Modeling chemical and physical phenomena in polyacrylamide gel dosimeters

Abstract

Polyacrylamide gel (PAG) dosimetry provides a promising means for the calibration and verification of three-dimensional radiation dose delivery in modern conformal radiotherapy. PAG dosimetry is based on the radiation-induced copolymerization of acrylamide and bisacrylamide monomers in water and gelatin. While the basic mechanisms of the radiation-induced polymerization that gives rise to this technique have been studied experimentally, little work has been performed in modeling the polymerization processes. We have reported such models for homogeneous irradiations of PAG dosimeters previously. In this work we present a more complex model that can account for spatial variations in the dose distribution. The models are intended to provide a better understanding of fundamental dosimeter behaviour, so that the use of PAG systems may become more reliable and improved dosimeters may be developed in the future.