Axisymmetric modelling of microwave ablation in biological tissue

Microwave ablation (MWA) therapy is a hyperthermic treatment for cancerous tumors whereby microwave energy is dispersed into a target tissue region. Absorption of these waves leads to temperature rise through microwave heating with the aim of exposing cancerous cells to a thermal dose sufficient to kill them whilst minimizing the damage to the surrounding healthy tissue. Being able to predict the progression of ablation during a procedure is of high value when designing equipment and planning patient-specific care, as current dosimetry is given in guidelines by the equipment provider. From a modelling standpoint this poses a complex multi-physics problem coupling electro-magnetics and heat conduction. Added to this there are existence of multiple temperature sensitive properties of tissue, as well as physiological processes such as blood perfusion which are heavily influential in the overall temperature profile. Here, we create a two dimensional axisymmetric geometry of a probe embedded within a tissue material, solving the coupled electromagnetic and bioheat equation using the finite element method, utilizing hp discretisation and the NGSolve library. Temperature, electric field strength and energy absorption can be calculated and investigations into the effects of the highly temperature-sensitive properties of tissue on the distribution of temperature throughout ablation.