A New Approach to Shimming: The Dynamically Controlled Adaptive Current Network

Chad Tyler Harris¹, William B. Handler¹, Blaine A. Chronik¹, ²

Active magnetic shim coils, used to correct field inhomogeneities caused by susceptibility differences between tissue interfaces, are typically composed of sets of cylindrical layers, with each layer producing a magnetic field profile of a particular spherical harmonic. A radically different approach to shimming is to dynamically and adaptively control the flow of current over a given surface. This could be achieved with the use of a network of metal-oxide-semiconductor field-effect transistors (MOSFETs). In this work, we present computer simulations demonstrating the benefits that a supplementary, region specific shim coil utilizing this approach can provide, and experimental results of a proof-of-principle prototype.