title: The geometric accuracy of medical images andelastic image registration in radiation therapy
creator: Hub, Martina
subject: ddc-530
subject: 530 Physics
description: Radiotherapy relies on the accuracy of radiological images and image processing procedures. Here, the geometric uncertainty of magnetic resonance imaging (MRI) and elastic image registration are investigated. A new type of phantom to measure MRI distortions and a corresponding evaluation software were developed. As a result of phantom measurement, a tree-dimensional displacement vector field is obtained to correct the images. In tests, the distortions were reduced from 3.0 ± 3.6 mm to less than 1 mm in average. In addition, methods to estimate the uncertainty of the displacement vector field (DVF) were developed for a b-spline and a demons registration algorithm . In case of the b-spline algorithm, this was done by random variations of the coefficients resulting from the registration. A quantity was introduced to characterize the local sensitivity of the similarity measure to these variations. The significant statistical dependence between this quantity and the local image registration error was demonstrated. For the demons algorithm, the reproducibility under multiple registrations was regarded as a measure of uncertainty. The algorithms were tested with artificially deformed lung images. Both methods have the potential to divide an image in sub-regions which differ in the magnitude of their average registration error.
date: 2008
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/9372/1/Dissertation_Hub.pdf
identifier: DOI:10.11588/heidok.00009372
identifier: urn:nbn:de:bsz:16-opus-93724
identifier:   Hub, Martina  (2008) The geometric accuracy of medical images andelastic image registration in radiation therapy.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/9372/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng