Preliminary dose calibration results using a TENOMAG polymer gel dosimeter and optical CT (VISTA™)

We present a preliminary result of dose calibration for 3D dose evaluation using gel dosimetry in radiotherapy. In this work, we measured the percentage depth dose (PDD) and dose linearity using a normoxic polymer gel dosimeter (TENOMAG) and a commercial cone-beam optical CT scanner (VISTA™, Modus Medical Devices, Inc., London, ON, Canada). We confirmed that the PDD measured for 1 and 2 Gy had a build up region at 0.4 cm depth. However, the PDD measured for 3 and 4 Gy had not a build up region. In all cases, the PDD has not greatly decreased with depth above 4 cm depth. Moreover we confirmed that the optical density proportionally increased with dose at 1, 1.5 and 2 cm depth, while the response has not greatly increased with dose for other depths. In this study, we confirmed that we will be able to perform the dose calibration using optical density obtained from a TENOMAG gel data scanned with an optical CT scanner.