Rigid Body Registration

Rigid body registration is one of the simplest forms of image registration, so this chapter provides an ideal framework for introducing some of the concepts that will be used by the more complex registration methods described later. The shape of a human brain changes very little with head movement, so rigid body transformations can be used to model different head positions of the same subject. Registration methods described in this chapter include within modality, or between different modalities such as PET and MRI. Matching of two images is performed by finding the rotations and translations that optimize some mutual function of the images. Within modality registration generally involves matching the images by minimizing the sum of squared difference between them. For between modality registration, the matching criterion needs to be more complex.