Simulation of the point spread function for light in tissue by a Monte Carlo method.

We have been able by a Monte Carlo technique to generate the point spread function (PSF) for light in tissue for a generalized range of tissue characteristics. We have demonstrated that these can be described by an equation containing a gaussian, diffusion and exponential term. The PSF equation will allow one to estimate the limits of spatial resolution achievable with near infrared (NIR) imaging systems, and may be used in image deconvolution algorithms. Additionally an equation has been derived describing the average photon pathlength through the tissue. Finally, the light transmission and reflection (backscattering) have been illustrated as functions of scattering and absorption coefficients. These results can be used in attempting to quantify data from non-invasive NIR spectroscopy systems.