© 2015 SPIE. Diffuse correlation spectroscopy (DCS) can measure perfusion changes in deep tissue. However, DCS requires solving the diffusion equation with the proper boundary conditions which can be very difficult and even impossible in many cases. We present a DCS approach that is independent of boundary conditions. The approach is based on measuring the probability distribution function (PDF) of the photons€™ pathlengths by deconvolving the temporal point-spread function and the instrument-response function obtained from time-resolved measurements. The recovered PDF was then used to fit the field correlation function to extract perfusion changes. This approach can be applied to any geometry and is valid for diffusive, single-scattering and multiple-scattering, but non-diffusive media.