foil. The single sheet504of metal foil may be a metal and/or metal alloy that comprises niobium, tantalum, aluminum, stainless steel, or the like. The single sheet504of metal foil may have a thickness (e.g., thickness702) in a range between one to five millimeters. For example the single sheet504of metal foil may have a thickness of one millimeter. It should be noted, the thickness of the metal foil may be less than one millimeter (e.g., zero point five millimeters) or greater than five millimeters.

At804, the single sheet504may be aligned to a cavity form. The cavity form may include a template of the features (e.g., the lip508, the transition section514, the base506, the curved edges510and512, of the like) of the cavity226. The cavity form may be configured to define a depth (e.g., the depth604) of the cavity226when compressed with a sheet of metal (e.g., the single sheet504).

At806, punching the single sheet504of metal foil with the cavity form to form the cavity226. For example, once the single sheet504is aligned to the cavity form, high pressure fluid may be used to compress the single sheet504to the cavity form to form the cavity226. Additionally or alternatively, the punching operation may be performed by mechanically compressing the cavity form to the single sheet504. Optionally, the punching operation may be a form of hydroforming, hydraulic forming, flex-forming, or the like

At808, a cover (e.g., the cover member224) is coupled to the cavity226to enclose the cavity226. For example, the cover member224may be coupled to the lip508of the cavity226as shown inFIG. 2.

Optionally, the method800may include coupling the cooling system122to the cavity226. For example, the passages240and246may be a part of the cooling system122. The passages240and246may be coupled to the external surface502of the cavity226having a working fluid (e.g., gas or liquid, such as water) flowing through the passages240and246to absorb thermal energy from the cavity226.

It should be noted that the particular arrangement of components (e.g., the number, types, placement, or the like) of the illustrated embodiments may be modified in various alternate embodiments. For example, in various embodiments, different numbers of a given module or unit may be employed, a different type or types of a given module or unit may be employed, a number of modules or units (or aspects thereof) may be combined, a given module or unit may be divided into plural modules (or sub-modules) or units (or sub-units), one or more aspects of one or more modules may be shared between modules, a given module or unit may be added, or a given module or unit may be omitted.

As used herein, a structure, limitation, or element that is “configured to” perform a task or operation may be particularly structurally formed, constructed, or adapted in a manner corresponding to the task or operation. For purposes of clarity and the avoidance of doubt, an object that is merely capable of being modified to perform the task or operation is not “configured to” perform the task or operation as used herein. Instead, the use of “configured to” as used herein denotes structural adaptations or characteristics, and denotes structural requirements of any structure, limitation, or element that is described as being “configured to” perform the task or operation. For example, a processing unit, processor, or computer that is “configured to” perform a task or operation may be understood as being particularly structured to perform the task or operation (e.g., having one or more programs or instructions stored thereon or used in conjunction therewith tailored or intended to perform the task or operation, and/or having an arrangement of processing circuitry tailored or intended to perform the task or operation). For the purposes of clarity and the avoidance of doubt, a general purpose computer (which may become “configured to” perform the task or operation if appropriately programmed) is not “configured to” perform a task or operation unless or until specifically programmed or structurally modified to perform the task or operation.

As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “comprises,” “including,” “includes,” “having,” or “has” an element or a plurality of elements having a particular property may include additional such elements not having that property.