An overview of mathematical models and modulated-heating protocols for thermal ablation

Mostly thanks to its noninvasiveness, thermal ablation is a widely used technique to treat tumors in organs like liver, kidney and so on. With this technique tumor tissue necrosis is due to induced high temperature gradients. These gradients can be induced by electromagnetic energy if a needle that emits radiofrequencies or microwaves is used, by acoustic energy when focused ultrasound beams are employed, by light energy if the tumor is heated with lasers, or by cryoablation, in which necrosis is induced by very low temperatures. Nowadays, the challenge is to provide physicians of new techniques that allow to improve thermal ablation efficiency in terms of ablated zone extension, cancer recurrence and others. A technique proposed is based on time-variable modulated-heat protocols to optimize ablation zone. The present chapter is divided in three sections. In the first one, thermal ablation techniques are introduced, together with techniques used to estimate thermal damage. Next, heat transfer models for human tissue are reviewed, together with techniques used to calculate heat generation caused by hyperthermia. Finally, in the third section, a review of a modulating-heat protocol is proposed to optimize tumor necrotic zones. The scope of this chapter is to provide an overview of modeling techniques proposed during the years, and to introduce the potential of modulating-heat techniques.