Diffusion equation representation of photon migration in tissue

A time-dependent diffusion model of photon migration in tissue is used to develop analytic expressions for the diffusely reflected pulse detected some distance from a delta function input. Particular attention is paid to the nature of the boundary between the tissue and the surrounding nonscattering medium, and it is shown that the pulse shape is relatively insensitive to the nature of this boundary. Monte Carlo simulation and experimental results are presented which confirm the accuracy of the diffusion model. Finally, the authors show representative experimental data illustrating the solution of this inverse problem and discuss some problems in clinical implementation.<>