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MRI Scanner – MR Classification System

The MRI scanner uses radio waves and powerful magnets to create detailed images of the body. Because the magnetic field presents a hazardous atmosphere around certain items, hospitals and MRI facilities use an item classification system so that potentially dangerous items are not brought near the MRI scanner.

Potentially magnetic items must be tested before entering the controlled access areas of the MRI facility. Only items that are proven to be safe near that particular MR environment are allowed inside the MR Suite. When an item is tested, it is classified as MR Safe, MR Conditional or MR Unsafe. Specific icons, usually in the form of stickers, identify the category of each item. These icons may be reproduced in black and white; however, the use of color is encouraged because of added visibility.

MR Safe items pose no known hazards in all MR environments and are indicated by a green and white icon. Conversely, MR Unsafe items, such as any magnetic item, are unsafe in all MR environments. The MR Unsafe icon features “MR” inside of a red circle with a bar through it. Any items not clearly marked should be considered MR Unsafe. Finally, MR Conditional items do not pose any known hazards in a specific MR environment with specific conditions of use. The MR Conditional icon consists of “MR” inside of a yellow triangle.

Never bring MR Conditional items into the MR suite, and especially near the MRI scanner, without prior approval from MRI personnel. Most transports and medical devices will be designated as MR Conditional, so safety within the facility depends on knowing what the specific conditions are for each object.

Labeling items and following the MR Item Classification System helps prevent dangerous situations for both staff and patients within the MRI facility.

Hospital and MRI facility personnel that work near the MRI scanner must be aware of the powerful magnetic field and its associated hazards. For personnel not formally trained in a Radiology program, a safety program should be established for each individual facility. To supplement MRI safety, including the MR Classification System, many modern, high-quality Level 1 MRI safety films are available.

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MRI Scanner – 4 Zone

Due to the powerful magnetic field used by the MRI Scanner, many Magnetic Resonance Imaging (MRI) facilities and hospitals restrict access to the MR Suite by establishing four conceptual zones around the MRI scanner. Each boundary zone in this four-zone safety system is defined by its purpose and distance from the MRI scanner. Since the magnetic field extends in three dimensions, some zones may extend into other areas or floors of the facility.

Zone One consists of all areas freely accessible to the general public. This zone includes the entrance to the MR facility and the magnet poses no hazards in these areas.

Zone Two acts as a buffer between Zone One and the more restrictive Zone Three. Here, patients are under the general supervision of MR personnel. Normally, these areas are also safe from the powerful magnet. Zone Two may include the reception area, dressing room and interview room.

Access to Zone Three should be restricted by a physical barrier. Only approved MR personnel and patients that have undergone a medical questionnaire and interview are allowed inside Zone Three. The MR control room and/or computer room are located within Zone Three.

Zone Four is strictly the area within the walls of the MR scanner room, sometimes called the magnet room. Access into the MR scanner room should only be available by passing through Zone Three. Zone Four is sometimes considered to be inside of Zone Three because it does not have a direct entrance to unrestricted areas. Zone Three and Zone Four are sometimes collectively referred to as the MR Suite.

Inside the MR Suite is an invisible boundary defined by the magnetic field’s five Gauss line. The five Gauss line is the point at which the magnetic field begins to affect electromagnetic devices, such as pacemakers. Because the magnetic field extends in all directions, the five Gauss line can also extend to areas outside of the MR Suite, including other floors, if the magnetic field is large enough. Magnetic fields cannot be seen or felt, so the five Gauss line is sometimes marked on floors or walls for safety. Marking the five Gauss line is particularly important when it extends beyond the walls of the MR scanner room.

Hospital and MR facility personnel that work near the MRI scanner must be aware of the powerful magnetic field and its associated hazards. For personnel not formally trained in a Radiology program, an MR safety program should be established for each individual facility. To supplement MRI safety, including the Four-Zone Boundary System, many modern, high-quality Level 1 MRI Safety Films are available.

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