title: Intra-irradiation changes in the signal of polymer-based dosimeter (GAFCHROMIC EBT) due to dose rate variations.
abstract: The effect of dose rate on the real-time change in optical density (DeltaOD) of a GAFCHROMIC EBT film is quantified using a previously reported optical readout approach. A range of doses (5-1000 cGy) and dose rates (16-520 cGy min(-1)) are used, and a statistically significant difference between DeltaOD of films exposed at different dose rates occurs within approximately one order of magnitude change in the dose rate. A small increase in per cent standard deviation of measured DeltaOD values is also observed when the entire dose rate range was used, but in all cases combining all DeltaOD values produces per cent standard deviation of <4.5%. Thus, whether the dose rate effect is clinically significant depends on the specific application of EBT and the desired accuracy.
authors.affiliation: Department of Medical Biophysics and Radiation Oncology, University of Toronto, Princess Margaret Hospital/Ontario Cancer Institute, 610 University Avenue, Toronto, ON M5G2M9, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rink
authors.forename: I Alex
authors.initials: IA
authors.lastname: Vitkin
authors.forename: David A
authors.initials: DA
authors.lastname: Jaffray
mesh_terms: D005373:Film Dosimetry / Q000295:instrumentation / Q000379:methods*; D055095:Optics and Photonics; D011879:Radiotherapy Dosage