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Monte Carlo dosimetric characterization of the Cs‐137 selectron/LDR source: Evaluation of applicator attenuation and superposition approximation effects
Author(s) -
PérezCalatayud J.,
Granero D.,
Ballester F.,
Puchades V.,
Casal E.
Publication year - 2004
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1644640
Subject(s) - monte carlo method , dosimetry , superposition principle , brachytherapy , physics , computational physics , attenuation , dose rate , nuclear medicine , percentage depth dose curve , optics , materials science , ionization chamber , mathematics , statistics , medical physics , medicine , radiation therapy , ion , quantum mechanics , ionization
The purpose of this study is to calculate the dose rate distribution for the Amersham Cs‐137 pellet source used in brachytherapy with the Selectron low‐dose‐rate remote afterloading system in gynaecological applications using the Monte Carlo code GEANT4 . The absolute dose rate distribution for the pellet source was obtained and presented as a one‐dimensional absolute dose rate table as well as in the Task Group 43 dose‐calculation formalism. In this study, excellent agreement was found between the point source theoretical model using fitted polynomial values and Monte Carlo calculations of the dose rate distribution for the pellet source. A comparison study was also made between the dose rate distribution obtained from a complete Monte Carlo simulation (Cs‐137 pellet sources + remote afterloading system plastic guide tube + gynaecological applicator) and that calculated by applying the superposition principle to Monte Carlo data of the individual pellet sources. The data were obtained for a portion of uterine tandem of typical train source configurations. Significant differences with a strong dependence on polar angle have been found that must be kept in mind for clinical dosimetry.