Essentials of Algebraic Reconstruction in Cone-Beam Computed Tomography

Abstract—ART (algebraic reconstruction technique) in computed tomography (CT) and, in particular, the reconstruction under a limited number of cone-beam projections, along with conventional CT methods, allow an image quality sufficient for patient positioning, as well as reducing the dose payload and treatment toxicity and increasing local tumor control. In addition, such reconstructed images may serve as prognostic factors for patient selection. The proposed methods are overviewed for the bone structures imaging CT procedures for the further usage in planning, positioning and immobilization stages. The limited number of projection fields are chosen within circular scanning using 900 projections in the desired 90°–360° field of view angle. The dynamic range of image extension are presented, reconstruction isogonality degeneracies are discussed, as well as options of semi-convergence of low-noise solutions. The orthogonal images obtained with ART can be prospectively used in various radiotherapy techniques, with special attention to hypofractionated schemes. The algorithms were examined at the “Prometheus” proton beam facility and are beneficial in the therapeutic applications.