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Compatibility of selected dental alloys with magnetic resonance imaging
Linetskiy, Igor ; Hubálková, Hana (advisor) ; Suchánek, Jakub (referee) ; Dostálová, Taťjana (referee)
Magnetic resonance imaging (MRI) is one of the up-to-date and perspective methods of diagnostic medical imaging. It is highly valued for absence of ionizing radiation, non-invasiveness, acquiring of highly accurate images of hard and especially soft tissues in any plane. It is a method of choice in central nervous system imaging. Nowadays it is used in diagnostics of other diseases in the maxillofacial area. The major shortcoming of MRI is interaction of magnetic fields of MRI system with metallic objects present in human body. As a result, this may lead to their heating, movement, and also to imaging artifacts. Since different metallic constructions (fixed bridges, dental implants, splints, plates, orthodontic appliances, etc.) are often used in the contemporary dentistry, the problem of their compatibility with MRI is relevant. The aim of this study was to validate the compatibility of dental alloys with MRI, classify the materials according to the degree of compatibility and to establish the range of their possible negative impact on quality of MRI in head and neck area. In order to find dental metals and alloys, General Health Insurance Company code- list, catalogues of manufacturers' and Prague dental labs were used. Measurement methods of magnetic susceptibility (MS), electric conductivity...
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Scanning Probe Microscopy: Measuring on Hard Surfaces
Matějka, Milan ; Urbánek, Michal ; Kolařík, Vladimír
During a measurement by scanning probe microscopy (SPM) an image artifacts can appear in a measurement data. The source of image artifacts during an SPM measurement could be in parts of the SPM tool: mechanical system, piezoelectric crystal, scanner electronic. However, the main source of image artifact is the probe tip geometry and properties of the sample. For example, probe wearing, which occurs during the contact measurement on a sample with a hard surface, could result in heavy probe shape change, causing probe-related image artifacts. Measurement could appear problematic on a sample with periodical relief structure (e.g. gratings with sub 10 μm periodicity) prepared in hard materials (e.g. silicon), when the structure height is greater than about 500 nm. In this case, probe can easily get struck during the scanning, on the hard surface as well as at the high aspect ratio relief structure, causing image artifact thus reducing measurement quality.
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