Control de calidad tridimensional preliminar mediante dosimetría de gel polimérico para radiocirugía estereotáctica

FACUNDO MATTEA; DAVID CHACÓN; JOSÉ VEDELAGO; MAURO VALENTE

Simposio; XX International Symposium on Solid State Dosimetry (ISSSD 2020); 2020

Polymer gel dosimeters represent one of the most promising devices for the assessment of clinical radiotherapy treatments[1,2]. Modern techniques like stereotactic body radiation therapy (SBRT) or stereotactic radiosurgery (SRS) can deliver high dose gradients and great accuracy in complex geometries, therefore achieving shorter treatments plans, and ensuring the protection of surrounding healthy tissue. Nevertheless, dose verification and quality assurance of these complex treatments demand inherent three-dimensional methods, with high spatial resolution, and tissue-equivalence. In this study polymer gel dosimetry systems based on acrlamide and N N´ - methylenebisacrilamide in a gelatin matrix crosslinked with glutaraldehyde were used for SRS verification involving doses between 5 and 20 Gy, attaining 5 targets, as planning treatment volumes (PTV) with diameters lower than 1 cm. The main objective of using this polymer gel dosimeter is to provide a stable dose distribution by minimizing the polymerization on the high gradient dose regions after the irradiation, which generates an overdose readout. With that in mind, the mobility of the chemical species involved in the polymerization reaction was affected by increasing the crosslinking degree in the gelatin matrix. Results comparing the dose profiles crossing the PTVs indicate that the overestimation of the dose in the boundary regions can be reduced and eliminated by the proposed approach regardless of the dose values within a dose range of 5 Gy to 20 Gy