(Saturday, 4/7/2018)
Room: Foyer
Purpose: The purpose of this work is to characterize annealing and decay characteristics of OSLD’s using the NMPC annealer and ambient clinical light. This required commissioning a new MicroSTAR ii system.
Methods: To commission the MicroSTAR ii system, calibration OSLD’s spanning the whole clinical range were irradiated, and QC OSLD’s for a subset were also irradiated. Calibration files were verified by reading the dose of QC OSLD’s. To test decay by annealing, OSLD’s with various residual doses were initially read with the MicroSTAR ii reader prior to annealing. The active portions of multiple OSLD’s were exposed and placed into the annealer, and the dose was read periodically. The NMPC annealer has an aluminum case and uses blue LED’s to anneal the OSLD’s. To test decay by ambient clinic light, six OSLD’s were also left in different places with different amounts of ambient clinic light to characterize the decay that took place.
Results: With the annealer, OSLD’s with more dose required more annealing time to reach a background dose of 0.1 cGy. The dose on OSLD’s with their active portions open to the light decayed faster than those that had less ambient light exposure.
Conclusion: Our recommendation is that OSLD’s below 200 cGy need to be annealed for 45 minutes, between 200 cGy and 500 cGy they need to be annealed 60 minutes, and between 500 cGy and 1000 cGy they need to be annealed 90 minutes. Also, it is important not to leave OSLD’s with their active portion left open to the light.
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