Determination of the distribution of drug concentration and tissue optical properties for ALA-mediated anal photodynamic therapy release_pm3cutcfqnbg7pmuughfskry3a

by Yi Hong Ong, Andrew C Li, Theresa M Busch, Timothy C Zhu

Abstract

PDT efficacy depends on the availability and dynamic interactions of photosensitizer, light, and oxygen. Tissue optical properties influence the delivered light dose and impact PDT outcome. In-vivo measurements of tissue optical properties and photosensitizer concentration enable determination of explicit and implicit dose factors affecting PDT and helps to understand the underlying biophysical mechanism of PDT. In this study, we measure tissue optical properties (absorption μa (λ) and scattering μs' (λ) coefficients) and PpIX concentration in tissue simulating liquid phantoms with a geometry that resembles anal canal. In-vivo light fluence rate and photosensitizer fluorescence of 405nm excitation light source were acquired using a dual-motor continuous wave transmittance spectroscopy system. We characterized the tissue optical properties correction factor of fluorescence signal using a series of tissue simulating phantoms with known PpIX concentrations and with absorption coefficient between 0.1 - 0.9 cm-1 and reduced scattering coefficient between 5 - 40 cm-1. The results demonstrated that our spectroscopy system could determine the distribution of tissue optical properties and PPIX concentration during anal PDT.
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Type  article-journal
Stage   published
Date   2021-03-08
Language   en ?
DOI  10.1117/12.2581824
PubMed  34083860
PMC  PMC8171263
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ISSN-L:  0277-786X
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