The choice of the diffusion coefficient to be used in photon diffusion theory has been a subject of discussion in recent publications on tissue optics. We compared several diffusion coefficients with the apparent diffusion coefficient from the more fundamental transport theory, <i>D</i><sub>app</sub>. Application to point sources in turbid media, for which exact solutions are available, showed that <i>D</i><sub>app</sub> has to be preferred. We give a simple equation to approximate <i>D</i><sub>app</sub> for several phase functions that apply to tissue optics. Reasons for the remaining discrepancies in diffusion coefficients applied to time-resolved and time-averaged descriptions of photon propagation in homogeneous turbid media are discussed.
© 2000 Optical Society of America
(170.3660) Medical optics and biotechnology : Light propagation in tissues
(290.0290) Scattering : Scattering
(290.1990) Scattering : Diffusion
(290.4210) Scattering : Multiple scattering
(290.7050) Scattering : Turbid media
R. Graaff and J. J. Ten Bosch, "Diffusion coefficient in photon diffusion theory," Opt. Lett. 25, 43-45 (2000)