Principles of active acoustic control in gradient coil design

Area of Science:

• Acoustics
• Electrical Engineering
• Medical Imaging

Background:

• Gradient coils in Magnetic Resonance Imaging (MRI) generate acoustic noise due to Lorentz forces acting on current-carrying conductors.
• Controlling this acoustic noise is crucial for patient comfort and reducing motion artifacts.

Purpose of the Study:

• To introduce new principles for active acoustic control in gradient coil design.
• To develop theoretical expressions for predicting far-field acoustic output.
• To experimentally validate the effectiveness of the proposed control method.

Main Methods:

• Theoretical development of acoustic output expressions for multi-sector coil systems.
• Design of a gradient coil sector with a split plate and dual windings (primary and control).
• Experimental measurement of acoustic output with and without driving the control winding.

Main Results:

• Theoretical expressions for far-field acoustic output were derived for coil systems with four or more sectors.
• Experimental results for a single sector showed an average acoustic output reduction of 34.9 dB when the control winding was driven.
• The developed theoretical models demonstrated good agreement with the experimental data's output response form.

Conclusions:

• Active acoustic control using a re-entrant loop control winding is an effective method for reducing MRI gradient coil noise.
• The theoretical framework developed accurately predicts the acoustic output and validates experimental findings.
• This approach offers a promising strategy for mitigating acoustic noise in MRI systems.