title: Evaluations of absorbed dose ratio factor of Al2O3 dosemeter in radiotherapy photon beams using cavity theory.
abstract: The aim of the work was to evaluate the absorbed dose ratio factor f(md) of an Al(2)O(3) dosemeter to water in photon radiotherapy beams using cavity theory. Burlin theory was used for calculating of this ratio. The effective mass attenuation coefficient β was obtained by comparing Monte Carlo simulations in monoenergetic photon beams. The evaluations of the absorbed dose ratio factor f(md) were studied for Al(2)O(3) dosemeters of different sizes, which were placed at various depths of the water phantom in different radiation field sizes of Mohan's 6, 10 and 15-MV X-rays. Beyond the build-up region, the variation of f(md) increases by 0.25 % as the depth increases from 4 to 10 cm. The maximum variation due to different dosemeter sizes is 8.3 %. The difference in the f(md) due to different radiation field sizes is 1.5 %. The effect of the dosemeter size cannot be neglected. The difference in the f(md) due to the radiation field sizes of different beams would increase as the dosemeter size increases.
authors.affiliation: School of Physics Science and Engineering,  Sun Yat-Sen University, Guangzhou 510275,  China.
authors.forename: Jinhan
authors.initials: J
authors.lastname: Zhu
authors.forename: Shaowen
authors.initials: S
authors.lastname: Chen
authors.forename: Lixin
authors.initials: L
authors.lastname: Chen
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Liu
mesh_terms: D000042:Absorption; D000465:Algorithms; D000537:Aluminum Oxide / Q000528:radiation effects*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008962:Models, Theoretical; D017785:Photons / Q000627:therapeutic use; D011829:Radiation Dosage; D011882:Radiotherapy, High-Energy / Q000295:instrumentation*; D012542:Scattering, Radiation; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation*
chemical_list: D000537:Aluminum Oxide