title: Evaluation of exposure to (ultra) high static magnetic fields during activities around human MRI scanners.
abstract: OBJECTIVE
  To assess the individual exposure to the static magnetic field (SMF) and the motion-induced time-varying magnetic field (TVMF) generated by activities in an inhomogeneous SMF near high and ultra-high field magnetic resonance imaging (MRI) scanners. The study provides information on the level of exposure to high and ultra-high field MRI scanners during research activities.
  
  
  METHODS
  A three-axis Hall magnetometer was used to determine the SMF and TVMF around human 3- and 7-Tesla (T) MRI systems. The 7-T MRI scanner used in this study was passively shielded and the 3-T scanner was actively shielded and both were from the same manufacturer. The results were compared with the exposure restrictions given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP).
  
  
  RESULTS
  The recorded exposure was highly variable between individuals, although they followed the same instructions for moving near the scanners. Maximum exposure values of B = 2057 mT and dB/dt = 4347 mT/s for the 3-T scanner and B = 2890 mT, dB/dt = 3900 mT/s for 7 T were recorded. No correlation was found between reporting the MRI-related sensory effects and exceeding the reference values.
  
  
  CONCLUSIONS
  According to the results of our single-center study with five subjects, violation of the ICNIRP restrictions for max B in MRI research environments was quite unlikely at 3 and 7 T. Occasions of exceeding the dB/dt limit at 3 and 7 T were almost similar (30% of 60 exposure scenarios) and highly variable among the individuals.
authors.affiliation: Department of Biomedical Magnetic Resonance, H65-ZENIT, Otto-von-Guericke-University Magdeburg, Leipziger Street 44, 39120, Magdeburg, Germany. Mahsa.Fatahi@ovgu.de.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Fatahi
authors.affiliation: Laboratory of Electromagnetic Hazards, Central Institute for Labour Protection-National Res. Inst. (CIOP-PIB), Warsaw, Poland.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Karpowicz
authors.affiliation: Laboratory of Electromagnetic Hazards, Central Institute for Labour Protection-National Res. Inst. (CIOP-PIB), Warsaw, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Gryz
authors.affiliation: Department of Mechanical Engineering, Imperial College London, London, UK.
authors.forename: Amirmohammad
authors.initials: A
authors.lastname: Fattahi
authors.affiliation: Institute for Medical Engineering, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Rose
authors.affiliation: Department of Biomedical Magnetic Resonance, H65-ZENIT, Otto-von-Guericke-University Magdeburg, Leipziger Street 44, 39120, Magdeburg, Germany.|Leibniz Institute for Neurobiology, Magdeburg, Germany.|Center for Behavioral Brain Sciences, Magdeburg, Germany.|German Center for Neurodegenerative Disease, Site Magdeburg, Magdeburg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Speck
mesh_terms: D006801:Humans; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging; D060306:Magnetometry / Q000379:methods*; D016273:Occupational Exposure / Q000032:analysis*; D000069079:Radiation Exposure / Q000032:analysis*; D011834:Radiation Monitoring / Q000379:methods*; D011871:Radiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Electromagnetic fields; Exposure assessment; Occupational exposure; Static magnetic field; Time-varying field