MAGNETIC SHIELDING FOR HIGH FIELD MAGNET
Magnetic shielding for surrounding a magnet generating a magnetic field of maximum magnetic flux density substantially in excess of 5 Gauss, so as to reduce the magnetic flux density outside the shielding to no more than 5 Gauss wherein at least part of the shielding is composed of sheets of grain-oriented steel.
1 . Magnetic shielding for surrounding a magnet generating a magnetic field of maximum magnetic flux density substantially in excess of 5 Gauss (5×10 −4 T), so as to reduce the magnetic flux density outside the shielding to no more than 5 Gauss (5×10 −4 T), comprising a portion of the shielding being comprised of sheets of grain-oriented steel, and another portion of the shielding being composed of sheets of non-grain-oriented steel, in which layers of said sheets of non-grain-oriented steel are located in regions of relatively high magnetic flux density, and in which only layers said sheets of grain-oriented steel are located in regions of relatively low magnetic flux density.
2 . Magnetic shielding according to claim 1 surrounding a magnet generating a magnetic field of maximum magnetic flux density in excess of 0.5 T.
3 . Magnetic shielding according to claim 2 surrounding a magnet generating a magnetic field of maximum magnetic flux density in excess of 1.0 T.
4 . Magnetic shielding according to claim 3 surrounding a magnet generating a magnetic field of maximum magnetic flux density in excess of 1.5 T.
5 . Magnetic shielding according to claim 1 surrounding a magnet generating a magnetic field of maximum magnetic flux density in excess of 3 T.
6 . Magnetic shielding according to claim 1 , wherein a majority of the shielding is composed of said sheets of non-grain-oriented steel.
7 . Magnetic shielding according to claim 1 , comprising additional non-grain-oriented steel in regions where increased mechanical strength is required.
8 . Magnetic shielding according to claim 1 , comprising an outermost layer of the magnetic shielding formed of grain-oriented steel around an entire periphery of the shield, also with layers of said sheets of non-grain-oriented steel being provided within the outermost layer.
9 . Magnetic shielding according to any claim 1 , wherein the non-grain-oriented steel is C1006 steel.
10 . A mobile magnetic resonance imaging apparatus comprising:
a magnetic resonance imaging apparatus comprising a magnet that generates a magnetic field of a maximum magnetic flux density substantially in excess of 5 Gauss;
a mobile carrier on which said magnetic resonance imaging apparatus is mounted; and
magnetic shielding that surrounds said magnet so as to reduce the magnetic flux density outside the shielding to no more than 5 Gauss, a portion of the shielding being comprised of sheets of grain-oriented steel, and another portion of the shielding being composed of sheets of non-grain-oriented steel, in which layers of said sheets of non-grain-oriented steel are located in regions of relatively high magnetic flux density, and in which only layers said sheets of grain-oriented steel are located in regions of relatively low magnetic flux density.
11 . A mobile magnetic resonance imaging apparatus comprising:
a magnetic resonance imaging apparatus comprising a magnet that generates a magnetic field of a maximum magnetic flux density substantially in excess of 5 Gauss; and
magnetic shielding that surrounds said magnet so as to reduce the magnetic flux density outside the shielding to no more than 5 Gauss, a portion of the shielding being comprised of sheets of grain-oriented steel, and another portion of the shielding being composed of sheets of non-grain-oriented steel, in which layers of said sheets of non-grain-oriented steel are located in regions of relatively high magnetic flux density, and in which only layers said sheets of grain-oriented steel are located in regions of relatively low magnetic flux density.