Thanks to the powerful magnetic field used by the MRI scanner, many magnetic resonance imaging (MRI) objects and hospitals restrict access to the MR Suite, creating four conceptual zones around the MRI scanner. Each border zone in this four-zone security system is defined by its target and distance from an MRI scanner. Since the magnetic field extends in three dimensions, some zones may extend to other areas or floors of an object.
Zone 1 consists of all areas freely accessible to the general public. This zone includes the entrance to the MR unit and the magnet does not create any hazards in these zones.
Zone 2 acts as a buffer between the first zone and the more restrictive zone 3. Here, patients are under the general control of MR personnel. As a rule, these areas are also safe from a powerful magnet. Zone 2 may include a reception area, a dressing room and an interview room.
Access to Zone Three must be restricted by a physical barrier. Only authorized MRI personnel and patients who have completed a medical questionnaire and interviews are allowed in Zone Three. The MR control room and / or computer room are located in Zone Three.
Zone Four is a strictly area within the walls of the MR scanner room, sometimes called the magnetic room. Access to the MR scanner room should only be available through Zone Three. Zone four is sometimes considered to be located inside the third zone, because it does not have direct access to unlimited areas. Zone three and zone four are sometimes called MR Suite.
Inside the MR Suite there is an invisible border defined by a five Gaussian magnetic field line. Five Gaussian lines are the point at which a magnetic field begins to affect electromagnetic devices, such as pacemakers. Since the magnetic field extends in all directions, the five Gaussian lines can also extend to areas outside the MR Suite, including other floors, if the magnetic field is large enough. Magnetic fields are not visible and not felt, so five Gauss lines are sometimes marked on the floor or walls for safety. The marking of five Gauss lines is especially important when it goes beyond the walls of the MR scanner room.
Hospital staff and MRI working near an MRI scanner should be aware of a strong magnetic field and the associated hazards. For personnel who have not officially received training in a radiological program, an MR safety program should be established for each individual object. In addition to safety training for those who work alongside an MRI scanner, there are many advanced, high-quality MRI Level 1 safety films available.
