Why is the scanner in a special room?
In every MRI scanner, the patient lies in a strong magnetic field. Although the magnetic field is invisible and the patient cannot sense it, the strength of the field can be seen by its effect on a ferromagnetic object. For example, if one holds a metal paper clip in the “fringe” field surrounding an MRI scanner, one can feel the tug of the magnetic field on the paper clip, pulling it toward the center of the magnet. The scanner is in a special shielded room because the scanner itself needs shielding from outside radio wave interference that can degrade the pictures. The purpose of the shielding is the opposite of what it is for the CAT scanner (an X-ray machine) and other X-ray equipment.
