Patent ID: 6845144

Claim:
A three dimensional back projection method comprising the steps of: defining a direction perpendicular to at least one of a rotating plane of an X-ray tube, a multidetector, and a direction of linear displacement of a helical scan as a z-axis, a direction of a center axis of an X-ray transmission beam at view=0° as a y-axis, and a direction normal to both the z- and y-axis as an x-axis; defining a first xz projection plane as the projection plane that passes through a center of rotation in a view angle range that is approximately −45°≦view<45° and also includes the periphery thereof or in a view angle range that is approximately 135°≦view<225° and also includes the periphery thereof; projecting projection data D 0 gathered by at least one of an axial scan and the helical scan, using the multidetector, onto a projection plane which is planar to determine planar projection data D 1 , the multidetector comprising a plurality of detector arrays; defining a second yz projection plane as the projection plane that passes through the center of rotation in a view angle range that is approximately 45°≦view<135° and also includes the periphery thereof or in a view angle range that is approximately 225°≦view<315° and also includes the periphery thereof; projecting the data D 1 onto a reconstruction area in a direction of the X-ray transmission beam to determine back projection pixel data D 2 , the reconstruction area comprising a plurality of pixels; and adding for each corresponding pixel the back projection pixel data D 2 of all views for use in an image reconstruction plane to determine back projection pixel data D 3 .