Using analytic and experimental methods, we have investigated the design, fabrication, and performance of axially symmetric shields which minimize the field perturbation within the central bore of an MR magnet. Magnetic resonance shields have been built for 1.9 tesla/60 cm bore and 1.5 tesla/100 cm bore superconducting magnets. The 1.9 T system is enclosed by a simple cylindrical shield having a weight of 49, 000 pounds. The 1.5 T system shield is a 100, 000 pound tapered thickness cylinder with conic ends. The shields are constructed from cold rolled steel sections which are welded in place at the magnet site. A low carbon, specially annealed steel with particularly desireable properties of induced magnetism has been employed. The 5 gauss line is constrained to a point 4.0 meters to the side of the 1.9 T magnet, 3.0 meters to the side of the 1.5 T magnet and 7.0 meters off the end of both magnets.
|Original language||English (US)|
|Number of pages||7|
|Journal||Proceedings of SPIE - The International Society for Optical Engineering|
|State||Published - Sep 19 1985|