title: Exact reconstruction in 2D dynamic CT: compensation of time-dependent affine deformations.
abstract: This work is dedicated to the reduction of reconstruction artefacts due to motion occurring during the acquisition of computerized tomographic projections. This problem has to be solved when imaging moving organs such as the lungs or the heart. The proposed method belongs to the class of motion compensation algorithms, where the model of motion is included in the reconstruction formula. We address two fundamental questions. First what conditions on the deformation are required for the reconstruction of the object from projections acquired sequentially during the deformation, and second how do we reconstruct the object from those projections. Here we answer these questions in the particular case of 2D general time-dependent affine deformations, assuming the motion parameters are known. We treat the problem of admissibility conditions on the deformation in the parallel-beam and fan-beam cases. Then we propose exact reconstruction methods based on rebinning or sequential FBP formulae for each of these geometries and present reconstructed images obtained with the fan-beam algorithm on simulated data.
authors.affiliation: Département Microtechnologies pour la Biologie et la Santé (DTBS), Direction de la Recherche Technologique (DRT), Commissariat a l'Energie Atomique (CEA), Grenoble 38054, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Roux
authors.forename: Laurent
authors.initials: L
authors.lastname: Desbat
authors.forename: Anne
authors.initials: A
authors.lastname: Koenig
authors.forename: Pierre
authors.initials: P
authors.lastname: Grangeat
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D016247:Information Storage and Retrieval / Q000379:methods; D009068:Movement; D009716:Numerical Analysis, Computer-Assisted; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods; D015203:Reproducibility of Results; D012119:Respiration; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*