Nuclear magnetic resonance imaging apparatus using asymmetric torque-free active shield gradient coils
US5793209A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 15, 1996 |
| Grant date | Aug 11, 1998 |
| Priority date | — |
| Expiry date | Mar 15, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/4215
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A nuclear magnetic resonance imaging apparatus using asymmetric torque-free active shield gradient coils for realizing a sufficient imaging field of view, a sufficient eddy current magnetic field suppression effect, and a substantially complete torque cancellation. The gradient coil is formed by: a primary coil having an asymmetric current distribution in which all current returns are asymmetrically arranged toward one side of the primary coil, a shield coil having a current distribution for cancelling out a leakage magnetic field generated by the asymmetric current distribution of the primary coil, and a torque cancellation coil, provided adjacent to the primary coil and the shield coil, having a current distribution for cancelling out a torque acting on the primary coil and the shield coil in a static magnetic field. The primary coil generates the gradient magnetic field which cancels out a gradient field contribution from the torque cancellation coil to produce a desired gradient magnetic field.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.