Light scattering methods are currently actively used to study biological tissues, primarily for medical applications. An important area is the rapid field diagnosis of various brain injuries. We present results of numerical simulations of the infrared radiation backscattering from a layered biological tissue, primarily from the 'skull-brain' system. The Monte Carlo simulations are based on the Bethe-Salpeter equation. We modified the standard procedure for detecting backscattered photons, which led to a significant reduction in the computation time.