R 333.5315 Enclosures.

Rule 315. (1) An enclosure shall be a permanent part of the building or equipment. Portable protective barriers shall not be used for permanent installations. (2) The degree of protection required for an enclosure shall be determined by the workload, use and occupancy factors, and the tube potential, tube current, mechanical movement, and distance. The design shall be subject to approval by the department. (3) All wall, ceiling, and floor areas that can be irradiated by the useful beam plus an additional area extending at least 30 centimeters (1 foot) beyond shall be provided with a primary protective barrier. (4) For equipment capable of operating above 150 kVp, the control station shall be outside of the therapy room. (5) The enclosure shall be so constructed that individuals may at all times be able to escape from within. (6) If the radiation exposure rate within the therapy room is so high that an individual who is accidentally in the treatment room when the machine is turned "ON" may receive as much as 1250 mR exposure during the time required to reach an access door, special cut-off, or panic buttons shall be required. When pressed, these buttons, operable by open hand at appropriate positions about the treatment room, shall cause the irradiation to be terminated. (7) Effective means shall be provided to prevent access to the treatment room during exposure. For equipment capable of operating above 150 kVp, each access door to the treatment room shall be provided with a fail-safe interlock. The interlock system shall be so designed that the failure of any 1 component cannot jeopardize the safety of the system, such as the use of series connected double switch assemblies at access doors, and dual interlock relays. If an access door is opened when the machine is "ON", the interlock shall cause termination or reduction of exposure as specified in R 333.5312(14). (8) Red warning signal lights, energized only when the useful beam in "ON", shall be located on the control panel and near each entrance to the therapy room. Under conditions as specified in subrule (6) of this rule a visible signal shall also be located within the therapy room. Depending upon control panel and door locations, a single warning signal light may be sufficient to comply with this subrule.