The complete process of generating a 3D data image from a set of 2D projections acquired from different angles. This process consists of three major stages, preprocessing, backprojection and postprocessing. The preprocessing stage takes raw projections as input and produces corrected projections as output. The backprojection stage takes corrected projections as input and produces a raw 3D image as output. The postprocessing stage applies corrections to the raw 3D images, thus producing the final 3D images. Each processing stage can be further subdivided into algorithmic steps. See also back projection; preprocessing projections; postprocessing 3D images.