title: Evaluation of Al2O3:C optically stimulated luminescence (OSL) dosimeters for passive dosimetry of high-energy photon and electron beams in radiotherapy.
abstract: This article investigates the performance of Al2O3: C optically stimulated luminescence dosimeters (OSLDs) for application in radiotherapy. Central-axis depth dose curves and optically stimulated luminescence (OSL) responses were obtained in a water phantom for 6 and 18 MV photons, and for 6, 9, 12, 16, and 20 MeV electron beams from a Varian 21EX linear accelerator. Single OSL measurements could be repeated with a precision of 0.7% (one standard deviation) and the differences between absorbed doses measured with OSLDs and an ionization chamber were within +/- 1% for photon beams. Similar results were obtained for electron beams in the low-gradient region after correction for a 1.9% photon-to-electron bias. The distance-to-agreement values were of the order of 0.5-1.0 mm for electrons in high dose gradient regions. Additional investigations also demonstrated that the OSL response dependence on dose rate, field size, and irradiation temperature is less than 1% in the conditions of the present study. Regarding the beam energy/quality dependence, the relative response of the OSLD for 18 MV was (0.51 +/- 0.48)% of the response for the 6 MV photon beam. The OSLD response for the electron beams relative to the 6 MV photon beam. The OSLD response for the electron beams relative to the 6 MV photon beam was in average 1.9% higher, but this result requires further confirmation. The relative response did not seem to vary with electron energy at dmax within the experimental uncertainties (0.5% in average) and, therefore, a fixed correction factor of 1.9% eliminated the energy dependence in our experimental conditions.
authors.affiliation: Department of Physics, Oklahoma State University, Stillwater 74078, USA. eduardo.yukihara@okstate.edu
authors.forename: E G
authors.initials: EG
authors.lastname: Yukihara
authors.forename: G
authors.initials: G
authors.lastname: Mardirossian
authors.forename: M
authors.initials: M
authors.lastname: Mirzasadeghi
authors.forename: S
authors.initials: S
authors.lastname: Guduru
authors.forename: S
authors.initials: S
authors.lastname: Ahmad
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002138:Calibration; D002244:Carbon / Q000737:chemistry*; D004307:Dose-Response Relationship, Radiation; D004583:Electrons; D006801:Humans; D049449:Luminescence; D055095:Optics and Photonics; D019047:Phantoms, Imaging; D017785:Photons; D011829:Radiation Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods; D013696:Temperature
chemical_list: D002244:Carbon; D000537:Aluminum Oxide