Active-passive gradient shielding for MRI acoustic noise reduction.
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.
Edelstein
William A
WA
MRScience LLC, Schenectady, NY 12309, USA. wedelst1@nycap.rr.com
Kidane
Tesfaye K
TK
Taracila
Victor
V
Baig
Tanvir N
TN
Eagan
Timothy P
TP
Cheng
Yu-Chung N
YC
Brown
Robert W
RW
Mallick
John A
JA
D000162:Acoustics; D003300:Copper; D004867:Equipment Design; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009622:Noise; D014732:Vibration
D003300:Copper