The University Medical Center (UMC) Utrecht has a PhD candidate position available for four years. You would be working on real-time plan adaptations for a hybrid radiotherapy system. This system, developed between UMC Utrecht, in collaboration with Elektra and Philips, is the world’s first radiotherapy system integrated with a 1.5 T MRI scanner. The system can deliver radiation with mm accuracy while the target is visualized by MRI. The current project concerns the use of real-time MRI guidance for radiotherapy plan adaptations.
More information can be found here. The closing date for this job opening is March 2013. On this page more information about the project and sub-projects is available. From the looks of it, they actually have two positions available.