Numerical study of currents in occupational workers induced by body-motion around high-ultrahigh field MRI magnets

In modern MRI, occupational workers are exposed to strong, non-uniform static magnetic fields generated by the main superconducting magnet. Previous studies have indicated that movement of the body through these fields can stimulate in situ electric fields/ current densities approaching physiological significance. The relationship between the magnetic field pattern/strength and the current distribution/level induced in the body is not well understood. This paper presents numerical evaluations of electric fields/currents in tissue-equivalent, whole-body male and female human models (occupational workers) at various positions and a variety of normalized body motions around three superconducting magnets with central field strengths of 1.5T, 4T and 7T. Possible correlations between the magnetic field characteristics and the induced current density distribution are described and simulations show that it is possible to induce electric fields/current densities above the ICNIRP and IEEE safety standards when the worker is moving very close to the magnets.