ABSTRACT
This chapter focuses on the steps in the computed tomography (CT) imaging chain that start from a complete set of projection data in digital form and end with the generation of a digital tomographic image. It deals with inversion formulas for the Radon transform in the simplest case of two dimensional parallel-beam geometry. The chapter examines the X-ray transform to describe the projection data of CT scanners operating in fan-beam and cone beam geometry. Exact reconstruction has limited application in real-world cone beam CT imaging. The most used source trajectory for most CT and micro-CT scanners is a circle, which does not fulfill the Tuy–Smith sufficiency condition. The basic idea behind the Feldkamp method, or Feldkamp–Devis–Kress method, is that for moderate axial apertures of the detected cone beam, the acquisition geometry should not deviate too much from a multi-slice fan-beam acquisition.
