Method of MRI gradient coil design that allows control of the residual eddy current effect
Abstract
We address the need to shield the magnetic field produced by the gradient coil used in magnetic resonance imaging (MRI). In the conventional shielded gradient coil design the shield coil is modeled in the first step as infinitely long and in the second step it is truncated (apodized) to fit the physical dimension of the MRI system. This introduces field leakage outside the shield and increases the eddy currents in surrounding metal structures, hence producing an increase in interfering "residual" magnetic fields. This field leakage can be characterized by the "residual eddy current effect" that is a measure of how well the coil has been shielded. Eddy current effects that are not constant throughout the imaging volume make correction more difficult. We present a method of shielded gradient coil design that includes a finite coil length from the beginning of the design and allows one to control the uniformity of the eddy current effect over the surface of the imaging volume to a desirable level.
- Publication:
-
APS Ohio Sections Fall Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..OSF.C5003S