Dosimetry of the 198Au Source used in Interstitial Brachytherapy
The American Association of Physicists in Medicine Task Group 43 report, AAPM TG-43, provides an analytical model and a dosimetry protocol for brachytherapy dose calculations, as well as documentation and results for some sealed sources. The radionuclide {sup 198}Au (T{sub 1/2} = 2.70 days, E{gamma} = 412 keV) has been used in the form of seeds for brachytherapy treatments including brain, eye, and prostate tumors. However, the TG-43 report has no data for {sup 198}Au seeds, and none have previously been obtained. For that reason, and because of the conversion of most treatment planning systems to TG-43 based methods, both Monte Carlo calculations (MCNP 4C) and thermoluminescent dosimeters (TLDs) are used in this work to determine these data. The geometric variation in dose is measured using an array of TLDs in a solid water phantom, and the seed activity is determined using both a well ion chamber and a High Purity Germanium detector (HPGe). The results for air kerma strength, S{sub k}, per unit apparent activity, are 2.06 (MCNP) and 2.09 (measured) U mCi{sup -1}. The former is identical to what was published in 1991 in the AAPM Task Group 32 report. The dose rate constant results, {Lambda}, are 1.12 (MCNP) and 1.10 (measured), cGy h{sup -1} U{sup -1}. The radial dose function, g(r), anisotropy function, F(r,{theta}), and anisotropy factor, {psi}{sub an}(r), are given. The anisotropy constant values are 0.973 (MCNP) and 0.994 (measured) and are consistent with both source geometry and the emitted photon energy.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15020079
- Report Number(s):
- UCRL-JRNL-204244; MPHYA6; TRN: US0504438
- Journal Information:
- Medical Physics, Vol. 32, Issue 6; ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANISOTROPY
BRACHYTHERAPY
BRAIN
DOCUMENTATION
DOSE RATES
DOSEMETERS
DOSIMETRY
GE SEMICONDUCTOR DETECTORS
GEOMETRY
INTERSTITIALS
KERMA
NEOPLASMS
PHOTONS
PROSTATE
RADIOISOTOPES
SEALED SOURCES
SEEDS