Patient registration is the concept an set of methods needed to corelate the reference position of a virtual 3D dataset gathered by computer medical imaging with the reference position of the patient. This procedure is crucial in computer assisted surgery, in order to insure the reproductibility of the preoperative registration and the clinical situation during surgery. The use of the term “patient registration” out of this context can lead to a confusion with the procedure of registering a patient into the files of a medical institution. This is why a better term would be patient reference registration.