Dosimetry of Exposure of Patients to Pulsed Gradient Magnetic Fields in MRI

作者：Lu Mai^*; Ueno Shoogo

来源：IEEE Transactions on Magnetics, 2011, 47(10): 3841-3844.

DOI：10.1109/TMAG.2011.2157086

• Dosimetry
• gradient coils
• International Commission on Non-Ionizing Radiation Protection (ICNIRP)
• magnetic resonance imaging (MRI)

In magnetic resonance imaging, time-varied 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, realistic transverse x-, y-gradient coils and longitudinal z-gradient coil were numerically designed. The magnetic flux density, current density and electric fields in a 3-D real human man model were calculated by employing impedance method. The exposure levels have been compared with the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). It was found that the spatially averaged magnetic flux density greatly exceeds the ICNIRP reference level, and the maximum value of the 1-cm(2)-averaged induced current density in central nervous system greatly exceeds the ICNIRP basic restriction. The strongest levels of exposure are observed when all three gradient coils are operated simultaneously.

• 出版日期2011-10