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Strontium Aluminate Phosphorescent Materials: Bright Idea for in Vivo Dosimetry

X Tang*, E Ehler, D Mathew, University of Minnesota, Minneapolis, MN

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: To evaluate the use of strontium aluminate phosphorescent powder as an in vivo TL dosimeter and real-time fluence monitor for electron beams.

Methods: Europium-doped strontium aluminate powder (SrAl2O4:Eu) was placed inside several identical light-tight cases and annealed. After cooling, the powder-filled cases were irradiated using an 18 MeV beam at 3.0 cm depth. The samples were irradiated to five dose levels from 40 cGy to 520 cGy. The delivered dose was determined with OSLD measurements. OSLDs were placed in identical containers as the SrAl2O4:Eu, positioned beside the SrAl2O4:Eu cases and irradiated along with the SrAl2O4:Eu cases. The SrAl2O4:Eu samples were read with a Harshaw TLD reader in a dark room one day after irradiation. A linear temperature ramp from 20 degrees Celsius to 350 degrees Celsius with a high-temperature hold for 60 seconds was used. In addition, the phosphorescent (glow) spectrum was measured. The powder was placed in glass cuvettes, irradiated and immediately read out on an Exemplar Plus spectrometer.


Results: The TLD reading signal was integrated across the temperature ramp and plotted against the dose measured with OSL dosimeters. The relationship between the integrated TLD signal and the dose can be modeled using linear regression. The powder phosphorescence spectrum was measured with a peak at 520 Å, consistent with SrAl2O4:Eu. The glow was observed both with the vault video camera as well as visually after the treatment was completed


Conclusion: Strontium aluminate is a potential TL dosimeter for electron beams. A linear dose response was observed from 40 – 180 cGy; superlinearity was observed above 180 cGy. The persistent afterglow of SrAl2O4:Eu allows for visual inspection of the radiation field both during and immediately after radiation treatment. Future work will focus on quantifying the phosphorescence intensity of SrAl2O4:Eu.

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Keywords

TLDs, In Vivo Dosimetry, Photostimulable Phosphor

Taxonomy

TH- Radiation dose measurement devices: TLD

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