Room: Stars at Night Ballroom 1
Purpose: A DNA dosimeter was developed to measure double-stranded breaks (DSBs) and has shown to be effective for radiation measurements. However, the scavenging environment of the dosimeter, which can affect the quantity of DSBs, was not yet similar to that in cells. The goal was to evaluate the effect of introducing a more appropriate scavenging environment on the dosimeter response.
Methods: The dosimeter comprises of a 4-kilobase-pair DNA strand attached with fluorescein and biotin at opposite ends. The biotin end binds to streptavidin-coated beads and the fluorescence signal from fluorescein is used to determine whether a DSB has occurred and determine the probability for DSB (PDSB). To better retain and minimize loss of dosimeter during handling, the procedure was reduced to a one-step magnetic separation process. A Varian 600C with 6 MV photons was used for irradiation. Measurements were made in a solid water setup, with a 10 x 10 cm field, and at a 1.5 cm depth. The effect of scavengers on the PDSB was evaluated by irradiating dosimeter that was re-suspended in phosphate-buffered saline (PBS), Tris buffer, and glycerol at 0, 50, and 100 Gy. Tris and glycerol at reported concentrations provide a scavenger environment similar to that for intracellular DNA.
Results: The measured PDSB was 0.053 and 0.106 at 50 and 100 Gy, respectively, for PBS. These same numbers changed to 0.060 and 0.130, respectively, for Tris and to 0.068 and 0.297, respectively, for glycerol.
Conclusion: Introducing more realistic scavenging conditions to the DNA dosimeter still enabled it to produce a measurable response. Future experiments will focus on evaluating response at lower doses and signal-to-noise ratios for these new conditions.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by the following grants: SABER IRACDA K12 (K12GM111726), CPRIT RTA (RP 170345)