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Probing the Dose Enhancement Due to a Clinically-Relevant Concentration of Gold Nanoparticles and Yb-169 Gamma Rays Using PRESAGE Dosimeters

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J Cho

J Cho1,2*, M Alqathami1 , F Reynoso1,3 , S Cho1 , (1) UT MD Anderson Cancer Center, Houston, TX, (2) Oklahoma State University, Stillwater, OK, (3) Washington University School of Medicine, St. Louis, MO


TU-H-CAMPUS-TeP3-4 (Tuesday, August 2, 2016) 5:30 PM - 6:00 PM Room: ePoster Theater

Purpose: To probe physical evidences of the dose enhancement due to a low/clinically-relevant concentration of gold nanoparticles (GNPs) and Yb-169 gamma rays using PRESAGE dosimeters.

Methods: A PRESAGE cuvette was placed at approximately 2 mm above the plane containing three novel Yb-169 brachytherapy seeds (3.2, 3.2, and 5.3 mCi each). Two types of PRESAGE dosimeters were used – plain PRESAGEs (controls) and PRESAGEs loaded with 0.02 wt. % of GNPs (GNP-PRESAGEs). Each PRESAGE dosimeter was irradiated with different time durations (0 to 24 hours) to deliver 0, 4, 8, 16 and 24 Gy of dose. For a reference/comparison, both types of PRESAGEs were also irradiated using 250 kVp x-rays with/without Er-filter to deliver 0, 3, 10, and 30 Gy of dose. Er-filter was used to emulate Yb-169 spectrum using 250 kVp x-rays. The absorption spectra of PRESAGEs were measured using a UV spectrophotometer and used to determine the corresponding optical densities (ODs).

Results: GNP-PRESAGEs exposed to Yb-169 sources showed ~65% increase in ODs compared with controls. When exposed to Er-filtered and unfiltered 250 kVp x-rays, they produced smaller increases in ODs, ~41% and ~37%, respectively. There was a linear relationship between ODs and delivered doses with a goodness-of-fit (R²) greater than 0.99.

Conclusion: A notable increase in the ODs (~65%) was observed for GNP-PRESAGEs irradiated by Yb-169 gamma rays. Considering the observed OD increases, it was highly likely that Yb-169 gamma rays were more effective than both Er-filtered and unfiltered 250 kVp x-rays, in terms of producing the dose enhancement. Due to several unknown factors (e.g., possible difference in the dose response of GNP-PRESAGEs vs. PRESAGEs), however, a further investigations is necessary to establish the feasibility of quantifying the exact amount of macroscopic or microscopic/local GNP-mediated dose enhancement using PRESAGE or similar volumetric dosimeters.

Supported by DOD/PCRP grant W81XWH-12-1-0198

Funding Support, Disclosures, and Conflict of Interest: This investigation was supported by DOD/PCRP grant W81XWH-12-1-0198.

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