Theoretical and experimental determination of dosimetric characteristics for ADVANTAGE™ Pd-103 brachytherapy source

Abstract

ADVANTAGE™ Pd-103 brachytherapy source has been recently introduced by IsoAid™ for prostate permanent implants. Dosimetric characteristics (Dose rate constant, radial dose function, 2D-, and 1D-anisotropy functions) of this source model have been determined using both theoretical and experimental methods, following the updated TG-43U1 protocol. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with the 1999 Standards. Measurements were performed in Solid Water™ using LiF TLD chips and the theoretical calculations were performed in Solid Water™ and liquid water phantom materials using PTRAN Monte Carlo code. The results of the Monte Carlo simulation have shown a dose rate constant of 0.69 cGy h −1 U −1 in liquid water and 0.67 cGy h −1 U −1 in Solid Water™ medium. The measured dose rate constant in Solid Water™ was found to be 0.68±8% cGy h −1 U −1, which is in a good agreement (within ±5%) to the Monte Carlo simulated data. The 2D- and 1D-anisotropy functions of the ADVANTAGE™ Pd-103 source were calculated for radial distances ranging from 0.5 to 5.0 cm. Radial dose function was determined for radial distances ranging from 0.2 to 8.0 cm using line source approximation. All these calculations are based on L eff equal to 3.61 cm, calculated following TG-43U1 recommendations. The tabulated data for 2D-anisotropy function, 1D-anisotropy function, dose rate constant and radial dose function have been produced for clinical application of this source model.