"What we are doing [in MRI shielding] is making a continuous, seamless, six-sided box out of metals," explains Mike Profeta, Magnetic Resource Technologies, Willoughby, OH. "Primarily [silicon] steel shields are set up to contain the magnetic field....You can take any metal to create the RF shield." Profeta recommends a soldered copper room. However, some companies use aluminum or galvanized steel panels for RF protection.


The OEM that manufactured the MRI provides performance specifications for the room in terms of allowable measurements for RF or magnetic readings. However, it's often left to the contractors, such as independent service companies that specialize in MRI shielding to determine the best materials and design approach.
"We use copper, galvanized and welded steel in our rooms. Each material has a different application determined by the system and the existing site," says Gregory Vojak, Medesign, Solon, OH. "We feel a copper soldered room is best for RF attenuation, although some low- and mid-field systems can benefit from the use of galvanized steel to control any outside EMI and magnetic fields that may be present. With high-field systems and 3T units, a steel shield of one quarter inch or more is recommended to help control the field produced by the magnet."
ETS-Lindgren offers all three types of RF shielding: copper, galvanized steel, or aluminum, depending on the needs of hospitals and imaging centers.

"If the need is only for RF shielding, most of the RF copper, galvanized steel and aluminum are fairly lightweight with galvanized being the heaviest of the three," says Ben Turner, Vice President of Sales and Marketing, ETS-Lindgren, whose shielding division is based in Glendale Heights, IL. "When you get into magnetic shielding that is of significant weight that begins to dictate structural issues and may force the customers to look at only a ground floor or basement site." (A super high-field magnet might require hundreds of tons of shielding.)




Contractors must work out site-specific details such as weight bearing and other engineering considerations. However most agree on some basic suggestions for hospitals and imaging centers planning to install or replace an MRI.

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