3D ROI imaging for cone-beam computed tomography

C-arm X-ray systems can be used to acquire rotational cone-beam projections during interventions, from which CT-like 3D images can be reconstructed. For intraprocedural 3D imaging, changes of the imaged object are often restricted to a certain part of the possible field of view, suggesting region of interest (ROI) imaging by irradiating this area only. Because projections acquired for ROI imaging do not contain the entire object, reconstructed images suffer from truncation-caused artifacts that cannot be fully compensated by commonly used methods. In this paper, we present a novel method that enables low-dose ROI imaging in cone-beam computed tomography by accurately extending truncated projections, in that way, avoiding truncation artifacts. For this purpose, a previously acquired 3D image covering the whole object is combined with the truncated projections of the ROI acquired during the intervention. (C) 2004 CARS and Elsevier B.V. All rights reserved.