title: Motion Compensation in Cardiac X-Ray Computed Tomography
creator: Lebedev, Sergej
subject: ddc-530
subject: 530 Physics
description: Motion artifacts in cardiac CT remain an issue that can degrade image quality. In addition to  artifacts originating from cardiac motion in general, irregular motion in particular may lead  to unique artifacts for scanners with partial coverage of the heart. If multiple sub-volumes, or  stacks, have to be reconstructed to cover the heart, irregular motion may introduce discrepancies  between these stacks. The resulting artifacts in the finally assembled CT volume are, herein,  referred to as stack transition artifacts. A stack transition artifact removal (STAR) method  based on symmetric image registration was developed. The registration computed a smooth  motion vector field using data from the overlap of neighboring stacks. The extent of the vector  field smoothing was set automatically for individual registration tasks. Furthermore, a motion  compensation (MoCo) was developed to address the general motion artifacts in short-scan  data. This method is based on partial angle reconstructions to which a 4D motion model  is applied. The latter was optimized using a cost function consisting of a penalized image  entropy. The penalties refer to cardiac velocity and strain. Both methods were applied to  single-phase reconstructions from clinical data. In addition, simulations were used with STAR.  STAR considerably improved image quality. Discontinuities were removed or clearly reduced.  The MoCo improved image quality for all artifact impaired reconstructions. In case of artifactfree  images, image quality was maintained, however, a tendency for a minor blurring in the  motion-compensated images was observed. Finally, both artifact correction methods showed a  capability to clearly improve image quality.
date: 2021
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/30242/1/Dissertation%20Lebedev.pdf
identifier: DOI:10.11588/heidok.00030242
identifier: urn:nbn:de:bsz:16-heidok-302421
identifier:   Lebedev, Sergej  (2021) Motion Compensation in Cardiac X-Ray Computed Tomography.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/30242/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng