High accuracy patient-image registration using ultrasonography

In point-based registration between the patient and the image, skin -affixed fiducial markers can only be attached to the patient skin. Registration accuracy is relatively high in the region around the markers. However, the accuracy gradually decreases proportionally to the distance from the surface where the markers are attached. To decrease the target registration error (TRE) rather than the fiducial registration error (FRE) around the target, reference points should be located near the target organ. In order to decrease the TRE, a method is proposed that makes it possible to register an anatomical landmark as a reference point around the target using ultrasonography.