1. A method for three dimensional (3D) computerized tomographic (CT) imaging of a region-of-interest (ROI) in an object, comprising: acquiring a plurality of sets of 2D cone beam projection data by irradiating the object with energy from a cone beam source that is directed toward a 2D detector at a corresponding plurality of scan path source positions located about the object; applying a mask to each set of the 2D cone beam projection data to form a corresponding plurality of masked 2D data sets; processing the 2D cone beam projection data inside the mask boundaries of each masked 2D data set to develop a corresponding plurality of processed 2D data sets, each processed 2D data set corresponding to a calculation of a first estimate of Radon derivative data determined for a given set of the 2D cone beam projection data; adaptively developing a predetermined limited amount of 2D correction data for each of the first estimates of Radon derivative data; and combining each processed 2D data set and the 2D correction data adaptively developed therefore, in a weighted 3D backprojection manner into a common 3D space, thereby reconstructing in said 3D space a 3D image of the ROI in the object.