TY - THES A1 - Schielein, Richard T1 - Analytische Simulation und Aufnahmeplanung für die industrielle Röntgencomputertomographie T1 - Analytical simulation and acquisition planning for industrial x-ray computed tomography N2 - Röntgencomputertomographie (CT) hat in ihrer industriellen Anwendung ein sehr breites Spektrum möglicher Prüfobjekte. Ziel einer CT-Messung sind dreidimensionale Abbilder der Verteilung des Schwächungskoeffizienten der Objekte mit möglichst großer Genauigkeit. Die Parametrierung eines CT-Systems für ein optimales Messergebnis hängt stark vom zu untersuchenden Objekt ab. Eine Vorhersage der optimalen Parameter muss die physikalischen Wechselwirkungen mit Röntgenstrahlung des Objektes und des CT-Systems berücksichtigen. Die vorliegende Arbeit befasst sich damit, diese Wechselwirkungen zu modellieren und mit der Möglichkeit den Prozess zur Parametrierung anhand von Gütemaßen zu automatisieren. Ziel ist eine simulationsgetriebene, automatische Parameteroptimierungsmethode, welche die Objektabhängigkeit berücksichtigt. Hinsichtlich der Genauigkeit und der Effizienz wird die bestehende Röntgensimulationsmethodik erweitert. Es wird ein Ansatz verfolgt, der es ermöglicht, die Simulation eines CT-Systems auf reale Systeme zu kalibrieren. Darüber hinaus wird ein Modell vorgestellt, welches zur Berechnung der zweiten Ordnung der Streustrahlung im Objekt dient. Wegen des analytischen Ansatzes kann dabei auf eine Monte-Carlo Methode verzichtet werden. Es gibt in der Literatur bisher keine eindeutige Definition für die Güte eines CT-Messergebnisses. Eine solche Definition wird, basierend auf der Informationstheorie von Shannon, entwickelt. Die Verbesserungen der Simulationsmethodik sowie die Anwendung des Gütemaßes zur simulationsgetriebenen Parameteroptimierung werden in Beispielen erfolgreich angewendet beziehungsweise mittels Referenzmethoden validiert. N2 - Industrial X-ray computed tomography (CT) can be applied to a large variety of different specimens. The result of a CT measurement is a three-dimensional image containing the position-dependent attenuation coefficient of the specimen. For an optimal imaging CT-measurement parameters depend on both the properties of the CT-System and the specimen. To predict such an optimal parameterization both the physical interactions with X-rays of the CT-System and the specimen, must be taken into account. This thesis sets out to address the modelling of the interactions as well as the automatization of the parameter finding. The latter is based on a figure of merit for CT-measurements. Aim is a simulation-based, automatic parameter optimization method which includes the object-dependency on distinct specimens. The currently existing X-ray simulation methods are enhanced with respect to accuracy and efficiency. Therefore a method for the calibration of the simulation to a real CT-system is presented. Additionally, a model for second order X-ray scattering is developed in order to calculate the specimen-scattered radiation. This is done using an analytical ansatz and no Monte-Carlo method has to be applied. So far, no universal definition of a figure of merit for CT-results has been given in literature. Using Shannon's information theory such a definition is developed. The improvements of the simulation method and the application of the figure of merit for simulation-based parameter optimization are used in examples or are validated using reference methods. KW - Computertomografie KW - Zerstörungsfreie Werkstoffprüfung KW - Optimierung KW - Aufnahmeplanung KW - Analytische Simulation KW - CT KW - Computersimulation Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169236 ER - TY - JOUR A1 - Jobst, Bertram J. A1 - Wielpütz, Mark O. A1 - Triphan, Simon M.F. A1 - Anjorin, Angela A1 - Ley-Zaporozhan, Julia A1 - Kauczor, Hans-Ulrich A1 - Biederer, Jürgen A1 - Ley, Sebastian A1 - Sedlaczek, Oliver T1 - Morpho-Functional 1H-MRI of the Lung in COPD: Short-Term Test-Retest Reliability JF - PLOS ONE N2 - Purpose Non-invasive end-points for interventional trials and tailored treatment regimes in chronic obstructive pulmonary disease (COPD) for monitoring regionally different manifestations of lung disease instead of global assessment of lung function with spirometry would be valuable. Proton nuclear magnetic resonance imaging (1H-MRI) allows for a radiation-free assessment of regional structure and function. The aim of this study was to evaluate the short-term reproducibility of a comprehensive morpho-functional lungMRI protocol in COPD. Materials and Methods 20 prospectively enrolled COPD patients (GOLD I-IV) underwent 1H-MRI of the lung at 1.5T on two consecutive days, including sequences for morphology, 4D contrast-enhanced perfusion, and respiratory mechanics. Image quality and COPD-related morphological and functional changes were evaluated in consensus by three chest radiologists using a dedicated MRI-based visual scoring system. Test-retest reliability was calculated per each individual lung lobe for the extent of large airway (bronchiectasis, wall thickening, mucus plugging) and small airway abnormalities (tree in bud, peripheral bronchiectasis, mucus plugging), consolidations, nodules, parenchymal defects and perfusion defects. The presence of tracheal narrowing, dystelectasis, pleural effusion, pulmonary trunk ectasia, right ventricular enlargement and, finally, motion patterns of diaphragma and chest wall were addressed. Results Median global scores [10(Q1:8.00; Q3:16.00) vs. 11(Q1:6.00; Q3:15.00)] as well as category subscores were similar between both timepoints, and kappa statistics indicated "almost perfect" global agreement (\(\kappa\)= 0.86, 95%CI = 0.81-0.91). Most subscores showed at least "substantial" agreement of MRI1 and MRI2 (\(\kappa\)= 0.64-1.00), whereas the agreement for the diagnosis of dystelectasis/effusion (\(\kappa\)= 0.42, 95%CI = 0.00-0.93) was "moderate" and of tracheal abnormalities (\(\kappa\)= 0.21, 95%CI = 0.00-0.75) "fair". Most MRI acquisitions showed at least diagnostic quality at MRI1 (276 of 278) and MRI2 (259 of 264). Conclusion Morpho-functional 1H-MRI can be obtained with reproducible image quality and high short-term test-retest reliability for COPD-related morphological and functional changes of the lung. This underlines its potential value for the monitoring of regional lung characteristics in COPD trials. KW - capability KW - obstructive pulmonary disease KW - quantitative computed tomography KW - cystic fibrosis KW - proton MRI KW - perfusion KW - emphysema KW - CT KW - agreement KW - dysfunction Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151365 VL - 10 IS - 9 ER -