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Proceedings Paper

Monte Carlo simulation of elastic-scattering spectroscopic measurement using the optical pharmacokinetic system (OPS): analysis of sensitivity to heterogeneous chromophore distribution
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Paper Abstract

Effective photodynamic therapy depends on an adequate supply of photosensitizer, oxygen, and light fluence. During light exposure, the rapid depletion of molecular oxygen within tissue can lead to the development of hypoxic regions, which decreases the generation of reactive oxygen species and can result in non-uniform tissue necrosis. The Optical Pharmacokinetic System (OPS) is a fiber-optic based spectroscopy device that may be able to monitor local tissue oxygen concentrations during treatment and identify problematic hypoxic regions in vivo. However, the 'bulk' signal detected by the OPS is potentially limited in its ability to discern the development of small hypoxic regions within tissue. This study employs a Monte Carlo simulation of the elastically-scattered light as measured by the OPS to investigate the effect of heterogeneous chromophore distributions on the detected signal. The model tissue geometry is constructed to mimic tissue in vivo, with discrete capillaries interspersed throughout. Tissue optical properties are specified spatially, allowing investigation of heterogeneous chromophore distribution. Simulations investigate the effect that discrete, highly absorbing regions within a measured sample have on the light collected by the OPS. Simulations also consider OPS measurement of a sample with a depth-dependent chromophore concentration gradient and quantitate the ability of the OPS to detect the presence of a sub-population of hypoxic vessels within a network of oxygenated vessels.

Paper Details

Date Published: 28 February 2007
PDF: 10 pages
Proc. SPIE 6427, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVI, 642710 (28 February 2007); doi: 10.1117/12.699137
Show Author Affiliations
Stephen Chad Kanick, Univ. of Pittsburgh (United States)
Robert S. Parker, Univ. of Pittsburgh (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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