Combined Monte Carlo and Finite-Difference Time-Domain modeling for biophotonic analysis

Abstract

Monte Carlo (MC) modeling is widely used to study photon transport in tissues but is generally performed using simplified phase functions that only approximate the angular scattering probability distribution of microscopic tissue constituents such as cells. Finite-Difference Time-Domain (FDTD) modeling has recently provided a flexible approach to compute scattering phase functions for realistic cell geometries. We present a computational framework that combines MC and FDTD modeling and allows random sampling of scattering directions from cellular phase functions computed using the FDTD method. Combined MC/FDTD simulation results indicate that the exact form of the phase function used is an important factor in determining the modeled optical response of tissues. Subtle differences in angular scattering probability distribution can lead to significant changes in detected reflectance intensity and the extent of these changes depends on the specific range of scattering angles to which a given optical sensor design is most sensitive.