title: An improved analytic function for predicting light fluence rate in circular fields on a semi-infinite geometry.
abstract: Accurate determination ofin-vivolight fluence rate is critical for preclinical and clinical studies involving photodynamic therapy (PDT). This study compares the longitudinal light fluence distribution inside biological tissue in the central axis of a 1 cm diameter circular uniform light field for a range ofin-vivotissue optical properties (absorption coefficients (μa) between 0.01 and 1 cm-1and reduced scattering coefficients (μs') between 2 and 40 cm-1). This was done using Monte-Carlo simulations for a semi-infinite turbid medium in an air-tissue interface. The end goal is to develop an analytical expression that would fit the results from the Monte Carlo simulation for both the 1 cm diameter circular beam and the broad beam. Each of these parameters is expressed as a function of tissue optical properties. These results can then be compared against the existing expressions in the literature for broad beam for analysis in both accuracy and applicable range. Using the 6-parameter model, the range and accuracy for light transport through biological tissue is improved and may be used in the future as a guide in PDT for light fluence distribution for known tissue optical properties.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Zhu
authors.affiliation: The Warton School, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Lu
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Yi-Hong
authors.initials: YH
authors.lastname: Ong
keywords: MC; PDT; analytical expression; semi-infinite medium