Exact region of interest cone beam imaging without circle scans

Abstract

A scanning and data acquisition method and apparatus for three dimensional (3D) computerized tomography (CT) imaging of an ROI in an object, wherein data is calculated on a plurality of line segments L formed in cone beam projection data acquired on a detector at a plurality of source positions. The endpoints of the line segments L formed in the data acquired at each of the source positions is determined by a data combination mask having its bounds formed by cone beam projection onto the plane of the detector of portions of the source scan path that are above and below the source position that acquired the cone beam data in which the data for the line segments L are being calculated. When processing cone beam data near the top or bottom edges of the ROI, a first group of the line segments L has both of its endpoints determined by the boundaries of the data combination mask, and a second group of the line segments L has one of its endpoints determined by a boundary of the data combination mask, and another of its endpoints determined by the x-axis of the mask, so as to avoid data corruption from x-rays that passed outside the ROI. The line integral data calculated for both groups of the line segments L formed in the mask are then processed using an image reconstruction technique for providing a contribution to a 3D image reconstruction of the ROI in the object.