Numerical modeling of light propagation in biological tissues: time-resolved 3D simulations based on light diffusion model and FDTD solution of Maxwell's equations

In this work, optical propagation through turbid media is analyzed by FDTD simulation. In particular, the method is applied to biological tissues. Continuous light propagation in turbid media has been widely studied, but pulsed light propagation has received less interest due to its complexity. Therefore, in this work we focus on pulsed light. FDTD method is applied to several media with optical parameters in the typical range of those observed in biological tissues. We perform an analysis of the variations of pulsed light propagation as a function of the scatterers characteristics (namely size, concentration, and optical contrast). The results are compared with those obtained by the use of the diffusion approximation. The potential of the FDTD method over the diffusion model is given by its high accuracy, its capacity to perform time-resolved simulations, and the fact that it carries all the information about the phase and coherence of the wavefront. The results of this work can be applied to a wide range of areas of interest like the time-resolved study of ultrashort light pulses propagation, the optimization of optical penetration depth, the coherence properties of pulsed light, and the effect of modified wavefronts in light propagation.