On the Monte Carlo Calculation of the Air-Kerma Strength for Brachytherapy Sources

Purpose: To study in detail how the various quantities entering the calculation of the air-kerma strength of brachytherapy sources affect the final value of this key quantity. Specifically, this study examines the role of the electrons emitted by the β radioisotopes used in brachytherapy sources, the effect of using μen/ρ instead of μtr/ρ, how the size of the bin used to determine the detected photon fluence modifies the final value of the air-kerma strength, the dependence of this value on the considered threshold photon energy, and how the level of detail with which simulations are carried out may affect the results of the calculations.