On Friday 2 March, 2018, Pegah Takook from the Biomedical Electromagnetics Research Group at E2, Chalmers, will defend her doctoral thesis with the title “Optimizing microwave hyperthermia antenna systems”.
When? 13:00, Friday March 2, 2018
Where? Room EA, Hörsalsvägen 11, Campus Johanneberg, Chalmers
Faculty Opponent: Professor Peter Wust, Department of Radiation Oncology and Radiotherapy, Berlin Germany
Supervisor: Assistant Professor Hana Dobsicek Trefna, Chalmers
Examiner: Mikael Persson, Chalmers
This thesis presents the design and optimisation of a microwave hyperthermia antenna system for treatment of head-and-neck cancer as well as brain cancer. Hyperthermia (HT) has shown the ability to enhance the performance of radiotherapy and chemotherapy in many clinical trials. The incidence of increased tissue toxicity as a result of high radiotherapy dose has made hyperthermia a safe adjuvant treatment to radiotherapy. Although many clinical studies have shown the effectiveness of hyperthermia for treatment of head-and-neck (H&N) cancer, the presence of large vessels, tissue transitions and critical tissues in the head and neck poses therapeutic challenges for treatment of advanced tumours in this region. Late side-effects of conventional therapies in treatment of brain tumours in children have made hyperthermia an attractive method. However, heating tumours in the brain is even more challenging due to the brain’s high levels of sensitivity, thermal conductivity and perfusion. This thesis presents microwave hyperthermia applicators as an efficient means
to heat H&N and brain tumours. An ultra-wideband antenna (as the radiating element in microwave hyperthermia applicators) has therefore been designed, built and evaluated. The time-reversal focusing technique is used to target electromagnetic energy into the tumour. The effect of frequency and virtual source positions in the time-reversal method are studied, for different tumour sizes and positions, so as to obtain more accurate treatment planning. The optimal detailed design of the applicator, such as the number of antennae and their positions, are also investigated. The second part of this thesis focuses on applicators for the treatment of brain tumours in children. Helmet applicators are presented and there is an investigation into how the number of antennae and their frequencies affects applicator’s performance when heating large, deep-seated brain tumours. Finally, the optimum position of antennae in helmet applicators is discovered by running optimisations on simplified and realistic models of a child’s head.