X-ray microtomography - methodological studies and applications for evo-devo
Year: 2016
Type: dissertation
Abstract: X-ray tomography is a widely used and powerful tool; its significance to diagnostics was recognized with the Nobel award, and tomographic imaging has also become a large contributor to several fields of science, from material physics to biological and palaeontological sciences. Current technology enables tomography on the micrometre scale, microtomography, in the laboratory. This provides a non-destructive three-dimensional microscope to probe the internal structure of radiotranslucent objects, which has obvious implications towards its applicability. Further, x-rays may be utilized for x-ray scattering experiments, which probes material properties on the ångström-scale. Crystallographic studies on various forms of matter, not least of which famously being the DNA molecule, have also been awarded the Nobel. In this thesis, the construction of a combined experimental set-up for both x-ray microtomography and x-ray scattering is documented. The device may be used to characterize materials on several levels of their hierarchical structure, and the microtomography data may be used as a reference for targeting the crystallographic experiment. X-ray diffraction tomography is demonstrated. An algorithm for x-ray tomography from sparse data is presented. In many scenarios, the amount of data collected for a tomogram is not sufficient for traditional algorithms, and would benefit from more robust computational schemes. Real x-ray data was used for computing a tomographic reconstruction from a data set two orders of magnitude smaller than what is conventionally used with set-ups such as the one presented in the thesis. Additionally, x-ray microtomography was utilized for morphological studies in developmental and evolutionary biology, evo-devo for short. The fossil record shows vast changes in morphology as more complex forms of life evolved, while the morphology of any given individual organism is the product of its developmental process. Understanding both evolution and development is essential for a comprehensive view on the history of life. In this thesis, two studies on teeth and their development are discussed. In both, dental morphology was investigated with high-resolution x-ray tomography.
Source: Työväentutkimus Vuosikirja
Author: Aki Kallonen
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2484833102