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Proceedings Paper

Light dosimetry for photodynamic therapy in the esophagus
Author(s): Xiaodong Zhou; Brian W. Pogue; Norman S. Nishioka; Bill Puricelli; Tayyaba Hasan
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Paper Abstract

Evaluating the light distribution in the esophagus is central to understanding how to optimize treatment of Barrett's esophagus with PDT. The light distribution of a cylindrical light diffuser in the esophagus was investigated by Monte Carlo simulations and experiments in esophageal simulating phantoms. Simulation of light transport in the esophagus requires knowledge of several biological parameters including radius, height, mucosal wall thickness and optical parameters such as reduced scattering coefficient, absorption coefficient, scattering anisotropy and refractive index. Results of Monte Carlo simulations were tested by measuring the light fluence rate in an esophagus phantom (absorption coefficient = 0.27 mm-1, reduced scattering coefficient = 1.9 mm-1, g = 0.9, n= 1.37) irradiated at 633nm with a 5cm long cylindrical light diffuser. We evaluated the light distribution within the esophagus for the on-axis and off-axis treatment fiber conditions both experimentally and mathematically. Results showed the reflected light from the walls of the esophagus increased the incident light dose at all points being treated by a factor of 1.6, compared to the dose given off by the fiber itself. Also, when the fiber was moved from one side of the esophagus to the other, it increased the light dose to the proximal area by a factor of 2, and decreased the light dose to the distal region by a factor of 2 in the phantom study, and in Monte Carlo simulation, factor of 18 and factor of 3 respectively.

Paper Details

Date Published: 13 June 2003
PDF: 12 pages
Proc. SPIE 4952, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XII, (13 June 2003); doi: 10.1117/12.474083
Show Author Affiliations
Xiaodong Zhou, Dartmouth College (United States)
Wellman Labs. of Photomedicine/Massachusetts General Hospital (United States)
Harvard Medical School (United States)
Brian W. Pogue, Dartmouth College (United States)
Wellman Labs. of Photomedicine/Massachusetts General Hospital (United States)
Harvard Medical School (United States)
Norman S. Nishioka, Wellman Labs. of Photomedicine/Massachusetts General Hospital (United States)
Harvard Medical School (United States)
Bill Puricelli, Wellman Labs. of Photomedicine/Massachusetts General Hospital (United States)
Harvard Medical School (United States)
Tayyaba Hasan, Wellman Labs. of Photomedicine/Massachusetts General Hospital (United States)
Harvard Medical School (United States)


Published in SPIE Proceedings Vol. 4952:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XII
David Kessel, Editor(s)

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