Characterization of vibration and acoustic noise i

Authors: G Z Yao C K Mechefske B K Rutt

Publish Date: 2004/06/23

Volume: 17, Issue: 1, Pages: 12-27

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Abstract

Highspeed switching of current in gradient coils within high magnetic field strength magnetic resonance imaging MRI scanners results in high acoustic sound pressure levels SPL in and around these machines To characterize the vibration properties as well as the acoustic noise properties of the gradient coil a finiteelement FE model was developed using the dimensional design specifications of an available gradientcoil insert and the concentration of the copper windings in the coil This FE model was then validated using experimentally collected vibration data A computational acoustic noise model was then developed based on the validated FE model The validation of the finiteelement analysis results was done using experimental modal testing of the same gradient coil in a freefree state no boundary constraints Based on the validated FE model boundary conditions supports were added to the model to simulate the operating condition when the gradientcoil insert is in place in an MRI machine Vibration analysis results from the FE model were again validated through experimental vibration testing with the gradientcoil insert installed in the MRI scanner and excited using swept sinusoidal time waveforms The simulation results from the computational acoustic noise model were also validated through experimental noise measurement from the gradientcoil insert in the MRI scanner using swept sinusoidal time waveform inputs Comparisons show that the FE model predicts the vibration properties and the computational acoustic noise model predicts the noise characteristic properties extremely accuratelyThe authors wish to offer special thanks to Andrew Alejski and Carl Gazdzinski at the Robarts Research Institute London Ontario Canada for their kind help in providing the structural dimensions of the gradientcoil insert and setting up the vibration and noise measurement experiments This work was funded through an NSERCCIHR Collaborative Health Research Project grant 227285–9 CHRPJ and an Ontario Research and Development Challenge Fund grant

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