An accurate and simple method of dose rate calculation at the entrance of mazes of medical linear accelerator facilities, based on the equations given in NCRP 49, is presented. It was found that the dose rate calculated using this method is nearer to both the measured and to the Monte Carlo simulated values by Al-Affan et al than the value obtained using the formula contained in NCRP 51. The proposed method takes into account the contribution of leakage radiation besides scattered radiation, while the NCRP 51 considers only the scattered radiation. In the present work, the dose equivalent rate due to scattered radiation is obtained by a different formalism from that of NCRP 51. It is shown that for the specific maze design, the weekly dose equivalent rate at the maze entrance obtained using the equation of NCRP 51 is greater than the value calculated by the method proposed in this paper. The thickness of door shielding, located at the maze entrance, is computed for both methods.