(1) Each X-ray exposure button must be located to meet the following criteria:

(a) For stationary X-ray systems, the X-ray exposure button must be permanently mounted in a protected area so that the operator can make an exposure only from the protected area; and

(b) Mobile X-ray systems must have an X-ray exposure button located at the end of a cord at least twelve feet (3.7 meters) long.

(2) Shielding for cephalometric X-ray must meet the following criteria:

(a) Be at least one foot (30.5 centimeters) larger, in both the horizontal and vertical directions, than the area of the primary beam where it strikes the nearest wall; and

(b) Shielding between the nearest wall struck by the primary beam and the next occupied area must have two-pound lead or equivalent installed in the wall. Exterior walls or concrete block walls need no additional shielding.

(3) Acceptable shielding materials for dental X-ray facilities are as follows:

(a) The minimum shielding for intra-oral stray radiation protection is standard gypsum wallboard/sheetrock construction (two layers each of five-eighths inch thickness).

(b) Where windows are provided to observe patients during radiography, the windows are at least one-half inch plate glass, or equivalent ability to reduce exposure.

(c) All other materials used for shielding between operatories and for operator protection areas are equivalent to 0.2 millimeters of lead.

(4) Barriers surrounding dental X-ray rooms and dental operatories where intra-oral X-ray equipment is installed must meet the following criteria:

(a) Be at least six feet (1.83 meters) high and composed of materials capable of reducing scattered radiation as required under subsection (3) of this section;

(b) There must be no line of sight between workers or patients in one operatory and the X-ray tube housing assembly in the next operatory when that X-ray tube housing assembly is in its operating position;

(c) X-ray tube housing assemblies must not be mounted between operatories on top of barriers less than six feet (1.83 meters) high, unless those barriers are at the foot end of the patient chairs, and there is no line of sight between adjacent operatories.