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8 years old
6 years old
5 years old
9 years old
12 years old
15 years old
Electromagnetic Fields in Biological Systems
obtain a 10-year-old child head based on statistical measurement data of head- and
facial-age-related parameters.
However, inaccuracies in the size of the nonuniform downscaled child models are still
present. Furthermore, aside from the physical size, the tissue electromagnetic properties
vary with age. As a result, recently, whole-body child models have been developed based
on MRI or CT databases of children. In research of Wiart et al. (2008), several MRI datasets of children at different ages from three different French hospitals were used to provide
segmented versions of child head models. Six child head models at different ages (5, 6, 8,
9, 12, and 15 years old) were built using this approach, as illustrated in Figure 5.7. The
model of a 7-year-old child based on MRI scans and consisting of approximately 20 different tissues was presented in the studies of Schoenborn, Burkhardt, and Kuster (1998).
Furthermore, Dimbylow and Bolch (2007) have recently reported the use of a series of
pediatric voxel models (a 9-month-old male, 4- and 8-year-old females, and 11- and
14-year-old males) with 2 mm resolution, based on data acquired from CT imaging.
5.2.1.2.3 Females
Several models of females have been developed in the literature, as illustrated in Table 5.1.
Pregnant female anatomically based models have also been developed recently.
Although most of the calculated SAR values of the fetus or embryo models are similar
or lower than that of the mother, dosimetry in pregnant female models is required for a
more comprehensive risk assessment of RF exposure of fetuses and embryos (ICNIRP
2009; Kawai et al. 2010). Models of pregnant females include the model representing
nine gestational ages (Wu et al. 2006; Figure 5.8a), a truncated body model of a mother
Figure 5.7 Child head models based on MRI datasets of children at different ages (From
Wiart, J., A. Hadjem, M. Wong, and I. Bloch. 2008. Phys Med Biol, 53, 95. With permission.)