Characterisation of thermal property in ex vivo samples and thermal measurement challenges.

Nuno SilvaElectromagnetic-based hyperthermic therapies induce a controlled increase of temperature in a specific tissue target in order to increase the tissue perfusion or metabolism, or even to induce cell necrosis. These therapies require accurate knowledge no both dielectric and thermal properties. Characterisation of biological tissues must be considered to optimise treatment plans for patients that will be treated using hyperthermic applications. No literature information sufficiently reports the thermal properties (thermal conductivity, specific heat capacity and thermal diffusivity) of biological tissues considering their dependency in temperature and water content. Characterisation of different ex vivo tissue samples show that a significant increase in thermal properties is observed only above 90 °C. Thermal properties are also investigated during the natural cooling of the heated tissue. A reversible phenomenon of the thermal properties is observed; during the cooling, thermal properties followed the same behaviour observed in the heating process. Different challenges in thermal property measurements must be considered to obtain realistic thermal property values in order to be correctly applied in treatment plans or numerical models.