Optical Computed Tomography and Magnetic Resonance Imaging Studies of Three-Dimensional Gel Dosimeters

This thesis aimed to further assess a specific version of a Fricke Gel Dosimeter developed in the last decade at the University of Pisa Department of Civil and Industrial Engineering (DICI) by the research group led by Professor Francesco d’Errico, for the measurement of three-dimensional dose distribution in radiotherapy. This work upheld and expanded the current knowledge on this tissue-equivalent radiochromic gel based on polyvinyl alcohol (PVA) chemically cross-linked with glutaraldehyde (GTA) by utilizing larger samples to study beam interaction, shifting from cuvettes (with dimensions of 1 x 1 cm²) to containers (with a diameter of 5.9 cm) and an irradiated area of 3 x 3 cm². Thanks to its high sensitivity and low diffusion, this gel contributed to research aimed at verifying the agreement between delivered dose and prescribed treatment plans. Particular emphasis was placed on the study of signal diffusion effects in the gel, which is considered as one of the main problems associated with the use of ferric ions. After irradiating with different levels of high-energy X-rays in a linear accelerator, and due to its transparency, imaging was performed using optical techniques. This complemented the magnetic resonance scanning that had historically been central to studies of this gel. The research performed in previous years was used to compare and expand the data available regarding signal diffusion.