  Light propagation in turbid media is driven by the equation of radiative
transfer. We give a formal probabilistic representation of its solution in the
framework of biological tissues and we implement algorithms based on Monte
Carlo methods in order to estimate the quantity of light that is received by an
homogeneous tissue when emitted by an optic fiber. A variance reduction method
is studied and implemented, as well as a Markov chain Monte Carlo method based
on the Metropolis-Hastings algorithm. The resulting estimating methods are then
compared to the so-called Wang-Prahl (or Wang) method. Finally, the formal
representation allows to derive a non-linear optimization algorithm close to
Levenberg-Marquardt that is used for the estimation of the scattering and
absorption coefficients of the tissue from measurements.
