Monte Carlo simulation of converging laser beams propagating in skin tissue phantoms

Abstract

Numerical simulations have been performed to investigate the light distribution in strongly scattering tissues for collimated laser beams. However, very little is known for the propagation of converging laser beams with large cone angles for the lack of efficient algorithms to deal with the difficult boundary conditions. Furthermore, the important effect of surface roughness on the light distribution inside the skin tissues has not been studied. We developed a new Monte Carlo method to simulate the distribution of photon density of converging laser beams propagating in skin tissue phantoms. This method can be used to obtain directly the photon density distribution in the framework of radiative transfer theory. We calculated the steady-state distributions of the photon density and found several important features that are uniquely related to the propagation of the converging beams in skin tissues. We also conducted preliminary study on the effect of roughness of skin surface on the light distribution inside the skin tissue with the new Monte Carlo method.