Linear Accelerator Drift Tube

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Linear Accelerator Drift Tube
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Positive Ion Cyclotron Operation
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CS-15 Positive Ion CyclotronWashington
University School of Medicine
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Target
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Targets for Cyclotron
1. Metals 111Cd(p,n)111In (111In-DTPA) 201H
g(d,2n)201Tl (201Tl-chloride)
68Zn(p,2n)67Ga (67Ga-citrate) 2.
Gases 14N(d,n)15O (H215O, 15O2) 14N(p,?)11C
(11C-acetate, 11C- palmitate, 11C-
glucose) 3. Liquids 16O(p,?)13N (13N-ammonia
) 18O(p,n)18F (18F-FDG)
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Simple X-ray Tube
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• Fast neutrons (E of 1.5 MeV) have a low
  probability of interaction with other nuclei.
• They are thermalized or slowed down (0.025 eV)
  to interact with other nuclei.
• Moderators (low MW materials like heavy water,
  beryllium or graphite) are distributed
• in spaces between fuel rods

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University of Missouri Research Reactor
(MURR) Columbia, MO
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Nuclear Fission
235U144 n
236U144
236U144
144Ba88 89Kr53 3n
99Mo42 135Sn50 2n

• 236U unstable - undergoes fission immediately
• wide range of fission products - usually 1/3 and
  2/3 split of the mass number

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I-131
Mo-99
Fission products useful in nuclear medicine
include 99Mo, 131I, 133Xe, 137Cs and 90Sr
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Reactor-Produced RadionuclidesThermal Neutron
Reactions

• (n, g) reaction formed by reactions between
  targets and thermalized neutrons

YAz n
Y1Az g
Atarget Aisotope produced same atomic number,
different mass

• (n, g) reaction
• not carrier-free, since target and product are
  same
• radioisotopic purity can be high if cross section
  is sufficiently large (e.g. 176Lu(n,g)177Lu)

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Reactor-Produced RadionuclidesThermal Neutron
Reactions, contd

• (n, p) reaction formed by reactions between
  targets and thermalized neutrons

YAz n
YBz-1 p
Atarget Bisotope produced different atomic
number, same mass

• (n, p) reaction
• carrier-free, since target and product are
  different
• example 64Zn(n,p)64Cu

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Fisson/Reactor Products Cyclotron Products

• Generally decay by b- emission because of excess
  neutrons
• Not many are useful for diagnostic imaging, but
  several are useful for radiotherapy

• Generally decay by b emission or electron
  capture because of excess protons
• Many are useful for diagnostic imaging
• (gamma scintigraphy or positron emission
  tomography)

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Alpen, E.L. (1998) Radiation Biophysics Academic
Press, San Diego, p. 87
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Alpen, E.L. (1998) Radiation Biophysics Academic
Press, San Diego, p. 105
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Hall, E.J. (1994) Radiobiology for the
Radiologist J.B. Lippincott Company,
Philadelphia, p. 154
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Latorre Travis, E. (1989) Primer of Medical
Radiobiology Year Book Medical Publishers,
Inc., Chicago, p. 92
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RBE
LET
Hall, E.J. (1994) Radiobiology for the
Radiologist J.B. Lippincott Company,
Philadelphia, p. 160
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Hall, E.J. (1994) Radiobiology for the
Radiologist J.B. Lippincott Company,
Philadelphia, p. 160
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Alpen, E.L. (1998) Radiation Biophysics Academic
Press, San Diego, p. 52