TaBlE 1.7 Debye Constants for Tissues with τ 1 = 46.2 × 10 –9 s and τ 2 = 0.91 ×
10 –10 s, Which Are the Average of the Optimized Values for Fat and Muscle
Tissue
ε ∞
ε s1
ε s2
Muscle
Bone/cartilage
Blood
Intestine
Liver
Kidney
Pancreas/spleen
1/3 Lung
Heart
Brain/nerve
Skin
Eye
40.0
3.4
35.0
39.0
36.3
35.0
10.0
10.0
38.5
32.5
23.0
40.0
3948.0
312.8
3563.0
4724.0
2864.0
3332.0
3793.0
1224.0
4309.0
2064.0
3399.0
2191.0
59.09
7.11
66.43
66.09
57.12
67.12
73.91
13.06
54.58
56.86
55.59
56.99
Source: Lin, J. C., and P. Bernardi. 2007. Computer methods for predicting field
intensity and  temperature change. In Bioengineering and Biophysical Aspects of
Electromagnetic Fields, ed. F. Barnes and B. Greenebaum, Chapter 10, 293–380. Boca
Raton, FL: CRC Press. With permission.
54
Electromagnetic Fields in Biological Systems
averaging of tissue properties in cells of the heterogeneous human model. Having τ 1
and τ 2 constant for all tissues allowed linear (volume) averaging of the ε values for each
tissue in a given cell so as to calculate ε values for that cell.
The internal fields and vertical currents passing through various layers of the body are
calculated, by using the following equation:
∂D
I z (t ) = δ
2
∑
z
(1.66)
i , j ∂t
where δ is the cell size (1.31 cm), and the summation is carried out for all cells in a given
layer. The layer-averaged absorbed energy density or SA and the total energy W absorbed
by the whole body can be calculated using the following equations:
δ t
∑
E(i , j, k,t ) ∂ D( i
·
, j, k,t) )
SA | layer k =
(1.67)
N k i , j ,t ρ(i , j,k)
∂t
∂D(i,
W = δt·
j,k,t)
δ
3
∑ E(i , j, k,t )·
(1.68)
i , j , k,t
∂t
In Equations 1.67 and 1.68, δt is the time step (δ/2c = 0.02813 ns) used for time-domain
calculations, N k is the number of cells in layer k of the body, and ρ(i, j, k) is the mass
density in kilogram per cubic meter for each cell in the corresponding layers.