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Electromagnetic Fields in Biological Systems
fields in the brain exposed to 1 mT from side to side were 1.67 mA/m 2 and 24.78 mV/m,
respectively. From exposure to nonuniform magnetic fields generated from hair dryers
and hair clippers, the calculated induced current density distributions are obtained.
Hamada and Kobayashi (2006a, 2008) developed a fast-multipole, surface-chargesimulation method for calculating three-dimensional Laplacian fields in voxel models and applied this method to calculate the induced electric fields in a human head
model with 1 × 1 × 1 mm 3 voxel size exposed to homogeneous ELF magnetic fields. This
method treats a surface of a voxel with different outside and inside conductivities as a
surface element of the indirect BEM. Their group also developed a generalized equivalent multipole-moment method for calculating three-dimensional Laplacian fields in a
multispherical system and applied this method to calculate induced electric fields in a
human head model with two eyeballs exposed to ELF magnetic fields. The validity of
this method was confirmed by comparing the calculated electric fields with those of the
fast-multipole surface-charge-simulation method (Hamada, Yamamoto, and Kobayashi
2006b; Kitano, Hamada, and Kobayashi 2009).
Yamazaki and coworkers published a series of research papers on the magnetically induced currents inside a simple human body model (Yamazaki, Kawamoto,
and Shigemitsu 1996; Yamazaki et al. 2000b,c, 2001a). As for experimental dosimetry,
they first measured the induced current distributions inside an inhomogeneous saline
model caused by ELF magnetic fields and calculated induced values through the CSM
(Figure 4.6). After these fundamental approaches, they developed a human body model
with several organs (brain, heart, lungs, liver, and intestines). The shapes of other parts
were modeled using spheroids and cylinders. Later, a numerical algorithm was developed based on the surface charge method, and the validity of the developed code was
compared with an analytical solution. Using the BEM, Min and Song (2006a) analyzed
the induced current densities inside a human body model with various conductivities
exposed to 60 Hz magnetic fields. They applied the Korean magnetic field standard to
their model and found that the maximum induced current densities inside the human
body model satisfied the safe level of ICNIRP. Their human body model had several
organs (brain, heart, lung, liver, and intestine) and many other parts, and their shape
was spheroidal or cylindrical.
4.5.2.2 Coupling with Realistically Shaped Models
The research group at the University of Victoria applied the IM to calculations in a
human body model (Xi, Stuchly, and Gandhi 1994a; Xi and Stuchly 1994b; Stuchly and
Zhao 1996; Cheng et al. 1995). From the 1990s, research groups at University of Utah
and University of Victoria calculated electric fields and induced currents inside anatomically, MRI-based human body phantom models with voxel resolution of 6 and 7.2 mm
(Gandhi and Chen 1992; Dawson, de Moerloose, and Stuchly 1996). Gandhi and
Chen (1992) developed the FDTD method for calculating induced current densities in
an anatomically based human body model with 1.31-cm resolution exposed to electric
field, magnetic field, and EMF at 60 Hz.
As a step in numerical dosimetry for 60 Hz magnetic fields, Xi, Stuchly, and Gandhi
(1994a) computed the induced electric currents in models of man, rat, and mouse using
the IM. All models had realistic shapes, and in the case of rodents, models were based on