Dosimetric analysis of patient to a Z-Gradient coil in head magnetic resonance imaging

Abstract

In magnetic resonance imaging (MRI), timevaried gradient magnetic fields may stimulate nerves and muscles by inducing electric fields and currents in patients, which may potentially cause health problem. In this study, a 3D human body model was placed in a realistic z-gradient coil to simulate the head MRI exam. The exposure level in central nerve system (CNS) was evaluated by calculating the magnetic flux density and the electric fields in body model by impedance method. Results were compared with the new version of guidelines of the InternationalCommission on Non-Ionizing Radiation Protection (ICNIRP) with new averaging scheme. The spatially averaged magnetic flux density was found to be approximately 9.49 times the ICNIRP reference level, and the maximum value of the induced electric fields in CNS was found to be 5.95 times the ICNIRP basic restriction.