Description of magnetic shielding for strong fields

Soft iron or magnetic sheet steel is used to screen the fringe fields of MRI magnets.

IMEDCO has developed its own technique for magnetic shielding. The shielding necessary for a particular project is designed at the works and the parts are prefabricated. On site, the sheet metal shielding panels are mounted on a strip metal frame on the walls or the concrete ceiling. This procedure shortens the installation time.
The required thickness is built up by fitting several layers of panels which are rolled and also overlap in the direction of the flux. The overlapping of the panels and the pressure applied at the points of contacts ensure a homogeneous shielding effect which has a positive influence on the homogeneity of the MRI field.

Magnetic shields are engineered according to the MRI equipment manufacturer’s specification.
For example, after rolling, the soft iron is subjected to a tightly controlled annealing process which considerably improves the magnetic characteristics of the iron.
Magnetic sheet steel is available in different qualities and depending on the requirements, either grain oriented or non-oriented sheet steel with gauges between 0.35 mm and 0.5 mm is used.
IMEDCO maintains a stock of 20 to 30 tons of magnetic sheet steel and soft iron sheet of different gauges.