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Hyperthermia and ablation 275

Figure 8.17 Unsteady heating; temperature fluctuations superpose over the general heating trend.
(A) Temperature at Station P and (B) Average temperature at Station Q (Morega et al., 2014).

Some more results obtained from the numerical simulation show by blue stream-
lines in Fig. 8.18 the distributions of the electric (left) and magnetic (right) compo-
nents, influenced by the dielectric properties of the blood inside the vessels. The
influence of the large artery is visible in Fig. 8.19 for the cooling effect and tempera-
ture distribution; the image is captured during the heating process, after 480 s.

Temperature-dependent dielectric properties
Heating is monitored by a transient mode. The literature does not provide much informa-
tion on the temperature dependency for tissues' physical properties in humans. In mild
hyperthermia, where the heating does not go beyond 10 degrees, it was shown that varia-
tion of dielectric properties of the tissue with the temperature is insignificant to the accuracy
of results (Morega et al., 2008); the consequence is that the electromagnetic and heat transfer
problems are one-way coupled, that is, the first problem is solved for constant dielectric proper-
ties and its solution is transferred to the thermal problem by a constant heating source,
which steadily contributes to the transient heating process. In ablation, however, the