(Saturday, 4/7/2018)
Room: Foyer
Purpose: OSLDs are used to make in vivo measurements (ie.e TBI, TSEI). Most users calibrate the OSLDs using the software provided by Landauer which typically covers doses up to about 3 Gy. OSLDs that reach that dose are discarded and new ones purchased and calibrated. each. We have developed an accurate method of reusing OSLDs up to at least 50 Gy and may be applicable far above that dose.
Methods: Instead of using the calibration routine in the InLight microStar software (Landauer, Inc.), we anneal them with a fluorescent light source to less than 200 counts (~0.3cGy), irradiate them with 50 cGy, and use the hardware mode in the software to read OSLDs to produce an OSLD serial number-specific calibration factor. After total body irradiation delivery, we read them in hardware mode and apply the calibration factor to get the dose. We then repeat this process for the next usage.. In this study we retrospectively analyzed the measured calibration factors vs accumulated doses for 9 OSLDs irradiated up to 29 times to nearly 50 Gy total dose. All OSLD’s responded linearly with dose with the value of R2 between 0.95 and 0.98. With this finding, we propose an efficient and accurate method to reuse OSLDs with intermittent recalibration with less than 5% maximum error.
Results: Within the 29 uses, sets of three predicted calibration factors were compared to the measured calibration factors. The average precision was 1.9% ± 0.58%, 2.27% ± 0.74%, 2.96% ± 0.52%, and 3.64% ± 0.78%.
Conclusion: Our method is a cost-saving and feasible method that allows a user to reuse an OSLD up to at least 50Gy accumulated dose with minimal recalibration effort., and predict calibration factors with a precision better than the 5% value one can achieve with the conventional batch calibration method.
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