Light distributions in biological tissues are summarized in simple expressions for spherical, cylindrical and planar geometries due to point sources, line sources and planar sources. The goal is to provide workable tools for computing light distributions that govern the amount and distribution of photochemical reactions in experimental solutions, films and biological tissues. Diffusion theory expressions are compared with Monte Carlo simulations. Analytic expressions that mimic accurate Monte Carlo simulations are presented. Application to fluorescence measurements and prediction of necrotic zones in photodynamic therapy are outlined.
S. L. Jacques, "Light distributions from point, line and plane sources for photochemical reactions and fluorescence in turbid biological tissues," Photochem Photobiol 67(1), 23-62 (1998).