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An Analytical Approach to the Design of Quiet Cylindrical Asymmetric Gradient Coils in MRI

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Forbes, LK and Brideson, MA and Crozier, S and While, PT (2007) An Analytical Approach to the Design of Quiet Cylindrical Asymmetric Gradient Coils in MRI. Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering, 31B (4). pp. 218-236. ISSN 1552-5031

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Abstract

We consider the design of asymmetric gradient coils in a conventional
cylindrical bore magnetic resonance imaging system. The gradient coils are switched on
and off during the scan, and are therefore subject to Lorentz forces that cause them to
buckle during the switching process. This in turn creates a pressure wave within the coil,
and that gives rise to acoustic noise. We present a simplified linearized model for the
deflection of the coil due to electromagnetic forces, which is amenable to solution using
analytical methods. Closed-form solutions for the coil deflection and the pressure pulse
and noise level within the coil are obtained. These are used to design new coil winding
patterns so as to reduce the acoustic noise. Sample results are shown both for
unshielded and shielded gradient coils. Extensions of this model are indicated, although
it is suggested that the advantages of the present closed-form solutions might then not
be available, and fully numerical solutions may be needed instead.

Item Type: Article
Keywords: gradient coils; switching functions; Lorentz forces; elastic deformation; acoustic noise reduction
Journal or Publication Title: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering
Publisher: John Wiley & Sons Inc
Page Range: pp. 218-236
ISSN: 1552-5031
Identification Number - DOI: 10.1002/cmr.b.20095
Additional Information:

The original publication is available at
http://www.interscience.wiley.com/

Date Deposited: 07 Apr 2008 14:03
Last Modified: 18 Nov 2014 03:32
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