An analytic approach to the dosimetry of a new BEBIG 60Co high-dose-rate brachytherapy source.

We present a simple analytic tool for calculating the dose rate distribution in water for a new BEBIG high-dose-rate (HDR) 60Co brachytherapy source. In the analytic tool, we consider the active source as a point located at the geometric center of the 60Co material. The influence of the activity distribution in the active volume of the source is taken into account separately by use of the line source-based geometric function. The exponential attenuation of primary 60Co photons by the source materials (60Co and stainless-steel) is included in the model. The model utilizes the point-source-based function, f(r) that represents the combined effect of the exponential attenuation and scattered photons in water. We derived this function by using the published radial dose function for a point 60Co source in an unbounded water medium of radius 50 cm. The attenuation coefficients for 60Co and the stainless-steel encapsulation materials are deduced as best-fit parameters that minimize the different [ABSTRACT FROM AUTHOR]