Shielding static magnetic fields from magnetic resonance imaging units by ferromagnetic material

Abstract

This study investigated the effectiveness of iron sheets in shielding static magnetic fields from MRI units. The neighbouring rooms of two 3T MRI units were measured, located in different healthcare facilities, one fully shielded and the other only partially shielded (only the ceiling was shielded) from static magnetic fields. In order to achieve a significant shielding effectiveness from the MRI static magnetic field, the examination room should be fully shielded, including the walls, ceiling and the floor. The MRI unit with only partially shielded room allowed ten times more static magnetic field to propagate into the premises one floor below. The average static magnetic field below partially shielded MRI unit was 1.178 mT, whereas below fully shielded MRI unit 0.176 mT.