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High-Resolution Deterministic-Based Anisotropic Dose Distribution in Gold Nanoparticles Aided Radiotherapy

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S Gadoue

S Gadoue4*, D Toomeh4,3 , P Zygmanski3 , E Sajo4 , (1) ,Lowell, MA, (2) ,Burlington, MA, (3) Brigham & Women's Hospital, Boston, MA, (4) Univ Massachusetts Lowell, Lowell, MA


SU-F-108-6 (Sunday, July 30, 2017) 2:05 PM - 3:00 PM Room: 108

Purpose: Gold nanoparticle (GNP) based radiotherapy is a promising potential cancer treatment modality. The use of gold can lead to enhanced radiation dose in tumors due to low-energy electrons depositing their energy in the vicinity of the GNP. The dose enhancement ratio (DER) has been used in the literature to quantify the GNP’s capacity to increase local energy deposition. Conventional Monte Carlo (MC) models use an effectively one-dimensional geometry, in which the dose is tallied in concentric volumes about the GNP and an average dose is plotted versus radial distance. There are known anisotropies in the secondary electron emission that may lead to important dose non-uniformities about the GNP. However, to obtain the angular details of dose in the nanoscale a very large number of submicron tally volumes are necessary, which is difficult using MC methods. Alternatively, deterministic computational methods present a practical approach.

Methods: In this work, we use the next-generation deterministic coupled photon-electron radiation transport code SCEPTRE, which has been extensively benchmarked against MC models. By applying an unstructured spatial mesh, we were able to obtain high-resolution nanometric 3D dose distributions around the GNP for various incident photon beams and GNP sizes.

Results: The angular distribution of the dose around GNP is not uniform and the degree of anisotropy depends on the energy spectrum of the incident x-rays, and the size of the GNP. Notable difference exists in the dose profile and DER in various directions, approaching 20%.

Conclusion: Detailed knowledge of angular dose anisotropy about GNP is important for accurate dosimetric computations and radiobiological evaluation of radiation therapy outcome. General radiation oncology practice aims to treat the tumor within 5% uncertainty. Therefore the finding of up to 20% dose anisotropy has to be taken into consideration.

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