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Journal of Biomedical Optics

Protoporphyrin IX fluorescence photobleaching
Author(s): Brian W. Pogue; Chao Sheng; Juan Manuel Benavides; David Forcione; Bill Puricelli; Norman S. Nishioka; Tayyaba Hasan
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Paper Abstract

Fluorescence measurements have been used to track the dosimetry of photodynamic therapy (PDT) for many years, and this approach can be especially important for treatments with aminolevulinic-acid-induced protoporphyrin IX (ALA-PpIX). PpIX photobleaches rapidly, and the bleaching is known to be oxygen dependent, and at the same time, fractionation or reduced irradiance treatments have been shown to significantly increase efficacy. Thus, in vivo measurement of either the bleaching rate and/or the total bleaching yield could be used to track the deposited dose in tissue and determine the optimal treatment plans. Fluorescence in rat esophagus and human Barrett's esophagus are measured during PDT in both continuous and fractionated light delivery treatment, and the bleaching is quantified. Reducing the optical irradiance from 50 to 25 mW/cm did not significantly alter photobleaching in rat esophagus, but fractionation of the light at 1-min on and off intervals did increase photobleaching up to 10% more (p value=0.02) and up to 25% more in the human Barrett's tissue (p value<0.001). While two different tissues and two different dosimetry systems are used, the data support the overall hypothesis that light fractionation in ALA-PpIX PDT esophageal treatments should have a beneficial effect on the total treatment effect.

Paper Details

Date Published: 1 May 2008
PDF: 10 pages
J. Biomed. Opt. 13(3) 034009 doi: 10.1117/1.2937476
Published in: Journal of Biomedical Optics Volume 13, Issue 3
Show Author Affiliations
Brian W. Pogue, Dartmouth College (United States)
Chao Sheng, Dartmouth College (United States)
Juan Manuel Benavides, Dartmouth Medical School (United States)
David Forcione, Dartmouth Medical School (United States)
Bill Puricelli, Massachusetts General Hospital (United States)
Norman S. Nishioka, Massachusetts General Hospital (United States)
Tayyaba Hasan, Massachusetts General Hospital (United States)

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