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Abstract

A medical NMR scanner having a primary field magnet assembly is disclosed. The scanner includes a ferromagnetic frame defining a patient-receiving space adapted to receive a human body. It also includes a pair of opposed polar regions aligned on a polar axis. The polar regions are disposed on opposite sides of the patient-receiving space. Structure including either electrical windings or a permanent magnet is provided in each of the polar regions for producing a magnetic field within the patient-receiving space. Windings positioned in proximity to each of the polar regions are provided for producing gradients in the magnetic field, when energized. A layer of an electrically resistive but magnetically permeable material such as a ferrite, a sintered metal or a metal containing composite, is positioned in each of the polar regions for limiting eddy current generation in the polar regions when the gradient producing auxiliary coils are energized. Each of the ferrite layers is oriented generally perpendicular to the polar axis.

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First Claim