Preliminary Investigation of the Dosimetric Properties of 'RadGel'

A preliminary investigation into the efficacy of a new 3D dosimetry material, RadGelTM, for verification of radiation therapy dose distributions is presented. Small volumes of RadGelTM were found to exhibit a linear, reproducible response to dose. A gradual increase in optical-density (OD) with time was observed, suggesting scanning should be completed within 18 hours to keep a linear correlation of R2 > 0.99. A larger 10 cm diameter volume of RadGelTM was irradiated with a rotationally symmetric 'spoke' plan designed to rigorously evaluate scanner/dosimeter combined performance. The dosimeter was imaged with the Duke Mid-sized Optical-CT Scanner (DMOS). Promising OD and corresponding dose maps were obtained. Edge artefacts were observed and are suspected to be exacerbated by the particular container used in this early study. Further studies will evaluate new containers and methods for refractive matching at the gel-container-fluid interface.