Abstract
A Monte Carlo computer model has been developed to study the propagation of light in tissues. Light attenuation is assumed to result from absorption and isotropic scattering. The model has been used to predict the distribution of absorbed dose in homogeneous tissues of different absorption/scattering ratios, for illumination both by external light beams and via implanted optical fibers. The photon flux into optical fibers placed in the tissue as detectors has also been investigated. The results are interpreted in relation to the use of visible light irradiation for photo radiation therapy.