Which material could be used to line the walls and/or floors of the MR magnet room to reduce the fringe field, and is defined as __________ shielding?

The correct answer is that steel can be used to line the walls and/or floors of the MR magnet room to reduce the fringe field, and this is defined as passive shielding. Passive shielding refers to the use of materials that do not require external power to provide shielding from magnetic fields. Steel is an effective passive shielding material because it can absorb and redirect magnetic fields, thereby minimizing the extent of the fringe field.

In a magnet room, controlling the fringe field is crucial to ensure that surrounding areas remain safe for both individuals and equipment, keeping the influence of the magnetic field contained within a specified area. By using steel, which is dense and ferromagnetic, the magnetic field lines are redirected, effectively reducing the strength of the fringe fields in areas outside the magnet’s core.

In contrast, active shielding involves the use of coils that generate magnetic fields to counteract the fringe fields, which requires a power source. While both techniques aim to mitigate the effects of the magnetic field, passive shielding with steel is a more straightforward, static solution that is often employed in the design of MRI facilities.