Differential Least-Square Microwave Thermometry: A Feasibility Study on a Realistic Patient Model

Report, 2023

Microwave thermometry (MWT), among all the non-invasive thermometry methods proposed so far, stands a good chance to close the feedback loop of Hyperthermia (HT) systems in a cost-effective fashion. Previous studies in this context proved the suitability of the method when applied to simple scenarios. There remain, however, a lot of challenges to be addressed before the method can pave its way toward a successful clinical integration into
the Hyperthermic systems currently in use. Dealing with a realistic patient scenario, the present study tries to cast light on some of the challenges/ pitfalls of MWT implementation. To this end, Comsol was used as the full-wave EM simulation package of choice, while its thermal result was cross-checked with that of a customized open-source computational platform, called FEniCS. Assuming that the dielectric properties of tissues change slightly under Hyperthermic thermal stress, the well-established differential linear least-square inversion method was then used to obtain a thermogram of property changes in the steady-state phase of the treatment. By successfully retrieving the tangible property changes at the HT focal point and by also capturing some of the hotspot locations, the inversion method sounds promising for being utilized in realistic scenarios. Nevertheless, the final image is still cluttered with reconstruction artifacts, demanding the application of a more rigorous inversion/ image restoration technique in future studies.