Simulation of light scattering in biological tissues: the coherent component

摘要

Light propagating in turbid medium can be separated into two parts - the unattenuated part and the scattered part. The two parts coexist everywhere in the medium and can be described by radiative transport theory. In an optically thick sample of turbid medium, very small portion of the light remain unattenuated and the diffusion model is widely used to describe the propagation of light. Monte Carlo method, having the potential of reaching high accuracy, can be used to account for both parts of the light distribution and has acquired considerable attention lately. We have developed a new method of Monte Carlo simulation and conducted large-scale simulation of converging laser beam propagating through tissue phantoms in slab configurations. In our cases, the unique geometry of the converging laser beams gathers the unattenuated photons together near the focal point and makes it significant even for optically thick samples in comparison with the scattered part. Numerical results were obtained for tissue slabs of different parameters to study the variation of the distribution of the transmitted light. We have also investigated the possibility of characterizing biological tissues through the measurement of unattenuated photons.