Exposure of workers to pulsed gradients in MRI.
OBJECTIVE
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.


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.


CONCLUSIONS
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.
Crozier
Stuart
S
School of Information Technology and Electric Engineering, The University of Queensland, Brisbane, Queensland, Australia. stuart@itee.uq.edu.au
Wang
Hua
H
Trakic
Adnan
A
Liu
Feng
F
D001822:Body Burden; D003198:Computer Simulation; D004574:Electromagnetic Fields; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008503:Medical Staff; D008954:Models, Biological; D016273:Occupational Exposure / Q000032:analysis*; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000379:methods*; D012062:Relative Biological Effectiveness