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Proceedings Paper

Assessment of proton radiographic sensitivity limits for gold nanoparticle tagged tumors using gold leaf phantoms
Author(s): Rachel B. Sidebottom; Ethan F. Aulwes; Matthew S. Freeman; Per E. Magnelind; Frank E. Merrill; Dale Tupa; Michelle Espy
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Paper Abstract

Proton radiography is a potentially valuable tool for the image guidance of proton therapy cancer treatment. While proton therapy is desirable due to its high dose deposition accuracy, proton radiography, which could, in theory, be applied simultaneously to treatment, has an intrinsically low soft tissue contrast, making it difficult to visualize tumors. To enhance this tumor contrast, high-Z nanoparticles could be targeted to a tumor before imaging. To assess the efficacy of gold as a contrast agent, phantoms consisting of gold leaf mounted on acrylic backing were developed to simulate a tumor tagged with gold nanoparticles (AuNPs). Calculations are presented to correlate a given thickness of gold with scenarios for tagging cancers with AuNPs, in terms of the size of the functionalized nanoparticles, the diameter of the tumor, as well as the efficiency by which the nanoparticles are taken up by the malignant cells. These calculations determined phantoms that best describe particular tagging conditions, and are also applicable to ex vivo specimens made by injecting AuNPs into a mouse model. Using a ×3 proton magnifying lens with the 800-MeV LANSCE proton beam, a 1-μm-thick Au foil was radiographically discernible within 1 cm of acrylic, representing sensitivity to a material percent density change of 0.2%. This indicates that AuNP-enhanced proton radiography could be used to characterize small tumors, allowing for early detection and treatment of malignant tissues, as well as for in situ imaging for enhanced treatment localization.

Paper Details

Date Published: 16 March 2020
PDF: 9 pages
Proc. SPIE 11312, Medical Imaging 2020: Physics of Medical Imaging, 113123H (16 March 2020); doi: 10.1117/12.2548486
Show Author Affiliations
Rachel B. Sidebottom, Los Alamos National Lab. (United States)
Occidental College (United States)
Ethan F. Aulwes, Los Alamos National Lab. (United States)
Dartmouth College (United States)
Matthew S. Freeman, Los Alamos National Lab. (United States)
Per E. Magnelind, Los Alamos National Lab. (United States)
Frank E. Merrill, Los Alamos National Lab. (United States)
Dale Tupa, Los Alamos National Lab. (United States)
Michelle Espy, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 11312:
Medical Imaging 2020: Physics of Medical Imaging
Guang-Hong Chen; Hilde Bosmans, Editor(s)

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