Study of light transmittance from layers of Fricke-xylenol-orange-gel dosimeters having different composition and analysed with variuos modalities.

In-phantom absorbed dose is imaged by measuring the optical transmittance through ferrous-sulphate and xylenol-orange infused gel, in form of layers. Images are acquired with a CCD camera provided with a suitable optical filter. The dependence of dosimeter sensitivity and of linearity range on the amount of xylenol orange and on parameters of optical analysis has been inspected. In order to check the capability of the method, dose profiles in the central axis of a phantom irradiated with a collimated gamma -beam have been compared with the results obtained with a ionisation chamber.