Jonathan Samuel Jackson1, Daniel Tozer1, Jerome M. Goffin2, John S. Thornton3, Paul S. Tofts4, Claudia A. M. Wheeler-Kingshott1, Mark Symms5
1Department of Neuroinflammation, UCL Institute of Neurology, London, UK; 2University of Edinburgh, Edinburgh, UK; 3National Hospital for Neurology and Neurosurgery, London, UK; 4Brighton and Sussex Medical School, Brighton, UK; 5Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
Measuring geometric distortion due to gradient non-uniformity has previously required image processing tools specific to the phantom design. Here we demonstrate geometric distortion measurement achieving a precision of 0.3mm over 95% of the useful volume (6.2 litres) of a phantom using off-the-shelf non-linear registration. This method can be used with any sufficiently detailed phantom. Geometric distortion is measured in a short-bore interventional MRI system, finding residual errors of 2mm at a distance of 9cm from the isocenter after the built-in gradient non-uniformity correction.