Characterizing a PTW microDiamond detector in kilovoltage radiation beams
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-06-17 |
| Journal | Medical Physics |
| Authors | Ahtesham Ullah Khan, Wesley S. Culberson, Larry A. DeWerd |
| Institutions | University of WisconsinâMadison |
| Citations | 14 |
Abstract
Section titled âAbstractâPurpose The aim of this work was to characterize the dosimetric properties of the PTW microDiamond (60019) single crystal synthetic diamond detector (DD) in kilovoltage xâray beams. The following characteristics were addressed in this study: required preirradiation dose, doseârate linearity, energy dependence, and percent depth dose response of the DD. Methods UWADCL xâray beams, characterized by NISTâtraceable ionization chambers, were used in this study. Preirradiation dose required by the DD, in order to stabilize the detectorâs response to within 0.1%, was quantitated. Doseârate dependence was also investigated using the UW250âM and UW50âM beams, where the dose rate was varied by changing the tube current. and calibration coefficients for all the available M series beams at UWADCL were obtained to determine the energy dependence of the DD, Diode E, Diode P, and P11 parallelâplate ionization chamber. A customâbuilt water tank was utilized to measure the percent depth dose (PDD) response of the DD, Diode E, Diode P, and P11 chamber in UW250âM, UW100âM, and UW50âM beams. The measured PDD response of the detectors was compared with the simulated PDD data using EGSnrc Monte Carlo code. Results A 1.5 Gy doseâtoâwater or airâkerma was found to be sufficient for the given DDâs response to stabilize to within 0.1% in all of the beams used in this study. The doseârate dependence parameter, Î, was found to be 1.00 ± 0.02 and 1.016 ± 0.05 for the UW250âM and UW50âM beams, respectively. Relative to the Co calibration coefficients, the DD was found to underârespond relative to calculated absorbed dose to water response and overârespond relative to the calculated airâkerma response in the Mâseries beams. Agreement of 1.5% was found between the measured PDD values and Monte Carlo simulated PDD values for UW250âM, UW100âM, and UW50âM beams. Conclusions In order to stabilize the response, the DD needs a preirradiation dose, which is unique to every DD. A linear relationship between detector response and dose rate was found within the evaluated uncertainty. An energy dependence of the DD was studied, which is more pronounced in the lowâenergy beams and can be partially attributed to the metal contact material around the sensitive volume of the DD. Overall, the DD was found to be suitable for kilovoltage xâray dosimetry.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2015 - Superficial Radiation Therapy for the Treatment of Nonmelanoma Skin Cancers