Mri system having a gradient magnet system with a balance member

Abstract

The invention relates to a magnetic resonance imaging (MRI) system () comprising an examination volume (), a main magnet system () for generating a main magnetic field (B) in the examination volume in a Z-direction, a gradient magnet system () for generating gradients of the main magnetic field, and an anti-vibration system () for reducing vibrations of the gradient magnet system caused by a mechanical load (M, M) exerted on the gradient magnet system as a result of electromagnetic interaction between the main magnetic field and electrical currents in the gradient magnet system. According to the invention the anti-vibration system () comprises a balance member (), which is coupled to the gradient magnet system () by means of an actuator system () and a coupling device () allowing displacements of the balance member relative to the gradient magnet system. The MRI system () also has a control system () which controls the actuator system in such a manner that the actuator system exerts upon the balance member a compensating mechanical load (M, M) which substantially corresponds to the mechanical load (M, M) exerted on the gradient magnet system. As a result, the actuator system exerts a mechanical reaction load (M, M) on the gradient magnet system which has the same magnitude as but is oppositely directed to the mechanical load (M, M) exerted on the gradient magnet system, so that vibrations of the gradient magnet system are effectively limited.