ACTIVE VIBRATION ISOLATION APPLIED TO A MAGNETIC RESONANCE IMAGING (MRI) SYSTEM

摘要

A magnetic resonance imaging system (MRI) produces high acoustic noise levels during scanning. In these systems, a strong static magnetic field is used in the order of a few Tesla. Additionally, a magnetic gradient field is generated which varies in time. This gradient field is created by means of a so-called gradient coil, in which electrical currents are used in the order of a few hundred amperes. The combination of these alternating electrical currents running through the gradient coil and the strong magnetic field that is created by the superconducting main magnet causes Lorentzforce induced vibrations and thus acoustic noise. Especially at the structural resonance frequencies of the gradient coil, high vibration levels occur. Some typical resonance modes of the gradient coil will be discussed.