Room: ePoster Forums
Purpose: The aim of this work was to study the dosimetric properties of the PTW microDiamond (60019) single crystal synthetic diamond detector (DD) in orthovoltage beams. To our knowledge, this is the first attempt to characterize the microDiamond detector in low energy x-ray beams.
Methods: NIST-traceable ADCL x-ray beams were used in this study. Pre-irradiation dose required by the DD, in order to stabilize the detector's response to within 0.5%, was quantified by recording the DD's current as a function of irradiation time, which was then used to determine air-kerma or dose-to-water delivered. Dose-rate dependence was also investigated using the UW250-M and UW60-M beams, where the dose-rate was varied by changing the tube current. N(k) calibration coefficients for all the available M and L series beams, and N(D, w) coefficients for the M series beams were obtained to determine the energy dependence of the detector.
Results: A 2 Gy dose-to-water or air-kerma was found to be sufficient for the given DD's response to stabilize in all of the beams used in this study to within 0.5%. A 15-minute rest period between irradiations was sufficient for the DD to be pre-irradiated again. The dose-rate dependence factor, Î”, was found to be 1.015 and 0.996 for the UW250-M and UW60-M beams, respectively. A variation of up to 198%, relative to â?¶â?°Co, in the calibration coefficients was found in the investigated energy range.
Conclusion: In order to stabilize the response, the DD needs a pre-irradiation dose, which was found to be independent of beam energy used. DD's response was found to be linear with dose-rate. An energy dependence of the DD was found, which is more pronounced in the low energy beams and can be partially attributed to the metal contact material around the sensitive volume of the DD.