Low eddy current radio frequency shield for magnetic resonance imaging
US5592087A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 27, 1995 |
| Grant date | Jan 7, 1997 |
| Priority date | — |
| Expiry date | Jan 27, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/4215
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A magnetic resonance imaging apparatus includes a magnet assembly (10) for generating a temporally constant primary magnetic field through a central bore (14). The central bore is surrounded by a gradient coil assembly (30) including a dielectric former (32) and gradient coils (34, 36, 38) for generating magnetic field gradient pulses across the examination region. A radio frequency coil assembly (50) including a birdcage coil (52) is mounted inside of the gradient coil assembly and surrounding the examination region. A radio frequency shield (60) includes a dielectric sheet (62) having a plurality of first metal foil strips (72) defined on each surface. The metal strips are defined by etching or cutting gaps (70) in a continuous sheet of copper foil, leaving bridges (74) across the gaps adjacent opposite ends of the foil strips. The foil strips on opposite faces of the dielectric sheet are offset by half the width of one strip such that each strip is capacitively coupled to two strips on the opposite surface. The radio frequency coil induces radio or megahertz frequency eddy currents to which the capacitive coupling appears as a short-circuit, allowing the induced radio frequency …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.