The impact of self-oxidation on the dosimetric performance of ferrous-sulfate/xylenol-orange gels

Since their introduction in the 1980’s, most of the research on ferrous-sulfate gel dosimeters has aimed at minimizing the ferric ion diffusion phenomena that blur the 3D distribution of the signal. However, equally important are the spontaneous oxidation effects, which alter the sensitivity of the gels over time. In some gels, this effect is very pronounced and must be accounted for even when production, calibration and use of the gels are separated by just a few days. In other cases, the effect is much milder, but should still be properly accounted for when gels are used over a long period a time, such as in the proposed monitoring of adaptive radiotherapy treatments. Our work examined an…