Patent ID: 7170966
Filing Date: 2007-01-30
Classification: A61B,G01N,G06T

Abstract:
1. In a computer tomography (CT) system, including one cone beam x-ray source and opposing 2-D (two dimensional) x-ray detector assembly and an object which is being imaged, said system being operable for relative rotation between the said assembly and said object, a method for obtaining a group of 2-D projection datasets from which 3-D (three dimensional) or 2-D images are obtained of a portion or whole of the said object comprising the steps of: providing relative rotation between said assembly and said object by means of a rotating gantry in a vertical plane, which rotates while keeping the relative positions of the source and detector fixed to each other, the axis of rotation of the gantry being a horizontal axis substantially perpendicular to said vertical plane and passing through the center of system, which is the intersection of the said horizontal axis with the line joining the source and detector assembly in said vertical plane of gantry, for scanning to obtain related 2-D projection data sets from which backprojection is used to produce a first 3-D image over a 3-D grid encompassing the whole of the said object; providing a substantially 90° or 270° rotation of the said object in a horizontal plane passing through the said center of system about a vertical axis in said vertical plane passing through said center of system, while the said assembly remains in a fixed location in space; providing relative rotation between said assembly and said object in said vertical plane by means of said rotating gantry, the axis of rotation of the gantry being a horizontal axis in said horizontal plane and substantially perpendicular to said vertical plane, for scanning to obtain 2-D projection data sets from which backprojection is used to produce a second 3-D image over the same said 3-D grid encompassing the whole of the said object; processing by combining the said first and said second images for obtaining a 3-D grid of data representative of a portion or whole of said object.