PhD defence S.V.A. (Sophie) Heymans

Comprised in the cure of approximately 50% of all cancer patients, radiation therapy is a fundamental pillar in cancer treatment. Recent advances in radiation therapy enable the planning and delivery of complex dose distributions exhibiting high tumor conformity and thereby minimal healthy tissue damage. In addition, proton therapy is rapidly expanding, and has the potential to spare healthy tissues and organs at risk located behind the tumor. This increase in treatment accuracy implies a growing need for appropriate treatment verification strategies effectively measuring the actual radiation dose imparted on the tumor, in order for radiation therapy to exploit its full capability. This problem is particularly important for proton therapy, as uncertainties on the proton range forces clinicians to adopt substantial safety margins. In this thesis, we developed a novel method for in vivo radiotherapy monitoring, consisting in the use of nanometer-sized, injectable droplets which accumulate in tumor tissues and vaporize into microbubble contrast agents upon exposure to ionizing radiation. The vaporization process is monitored by means of ultrasound imaging, as microbubbles are very echogenic. We first explored the conditions under which radiation-induced vaporization could take place and validated the feasibility of the concept both for proton and conventional radiation therapy.  Then, we investigated different ultrasound imaging strategies to detect and localize vaporization events and correlated the latter with the radiation dose distribution. Finally, we explored means to bring this technology to the clinic.

The PhD defences will not take place publicly in the usual way. A live stream link has been provided to candidate. The ceremony will begin exactly at 13.00.