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Electromagnetic fields in the human body due to switched transverse gradient coils in MRI


While, PT and Forbes, LK, Electromagnetic fields in the human body due to switched transverse gradient coils in MRI, Physics in Medicine and Biology, 49, (13) pp. 2779-2798. ISSN 0031-9155 (2004) [Refereed Article]

DOI: doi:10.1088/0031-9155/49/13/002


Magnetic resonance imaging scans impose large gradient magnetic fields on the patient. Modern imaging techniques require this magnetic field to be switched rapidly for good resolution. However, it is believed that this can also lead to the unwanted side effect of peripheral nerve stimulation, which proves to be a limiting factor to the advancement of MRI technology. This paper establishes an analytical model for the fields produced within an MRI scanner by transverse gradient coils of known current density. Expressions are obtained for the magnetic induction vector and the electric field vector, as well as for the surface charge and current densities that are induced on the patient's body. The expressions obtained are general enough to allow the study of any combination of gradient coils whose behaviour can be approximated by Fourier series. For a realistic example coil current density and switching function, it is found that spikes of surface charge density are induced on the patient's body as the gradient field is switched, as well as loops of surface current density that mimic the coil current density. For a 10 mT m-1 gradient field with a rise time of 100 μs, the magnitude of the radial electric field at the body is found to be 10.3 V m-1. It is also found that there is a finite limit to radial electric field strength as rise time approaches zero. © 2004 IOP Publishing Ltd.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Condensed matter physics
Research Field:Electronic and magnetic properties of condensed matter; superconductivity
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the mathematical sciences
UTAS Author:While, PT (Dr Peter While)
UTAS Author:Forbes, LK (Professor Larry Forbes)
ID Code:30887
Year Published:2004
Web of Science® Times Cited:7
Deposited By:Mathematics
Deposited On:2004-08-01
Last Modified:2005-04-26

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