Over the last decade, physicians have noted a rise in the prevalence of plagiocephaly. This sudden increase combined with the variability in presentation of infant head deformities makes the management of these cases often difficult. Currently, assessment for treatment is solely based largely on subjective determination of the severity of the patients skull malformation. Existing cephalometric techniques, such as external caliper measurements are commonly used, however these technique still contain inaccuracies, due to movement of an infant during measurement, soft tissue compression by the calipers, and lack of precise defined landmarks. (10) Given that no type of normalized measurement exists to identify objectively the severity of a patients skull deformity, the grading and selection of treatment modality has been relegated largely to experienced plastic surgeons and neurosurgeons. We report of a novel measurement that utilizes both CT scan and digital images combined with basic geometry to determine, objectively, the severity of an infants skull deformity, enabling all physicians to better decide what therapeutic intervention to employ.

More than hundred years after the discovery of X-rays different kinds of ionizing radiation are ubiquitous in medicine, applied to clinical diagnostics and cancer treatment as well. Irrespective of their nature, the widespread application of radiation implies its precise dosimetric characterization and detailed knowledge of the radiobiological effects induced in cancerous and normal tissue. Starting with in vitro cell irradiation experiments, which define basic parameters for the subsequent tissue and animal studies, the whole multi-stage process is completed by clinical trials that translate the results of fundamental research into clinical application. In this context, the present dissertation focuses on the establishment of radiobiological in vitro cell experiments at unconventional, but clinical relevant radiation qualities. In the first part of the present work the energy dependent biological effectiveness of photons was studied examining low-energy X-rays (≤ 50 keV), as used for mammography, and high-energy photons (≥ 20 MeV) as proposed for future radiotherapy. Cell irradiation experiments have been performed at conventional X-ray tubes providing low-energy photons and 200 kV reference radiation as well. In parallel, unconventional quasi-monochromatic channeling X-rays and high-energy bremsstrahlung available at the radiation source ELBE of the Forschungszentrum Dresden-Rossendorf were considered for radiobiological experimentation. For their precise dosimetric characterization dosimeters based on the thermally stimulated emission of exoelectrons and on radiochromic films were evaluated, whereas just the latter was found to be suitable for the determination of absolute doses and spatial dose distributions at cell position. Standard ionization chambers were deployed for the online control of cell irradiation experiments. Radiobiological effects were analyzed in human mammary epithelial cells on different subcellular levels revealing an increasing amount of damage for decreasing photon energy. For this reason, the assumed photon energy dependence was reconfirmed for a cell line other than human lymphocytes, an important finding that was discussed on the 2007 Retreat of the German Commission on Radiological Protection. After successful finalization of the photon experiments the focus of the present dissertation was directed to the realization of in vitro cell irradiation experiments with laser-accelerated electrons. This research was carried out in the frame of the project onCOOPtics that aims on the development of laser-based particle accelerators, which promise accelerators of potentially compact size and more cost-effectiveness suitable for a widespread medical application, especially for high precision hadron therapy. The unique properties, i.e., the ultrashort bunch length and resultant ultrahigh pulse dose rate, of these unconventional particle accelerators demand for extensive investigations with respect to potential effects on the dosimetric and radiobiological characterization. Based on the experiences gained at ELBE first experiments on the radiobiological characterization of laser-accelerated electrons have been performed at the Jena Titanium:Sapphire laser system. After beam optimization, a sophisticated dosimetry system was established that allow for the online control of the beam parameters and for the controlled delivery of dose to the cell sample. Finally, worldwide first systematic in vitro cell irradiation experiments were carried out resulting in a reduced biological effectiveness for laser-accelerated electrons relative to the 200 kV X-ray reference, irrespectively on the biological effect and cell lines examined. These successful results are the basis for future in vivo studies and experiments with laser-accelerated protons.

Thesis (Ph.D. in Molecular Biology) -- University of Colorado Denver, 2007. / Typescript. Includes bibliographical references (leaves 96-117). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;

Thesis (Ph. D.)--Open University. BLDSC no. DX193558.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

Ph.D.

Thesis (M.S.)--Brigham Young University. Dept. of Physics and Astronomy, 2003. / Includes bibliographical references (p. 57-59).

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 225-235). Available also in a digital version from Dissertation Abstracts.

Quasicrystal is the term used for a solid that possesses an essentially discrete diffraction pattern without having translational symmetry. Compared to periodic crystals, this difference in structure gives quasicrystals new properties that make them interesting to study -- both from a mathematical and from a physical point of view. In this thesis we review a mathematical description of quasicrystals that aims at generalizing the well-established theory of periodic crystals. We see how this theory can be connected to the cohomology of groups and how we can use this connection to classify quasicrystals. We also review an experimental method, NIXSW (Normal Incidence X-ray Standing Waves), that is ordinarily used for surface structure determination of periodic crystals, and show how it can be used in the study of quasicrystal surfaces. Finally, we define the reduced lattice and show a way to plot lattices in MATLAB. We see that there is a connection between the diffraction pattern and the reduced lattice and we suggest a way to describe this connection.

No description available.