Characterization of Phosphorescent Strontium Aluminate as a Real-Time Dosimeter
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PO-GePV-T-226 (Sunday, 7/25/2021) [Eastern Time (GMT-4)]
Purpose: A novel dosimeter capable of displaying dose in real time would enable one to verify the distribution of dose on the surface of a patient during treatment. The purpose of this study was to characterize the response of phosphorescent strontium aluminate (SrAl(2)O(4):Eu2+Dy3+) to high energy x-rays and to subsequently determine how the signal decays with respect to time. The wide range of application and low cost makes it a promising and attractive alternative to relative dosimetry.
Methods: Glass cuvettes were filled with phosphorescent strontium aluminate powder and individually irradiated by a 6 MV beam at 100 cm SSD with a 10x10cm(2) field size at 1.5 cm depth. Post-irradiated cuvettes were placed in a black box and remotely photographed using a Nikon DSLR camera 1.5 minutes after irradiation. The resultant images were analyzed in MATLAB. Using a dose rate of 600 MU/min, we irradiated samples with 25, 50, 100, 200 400, 600, 800, and 1000 MU’s to test linearity. Signal decay over time was measured by irradiating a cuvette at 600 MU and obtaining images in 5-minute intervals.
Results: Strontium Aluminate exhibited a linear relationship to an increase in dose, within a dynamic range of 400-1000 MU with an R-square of .9922. For the signal decay over time test, the signal decreased roughly by a factor of 5 within the first 5 minutes and gradually decayed for the remaining intervals. The decay in signal was best fit by a rational function to the first degree.
Conclusion: Phosphorescent Strontium Aluminate showed a favorable response in its linearity trials with changing dose and could potentially be used as a real time dosimeter during treatment or for routine QA procedures. Future experiments will focus on solidifying its functionality as an alternative to the current and more expensive relative dosimeters in use.
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