Aperture sized disc shaped end caps of a ferromagnetic shield for magnetic resonance magnets

摘要

A shield for a MR magnet is provided comprising a cylindrical shell of magnetic material surrounding the MR magnet. The cylindrical shell is situated so that its longitudinal axis is coaxial with the magnetic axis of the MR magnet. Two disk shape end caps of magnetic material are secured to either end of the cylindrical shell. The end caps each define a central aperture extending longitudinally through the disk, with the radial extent of each of the apertures sized so that the perturbation of the field in the working volume of the MR magnet due to the cylindrical shell is compensated for.