Dosimetric comparison of four new design 103Pd brachytherapy sources: Optimal design using silver and copper rod cores

Four new brachytherapy sources, IRA1-Pd-103, IRA2-Pd-103, IRA3-Pd-103, and IRA4-Pd-103, have been developed at Agricultural, Medical, and Industrial Research School and are designed for permanent implant application. With the goal of determining an optimal design for a Pd-103 source, this article compares the dosimetric properties of these sources with reference to the authors' earlier IRA-Pd-103 source. The four new sources differ in end cap configuration and thickness and in the core material, silver or copper, that carries the adsorbed Pd-103. Dosimetric data derived from the authors' Monte Carlo simulation results are reported in accordance with the updated AAPM Task Group No. 43 report (TG-43U1). For each source, the authors obtained detailed results for the dose rate constant Lambda, the radial dose function g(r), the anisotropy function F(r,theta), and the anisotropy factor phi(an)(r). In this study, the optimal source IRA3-Pd-103 provides the most isotropic dose distribution in water with the dose rate constant of 0.678(+/- 0.1%) cGy h(-1) U-1. The IRA3-Pd-103 design has a silver rod core combined with thin-wall, concave end caps. Finally, the authors compared the results for their optimal source with published results for those of other source manufacturers.