Minimizing entrance door thickness for direct-entry radiotherapy rooms

When medical linear accelerator rooms are constructed without entrance mazes, the entrance doors can be as thick as 50 cm, weigh 10,000 kg, and cost 50-60 thousand dollars. We describe a method of room design in which the therapy unit is positioned 180 degrees from the usual orientation. A short stub wall that attenuates the leakage component of the secondary radiation protects the door. Using this approach, the door can be reduced to approximately half the usual thickness with a significant impact on cost. For these motor-driven doors, there are also long-term benefits related to maintenance of the operating hardware.