Optimized RF shield design

摘要

Radio frequency (RF) shields used with magnetic resonance imaging (MRI) apparatus may experience gradient field induced eddy currents and RF field induced eddy currents. These eddy currents can cause the RF shield to heat up at an undesirable rate. RF shields are designed to have a desired degree of RF shielding and a desired heating attribute. Design goals for RF shields include gradient field transparency and RF field opacity, both of which can be influenced by eddy currents. Example methods identify a gradient field that will induce eddy currents and identify an RF field that will induce eddy currents. If a region on the RF shield is identified where the desired heating attribute will not be achieved, then a pattern of axial cuts and azimuthal cuts can be made in the RF shield to reduce gradient eddy current heating in the RF shield while maintaining desired RF shielding.

主权项

1. A method for providing a magnetic resonance imaging (MRI) radio frequency (RF) shield, comprising:
controlling a processor in an RF shield fabricator to identify a desired degree of RF shielding to be achieved by the RF shield; controlling the processor in the RF shield fabricator to identify a desired heating attribute for the RF shield; controlling the processor in the RF shield fabricator to identify a gradient field to which the RF shield will be exposed, the gradient field being produced by a gradient coil in an MRI apparatus; controlling the processor in the RF shield fabricator to identify an RF field to which the RF shield will be exposed, the RF field being produced by an RF transmission coil in the MRI apparatus; and controlling the processor in the RF shield fabricator to, upon identifying a hot region on the RF shield where a determined heating attribute does not satisfy the desired heating attribute,
controlling the processor in the RF shield fabricator to automatically identify one or more axial cuts to be made in the RF shield to reduce gradient eddy current heating produced in the RF shield by the gradient field and then to identify one or more azimuthal cuts to be made in the RF shield to reduce gradient eddy current heating produced in the RF shield by the gradient field,where the one or more axial cuts and the one or more azimuthal cuts are configured to cause the RF shield to exhibit the desired heating attribute while maintaining the desired degree of RF shielding,andcontrolling the RF shield fabricator to cut the one or more axial cuts and the one or more azimuthal cuts in the RF shield.