Energy Dependence Investigations of GafChromic EBT Films for Pretreatment Dosimetric Verification of IMRT Plans

Abstract

The purpose of the study was examination of energy dependence of Gafchromic EBT – a new radiochromic dosimetry film. The film response was measured irradiating the samples with doses from 0.1 Gy to 12 Gy using photon beams from the energy range 1.25 MV-25 MV. The samples were scanned and the film response was compared for different beam energies. The measurements were performed in order to evaluate potential use of radiochromic films in pretreatment dosimetric verifications of intensity modulated radiotherapy (IMRT) plans. A high uncertainty in readout of the film response was observed for films irradiated with doses lower than 1 Gy. The relative difference exceeds 20 % for doses below 1 Gy while for doses over 1 Gy the measured film response differs by less than 5 % for the whole examined energy range. No energy dependence of Gafchromic EBT film response was observed in the investigated energy range but the doses measured for pretreatment plan verifications should exceed 1 Gy.