Electromagnetic Interaction Simulation of Parallel-Plate Waveguide and Maxwell Gradient Coils in Low Field Magnetic Resonance Imaging Systems

摘要

The parallel-plate waveguide (PPWG) has been employed due to the fact that all frequencies can propagate, because its cut-off frequency is zero for the lowest-order transverse electric mode. The electromagnetic interaction between the waveguide and the RF subsystem of a Magnetic Resonance Imaging (MRI) scanner may be a cause of concern in terms of the Specific Absorption Rate (SAR) and image distortion. We have numerically simulated the electromagnetic interaction between a parallel-plate waveguide and a Maxwell gradient in the z-axis direction. Theoretical results were also obtained for the gradients only and compared with the numerically-acquired results involving the waveguide agreement was found between numerical and theoretical results. SAR calculations of a phantom inside the waveguide were also obtained to evaluate the parallel-plate waveguide performance. Global SAR values within the safety limits for human. Numerical results of SAR also showed that the use of a parallel-plate waveguide attenuates the global SAR values.