Patent Publication Number: US-9894746-B2

Title: Target windows for isotope systems

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates generally to isotope production systems, and more particularly to target windows for isotope production systems. 
     Radioisotopes (also called radionuclides) have applications in medical therapy, imaging, and research, as well as other applications that are not medically related. Systems that produce radioisotopes typically include a particle accelerator, such as a cyclotron, that has a magnet yoke that surrounds an acceleration chamber. Electrical and magnetic fields may be generated within the acceleration chamber to accelerate and guide charged particles along a spiral-like orbit between the poles. To produce the radioisotopes, the cyclotron forms a beam of the charged particles and directs the particle beam out of the acceleration chamber and toward a target system having a target material (also referred to as a starting material). The particle beam is incident upon the target material thereby generating radioisotopes. 
     In these isotope production systems, such as a Positron Emission Tomography (PET) cyclotron, a target window is provided between a high energy particle entrance side and a target material side of the target system. The target window needs to be capable of withstanding rupture under conditions of high pressure and high temperature. Conventional systems typically use a Havar foil to form this window. However, Havar foil activates with long lived radioactive isotopes. For certain target types, especially water targets, the target media is in direct contact with the foil and the long lived radioactive isotopes are transferred to the target media. The target media is normally processed before injection to a patient that removes the isotopes, but in some applications the isotopes will be injected in the patient, which can be harmful to the patient. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In accordance with various embodiments, a target window for an isotope production system is provided that includes a plurality of foil members in a stacked arrangement. The foil members have sides, and wherein the side of a least one of the foil members engages the side of at least one of the other foil members. Additionally, at least two of the foil members are formed from different materials. 
     In accordance with other various embodiments, a target for an isotope production system is provided that includes a body configured to encase a target material and having a passageway for a charged particle beam. The target also includes a target window between a high energy particle entrance side and a target material side. The target window includes a plurality of foil members in a stacked arrangement, wherein sides of different ones of the plurality of foil members engage one another. Additionally, at least two of the plurality of foil members has different material properties. 
     In accordance with yet other embodiments, an isotope production system is provided that includes an accelerator including a magnet yoke and having an acceleration chamber. The isotope production system also includes a target system located adjacent to or a distance from the acceleration chamber, wherein the cyclotron is configured to direct a particle beam from the acceleration chamber to the target system. The target system has a body configured to hold a target material and a target window within the body between a high energy particle entrance side and a target material side. The target window includes a plurality of foil members in a stacked arrangement, wherein sides of different ones of the plurality of foil members engage one another and at least two of the plurality of foil members has different material properties. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a target window formed in accordance with various embodiments. 
         FIG. 2  is a diagram of a target window formed in accordance with one embodiment. 
         FIG. 3  is a flowchart of a method for forming a target window in accordance with various embodiments. 
         FIG. 4  is a diagram of graphs illustrating changes in different properties of target foils formed in accordance with various embodiments. 
         FIG. 5  is a block diagram of an isotope production system in which a target window formed in accordance with various embodiments may be implemented. 
         FIG. 6  is a perspective view of a target body for a target system formed in accordance with various embodiments. 
         FIG. 7  is another perspective view of the target body of  FIG. 6 . 
         FIG. 8  is an exploded view of the target body of  FIG. 6  showing components therein. 
         FIG. 9  is another exploded view of the target body of  FIG. 6  showing components therein. 
     
    
    
     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. 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. 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. 
     Various embodiments provide a multi-member target window for isotope production systems, such as for producing isotopes used for medical imaging (e.g., Positron Emission Tomography (PET) imaging). It should be noted that the various embodiments may be used in different types of particle accelerators, such as a cyclotron or linear accelerator. Additionally, various embodiments may be used in different types of radioactive actuator systems other than isotope production systems for producing isotopes for medical applications. By practicing various embodiments, the amount of long lived isotopes produced in the target media (e.g., water) are reduced or eliminated. It should be noted that long-lived isotopes are generally radioisotopes that have very long half-lives, namely that remain radioactive for long periods. In some embodiments, the long-lived isotopes are isotopes that have half-lives of several months or longer. In other embodiments, the long-lived isotopes are isotopes that have half-lives of several years or longer. However, long-lived isotopes having shorter or longer half-lives also may be provided. 
     In accordance with some embodiments, a target window arrangement is provided that includes a plurality of foils (e.g., two or more foils). The foils in various embodiments have different properties or characteristics. More particularly, as shown in  FIG. 1 , a target window  20 , such as for an isotope production system may be provided that includes a multi-member window structure  22 . For example, in one embodiment, the multi-member window structure  22  is formed from two foil members  24  and  26  to define a dual-foil target window. However, additional members may be provided as desired or needed. Additionally, the relative sizes, thicknesses and materials of the foil members  24  and  26  may be varied as desired or needed and as described in more detail herein. 
     The foil members  24  and  26  in various embodiments are separate foils or members aligned in an abutting arrangement as described in more detail herein. Thus, the foil members  24  and  26  are separately formed or discrete components or elements that are arranged in a stacked arrangement in various embodiments. For example, the foil members  24  and  26  may define separate layers wherein one surface (e.g., a planar face) or side  25  of one of the foil members  24  and  26  engages one surface or side  27  of the other one of the foil members  24  and  26  in a stacked or abutting arrangement. 
     In the illustrated embodiment, the foil member  24  is positioned on a high energy particle entrance side  28  of the isotope production system (e.g., high energy particles or other particles enter the target window  20  on this side) and the foil member  26  is positioned on a target material side  30  of the isotope production system, which in various embodiments is a water target. As can be seen, a pressure force exists from the target material side  30  to the high energy particle entrance side  28  (illustrated by the P arrows) resulting from the vacuum force on the high energy particle entrance side  28  and the pressure force on the target material side  30 . For example, in one embodiment, the pressure force on the target material side  30  is 5-30 times the force on the high energy particle entrance side  28 . It should be noted that the high energy particle entrance side  28  may be configured differently in different systems. For example, configuration of the high energy particle entrance side  28  may be a vacuum side or a vacuum and helium side, among other configurations. 
     The materials forming the foil members  24  and  26  in various embodiments are selected based on desired or needed properties or characteristics. For example, in some embodiments, the foil member  24  is formed from a material that provides a needed strength to resist high pressure and high temperature conditions, such as an alloy disc formed from a heat treatable cobalt base alloy, such as Havar. Havar has a nominal composition of Co (42%), Cr (19.5%), Ni (12.7%), W (2.7%), Mo (2.2%), Mn (1.6%), C (0.2%), Fe balance. In one embodiment, for example, the foil member  24  has a tensile strength of at least 1000 MPa (mega-Pascals). The foil member  26  in some embodiments is formed from a material that has a particular characteristic, such as minimizing the transfer of long-lived radioactive isotopes to the target media or that includes chemically inert materials in contact with a target media, such as a Niobium material. However, other materials may be used, for example, Titanium or Tantalum. Thus, in one embodiment, one foil member, namely the foil member  24  provides strength for the multi-member window structure  22  to resist the vacuum force and the other foil member, namely the foil member  26  reduces the production of long-lived isotopes. In this embodiment, the foil member  24  is positioned towards or on the high energy particle entrance side  28  and the foil member  26  is positioned towards or on the target material side  30 . 
     It should be noted that different materials may be used or selected based on a particular property or characteristic, which may include additional foil member. For example, to provide heat dissipation or heat transport, one of the members  24  and  26  or an additional member is formed from aluminum or other heat dissipating or transport material, such as copper. The aluminum member (or other dissipation or heat transport member) may be added, which may positioned between the first and second members  24  and  26  in one embodiment, such as between the Havar and Niobium members. However, in other embodiments, the foils member may be stacked differently. It also should be noted that the different members may be arranged or stacked to obtain desired or required overall properties based on the specific properties or characteristics of the members. Thus, in one embodiment, the Havar material provides strength, the Niobium material provides chemically inert properties and the optional member formed from aluminum material provides thermal properties, such as heat dissipation. However, in other embodiments, a higher strength material is used, which may be Havar, a material having properties similar to Havar or a material having properties different than Havar. In still other embodiments, a higher strength foil member is not provided. For example, in one embodiment, a Havar foil member is not provided. In addition to the material used, the thickness of the members may be varied, such as based on the energy of the system or other parameters. 
     In various embodiments, the different foil members are formed or configured based on a particular parameter of interest. For example, some properties may include: 
     Thermal conductivity; 
     Tensile strength; 
     Chemical reactivity (inertness); 
     Energy degradation properties to which the material is subject; 
     Radioactive activation; and/or 
     Melting point. 
     Accordingly, different members may be formed or stacked in different orders to obtain different properties or characteristics. 
     The foil members  24  and  26  may be configured having a different shape or size. For example, the foil members  24  and  26  may be foil discs aligned in a stacked arrangement as shown in  FIG. 2 , which also illustrates an optional member  38 , for example, an aluminum member. The foil members  24  and  26  are generally aligned in a stacked or sandwiched arrangement and held in place, such as against a frame  32  by the pressure force difference between the high energy particle entrance side  28  and the target material side  30 . The frame generally includes an opening therethrough  34  that together with the foil members  24  and  26  define the target window  20 . Accordingly, the higher pressure side foil, illustrated as the foil member  26  in  FIG. 1  is pressed against the lower pressure side foil, illustrated as the foil member  24  in  FIG. 1 , which is pressed against the frame  32 , such as to a support area  36  (e.g., a rim) of the frame  32 . Accordingly, the foil member  24  provides a back support structure for the foil member  26 . 
     The foil members  24  and  26 , as well as the member  38  may have different thicknesses. For example, in one embodiment, the foil member  24  is formed from Havar and has a thickness of about 5-200 micrometers (microns) (e.g., 25-50 microns) and the foil member  26  is formed from Niobium and has a thickness of about 5-200 microns (e.g., 5-20 microns, such as 10 microns). If the optional member  38  is included, in one embodiment, the member  38  is formed from aluminum and has a thickness of about 50-300 microns. However, the thicknesses may be varied as desired or needed, for example, depending on the energy produced by the system. For example, in some embodiments, the various foil members range in thickness from about 5 microns to about 300 microns, for example, based on the energy of the system of as otherwise desired or required. However, the foil members may have greater or lesser thicknesses, for example, up to 400 microns or greater. The foil members also may have the same or different thicknesses. 
     Additionally, the material compositions of the various members, for example, the foil members  24  and  26  may be varied. For example, the foil members  24  and  26  may be formed from a combination of materials, such as a composite material to provide certain properties or characteristics, as well as different alloys. As another example, the foil members  24  and  26  may be formed from materials having different grain sizes. Additionally, two or more of the members may be formed from the same material or a single member may be formed from different sub-members having the same or different material(s). 
     A method  50  for forming a target window in accordance with various embodiments is shown in  FIG. 3 . The target window may be used, for example, in an isotope production system having a particle accelerator used to produce one or more radioisotopes, for example, 13N-ammonia. The method  50  includes providing a first target foil at  52 . The first target foil provides one or more properties or characteristics, such as a particular tensile strength and melting point. For example, in one embodiment, a Cobalt based alloy foil, such as Havar may be used. The first target member in various embodiments has a tensile strength of at least 1000 MPa and a melting point of at least 1200 degrees Celsius. However, in other embodiments, materials with greater or lesser tensile strength or melting point may be used. 
     The method  50  also includes providing one or more target foils at  54 . At least one of the additional target foils has a different property or characteristic than the first target foil, such as a different property of interest. For example, in one embodiment, the second target foil is formed from material that is chemically inert, such as Niobium. Additional target foils also may be provided, such as a foil having thermal dissipation properties, for example, an aluminum foil. 
     The thicknesses of the different foils may be determined based on different parameters, such as the energy of the isotope production system or an overall desired property. Additionally, if a member is formed from an alloy or composite, the quantity of different materials also may be varied. In various embodiments, the materials for each of the foils may be determined or selected based on different parameters of interest as described in more detail herein. 
     The method  50  further includes aligning or stacking the target foils in a determined order at  56 . For example, as discussed in more detail herein, the foils may be stacked to provide individual or overall properties for use in connection with a particular isotope production system. As shown in the graphs  60  and  66  of  FIG. 4 , the thicknesses of the materials as illustrated by the curves  62  and  64  in graph  60  and the thicknesses of the materials as illustrated by the curves  68  and  70  in graph  66  may affect one or more properties of the foil. Additionally, when stacking the foils, an overall property as illustrated by the graph  72  may be affected by the thicknesses of the combined materials forming each of the foils as illustrated by the curve  74 . Accordingly, using the graphs  60 ,  66  and  72 , a determination may be made at to a desired thickness for each of the foils. Using a combination of different materials and different thickness for the foil members, particular properties may be defined. Additionally, using different combinations, and in one embodiment, at least one unexpected overall property is provided, such as a target window having the tensile strength for use in an isotope production system while providing almost a total reduction of long-lived isotopes in the target material (e.g., water). It should be noted that for some properties or materials, different sets of graphs for each of the properties are used to provide desired or required properties, but an overall property graph is not used. 
     The method  50  then includes positioning or orienting the multi-foil target window in an isotope production system at  58 . For example, as described in more detail herein, one of the foils may be positioned towards a high energy particle entrance side and the other foil may be positioned toward a target material side. 
     A target window formed in accordance with various embodiments may be used in different types and configurations of isotope production systems. For example,  FIG. 5  is a block diagram of an isotope production system  100  formed in accordance with various embodiments in which a multi-foil target window may be provided. The system  100  includes a cyclotron  102  having several sub-systems including an ion source system  104 , an electrical field system  106 , a magnetic field system  108 , and a vacuum system  110 . During use of the cyclotron  102 , charged particles are placed within or injected into the cyclotron  102  through the ion source system  104 . The magnetic field system  108  and electrical field system  106  generate respective fields that cooperate with one another in producing a particle beam  112  of the charged particles. 
     Also shown in  FIG. 5 , the system  100  has an extraction system  115  and a target system  114  that includes a target material  116  (e.g., water). The target system  114  may be positioned inside, adjacent to or distance from an acceleration chamber of the cyclotron  102 . To generate isotopes, the particle beam  112  is directed by the cyclotron  102  through the extraction system  115  along a beam transport path or beam passage  117  and into the target system  114  so that the particle beam  112  is incident upon the target material  116  located at a corresponding target location  120 . When the target material  116  is irradiated with the particle beam  112 , radiation from neutrons and gamma rays may be generated, which pass through the target window  20  (shown in  FIG. 1 ). 
     It should be noted that in some embodiments the cyclotron  102  and target system  114  are not separated by a space or gap (e.g., separated by a distance) and/or are not separate parts. Accordingly, in these embodiments, the cyclotron  102  and target system  114  may form a single component or part such that the beam passage  117  between components or parts is not provided. 
     The system  100  may have one or more ports, for example, one to ten ports, or more. In particular, the system  100  includes one or more target locations  120  when one or more target materials  116  are located (one location  120  with one target material  116  is illustrated in  FIG. 5 ). If multiple locations  120  are provided, a shifting device or system (not shown) may be used to shift the target locations with respect to the particle beam  112  so that the particle beam  112  is incident upon a different target material  116 . A vacuum may be maintained during the shifting process as well. Alternatively, the cyclotron  102  and the extraction system  115  may not direct the particle beam  112  along only one path, but may direct the particle beam  112  along a unique path for each different target location  120  (if provided). Furthermore, the beam passage  117  may be substantially linear from the cyclotron  102  to the target location  120  or, alternatively, the beam passage  117  may curve or turn at one or more points there along. For example, magnets positioned alongside the beam passage  117  may be configured to redirect the particle beam  112  along a different path. It should be noted that although the various embodiments may be described in connection with a smaller cyclotron using smaller energies or beam currents, the various embodiments may be implemented in connection with larger cyclotrons having higher energies or beam currents. 
     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 No. 2005/0283199. 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 co-pending U.S. patent application Ser. Nos. 12/492,200; 12/435,903; 12/435,949; and 12/435,931. 
     The system  100  is 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 PET imaging, the radioisotopes may also be called tracers. By way of example, the system  100  may generate protons to make different isotopes. Additionally, the system  100  may also generate protons or deuterons in order to produce, for example, different gases or labeled water. 
     It should be noted that the various embodiments may be implemented in connection with systems that have particles with any energy level as desired or needed. For example, various embodiments may be implemented in systems with any type of high energy particle, such as in connection with systems having accelerators that use very heavy and specific atoms for acceleration. 
     In some embodiments, the system  100  uses  1 H −  technology and brings the charged particles to a low energy (e.g., about 16.5 MeV) with a beam current of approximately 1-200 μA. In such embodiments, the negative hydrogen ions are accelerated and guided through the cyclotron  102  and into the extraction system  115 . The negative hydrogen ions may then hit a stripping foil (not shown in  FIG. 4 ) of the extraction system  115  thereby removing the pair of electrons and making the particle a positive ion,  1 H + . However, in alternative embodiments, the charged particles may be positive ions, such as  1 H + ,  2 H + , and  3 He + . In such alternative embodiments, the extraction system  115  may include an electrostatic deflector that creates an electric field that guides the particle beam toward the target material  116 . It should be noted that the various embodiments are not limited to use in lower energy systems, but may be used in higher energy systems, for example, up to 25 MeV and higher energy or beam currents. For example, the beam current may be approximately 5 μA to over approximately 200 μA. 
     The system  100  may include a cooling system  122  that transports a cooling or working fluid to various components of the different systems in order to absorb heat generated by the respective components. The system  100  may also include a control system  118  that may be used by a technician to control the operation of the various systems and components. The control system  118  may include one or more user-interfaces that are located proximate to or remotely from the cyclotron  102  and the target system  114 . Although not shown in  FIG. 5 , the system  100  may also include one or more radiation and/or magnetic shields for the cyclotron  102  and the target system  114 , as described in more detail below. 
     The system  100  may produce the isotopes in predetermined amounts or batches, such as individual doses for use in medical imaging or therapy. Accordingly, isotopes having different levels of activity may be provided. However, the isotopes may be produced in different quantities and in different ways. For example, the various embodiments may provide bulk isotope production, such that are larger amount of the isotope is produced and then specific amounts or individual doses are dispensed. 
     The system  100  may 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 system  100  accelerates the charged particles to an energy of approximately 16.5 MeV or less. In particular embodiments, the system  100  accelerates the charged particles to an energy of approximately 9.6 MeV or less. In more particular embodiments, the system  100  accelerates the charged particles to an energy of approximately 8 MeV or less. Other embodiments accelerate the charged particles to an energy of approximately 18 MeV or more, for example, 20 MeV or 25 MeV. In still other embodiments, the charged particles may be accelerated to an energy of greater than 25 MeV. 
     The target system  114  includes a multi-foil target window within a target body  300  as illustrated in  FIGS. 6 through 9 . The target body  300  shown assembled in  FIGS. 6 and 7  (and in exploded view in  FIGS. 8 and 9 ) is formed from several components (illustrated as three components) defining an outer structure of the target body  300 . In particular, the outer structure of the body  300  is formed from a housing portion  302  (e.g., a front housing portion or flange), a housing portion  304  (e.g., cooling housing portion or flange) and housing portion  306  (e.g., a rear housing portion or flange assembly). The housing portions  302 ,  304  and  306  may be, for example, sub-assemblies secured together using any suitable fastener, illustrated as a plurality of screws  308  each having a corresponding washer  310 . The housing portions  302  and  306  may be end housing portions with the housing portion  304  being an intermediate housing portion. The housing portions  302 ,  304  and  306  form a sealed target body  300  having a plurality of ports  312  on a front surface of the housing portion  306 , which in the illustrated embodiment operate as helium and water inlets and outlets that may be connected to helium and water supplies (not shown). Additionally, additional ports or openings  314  may be provided on top and bottom portions of the target body  300 . The openings  314  may be provided for receiving fittings or other portions of a port therein. 
     As described below, a passageway for the charged particle is provided within the target body  300 , for example, a path for a proton beam that may enter the target body as illustrated by the arrow P in  FIG. 8 . The charged particles travel through the target body  300  from a tubular opening  319 , which acts as a particle path entrance, to a cavity  318  (shown in  FIG. 8 ) that is a final destination of the changed particles. The cavity  318  in various embodiments is water filled, for example, with about 2.5 milliliters (ml) of water, thereby providing a location for irradiated water (H 2   18 O). In another embodiment, about 4 milliliters of H 2   16 O is used. The cavity  318  is defined within a body  320  formed, for example, from a Niobium material having a cavity  322  with an opening on one face. The body  320  includes the top and bottom openings  314  for receiving therein fittings, for example. 
     It should be noted that the cavity  318 , in various embodiments, is filled with different liquids or with gas. In still other embodiments, the cavity  318  may be filled with a solid target, wherein the irradiated material is, for example, a solid, plated body of suitable material for the production of certain isotopes. However, it should be noted that when using a solid target or gas target, a different structure or design is provided. 
     The body  320  is aligned between the housing portion  306  and the housing portion  304  between a sealing ring  326  (e.g., an O-ring) adjacent the housing portion  306  and a multi-foil member  328 , such as the target window  20  (shown in  FIGS. 1 and 2 ), for example, a disc having one foil member formed from a heat treatable cobalt based alloy, such as Havar, and another foil member formed from an chemically inert material, such as Niobium, adjacent the housing potion  304 . It should be noted that the housing portion  306  also includes a cavity  330  shaped and sized to receive therein the sealing ring  326  and a portion of the body  320 . Additionally, the housing portion  306  includes a cavity  332  sized and shaped to receive therein a portion of the multi-foil member  328 . The multi-foil member  328  may include a sealing border  336  (e.g., a Helicoflex border) configured to fit within the cavity  322  of the body  320 , and the multi-foil member  328  is also aligned with an opening  338  to a passage through the housing portion  304 . 
     Another foil member  340  optionally may be provided between the housing portion  304  and the housing portion  302 . The foil member  340  may be referred to as a leading foil member because the proton beam is incident upon the foil member  340  prior to the multi-foil member  328 . The foil member  340  may be a disc similar to the multi-foil member  328  or may include only a single foil member in some embodiments. The foil member  340  aligns with the opening  338  of the housing portion  304  having an annular rim  342  there around. A seal  344 , a sealing ring  346  aligned with an opening  348  of the housing portion  302  and a sealing ring  350  fitting onto a rim  352  of the housing portion  302  are provided between the foil member  340  and the housing portion  302 . It should be noted that more or less foil members or foil members may be provided. For example, in some embodiments only the foil member  328  is included and the foil member  340  is not included. Accordingly, different foil arrangements are contemplated by the various embodiments. 
     It should be noted that the foil members  328  and  340  are not limited to a disc or circular shape and may be provided in different shapes, configurations and arrangements. For example, the one or more the foil members  328  and  340 , or additional foil members, may be square shaped, rectangular shaped, or oval shaped, among others. Also, it should be noted that the foil members  328  and  340  are not limited to being formed from particular materials as described herein. 
     As can be seen, a plurality of pins  354  are received within openings  356  in each of the housing portions  302 ,  304  and  306  to align these component when the target body  300  is assembled. Additionally, a plurality of sealing rings  358  align with openings  360  of the housing portion  304  for receiving therethrough the screws  308  that secure within bores  362  (e.g., threaded bores) of the housing portion  302 . 
     During operation, as the proton beam passes through the target body  300  from the housing portion  302  into the cavity  318 , the foil members  328  and  340  may be heavily activated (e.g., radioactivity induced therein). In particular, the foil members  328  and  340 , which may be, for example, thin (e.g., 5-400 microns) foil alloy discs, isolate the vacuum inside the accelerator, and in particular the accelerator chamber and from the water in the cavity  322 . The foil members  328  and  340  also allow cooling helium to pass therethrough and/or between the foil members  328  and  340 . It should be noted that the foil members  328  and  340  have a thickness in various embodiments that allows a proton beam to pass therethrough, which results in the foil members  328  and  340  becoming highly radiated and which remain activated. 
     It should be noted that the housing portions  302 ,  304  and  306  may be formed from the same materials, different materials or different quantities or combinations of the same or different materials. 
     Embodiments described herein are not intended to be limited to generating radioisotopes for medical uses, but may also generate other isotopes and use other target materials. Also the various embodiments may be implemented in connection with different kinds of cyclotrons having different orientations (e.g., vertically or horizontally oriented), as well as different accelerators, such as linear accelerators or laser induced accelerators instead of spiral accelerators. Furthermore, embodiments described herein include methods of manufacturing the isotope production systems, target systems, and cyclotrons as described above. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, the various embodiments are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. 
     This written description uses examples to disclose the various embodiments, including the best mode, and also to enable any person skilled in the art to practice the various embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if the examples have structural elements that do not differ from the literal language of the claims, or if the examples include equivalent structural elements with insubstantial differences from the literal languages of the claims.