Bjorn Stemkens1,
2, Rob H. N. Tijssen2, Cornelis A.T. van den Berg2,
Jan J.W. Lagendijk2, Chrit T.W. Moonen3, Mario Ries3,
Baudouin Denis de Senneville3, 4
1Department
of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands;
2Department of Radiotherapy, UMC Utrecht, Utrecht, Netherlands; 3Image
Science Institute, UMC Utrecht, Utrecht, Netherlands; 4IMB, UMR
5251 CNRS/University Bordeaux 1/INRIA, Bordeaux, France
MR-guided radiotherapy opens up the way to track organs during radiation. Tracking using optical flow has been successfully applied on EPI images for HIFU treatments. Geometrical distortions make EPI sequences unsuitable for radiotherapy purposes. Therefore, the feasibility of optical flow on undersampled radial acquisitions is investigated. Simulations and 2D in vivo scans are used to find the tradeoff between artifacts, temporal resolution and field-of-view. In addition multi-slice in vivo data is acquired to gain insight in the 4D motion of the pancreas for real-time position verification during radiation.