Use of Monte Carlo simulations for propagation of light in biomedical tissues

In problems relating to light propagation in biomedical tissues, the tissue is generally modeled as a turbid medium and Monte Carlo (MC) simulation is employed to compute quantities such as diffuse reflectance, fluence, and transmittance. Two prescriptions are available in the literature for MC simulations. The first prescription considers all input quantities, including phase function, as an average over the particle size distribution, and the second prescription considers the phase function of each scatterer individually. The two prescriptions have been compared and contrasted in this paper for a given soft tissue model. It is demonstrated that, in general, the two recipes do not yield identical results. The source of this disagreement has been traced.