Development and application of three-dimensional light distribution model for laser irradiated tissue

A three-dimensional model for estimating light distribution in laser irradiated tissue is presented. Multiple scattering and absorption of the laser beam are modeled using seven fluxes. One-, two-, and three-dimensional solutions are discussed and light distributions computed from the seven flux model are compared to those computed with the diffusion approximation. Methods for obtaining the phase function, absorption coefficient, and scattering coefficient for tissue are discussed and illustrated with measurements for human aortic vessel wall at the wavelength of 632.8 nm. Measured values are used in the seven flux model to estimate the rate of heat generation in the vessel wall.