ABSTRACT
With modern radiotherapy delivery techniques, it is possible to realize dose distributions that conform precisely to the shape of the target volume while avoiding healthy tissue. However, even the most advanced delivery techniques are ineective if they deliver the dose to the wrong position in the patient. As geometrical misses may cause large deviations from the prescribed dose to the target volume, margins are applied to ensure adequate coverage. Unfortunately, such margins result in the involvement of healthy tissue in the planning target volume. us, to take full advantage of the delivery techniques that are now at our disposal, high-quality position verication is essential.
