Approximating Sievert Integrals to Monte Carlo Methods to calculate dose rate distributions around P192PIr brachytherapy source

Abstract

Radiation dose rates along the transverse axis of a miniature P192PIr source were calculated using Sievert Integral (considered simple and inaccurate), and by the sophisticated and accurate Monte Carlo method. Using data obt-ained by the Monte Carlo method as benchmark and applying least squares regression curve fitting, a mathemat-ical relationship was established to parameterise errors inherent in the Sievert Integral outputs. The dose rate anisotropy distributions around the source were determined to evaluate the anisotropy corrections required to modify the Sievert Integral method to improve the accuracy in dose calculations. With the accuracy of Monte Carlo method incorporated in the Sievert Integral method, the model equation could be applied successfully in clinical practice to safe time.