PhD defence K. (Kemal) Sümser

The beneficial effect of hyperthermia as adjuvant to radiotherapy in head and neck cancers are well established with clinical trials. In general, the benefits of hyperthermia are found to be depend on thermal dose. To improve the delivery of thermal dose, a great deal of work has been and still is conducted on device development, treatment planning, patient modeling, and treatment monitoring. Treatment monitoring is an important aspect to ensure correct assessment of treatment quality and dose delivery, as well as validation of modeling and planning. However, in clinic, target temperature increase information is seldom available and clinicians rely on pretreatment SAR calculations. MR thermometry during head and neck hyperthermia is a potential solution to improve 3D information of the applied temperature distribution, but it at present is not yet clinically available and the required temperature measurement accuracy demands technology beyond the current available state of the art. This thesis starts with first presenting current state of the art MR compatible RF hyperthermia devices. From it, it follows that the field lacks standardization in validation and needs a MRI compatibility benchmark. Secondly it shows that MRT guidance during hyperthermia treatment is required due to the effect of the large vessel network in head and neck region on the temperature distribution. Thirdly, it describes the design and validation of a MR compatible head and neck hyperthermia applicator that can heat at equal quality as the non-MR compatible HYPERcollar3D. Fourthly, the apparent MRT errors due to the water bolus can be effectively and economically solved by doping the water bolus with contrast agents. Lastly, it shows that integration of multi-channel receiver coils in a phased array of RF-antennas is feasible and improves the SNR. These results validate our hypothesis that a suitable combination of hardware technologies enables precise monitoring of the temperature distribution which on its turn will provide the important information to exploit optimal SAR steering during MRT guided H&N HT.

Due to corona, the PhD defences do not take place publicly in the usual way in the Senate Hall or in the Professor Andries Querido Room. The candidates will defend their dissertation either in a small group or online.