Gradient Coil Design and Realization for a Halbach-Based MRI System

TL;DR

This paper presents the design and construction of gradient coils for a Halbach-based MRI system, adapting the target field method for transverse magnetic fields, and demonstrates successful imaging with minimal distortion.

Contribution

It extends the target field method to transverse fields in Halbach MRI systems and demonstrates practical coil construction and imaging performance.

Findings

Measured fields match simulations and target fields

High-quality 3D images obtained with low distortion

Gradient coils successfully constructed for Halbach MRI

Abstract

In this paper we design and construct gradient coils for a Halbach permanent magnet array magnetic resonance (MR) scanner. The target field method, which is widely applied for the case of axial static magnetic fields, has been developed for a transverse static magnetic field as produced by a Halbach permanent magnet array. Using this method, current densities for three gradient directions are obtained and subsequently verified using a commercial magneto-static solver. Stream functions are used to turn the surface current densities into wire patterns for constructing the gradient coils. The measured fields are in good agreement with simulations and their prescribed target fields. Three dimensional images have been acquired using the constructed gradient coils with very low degree of geometric distortion.