Relative Magnetic Force Measures and Their Potential Role in MRI Safety Practice.

Background: Magnetic field markings are occasionally used at MRI sites to provide visual feedback of magnetic field strength at locations within the MRI scan room for safety purposes. In addition to magnetic field line markings, relative magnetic force, or ratio of magnetic to gravitational forces on an object, may be considered a useful complementary metric to quantify the risk associated with bringing objects containing ferromagnetic material into the magnetic field.

Purpose: To develop and validate methods for deriving useful relative magnetic-force measures including a simple force index for application to MRI safety.