Combined radio frequency coil with integral magnetic field shim set
US5550472A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 13, 1995 |
| Grant date | Aug 27, 1996 |
| Priority date | — |
| Expiry date | Apr 13, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/422
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A toroidal housing (18), such as a vacuum dewar, contains magnets (10, 12) for generating a temporally constant magnetic field through a central bore (14). Gradient coils (32, 42) are mounted around the bore defining a space therebetween. A radio frequency shield (78) is disposed radially inward from the gradient coils. Inside the radio frequency shield, an inner shimming assembly (60) includes a dielectric cylinder (62) having annular grooves around its periphery. Segmented ferrous material (66) is arranged in annular rings in the grooves. The ferrous material is segmented into small pieces electrically insulated from each other to limit radio frequency and gradient frequency eddy currents. A radio frequency coil (70) is mounted inside of the annular ferrous shims (66). Preferably, additional shim trays (50) which carry shims (54) are mounted in the space between the primary and secondary gradient coils.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.