Gel dosimetry response comparison for 44 kVp and 6 MV photon beams

JOSÉ VEDELAGO; DAVID CHACÓN; DIANA CUEVAS; DANIEL VENENCIA; FACUNDO MATTEA; MAURO VALENTE

Córdoba

Simposio; 14th International Symposium on Radiation Physics (ISRP-14).; 2018

Oral Presentation: Dosimetry of ionizing radiation quantifies the energy imparted by the incident beam to the medium. When modern medical procedures for oncology diagnosis or treatments are considered, it is recommended to take into account reference detector measurements, like ionization chambers, together with tissue-equivalent detectors, as gel dosimeters [1]. Gel dosimeters present several advantages against reference dosimeters, being one of the most relevant ones its three-dimensional capability of experimentally determine absorbed dose distributions. Hence, a thorough characterization of gel dosimeters response is needed towards its implementation in clinical applications. This study presents the relative response of two differents gel dosimeters, an acid ferrous ion solution infused with Xylenol Orange known as Fricke gel [2] and a polymer gel know as PAGAT [3] based on acrylamide and N,N′-Methylenebis(acrylamide) with Tetrakis(hydroxymethyl)phosphonium chloride solution. Samples were irradiated with two photon beams, one from a conventional X-ray tube operated at 44 kVp and another from a LINAC operated at 6 MV. Dosimeters readout was made by optical absorbance and by magnetic resonance imaging. Optical absorbance was measured at 580 nm for Fricke dosimeter and at 540 nm for PAGAT dosimeter. Relaxometry spin-lattice was quantified for Fricke gel and spin-spin relaxation time changes for PAGAT system. Obtained results for both gel dosimeters indicates that systems response at 44 kVp are in average a 64 % of the response at 6 MV, regardless the readout system