Monte Carlo-based dosimetric studies of indigenously developed 170Tm LDR brachytherapy seed source.

170Tm is being explored as a source for applications in brachytherapy. Although it has adequate physical properties, such as a short half-life (128.6 d), high specific activity and a mean photon energy of about 66 keV, it has a drawback of low photon yield (only about six photon emissions/100 beta emissions). The objective of this work is to study the dosimetric characteristics of a locally developed170Tm brachytherapy seed source using the Monte Carlo-based EGSnrc code system. In this study, we calculate the dose rate constant, air-kerma strength, radial dose function, anisotropic function and 2D dose-rate distributions in water. Separate simulations are carried out by considering the photon (gamma and characteristic x-ray) and beta spectra of the source. For regions close to the source (surface of the source More