Validity of the interval method for the determination of the anisotropy factor of high dose rate 192Ir sources.

Abstract

This study investigates the validity of the interval method to determine the anisotropy factors of high dose rate (HDR) 192Ir sources. A calculation method, which is one of the various numerical implementations of the Sievert integral and known as the interval method, is applied to determine the anisotropy factors of a HDR 192Ir source. Calculated results from r = 1 cm to 10 cm are compared to published data. The comparison shows that the error resulting from the interval method increases from 1.3 to 28.1% as the radial distance increases from r = 1 cm to 10 cm and is significantly smaller than that previously reported. The interval method might be considered as a method that provides a very rough estimate of the anisotropy of HDR 192Ir sources whenever no conclusive anisotropy data is available.