Zone III.—This is the area where there is a potential danger of serious injury or death from
interaction between unscreened people or ferromagnetic objects and the magnetic field of the MR imaging unit. The imaging unit control room is typically in zone III, as are any hallways or areas with unopposed access to the magnet room doors. Access to zone III must be strictly restricted by lock or passkey systems, accessible and supervised only by MR imaging personnel.
Only MR imaging personnel shall be provided free access to zone III, and non–MR imaging personnel are not to be provided with independent access until they undergo the proper education, training, and certification to become MR imaging personnel themselves. Zone III, or at the very least, the area within it wherein the static magnetic field strength exceeds 5 G, should be demarcated as being potentially hazardous. It is important to know that the magnetic field is three-dimensional. Thus, the restricted area may extend not only in all directions on the same floor of the facility but also potentially through the floor and/or ceiling to adjacent floors.