Monte Carlo dosimetry of the Buchler high dose rate 192Ir source.

In this study a complete set of dosimetric data is presented for the high dose rate (HDR) source from Amersham used in the Buchler remote afterloading HDR unit. These data have been calculated by means of the Monte Carlo simulation code GEANT taking into account the detailed geometry of the source. Absolute dose rate distributions in water were calculated around this source and are presented as conventional 2D Cartesian look-up tables. All dosimetric quantities recommended by the AAPM Task Group 43 report have been calculated. Quantities determined are: dose rate constant, radial dose function, anisotropy function, anisotropy factor and anisotropy constant. The dose rate distributions of the Buchler HDR source are compared with those of other HDR sources used in brachytherapy, showing that the differences are large in zones near the long source axis due to oblique filtration. These Monte Carlo simulated data in water can be used for clinical applications.