Room: AAPM ePoster Library
Purpose: The aim of this work was to study and compare the dose-rate dependence of various solid-state detectors: PTW microDiamond, PTW Diode P, Diode SRS, Exradin D1H, and Sun Nuclear Edge. To our knowledge, this is the first attempt to investigate the dose-rate dependence of the aforementioned solid-state detectors.
Methods: A 6 MV photon beam from a Varian 21EX linear accelerator was utilized for all measurements. All of the detectors were placed at a depth of 1.5 cm inside a water tank with the field size set to 10x10 cm² and source-to-surface distance (SSD) of 100 cm. The dose-rate dependence was studied by varying both nominal repetition rate (NRR) and SSD. 100 MUs were delivered during each irradiation with the NRR of the linac varying from the nominal 100 MU/min to 600 MU/min settings. All of the readings were normalized to the reading acquired at 600 MU/min. The dose-rate dependence as a function of SSD was investigated by keeping the NRR at 600 MU/min and varying the SSD from 75 cm to 135 cm. An SSD correction factor was calculated by normalizing the diode and diamond readings by the Exradin A18 ionization chamber readings.
Results: Within the NRR range of 100 MU/min to 600 MU/min, the Diode SRS, A18, D1H, and Edge detectors were found to be dose-rate independent up to 1% and the microDiamond and Diode P detectors were found to be dose-rate independent up to 2%. Within the SSD range of 75 cm to 135 cm, all detectors, except microDiamond, were found to be dose-rate independent up to 1%. The microDiamond detector was found to be dose-rate independent up to 2%.
Conclusion: All of the studied detectors were found to have a dose-rate dependence of up to 2%. Therefore, these detectors are suitable for use within this limit.