SELF-SHIELDING TARGET FOR ISOTOPE PRODUCTION
SYSTEMS
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates generally to isotope
production systems, and more particularly to shielding of targets of the isotope
production systems.
[0002] Radioisotopes (also called radionuclides) have several 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. The acceleration chamber may include opposing pole tops that are spaced apart
from each other. 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.
[0003] During operation of an isotope production system, large amounts of
radiation (i.e., unhealthy levels of radiation for individuals nearby) are typically
generated within the target system and, separately, within the cyclotron. For example,
with respect to the target system, radiation from neutrons and gamma rays may be
generated when the beam is incident upon the target material. With respect to the
cyclotron, ions within the acceleration chamber may collide with gas particles therein and
become neutral particles that are no longer affected by the electrical and magnetic fields
within the acceleration chamber. These neutral particles, in turn, may also collide with
the walls of the acceleration chamber and produce secondary gamma radiation.
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[0004] Thus, during production of radio isotopes, such as for Positron Emission
Tomography (PET) applications, the starting material (confined in the target system) is
typically irradiated with high energy particles. Accordingly, the target system and the
materials used to construct the target system are also exposed to the high energy particles
and will thus also be highly radioactive. The high radioactive activation of the target
system makes servicing and handling of the equipment generally very time and cost
consuming, in particular, because of the need to wait for acceptable radiation levels to
decrease, which may take at least 24 hours. Even after this time period, precautions are
necessary when approaching the system because radiation exposure levels are strictly
regulated by law. Thus, servicing of this kind of equipment is also difficult as sendee
personnel may quickly reach maximal annual limits. Accordingly, in order to reduce
dose load per person, a relatively high number of people may be required to share the
dose to reasonable levels.
[0005] To protect nearby individuals from the radiation (e.g., employees or
patients of a hospital), isotope production systems may use shields to attenuate or block
the radiation. In conventional isotope production systems, shielding of the radiation (e.g.,
radiation leakage) has been addressed by adding a large amount of shielding that
surrounds both the cyclotron and the target system. However, the large amounts of
shielding may be costly and too heavy for the rooms where the isotope production system
are to be located. Alternatively or in addition to the large amounts of shielding, isotope
production systems may be located within a specially designed room or rooms. For
example, the cyclotron and the target system may be in separate rooms or have large
walls separating the two.
BRIEF DESCRIPTION OF THE INVENTION
[0006] In accordance with various embodiments, a target for an isotope
production system is provided. The target includes a body configured to encase a target
material and having a passageway for a charged particle beam, and a component within
the body, wherein the charged particle beam induces radioactivity in the component,
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Additionally, at least one portion of the body is formed from a material having a density
value greater than a density value of aluminum to shield the component.
[0007] In accordance with other various embodiments, an isotope production
system is provided that includes an accelerator. The accelerator includes a magnet yoke
and also has an acceleration chamber. The isotope production system further includes a
target system located adjacent to or a distance from the acceleration chamber. The
cyclotron is configured to direct a particle beam from the acceleration chamber to the
target system. The target system is configured to hold a target materia! and is selfshielded
to attenuate radiation from one or more activated parts within the target system,
and further includes one or more housing portions encasing the target material, wherein at
least one of the housing portions is aligned with the activated parts and is formed from a
material having a density greater than aluminum.
[0008] In accordance with yet other embodiments, a method for producing a
shielded target for an isotope production system includes forming one or more poxtions of
a target housing from a material having a density value greater than 5 g/cnr. The method
further includes encasing radioactive activated components with at least one of the
portions of the target housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 is a block diagram of an isotope production system having a
self-shielded target system formed in accordance with various embodiments.
[0010] Figure 2 is a perspective view of a target body for a target system formed
in accordance with various embodiments.
[0011] Figure 3 is another perspective view of the target body of Figure 2.
[0012] Figure 4 is an exploded view of the target body of Figure 2 showing
components therein.
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[0013] Figure 5 is another exploded view of the target body of Figure 2 showing
components therein.
[0014] Figure 6 is a simplified block diagram of a self-shielded target
arrangement formed in accordance with various embodiments,
[0015] Figure 7 is a flowchart of method for providing a self-shielded target for
an isotope production system in accordance with various embodiments.
DETAILED DESCRIPTION OF THE INVENTION
[0016] 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.
[0017] 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.
[0018] Various embodiments provide a self-shielded target system for isotope
production systems using higher density materials for forming portions of the target
systems, particularly, portions that encase components that are susceptible to high
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radioactive activation. The higher density material provides higher gamma radiation
attenuation to reduce the level of gamma radiation exposure, such as to personnel. In
various embodiments, supporting structures (e.g., a portion of a housing) around
activated parts (e.g. highly activated parts) are constructed from high density/high
attenuation materials such that the radiation levels/dose rates outside the target system are
reduced. Thus, an active shield for a target system for isotope production systems is
provided. The activated parts of the target system are shielded not only during operation,
but also when transporting, maintaining and storing the target system.
[0019] A self-shielded target system formed in accordance with various
embodiments may be used in different types and configurations of isotope production
systems. For example, Figure 1 is a block diagram of an isotope production system 100
formed in accordance with various embodiments in which a self-shielded target system
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.
[0020] Also shown in Figure 1, the system 100 has an extraction system 115
and a target system 114 that includes a target material 116. The target system 114 maybe
positioned adjacent to the cyclotron 102 and is self-shielded as described in more
detail herein. 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
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generated, which can activate portions of the target system 114, such as foil portions of
the target system 114.
[0021] 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.
[0022] The system 100 may have multiple target locations 120A-C where
separate target materials 116A-C are located. A shifting device or system (not shown)
may be used to shift the target locations 120A-C 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
120A-C. 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 therealong. For example, magnets positioned
alongside the beam passage 117 may be configured to redirect the particle beam 112
along a different path.
[0023] Examples of isotope production systems and/or cyclotrons having one or
more of the sub-systems are described in U.S. Patent 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. Patent 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 copending
U.S. Patent Application Nos. 12/492,200; 12/435,903; 12/435,949; and 12/435,931,
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[0024] 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 Positron
Emission Tomography (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.
[0025] In some embodiments, the system 100 uses "H" technology and brings
the charged particles to a low energy (e.g., about 8 MeV) with a beam current of
approximately 10-30uA. 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 Figure 1) of the
extraction system 115 thereby removing the pair of electrons and making the particle a
positive ion, IV. However, in alternative embodiments, the charged particles may be
positive ions, such as 'H+, H+, and "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 beam currents.
[0026] 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 userinterfaces
that are located proximate to or remotely from the cyclotron 102 and the target
system 114. Although not shown in Figure 1, the system 100 may also include one or
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more radiation and/or magnetic shields for the cyclotron 102 and the target system 114,
as described in more detail below.
[0027] 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 maybe provided.
[0028] 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.
[0029] The target system 114 includes a self-shielded target having a selfshielded
target body 300 as illustrated in Figures 2 through 5. The self-shielded target
body 300 shown assembled in Figures 2 and 3 (and in exploded view in Figures 4 and 5)
is formed from three components defining an outer structure of the self-shielded target
body 300. In particular, the outer structure of the self-shielded target body 300 is formed
from a housmg 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 31.0. 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
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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.
[0030] 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 Figure 4. 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 Figure 6) 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 (Hi O), 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.
[0031] 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,
[0032] 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 foil member 328, such as a metallic foil member, for example, an alloy
disc formed from a heat treatable cobalt base alloy, such as Havar, 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 foil member 328. The foil member 328 may include a sealing
border 336 (e.g., a Helicoflex border) configured to fit within the cavity 322 of the body
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320, and the foil member 328 is also aligned with an opening 338 to a passage through
the housing portion 304.
[0033] Another foil member 340 optionally may be provided between the
housing portion 304 and the housing portion 302. The foil member 340 similarly may be
an alloy disc similar to the foil member 328. 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, such as 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, single foil member or multi-foil member arrangements are
contemplated by the various embodiments.
[0034] 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 a particular material, but in various embodiments are formed from a an
activating material, such as a moderately or high activating material that can have
radioactivity induced therein as described in more detail herein. In some embodiments,
the foil members 328 and 340 are metallic and formed from one or more metals.
[0035] 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.
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[0036] 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., 5-50 micrometer or micron (p.m)) 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 having a thickness that allows a
proton beam to pass therethrough, which results in the foil members 328 and 340
becoming highly radiated and which remain activated.
[0037] Some embodiments provide self-shielding of the target body 300 that
actively shields the target body 300 to shield and/or prevent radiation from the activated
foil members 328 and 340 from leaving the target body 300. Thus, the foil members 328
and 340 are encapsulated by an active radiation shield. Specifically, at least one of, and
in some embodiments, all of the housing portions 302, 304 and 306 are formed from a
material that attenuates the radiation within the target body 300, and in particular, from
the foil members 328 and 340. 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. For example, housing portions 302 and
304 may be formed from the same material, such as aluminum, and the housing portion
306 may be formed from a combination or aluminum and tungsten.
[0038] In various embodiments, one or more of the housing portion 302,
housing portion 304 and/or housing portion 306, or parts thereof, are formed from a
material having a density higher or greater than aluminum. In some embodiments, the
material forming at least one of the housing portion 302, housing portion 304 and/or
housing portion 306 has a density value greater than that of aluminum, which has a
density near room temperature of 2,70 g/cnr\ For example, one or more of the housing
portion 302, housing portion 304 and/or housing portion 306 may be formed from
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material(s), such as a metal or alloy having a density greater than aluminum, such as a
density value of about 5 g/cm"5. In other embodiments, one or more of the housing
portion 302, housing portion 304 and/or housing portion 306 may be formed from
material(s), such as a metal or alloy having a density value greater than 5 g/cmJ, for
example, a density value of about 10 g/cm'. In these embodiments, for example, the
material generally has a density value greater than that of steel (having a density near
room temperature of about 8 g/crrr). In other embodiments, the density value is greater
than, for example, 10 g/cm\ However, it should be noted that other materials or alloys
may be used having greater or lesser density values, such as tungsten (having a density
near room temperature of 19.25 g/cm") or tungsten alloys having a lower density value
than tungsten alone. For example, in some embodiments, the tungsten alloy has a density
value less than 19.25 g/cm"' and includes other metals, such as nickel, copper or iron,
among others. In other embodiments, for example, a lead alloy may be used. It also
should be noted that when reference is made herein to a particular density value or being
greater than a particular density value, in some embodiments, the density value may also
be equal to or slightly less than that particular density value.
[0039] Thus, in various embodiments, one or more of the housing portion 302,
housing portion 304 and/or housing portion 306, or parts thereof, are formed from one or
more materials, that may include aluminum, and having a higher density value than
aluminum. For example, an alloy containing tungsten and a combination of one or more
of magnesium, copper and/or iron may be provided in some embodiments.
[0040] The housing portion 302, housing portion 304 and/or housing portion
306 are formed such that a thickness of each, particularly between the foil members 328
and 340 and the outside of the target body 300 provides shielding to reduce radiation
emitted therefrom. It should be noted that the housing portion 302, housing portion 304
and/or housing portion 306 may be formed from any material having a density value
greater than that of aluminum. Also, each of the housing portion 302, housing portion
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304 and/or housing portion 306 may be formed from different materials or combinations
or materials as described in more detail herein,
[0041] Thus, at least one of the housing portion 302, housing portion 304 and
housing portion 306 or portions thereof encompass or surround the foil members 328 and
340 to provide shielding, such as when radioactivity is induced in the foil members 328
and 340. For example, recesses within any one of the housing portion 302, housing
portion 304 and housing portion 306 may receive therein a portion of the one of the foil
members 328 and 340.
[0042] It should be rioted that the target body 300 may be provided in different
configurations and is not limited to the components and arrangements shown in Figures 2
through 5, Accordingly, the various embodiments may be implemented in connection
with any type or configuration of target by forming one or more of the housing portions
or components from a higher density material, particularly of a higher density than
aluminum to shield the outside of the target from radiation, such as from an activated
component within the target body. Thus, as shown in Figure 6, the various embodiments
may be implemented in connection with a target 400 wherein a radioactive activated
component 402 (e.g., a component susceptible to being radioactively induced), such as a
component that may be heavily activated by radiation during operation of an isotope
production system, is shielded within a casing 404 (or a portion thereof) formed from a
material having a higher density value, for example, a density value greater than
aluminum. The casing 404 may form a portion of a target housing.
[0043] Various embodiments also include a method 500 as shown in Figure 7
for providing self-shielded target for an isotope production system. The method includes
providing one or more portions of the target body at 502 to act as a radiation shield. The
portions of the target body may be formed from any suitable type of radiation shielding
material, such as a material having a density greater than aluminum as described in more
detail herein. Thereafter, the radioactive activated components, for example, foil
members that are activated during the operation of the isotope production system are
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encased by the shielded portions at 504, For example, portions of the target body that
include the radioactive activated components are aligned with the shielded portions, It
should be noted that as used herein, radioactive activated components generally refer to
components that may be activated by radiation or wherein radioactivity may be induced
in the component.
[0044] The target body is then assembled at 506 such that an active selfshielding
target system is provided. The active shielding provides gamma radiation
attenuation during operation of the isotope production system, as well as during
maintenance, transportation and storage of the target.
[0045] 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.
[0046] 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
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"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 forniat 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.
[0047] 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.

WHAT IS CLAIMED IS:
1. A target for an isotope production system, the target comprising:
a body configured to encase a target material and having a passageway for
a charged particle beam;
a component within the body, wherein the charged particle beam induces
radioactivity in the component; and
at least one portion of the body formed from a material having a density
value greater than a density value of aluminum to shield the component.
2. The target in accordance with claim 1 wherein the body comprises
a plurality of housing portions and wherein at least one of the housing portions is formed
from the material,
3. The target in accordance with claim 1 wherein the component
comprises at least one foil member,
4. The target in accordance with claim 3 wherein at least one foil
member is formed from an activating material.
5. The target in accordance with claim 1 wherein at least one portion
1
of the body comprises a material having a density value greater than 5 g/cm".
6. The target in accordance with claim 1 wherein at least one portion
of the body comprises a material having a density value greater than 10 g/cnv7. The target in accordance with claim 1 wherein at least one portion
of the body comprises a tungsten material.
8. The target in accordance with claim 1 wherein at least one portion
of the body comprises a tungsten alloy material.
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9. The target in accordance with claim 1 wherein at least one portion
of the body comprises a lead material.
10. The target in accordance with claim 1 wherein at least one portion
of the body comprises a lead alloy material,
11. The target in accordance with claim 1 wherein the charged particle
beam is configured to form a Positron Emission Tomography (PET) radioisotope from a
target material within the body.
12. An isotope production system comprising:
an accelerator including a magnet yoke and having an acceleration
chamber; and
a target system located adjacent to or a distance from the acceleration
chamber, the cyclotron configured to direct a particle beam from the acceleration
chamber to the target system, the target system configured to hold a target material and
being self-shielded to attenuate radiation from one or more activated parts within the
target system, and further comprising one or more housing portions encasing the target
material, wherein at least one of the housing portions is aligned with the activated parts
and is formed from a material having a density greater than aluminum.
13. The isotope production system in accordance with claim 12
wherein at least one of the housing portions is formed from tungsten.
14. The isotope production system in accordance with claim 12
wherein at least one of the housing portions is formed from a tungsten alloy.
15. The isotope production system in accordance with claim 12
wherein at least one of the housing portions is formed from lead.
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16. The isotope production system in accordance with claim 12
wherein at least one of the housing portions is formed from a lead alloy.
17. The isotope production system in accordance with claim 12
wherein at least one of the housing portions is formed from a material having a density
value greater than 5 g/cmJ.
18. The isotope production system in accordance with claim 12
wherein at least one of the housing portions is formed from a material having a density
value greater than 10 g/cm .
19. The isotope production system in accordance with claim 12
wherein the activated parts comprise one or more foil members.
20. The isotope production system in accordance with claim 19
wherem the foil members are formed from a metal material and have a thickness of
between about 5 microns and about 50 microns.
21. The isotope production system in accordance with claim 12
wherein the housing portions together form a target housing having one or more foil
members therein defining the activated parts.
22. The isotope production system in accordance with claim 12
wherein the target material is a Positron Emission Tomography (PET) target material.
23. The isotope production system in accordance with claim 12
wherein at least one of the housing portions surrounds the activated parts.
24. The isotope production system in accordance with claim 12
wherein the material does not include aluminum.
25. A method for producing a shielded target for an isotope production
system, the method comprising:
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WO 2011/133281 PCT7US2011/029499
forming one or more portions of a target housing from a material having a
density value greater than 5 g/emJ; and
encasing radioactive activated components with at least one of the portions
of the target housing.
26. The method in accordance with claim 25 wherein the one or more
portions are formed from a material having a density value greater than 10 g/cnar.
27. The method in accordance with claim 25 further comprising
forming one or more of the housing portions from one of tungsten, a tungsten alloy, lead
or a lead alloy.
28. The method in accordance with claim 25 wherein the radioactive
activated components comprise foil members.