Magnetic shielding may be required depending on the type of MRI magnet, its Tesla field strength and the location of the site. Magnetic shielding is required to reduce the spread of the 0.5mT (5 Gauss) line of the magnetic field to minimise the risk to people with pacemakers and implants, also to protect against sensitive medical equipment. If the proposed location of the magnet allows the gauss line to spread outside the room this can have serious repercussions to members of the public in this area.
The maximum field strength is achieved at the centre of the magnet, commonly known as the isocenter, and drops off with distance from this centre – this is known as the fringe field and is often measured in millitesla (mT) or the old unit of gauss (G). For fringe field measurements note that 0.5mT = 5G
Another factor to take into consideration is interference from the outside world. Moving objects with high levels of ferrous magnetic metals such as vehicles and lift shafts can cause interference to the operation of the MR scanner.
Introducing materials like silicon steel or low carbon plate as shielding will contain the magnetic field and avoid interference from the outside world.
Envirotect has experience in calculating, designing, manufacturing and installing magnetic shielding.