The angular dependence of a two dimensional monolithic detector array for dosimetry in small radiation fields
Year: 2017
Type: conference-paper
Abstract: The purpose of this study is to investigate the directional dependence of a two dimensional monolithic detector array (M512) under 6 MV photon irradiation and to evaluate the effect of field size on angular dependence. Square fields of sizes: 3x3 cm 2 and 10x10 cm 2 were measured at the iso-centre of a cylindrical phantom. Beam angles with incidences from 0 0 - 180 0 in increments of 15 0 were used to investigate the central pixel angular response of M512, normalized to the pixel response for normal (0°) beam incidence. The angular response of the detector was compared to the response of EBT3 radiochromic film in the identical geometric orientation. The maximum angular dependence was observed at the angle 90°±15° to be -18.62% and -17.70% for the field sizes 3x3 cm 2 and 10x10 cm 2 , respectively. The angular dependence of M512 showed no significant difference between field sizes of 3x3 cm 2 and 10x10 cm 2 (p>0.05). The maximum dose difference measured by the central pixel of M512 and EBT3 for all angles are -20% for 3x3 cm 2 field size and -18.58% for the 10x10 cm 2 field. The diode array's size and packaging effects the angular response of the detector. The angular correction factor is necessary to apply to increase accuracy in dosimetry for arc treatment delivery.
Institution: University of Wollongong
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W2583932013