Derivation of dosimetry data for brachytherapy sources using Monte Carlo for primary and scatter dose separation

Abstract

The scatter dose around brachytherapy sources is dependent on the characteristics and geometry of the scattering volume, while the primary dose depends only on the material along the source to calculation point path. Hence, algorithms based on primary and scatter dose separation will facilitate scatter dose integration and heterogeneity corrections. Source characterisation by means of Monte Carlo simulation of dose deposition per source emitted radiant energy allows dose separation into primary and scatter dose contributions [1]. The effects on the source geometry, self-absorption and attenuation in the source, encapsulation and wall material of the source channel are thus included in the calculated dose and kerma deposition. Radial dose distributions for the primary and total scatter dose were parameterised by exponential functions based on simple one-dimensional transport theory. Appropriate scaling and/or convolution techniques may be applied to each dose contribution separately to account for effects from scatter volume size, source placement and density variations [2].