EP0196511A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Ferromagnetic shield for magnetic resonance magnets
Assignee: OFFERTA DI LICENZA AL PUBBLICO
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Filing: 1986-03-12
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Granted: —
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Expires: 2006-03-12
Abstract
Abstract @ 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.
Inventors
- 👤 Madabushi Venkatakrishnama Chari
- 👤 Ahmed Kamal Kalafala
- 👤 John D'angelo
- 👤 Michael Anthony Palmo, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:48
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/42; G01R33/421; H; H01; H01F; H01F27/00; H01F27/34; H01F27/36; H01F27/366
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
98 words
A shield for an MR magnet comprising: a cylindrical shell of magnetic material surrounding the MR magnet, the cylindrical magnet situated so that the longitudinal axis of the magnet is coaxial with the magnetic axis of the MR magnet; and two disc shaped end caps of magnetic material secured to either end of the cylindrical shell, said end caps each defining a central aperture extending longitudinally through each disk, the radial extent of the apertures sized so that the perturbation of the field in the working area of the MR magnet due to the cylindrical shell is compensated.
Claim 2
Dependent Claim
98 words
A shield for an MR magnet comprising: a cylindrical shell of magnetic material surrounding the MR magnet, the cylindrical magnet situated so that the longitudinal axis of the magnet is coaxial with the magnetic axis of the MR magnet; and two disc shaped end caps of magnetic material secured to either end of the cylindrical shell, said end caps each defining a central aperture extending longitudinally through each disk, the radial extent of the apertures sized so that the perturbation of the field in the working area of the MR magnet due to the cylindrical shell is compensated.
Claim 3
Dependent Claim
61 words
The shield of claim 1 wherein the thickness in the radial direction of the cylindrical shell is greater in the central portion as measured in the longitudinal direction and decreases towards either end so that the cylindrical shell thickness is greater where the field density due to the MR magnet is high and less thick where the field density is lower.
Claim 4
Dependent Claim
22 words
The shield of claim 2 wherein said cylindrical shell has a radial thickness such that said cylindrical shell saturates during magnet operation.
Claim 5
Dependent Claim
27 words
The shield of claim 1 wherein said cylindrical shell comprises longitudinally extending plates having each end of said plates secured circumferentially about the disk shaped end caps.
Claim 6
Dependent Claim
122 words
A double shield for an MR magnet comprising: an inner cylindrical shell of magnetic material surrounding the MR magnet, the cylindrical magnet situated so that the longitudinal axis of the magnet is coaxial with the magnetic axis of the MR magnet; two disc shaped end caps of magnetic material secured to either end of the cylindrical shell, said end caps each defining a central aperture extending longitudinally through each disk, the radial extent of the apertures sized so that the perturbation of the field in the working area of the MR magnet due to the cylindrical shell is compensated; and an outer cylindrical shell of magnetic material spaced away from and surrounding said inner cylindrical shell and coaxial with said inner shell.
Claim 7
Dependent Claim
122 words
A double shield for an MR magnet comprising: an inner cylindrical shell of magnetic material surrounding the MR magnet, the cylindrical magnet situated so that the longitudinal axis of the magnet is coaxial with the magnetic axis of the MR magnet; two disc shaped end caps of magnetic material secured to either end of the cylindrical shell, said end caps each defining a central aperture extending longitudinally through each disk, the radial extent of the apertures sized so that the perturbation of the field in the working area of the MR magnet due to the cylindrical shell is compensated; and an outer cylindrical shell of magnetic material spaced away from and surrounding said inner cylindrical shell and coaxial with said inner shell.
Claim 8
Dependent Claim
62 words
The shield of claim 5 wherein the thickness in the radial direction of the inner cylindrical shell is greater in the central portion as measured in the longitudinal direction and decreases towards either end so that the cylindrical shell thickness is greater where the field density due to the MR magnet is high and less thick where the field density is lower.
Claim 9
Dependent Claim
13 words
The shield of claim 5 wherein said inner cylindrical shell saturates during operation.
Claim 10
Dependent Claim
37 words
The shield of claim 7 wherein said outer cylindrical shell is spaced apart from said inner shell so that during magnet operation the flux passing through said inner shell is not diverted to the outer cylindrical shell.
Claim 11
Dependent Claim
24 words
The shield of claim 8 wherein said outer cylindrical shell has a radial thickness such that said outer cylindrical shell saturates during magnet operation.
References Cited (Backward Citations)
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