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Proceedings Paper

Fluence rate variability among light delivery devices for esophageal photodynamic therapy
Author(s): Jarod C. Finlay; Gregory G. Ginsberg; Stephen M. Hahn
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Paper Abstract

Esophageal photodynamic therapy (PDT) is performed using a photosensitizing agent activated by light delivered via a cylindrically symmetric delivery device containing a diffusing optical fiber. In PDT treatment of dysplastic Barrett's esophagus, considerable variability in results is observed due to the non-uniform delivery of treatment light caused by source geometry and by luminal collapse. We compare the fluence rate at the tissue surface resulting from illumination with bare fiber, a centering balloon catheter (X-Cell, Cooke, Inc), and a fixed diameter transparent dilating catheter (Optical Dilator, Inscope, Ethicon ES). Measurements were made in a solid esophagus-simulating phantom illuminated by 2.5 and 5 cm diffusing fibers with and without each delivery device. The diffuser was coupled to a 630 nm dye laser pumped by a 532 nm KTP laser (LaserScope, Inc.) The total power emitted by the diffuser was 1W. The fluence rate as a function of position along the cavity was measured by a calibrated photodiode connected to an optical fiber with a 0.5 mm isotropic scattering tip, which was moved by a computer-controlled positioner. The mean fluence rate measured when the phantom was illuminated using either the centering balloon or the rigid dilator was approximately 50% less than that measured with a bare fiber. The decrease in fluence rate is due to attenuation of the primary light beam and to reduction in scattering from laterally adjacent points in the phantom. The importance of each of these effects as a function of tissue optical properties was confirmed using Monte Carlo simulation.

Paper Details

Date Published: 28 February 2007
PDF: 5 pages
Proc. SPIE 6427, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVI, 642712 (28 February 2007); doi: 10.1117/12.699541
Show Author Affiliations
Jarod C. Finlay, Univ. of Pennsylvania (United States)
Gregory G. Ginsberg, Univ. of Pennsylvania (United States)
Stephen M. Hahn, Univ. of Pennsylvania (United States)

Published in SPIE Proceedings Vol. 6427:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVI
David Kessel, Editor(s)

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