On-line patient tracking-a new approach to the registration problem in image-guided surgery and radiotherapy of the head

Image-guided systems for surgical and radiotherapeutic procedures in the region of the head require a method to correlate the diagnostic image data and the corresponding patient site of pathology. Considering that patient movements can occur as rotational and translational motions, detection and correction of such movement errors during the acquisition of the images is a basic prerequisite for accurate treatment. For that reason, we developed a new image registration technique based upon on-line tracking of a patient´s head. It has application primarily for surgery and radiotherapy in the region of the head. The method provides non-invasive active 3D patient registration for correction of movements during imaging and continuous update of the patient´s head position during surgery or for optimal and reproducible positioning of the patient during the course of radiotherapy. The patient motion correction applies the rigid body model to register the images using feature correspondence. The method is described and the results of the first experiments that were performed to evaluate its accuracy and reliability in a plastic skull model and in patients are provided. Advantages and disadvantages of the method are discussed