Ellipsoidal Harmonic Expansions for Efficient Approximation of Magnetic Fields in Medical Imaging

Abstract

Exact knowledge on the magnetic fields used in tomographic imaging systems is important for accurate sequence planning and model-based image reconstruction in existing devices. It is common to measure the magnetic fields on a small subset of points and use spherical harmonics to approximate the fields inside a spherical region. However, most scanner bores could be better filled using a cylindrical or ellipsoidal region. In this work, we present the application of ellipsoidal harmonics for efficient approximation of a typical magnetic field in magnetic particle imaging.