Section 325.5315. Enclosures.

   (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  kilovoltage, milliamperage, mechanical movement, and distance factor, and shall be subject to design 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 persons may at all times be able to escape from within.

(6)   If the radiation exposure rate within the therapy room is so high that a person 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 will not jeopardize the safety of the system, (e.g., 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 rule 312 (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) 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.

History: 1954 ACS 85, Eff. Dec. 3, 1975.