15. Interesting Facts About the Scanner
MRI Room Floor Preparation
MRI scanners use magnets and radio waves to generate images of the body. The magnet is very
sensitive to any metal in its vicinity. Consequently, preparation of the MRI scanner room entails
creating a floor base for the scanner that is free from all metal. The only way to ensure this is to dig out
the existing floor (to a depth of two feet) and re-fill it with “clean” dirt. The debris-free dirt is
compressed and covered with concrete to provide a level surface for the scanner.
MRI Shielding
Due to the strong magnetic field created by MRI scanners, they require protective shields to protect
both the scanner and the surrounding area.
An RF (radio frequency) shield must be used around the MRI scanner to block out specific radio waves
that may distort the images created by the MRI. The RF shielding must create a complete box around
the scanner, including walls, the ceiling and floor. It can be made of almost any metal, but the most
common types are copper, galvanized steel and aluminum.
Magnetic shielding must also surround the MRI scanner. This shield prevents the magnetic field created
by the scanner from interfering with surrounding areas. It needs to be strategically placed to contain the
magnetic field so that people (i.e. employees, patients, maintenance staff) cannot unknowingly pass
through it.
MRI Scanner Cooling System
The key to the efficiency and ability of any magnetic resonance imaging (MRI) scanner is the huge
superconducting magnet within the MRI’s outer ring. To reach maximum performance, these magnets
must be cooled down to -2 to -600 degrees celsius. Liquid helium is commonly used as a refrigerant to
accomplish this. In order to maintain the liquid helium cooling system, a water-cooled gradient
compressor needs to be used. The chiller is installed and functional prior to the delivery of the magnet
and installation.
