| 摘要 |
The present invention provides a magnetic shielding mechanism (MSM) for preventing penetration of metallic objects through an aperture, so that penetration into the open bore of an MRI device (MRD), where the magnetic field (B) is maximum, is prevented . The MRD produces a fringing magnetic field (B F/L ) which decreases with increasing distance (L) from the aperture; the MSM compris es at least one magnet with a magnetic field B MSM ; and the MSM is affixed at a distance L MSM from the MRD's aperture so that, at any distance L, B MSM > > B F/L . |
