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Active-passive gradient shielding for MRI acoustic noise reduction

✍ Scribed by William A. Edelstein; Tesfaye K. Kidane; Victor Taracila; Tanvir N. Baig; Timothy P. Eagan; Yu-Chung N. Cheng; Robert W. Brown; John A. Mallick

Publisher
John Wiley and Sons
Year
2005
Tongue
English
Weight
481 KB
Volume
53
Category
Article
ISSN
0740-3194

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✦ Synopsis

Abstract

An important source of MRI acoustic noise—magnet cryostat warm‐bore vibrations caused by eddy‐current‐induced forces—can be mitigated by a passive metal shield mounted on the outside of a vibration‐isolated, vacuum‐enclosed shielded gradient set. Finite‐element (FE) calculations for a z‐gradient indicate that a 2‐mm‐thick Cu layer wrapped on the gradient assembly can decrease mechanical power deposition in the warm bore and reduce warm‐bore acoustic noise production by about 25 dB. Eliminating the conducting warm bore and other magnet parts as significant acoustic noise sources could lead to the development of truly quiet, fully functioning MRI systems with noise levels below 70 dB. Magn Reson Med 53:1013–1017, 2005. © 2005 Wiley‐Liss, Inc.

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