Dosimetric characteristics, air-kerma strength calibration and verification of Monte Carlo simulation for a new ytterbium-169 brachytherapy source
- Washington Univ. School of Medicine, St. Louis, MO (United States)
Ytterbium-169 ([sup 169]Yb) is a promising new isotope for brachytherapy with a half life of 32 days and an average photon energy of 93 KeV. It has an Ir-192-equivalent dose distribution in water but a much smaller half-value layer in lead (0.2 mm), affording improved radiation protection and customized shielding of dose-limiting anatomic structures. The goals of this study are to: (a) experimentally validate Monte Carlo photon transport dose-rate calculations for this energy range, (b) to develop a secondary air-kerma strength standard for [sup 169]Yb, and (c) to present essential treatment planning data including the transverse-axis dose-rate distribution and dose correction factors for a number of local shielding materials. Several interstitial [sup 169]Yb sources (type 6) and an experimental high dose-rate source were made available for this study. Monte Carlo photon-transport (MCPT) simulations, based upon validated geometric models of source structure, were used to calculate dose rates in water. To verify MCPT predictions, the transverse-axis dose distribution in homogeneous water medium was measured using a silicon-diode detector. For use in designing shielded applicators, heterogeneity correction factors (HCF) arising from small cylindrical heterogeneities of lead, aluminum, titanium, steel and air were measured in a water medium. Finally, to provide a sound experimental basis for comparing experimental and theoretical dose-rate distributions, the air-kerma strength of the sources was measured using a calibrated ion chamber. To eliminate the influence of measurement artifacts on the comparison of theory and measurement, simulated detector readings were compared directly to measured diode readings. The final data are presented in the format endorsed by the Interstitial Collaborative Working Group. 33 refs., 8 figs., 3 tabs.
- OSTI ID:
- 6587758
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics; (United States), Vol. 28:4; ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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Monte Carlo characterization of a new Yb-169 high dose rate source for brachytherapy application
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Related Subjects
YTTERBIUM 169
DOSIMETRY
DOSE RATES
SPATIAL DOSE DISTRIBUTIONS
BETA DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MINUTES LIVING RADIOISOTOPES
NUCLEI
RADIATION DOSE DISTRIBUTIONS
RADIOISOTOPES
RARE EARTH NUCLEI
SECONDS LIVING RADIOISOTOPE
560101* - Biomedical Sciences
Applied Studies- Radiation Effects- Dosimetry & Monitoring- (1992-)