MRI RF Shielding & RF Cage Installation

What an RF cage does

An MRI receives extraordinarily weak signals from the patient. The surrounding environment is full of radiofrequency noise — broadcast transmitters, mobile networks, wireless devices, lifts, motors, switching power supplies. Without shielding, that noise swamps the signal and shows up as artefacts in the image.

The magnet room is therefore built as a continuous conductive enclosure — a room inside a room. Every wall, the floor, the ceiling and every opening form one unbroken shield. The shield is only as good as its worst penetration, which is why the detailing matters more than the panels.

What we install

• RF cage design, supply and installation — modular shielded enclosure forming a continuous conductive envelope across walls, floor and ceiling
• RF shielded door — the most demanding component, since it has to maintain shield continuity across a moving joint with contact surfaces that stay effective through years of daily use
• RF window to the control room, shielded and continuous with the enclosure
• Waveguides for services entering the room, sized so they attenuate rather than conduct RF
• Penetration panels and line filters for power, data, gases and control cabling — every conductor entering the shield is filtered, because an unfiltered cable carries noise straight through an otherwise perfect cage
• Quench pipe route and installation, penetrating the shield correctly and discharging clear of air intakes, windows and public areas
• Interior finishes within the cage, built so the shield is not compromised by later fixings
• RF leakage testing and certification on completion, with recorded attenuation values

Where RF shields fail

Almost never in the middle of a panel. Failures concentrate at the interfaces:

• Door contact surfaces that wear, corrode or fall out of adjustment — the commonest long-term failure, and it degrades gradually rather than suddenly
• Unfiltered penetrations — a data cable, a gas line or a power conductor brought through without proper filtering
• Later trade damage. An electrician drilling into a shielded wall to mount a fixture, months after the cage was certified, will breach it
• Waveguides used as conduits — running a cable through a waveguide defeats it entirely
• Floor shield damaged during equipment move-in

This is why we prefer to hold the shielding, the interior finishes and the services coordination together rather than have the cage installed by one vendor and breached by another.

Magnetic shielding is a separate question

RF shielding keeps radiofrequency noise out. It does not contain the magnetic field. Where the fringe field would extend into occupied or sensitive adjacent space — including above and below the magnet room — magnetic shielding is assessed separately as part of room planning. See MRI room planning.

Testing and handover

A cage that has not been tested is an assumption. On completion we carry out RF leakage testing and hand over recorded attenuation values, alongside the quench route and earthing documentation, so your equipment supplier's commissioning engineer has what they need.