RF Shielding to prevent interfering RF-Waves from entering or Leaving from Scanner Room, Room is Shielded

Radiofrequency shielding of an MR scanner is mandatory to prevent extraneous electromagnetic radiation from contaminating/distorting the MR signal and to prevent electromagnetic radiation generated by the MR scanner from causing interference in nearby medical devices

The most common form of RF interference comes from noise generated from nearby electrical equipment (transformers, motors, pumps) or electronic devices (computers, pulse oximeters, cardiac monitors). As a rule, most manufacturers require that the magnet room to have at least 100dB of RF attenuation at the Larmor frequency.

The RF-shield must encircle the entire room - walls, floor, and ceiling. Such a conductive box used to shield out stray electromagnetic interference is also known as a Faraday cage. Virtually any type of metal can be used, including aluminum and galvanized steel.

However, the most common RF-enclosure consists of wood panels wrapped with copper. At the range of frequencies used for MRI the skin conductive depth for copper is very small (on the order of 0.1 mm), meaning that only a thin layer of metallic shielding is required.

The floor is generally made of monolithic copper covered over with a solid antistatic flooring material. The interior walls are typically finished with drywall. The ceiling is suspended from the RF shield to allow space for recessed lighting and mechanicals. The door must not allow any RF leakage, being sealed by a set of electrical contact strips or a continuous metallic pneumatic tube. Because of repetitive opening and closing, RF-seals around the door are frequently damaged and a common source of RF-leakage into the room. Windows are laminated with blackened copper mesh between two pieces of glass that connects peripherally with the RF enclosure walls.