Angular dependence of the optically stimulated luminescent dosimeter / 中国辐射卫生

ABSTRACT

0bjective To study the angular dependence of optically stimulated luminescent dosimeter (OSLD) with solid phantoms under SSDL radiation level 60Co radiation field, and to discuss the possibility of OSLD in volumetric modulated arc therapy (VMAT) and other rotating irradiation dose audit. Methods OSLDs were embedded in the two phantoms with the same size and material, respectively. The phantom 1 was set to make the first OSLD perpendicular to the beam, and the phantom 2 was set to make the second OSLD parallel to the beam. The OSLDs were irradiated at 8 angles 0°, 45°, 90°, 135°, 180°, −45°, −90, −135°. The counts of the OSLSs were read and the response of each angle which normalized to 0° were calculated. Results When the OSLDs are perpendicular to the beam, the angular response is between −6.76% ～ +1.5%, with the maximum angular dependence at 90° and −90°. When the OSLDs are parallel to the beam, the angular response is between −1.74%～+1.67%, below 2%. Conclusion It is better to correct the sensitivity of dosimeters by Element Correction Factors (ECF) for dose audit. Under the condition of rotating irradiation, OSLD shoud be set parallel to the beam, which can better reduce the influence of angular dependence and facilitate further application research of VMAT dose audit.