Thermal ablation is a medical treatment commonly applied to malignant tumours and nerve supplies that cause chronic pain. In this procedure, the target is heated above normal body temperatures in an effort to damage or kill tumour or nerve cells. The heat is delivered to the target through electromagnetic (EM) energy, and the procedure is referred to as Radiofrequency (RF) or Microwave Ablation, depending on the frequency of the electromagnetic sources. RF or microwave energy can be delivered internally by inserting probes into the body close to the target, or externally by focusing EM waves at the target using sources outside, but close to, the body.
Existing ablation devices, both internal and external, suffer from drawbacks that limit their performance. For one, current designs attempt to elevate temperatures by focusing electric fields at the target, under the assumption that focused electric fields will create maxima in temperature profiles. This assumption may not hold true in realistic inhomogeneous tissue models, and thus do not, in general, lead to optimized temperature profiles. In this work, the validity of this assumption is tested by comparisons with an alternate approach: the EM sources are optimized using temperature as the target variable, rather than fields or energy. This may allow one to synthesize reconfigurable sources that can directly generate an arbitrary desired temperature profile.
The simulation and optimization methods for both internal and external sources will be discussed, and comparisons between temperature-based and field-based op- timization will be presented. Although this work is in its early stages, it is hoped that this presentation will provide the audience with a general understanding of this exciting application of EM in medicine.