U.S. Philips Corporation

Aart J Mateboer

Nicolaas Bernardus Roozen

Cornelis L G Ham

Gerardus B J Mulder

Johannes P M Verbunt

The MRI apparatus includes an actively shielded gradient system (,) with primary gradient coils and shielding coils (,). Despite the active shielding, such a system inevitably causes a magnetic field to some extent outside the shielding, so that eddy currents are generated in the conductive structures of the main magnet, said eddy currents causing heat dissipation and annoying noise. According to the invention, the gradient system also includes an eddy current shield (,) which consists of an electrically conductive, substantially closed plate; furthermore, the primary gradient coil (,) and the shielding coil (,) are arranged within the eddy current shield (,) and these three elements together constitute a mechanically rigid unit. As a result, eddy currents are avoided in the main magnet and annoying noise is strongly reduced.

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Eindhoven, Netherlands

Aart J Mateboer