Radius of a spherically symmetric object under gravitational and radiative collapse is described in the frame of the general relativity by using a flux factor of radiation, the variable Eddington factor and the Lorentz-Eddington closure relation between them in order to model disipation effects of radiation inside the matter. The post-quasistatic approximation provided by Herrera et al [Phys. Rev D 65,104004(2002)] and the Tolman VI equation of state are used. Density and presure of matter and radiation in an interior layer are showed. Is is mentioned that the conditions of energy (weak, strong and dominant) are satisfied.