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Assessment of Storage Stability and Dose-Rate Dependency of a DNA Double-Strand Break Dosimeter

M Obeidat

M Obeidat*, K McConnell , J Roring , S Stathakis , N Papanikolaou , K Rasmussen , E Shim , N Kirby , University of Texas HSC SA, San Antonio, TX


SU-F-108-2 (Sunday, July 30, 2017) 2:05 PM - 3:00 PM Room: 108

Purpose: A DNA double-strand dosimeter was developed to enable a more biologically relevant radiation measurement than the current dosimeters. The goal here was to explore the proper storage condition for the dosimeter and to evaluate its dose-rate dependency.

Methods: The DNA dosimeter has four kilo-base pair DNA double strands (labelled on one end with biotin and on the other one with fluorescein) attached to streptavidin magnetic beads and suspended in phosphate-buffered saline. The dosimeter is sensitive to both light and heat, so it was evaluated under three different storage conditions to explore its storage stability (room temperature/light, room temperature/dark, and refrigerated/dark). Three batches of the DNA dosimeter were made and stored. After storage for 1, 3, 5, 8, 12, 15, 22, and 29 days, five samples of 50 µL for each storage condition were irradiated to 50 Gy. The coefficient of variation (CoV) for the dosimeter response was utilized to monitor the effect of prolonged storage. For dose-rate dependency, five samples of 50 µL of the dosimeter were irradiated in a water phantom to 50 Gy for each of four different dose-rates (0.6, 1.6, 4.9, and 12.4 Gy/min).

Results: For the storage stability experiment, the lowest CoV was maintained by storing the dosimeter in refrigerated/dark condition (1.3, 1.6, 1.4, 2.0, 1.5, 0.1, and 2.1 % CoV for days 1, 3, 5, 8, 12, 15, 22, and 29, respectively). For the dose-dependency experiment the lower dose-rates produced higher response for the DNA dosimeter (24.7, 22.2, 18.3, and 18.1 % probability of double-strand breaks for 0.6, 1.6, 4.9, and 12.4 Gy/min, respectively).

Conclusion: The dosimeter is most stable when stored in refrigerated/dark conditions and it exhibits dose rate dependency.

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