Page 294 - Computational Modeling in Biomedical Engineering and Medical Physics

Hyperthermia and ablation 283

It is confirmed here that, when compared with the regular hyperthermia, magnetic
hyperthermia helps to deliver minimal yet enough power into a close focus that can
lead to the required increase in temperature while reducing the unwanted thermal side
effects. Figure 8.25 gives a detailed view of the three isotherms that are rendered in
Fig. 8.24. For 1.2 W, in magnetic hyperthermia, the temperature inside the tumor is

above 46 C whereas in regular hyperthermia it reaches 44 C. Again, the location of

the tumor can be identified between the temperature maxima, Fig. 8.26.
Magnetic hyperthermia may be optimized concerning the MNPs size, concentra-
tion, properties, etc. and numerical simulation may play a central role. Furthermore,
RF hyperthermia may be envisaged with the expected similar beneficial advantages,
and numerical modeling may help to cross the procedural and safety development
stages that have to be passed.

8.5 Ultrasound thermotherapy

Although thought-about since 1956 as an external method to treat cancer
(Hand et al., 1990), the High-Intensity Focused Ultrasound (HIFU) and Magnetic
Resonance guided High Intensity Focused Ultrasound (MRgHIFU) (Jolesz, 2009)
ablation has received recently increasing attention for the treatment of solid malignant
tumors. Without affecting the neighboring healthy tissue, US beams may propagate to
produce in focal volume high-intensity mechanical work that results in significant local
heating, which may lead to a local increase in temperature able to cause tissue necrosis.
US propagation properties and modes of destruction in tissues were investigated in the

Figure 8.25 The temperature distribution in magnetic MW hyperthermia, detailed view, values are
in degree Calsius. MW, Microwave.