Partial volume correction strategies for quantitative FDG PET in oncology

Purpose: Quantitative accuracy of positron emission tomography (PET) is affected by partial volume effects resulting in increased underestimation of the standardized uptake value (SUV) with decreasing tumour volume. The purpose of the present study was to assess accuracy and precision of different partial volume correction (PVC) methods. Methods: Three methods for PVC were evaluated: (1) inclusion of the point spread function (PSF) within the reconstruction, (2) iterative deconvolution of PET images and (3) calculation of spill-in and spill-out factors based on tumour masks. Simulations were based on a mathematical phantom with tumours of different sizes and shapes. Phantom experiments were performed in 2-D mode using the National Electrical Manufacturers Association (NEMA) NU2 image quality phantom containing six differently sized spheres. Clinical studies (2-D mode) included a test-retest study consisting of 10 patients with stage IIIB and IV non-small cell lung cancer and a response monitoring study consisting of 15 female breast cancer patients. In all studies tumour or sphere volumes of interest (VOI) were generated using VOI based on adaptive relative thresholds. Results: Simulations and experiments provided similar results. All methods were able to accurately recover true SUV within 10% for spheres equal to and larger than 1 ml. Reconstruction-based recovery, however, provided up to twofold better precision than image-based methods. Cl

Einfluss von physikalisch-chemischen Parametern auf das farbliche Erscheinungsbild von Lackierungen

Innerhalb der letzten 15 Jahre wurden die Anforderungen an Lacke immer höher. Speziell im Automobilbereich trat die Minimierung von umweltbelastenden Emissionen in den Vordergrund. Die BMW-Group war die erste Automobilfirma, welche diesen Anforderungen konsequent gerecht wurde, indem sie von herkömmlichen, lösemittelhaltigen 2-Komponenten-Klarlacken auf lösemittelfreie Pulverklarlacke umstellte. Dies bedeutet in Bezug auf Verarbeitung, Aushärtung und Applikation die Anwendung neuer Techniken, bei denen nur wenige Erfahrungen vorlagen. So zeigen Pulverklarlacke der ersten Generation gegenüber 2 Komponenten-Klarlacken auf gleichem Untergrund bei hellen Farbtönen unterschiedliche Farbnuancen. Vor allem bei Reparatur- und Nachbesserungsarbeiten wird die Farbdivergenz deutlich. Diese Ausbesserungen werden nämlich auch auf Pulverklarlackschichten mit einem 2 Komponenten-Klarlack vorgenommen. Gegenstand dieser Arbeit war es, diese Farbphänomene labortechnisch nachzustellen und die Ursachen zu finden, bzw. Abhilfemaßnahmen aufzuzeigen. Ausgehend vom �worst-case�-Farbton wurde eine zuverlässige und objektive Methode zur Messung der Farbe herangezogen. Unterschiedliche Lacksysteme und deren Zusammenspiel wurden auf ihre Farbänderung untersucht. Unter Verwendung von UV/VIS-, GPC-, GC und HPLC-Analytik wurden mögliche Verursacher ermittelt

Degradation of Solar Array Components in a Combined UV/VUV High Temperature Test Environment

BepiColombo is the joint mission of the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet mercury. The European contributions, namely the mercury transfer module (MTM) and the mercury planetary orbiter (MPO), are both powered by deployable solar arrays. Many materials and technologies are at their limit under the harsh high-intensity, high-temperature (HIHT) conditions of the mission. Synergistic effects like photo fixation and photo enhanced contamination by ultra violet and vacuum ultra violet radiation (UV/VUV) on sunlit surfaces are considered to play an important role in the HIHT environment of the BepiColombo mission. A design verification test under UV/VUV conditions of sun exposed materials and technologies on component level is presented which forms part of the overall verification and qualification of the solar array design of the MTM and MPO. The test concentrates on the self-contamination aspects and the resulting performance losses of the solar array under high intensity and elevated temperature environment representative for the photovoltaic assembly (PVA)

Degradation of Solar Array Components in a Combined UV/VUV High Temperature Test Environment

BepiColombo is the joint mission of the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet mercury. The European contributions, namely the mercury transfer module (MTM) and the mercury planetary orbiter (MPO), are both powered by deployable solar arrays. Many materials and technologies are at their limit under the harsh high-intensity, high-temperature (HIHT) conditions of the mission. Synergistic effects like photo fixation and photo enhanced contamination by ultra violet and vacuum ultra violet radiation (UV/VUV) on sunlit surfaces are considered to play an important role in the HIHT environment of the BepiColombo mission. A design verification test under UV/VUV conditions of sun exposed materials and technologies on component level is presented which forms part of the overall verification and qualification of the solar array design of the MTM and MPO. The test concentrates on the self-contamination aspects and the resulting performance losses of the solar array under high intensity and elevated temperature environment representative for the photovoltaic assembly (PVA)

Sputter yield measurements of thin foils using scanning transmission ion microscopy

Scanning transmission ion microscopy (STIM) has been applied to measure sputter yields of thin Kovar foil. The results have been found in very good agreement with values determined by the weight loss method, demonstrating STIM as a feasible alternative measurement technique for sputter yield estimation of thin material samples. Measurements have been carried out under normal xenon ion incidence for ion energies in the range between 100 eV and 1000 eV. In addition, sputter yields of Kovar bulk samples are reported. The data might be interesting for ion beam applications such as solar electric propulsion, in which materials with low sputter yields are preferred to ensure a long operational lifetime of the system components