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Exposure of workers to pulsed gradients in MRI
Author(s) -
Crozier Stuart,
Wang Hua,
Trakic Adnan,
Liu Feng
Publication year - 2007
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.21162
Subject(s) - electromagnetic coil , scanner , transverse plane , magnet , magnetic field , magnetic resonance imaging , physics , nuclear magnetic resonance , materials science , mechanics , acoustics , optics , medicine , radiology , quantum mechanics
Purpose To numerically evaluate the electric field/current density magnitudes and spatial distributions in healthcare workers when they are standing close to the gradient coil windings near the magnetic resonance imaging (MRI) scanner ends. Materials and Methods Anatomically realistic, whole‐body male and female voxel phantoms are engaged to model the workers at various positions near the ends of three cylindrical gradient coils (x‐, y‐, and z‐axis gradients). The numerical calculations of induced fields are based on an efficient, quasistatic finite‐difference method. Results The simulations show that it is possible to induce electric fields/current densities above levels recommended by the International Commission for Non‐ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE) standards when the workers are standing close to the gradient coils and when two or three gradients are switched simultaneously, as is often the case. Conclusion The longitudinal gradient tends to induce more fields in workers than the transverse coils. The strongest levels of field exposure are observed when all three gradients are operated simultaneously and can be above regulations when the healthcare worker is close to the gradient coils. Other postures such as bending into the magnet shall be investigated in further studies. J. Magn. Reson. Imaging 2007;26:1236–1254. © 2007 Wiley‐Liss, Inc.