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Monte Carlo dosimetry of the VariSource high dose rate 192 Ir source
Author(s) -
Wang Ruqing,
Sloboda Ron S.
Publication year - 1998
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 - 10.1118/1.598216
Subject(s) - dosimetry , monte carlo method , kerma , physics , anisotropy , isotropy , brachytherapy , percentage depth dose curve , nuclear medicine , computational physics , dose rate , ionization chamber , optics , mathematics , medical physics , medicine , statistics , radiation therapy , ionization , ion , quantum mechanics
The purpose of the work is to calculate basic dosimetry data for a VariSource high dose rate192 Ir source in water. These basic dosimetry data, expressed in the dose calculation formalism endorsed by the Interstitial Collaborative Working Group and AAPM Task group 43, include the dose rate constant, the radial dose function, and the anisotropy function. A modified version of the EGS4 Monte Carlo code was used to calculate (1) the transverse‐axis dose distribution at radial distances from 0.1 to 14 cm, (2) the two‐dimensional dose distribution for axial and radial distances from 0.1 cm to 10 cm, and (3) the air‐kerma strength, for the VariSource high dose rate192 Ir source. From these Monte Carlo results the basic dosimetry data were derived. The calculated dose rate constant for the high dose rate source is 1.044 ± 0.2 % cGy h− 1per unit air‐kerma strength. The anisotropy function exhibits 40%–60% deviations from isotropy at positions on the long axis. The radial dose function for the source is nearly identical to that for a microSelectron high dose rate192 Ir source, except at radial distances smaller than 0.5 cm where values for VariSource are 1.7%–2.8% smaller. These basic dosimetry data were compared with corresponding results from other authors for high and low dose rate192 Ir sources, as well as with Meisberger's fitting formula.