Water-equivalent calibration of 192Ir HDR brachytherapy source using MAGIC gel polymer

Abstract

Treatments with high dose rate (HDR) 192Ir sources deliver a high dose to tissues near the source. Due to the energy spectrum and the high gradient of dose delivered in these treatments, a proper calibration of the source is necessary. Calibration protocols for HDR brachytherapy sources recommend the use of reference air kerma rate measured using an ion chamber. Absorbed dose measurements in water have recently been proposed to be used to calibrate 192Ir HDR brachytherapy sources. MAGIC gel dosimeter with characteristics of Zeff equal to 7.41 (water-equivalent) and high spatial resolution has been shown as a potential dosimeter for many treatments in radiotherapy. The aim of the present work is to obtain percentage depth dose (PDD) and calibration parameters from 192Ir HDR sources using MAGIC gel, thermoluminescent dosimeters (TLD), ionization chamber and Monte Carlo simulation. The results show that MAGIC polymer gel is an adequate dosimeter to routinely calibrate 192Ir HDR sources for brachytherapy. © 2009 Springer-Verlag.