Motion correction in SPECT using virtual projections and 3D reconstruction

It is well known that head movement during the acquisition of brain SPECT studies can result in image distortion. The usual approach to this problem in SPECT is to attempt to restrain the head in some way, for example by placing a tight Velcro strap over the forehead, and to ask the patient to remain as still as possible. Despite such precautions, many patients are unable to cooperate fully. In the past, efforts to alleviate the motion problem have focussed on the prevention, rather than correction, of patient motion. This paper outlines a technique suitable for application in SPECT, which appears capable of correcting for both translational and rotational motion. The technique directly counteracts the mechanism by which motion produces image distortion in SPECT. Although the technique was developed with SPECT in mind it is envisaged that it could be applied in other imaging modalities which involve the acquisition of projections, such as position emission tomography. 3 refs., 2 tabs., 6 figs