In this work, the kT layer theory for quasi ballistic transport in nanodevices has been reinvestigated, underlying the impact of carrier heating on backscattering. Assuming a constant mean free path, a differential equation for the currents fluxes has been derived, including both the impact of collision and field on backscattering. By making proper approximations on the impact of heating on carrier distribution functions, the backscattering coefficient and velocity profiles have been re-derived, and successfully compared to Monte Carlo simulations of template potential profiles. These results open new perspectives in the development of new physically based compact models for MOSFETs, better accounting for non equilibrium transport effects.