Detection of ferromagnetic objects approaching a magnet

摘要

An apparatus for detecting a potentially dangerous ferromagnetic object carried inadvertently by a person approaching the magnet of a magnetic resonance imaging system ( 14 ) uses the fringe field ( 16 ) of the magnet and provides guide members ( 11 ) defining a path along which the person is prescribed to pass. The path ( 11 ) is generally or approximately parallel to the field the path. At least one sense coil and generally two sets of sense coils ( 12, 13 ) are located on respective sides of the path ( 11 ) s the movement of the ferromagnetic object in the field of the magnet causes a voltage to be generated in the sense coil.