Dosimetric evaluation for exposure of patient to a z-gradient coil in magnetic resonance imaging

Journal Article · Fri Apr 01 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3537934· OSTI ID:21560095

Mai, Lu ^[1]; Ueno, Shoogo ^[2]

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1. Institute of Biophysics and Biomedical Engineering, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon (Portugal)
2. Department of Applied Quantum Physics, Graduate School of Engineering, Kyushu University, Fukuoka, 812-8581 (Japan)

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 problems. In this paper, a realistic z-gradient coil was numerically designed and the exposure level in a 3D real human man model was calculated by using the impedance method. It was found that the z-gradient coil produces a magnetic flux density (B-field) with two regions of good homogeneity along the coil length, separated by a very weak B-field in the middle of the coil. The spatially averaged B-field is 281 times greater than that of the International Commission on Non-Ionizing Radiation Protection's (ICNIRP) reference level. The 1-cm{sup 2}-averaged induced current density in the central nervous system is 87 times greater than that of the ICNIRP's basic restriction. The maximum current density in all of the body tissues is above the nerve stimulation threshold.

• OSTI ID: 21560095
• Journal Information: Journal of Applied Physics, Vol. 109, Issue 7; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: DOI: 10.1063/1.3537934; (c) 2011 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CENTRAL NERVOUS SYSTEM
CURRENT DENSITY
DOSIMETRY
ELECTRIC FIELDS
ELECTRIC IMPEDANCE
EVALUATION
FLUX DENSITY
IONIZING RADIATIONS
MAGNETIC FIELDS
MAGNETIC FLUX
MAN
MUSCLES
NERVES
NMR IMAGING
NUCLEAR MEDICINE
PATIENTS
STIMULATION
ANIMALS
DIAGNOSTIC TECHNIQUES
IMPEDANCE
MAMMALS
MEDICINE
NERVOUS SYSTEM
PRIMATES
RADIATIONS
VERTEBRATES