Matthew Tarasek1, Tom Foo1, Mark Vermilyea1, Desmond Yeo1, Isabelle Jansen1, Eric Budesheim 1, and Keith Park1
1GE Global Research, Niskayuna, NY, United States
1GE Global Research, Niskayuna, NY, United States
In
this work we evaluate the MRI acoustic changes brought about by modifying the
RF shield structure in a head-only 3T imaging system. Results
indicate that a modification of the structural properties of the patient-bore
structure properties can provide acoustic reduction for MR imaging.
Figure
1. (Left) Elevation view of the head-only RF patient-bore structure. For the
structure made from FRP, a stainless-steel mesh RF shield was mounted on the
outer-diameter of the structure. In the case of CFRP, no stainless-steel mesh was
needed as the CRFP material acts as an RF shield at 128 MHz. (Right)
Experimental setup for measuring sound pressure levels. Here the patient-bore
structure has been inserted into the gradient, and acoustic measurements are
made at imaging isocenter, i.e., the narrow portion of the shield inner bore.
Figure
2. Results of the A-weighted, equivalent continuous sound level (LAeq,
dBA) tested for 11 clinical sequences or sequence variations using the
Fiberglass RF shield structure (black bars) and Carbon Fiber RF shield
structure (gray bars). Shown with the limits assuming hearing protection with
noise reduction rating (NRR) = 26 and 33 dB to reach the U.S.
Food and Drug Administration (FDA) and
IEC 60601-2-33 (3rd Edition) guidelines
for nonsignificant risk limit of 99 dBA.