Preplanning Computer Models for Radio Frequency Ablation of Kidney Tumors with Perfusion

This project jointly carried out with the University Hospital in Dusseldorf focuses on the simulation and the experimental verification of radiofrequency ablation used in kidney cancer therapy. A high frequency electric current is introduced into the affected tissue by a special applicator which is placed in the human body. The impact of the electric energy results in a warming of the tissue and leads to a necrosis of the tumor after a certain time. The objective of this work is to build a computer model which considers the changes in tissue properties caused during the ablation process in order to do a preplanning of a corresponding treatment. Different simulation tools are applied. The software package Femlab from Comsol offers the possibility of solving coupled partial differential equations, which occur in this problem. This is the bioheat-equation on the one hand and the equations for the electric and magnetic potentials, describing the electro-magnetic quantities, on the other hand. These equations have to be extended by the Navier-Stokes equations from fluid dynamics to take into account perfusion arising from blood and urine flows within the kidney and leading to a cooling of the target area. The simulation is compared with the results of an appropriate measurement system built in the lab. In order to verify the results in real-world experiments, a sample treatment is carried out with pigs where testing probes measure the temperature over time at different positions in the target tissue.