Studies of Fricke-PVA-GTA xylenol orange hydrogels for 3D measurements in radiotherapy dosimetry

The Fricke gels (FG) composition has been modified over the years in order to improve their dosimetric characteristic for spatial dose evaluation in radiotherapy. Some problems, in particular those related to the diffusion of ferric ions in the gel matrix, have limited the clinical use of FG and still represent significant challenges for the scientific community working in the field of gel dosimetry. In this work, FG based on poly-vinyl alcohol (PVA) as the gelling agent, glutaraldehyde (GTA) as a cross-linker and FG based on gelatine loaded with silicate nano-clay (laponite) were developed with the aim to overcome the diffusion drawbacks affecting the traditional FG. Neither the sensitivity to the radiation dose nor the diffusion coefficient were significantly altered by the addition of laponite into the Fricke xylenol orange gel formulation employed. By contrast, lower diffusion rates were obtained with PVA-GTA gels, suggesting that this matrix could have a promising use in the field of 3D dosimetry.