Dose-response of Fricke- and PAGAT-dosimetry gels in kilovoltage and megavoltage photon beams: impact of LET on sensitivity

JOSÉ VEDELAGO; DAVID CHACÓN; MARCELO ROMERO; DANIEL VENENCIA; FACUNDO MATTEA; MAURO VALENTE

PHYSICA MEDICA

IST EDITORIALI POLGRAFICI INT

Lugar: Roma; Año: 2021 vol. 84 p. 41 - 49

1120-1797

Purpose: Dosimetry of ionizing radiation quanties the energy deposited by an incident beam to the medium. This study presents the relative response of two types of gel dosimeters describing the dierences by estimating radiation chemical yields produced in water radiolysis. Methods: Two types of gel dosimeter were used, namely an acid ferrous ion solution infused with xylenol orange known as Fricke gel and a polymer gel based on acrylamide and N,N´-methylenebis(acrylamide) known as PAGAT. Samples were irradiated using two photon beam energies, one from a conventional X-ray tube operated at 44 kV and the other one from a LINAC operated at 6 MV. The dosimeters were analyzed by optical absorbance and magnetic resonance imaging. Additionally, the linear energy transfer of each beam was calculated using Monte Carlo simulations for further estimation of the radiation chemical yields produced during water radiolysis Results: Obtained results for both gel dosimeters indicate that their response at 44 kV and 6 MV are dierent, regardless of the read-out technique. On average, the sensitivity at 44 kV was found to be 65 % of the response at 6 MV. The calculated radiation chemical yields are in agreement with the observed experimental results. Conclusions: The main reason for the dierence in the response of the dosimeters may be related to the linear energy transfer of each photon beam, which varies the production of primary chemical species during water radiolysis.