A method to improve the accuracy of diode in vivo dosimetry for external megavoltage photon beams filtered by wedges
AbstractDiode in vivo dosimetry is widely considered to be an important tool for quality improvement of patient care in external radiotherapy. In vivo dose measurements for wedged photon beams require correction factor estimation for difference in wedge angles and field sizes. The diode dosimeters that were used in this study were two different models of PTW products; T60010L and T60010M models were used for 60Co and 6-MV photon beams, respectively. The values of off-axis wedge correction factor were determined at two different physical situations in the wedged and non-wedged directions on the entrance surface of the polystyrene phantom. The wedge correction factor at various depths was then estimated by a proposed method. Results show that the absorbed dose at each depth can be estimated by applying accurate wedge correction factor at depth, on entrance surface dose with negligible probable errors (below 1.2%).