**3.6. Magnetic fields and the missile effect**

The static magnetic field generated by a powerful magnet is tens of thousands times stronger than the earth's magnetic field which can attract objects containing ferrous mate‐ rials, transforming them into dangerous airborne projectiles (Dempsey *et al.,* 2002). There are two features of the magnetic field that are the source of most MRI incidents; the pro‐ jectile or missile effect which is the ability of the magnet to attract ferromagnetic objects and draw them rapidly into the bore with considerable force (Centre for Devices and Ra‐ diological Health, 1997). Ferromagnetic objects include metallic objects containing iron such as scissors, laryngoscopes, nail clippers, pocket knives and steel buckets. Larger items like wheelchairs, gurneys, intravenous poles have also become MR-system- induced missiles (Centre for Devices and Radiological Health, 1997). The other source of most MRI incidents is the translational attraction which occurs when one point of an object in a magnetic field is attracted to a great extent than the object's furthest point from the at‐ tracting source (Gould, 2008).
