An entrance, which provides easy accessibility while at the same time providing
complete protection from outside white light, is essential. Commonly used entrances are
of three general types: the single door, the lightlock (double doors), and the labyrinth or
maze. The one best suited for a particular situation will be determined largely by the
number of people using the processing room and by the floor space available.
a. Single Door. If the radiologist and x-ray specialists are the only persons who
routinely use the processing room, a single lightproof door with an inside bolt or lock will
usually suffice. (Figure 2-3).
Figure 2-3. Diagram of typical entrance maze.
b. Lightlock. This type of entrance may consist of a small hall with two doors, one
opening into the processing room and one to the outside. Electric or mechanical
interlocking devices can be installed to prevent the accidental opening of both doors
simultaneously. However, safety releases must be incorporated into the interlock so that
both doors can be opened at the same time to allow the movement of supplies into the
processing room or in case of an emergency. If interlocks are not provided, warning lights
or buzzers are useful. A lightproof louver should be installed to accommodate changes in
air pressure caused by opening and closing the doors and to provide some ventilation. All