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Determination of the AAPM TG-43 Brachytherapy Dosimetry Parameters for A New Titanium-Encapsulated Yb-169 Source by Monte Carlo Calculations

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F Reynoso

F Reynoso1,3*, J Munro2 , S Cho1 , (1) UT MD Anderson Cancer Center, Houston, TX, (2) Source Production & Equipment Co., Inc., St. Rose, LA, (3) Washington University School of Medicine, St. Louis, MO


SU-F-T-54 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To determine the AAPM TG-43 brachytherapy dosimetry parameters of a new titanium-encapsulated Yb-169 source designed to maximize the dose enhancement during gold nanoparticle-aided radiation therapy (GNRT).

Methods: An existing Monte Carlo (MC) model of the titanium-encapsulated Yb-169 source, which was described in the current investigators’ published MC optimization study, was modified based on the source manufacturer’s detailed specifications, resulting in an accurate model of the titanium-encapsulated Yb-169 source that was actually manufactured. MC calculations were then performed using the MCNP5 code system and the modified source model, in order to obtain a complete set of the AAPM TG-43 parameters for the new Yb-169 source.

Results: The MC-calculated dose rate constant for the new titanium-encapsulated Yb-169 source was 1.05 ± 0.03 cGy per hr U, indicating about 10% decrease from the values reported for the conventional stainless steel-encapsulated Yb-169 sources. The source anisotropy and radial dose function for the new source were found similar to those reported for the conventional Yb-169 sources.

Conclusion: In this study, the AAPM TG-43 brachytherapy dosimetry parameters of a new titanium-encapsulated Yb-169 source were determined by MC calculations. The current results suggested that the use of titanium, instead of stainless steel, to encapsulate the Yb-169 core would not lead to any major change in the dosimetric characteristics of the Yb-169 source, while it would allow more low energy photons being transmitted through the source filter thereby leading to an increased dose enhancement during GNRT.

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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