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Virtual histology by laboratory x-ray phase-contrast tomography

Time: Fri 2021-03-26 13.00

Location: Via zoom, (English)

Subject area: Physics, Biological and Biomedical Physics

Doctoral student: Jenny Romell , Biomedicinsk fysik och röntgenfysik

Opponent: Professor Julia Herzen, Department of Physics, Technical University of Munich, Munich, Germany

Supervisor: Professor Hans Hertz, Biomedicinsk fysik och röntgenfysik; Universitetslektor Anna Burvall, Biomedicinsk fysik och röntgenfysik

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Detailed imaging of biological samples is central to different fields of research, as well as for clinical pathology. Classical histology, using light- orelectron microscopy, can generate high-resolution images but is destructive and only gives two-dimensional information. With virtual histology, athree-dimensional reconstruction of the sample is instead generated, whichcan be virtually sectioned in arbitrary directions. This Thesis presents developments of x-ray phase-contrast computed tomography (CT) as a tool forvirtual histological analysis. In particular, the focus is imaging with laboratory systems as opposed to at large-scale synchrotron facilities, and usingphase-contrast imaging as an alternative to chemical contrast agents.A broad range of imaging applications are demonstrated, from archaeology to clinical pathology, where acquisition and data processing have beenoptimised for each sample. A micro-CT system based on a liquid-metaljet x-ray source was used for imaging centimetre-sized samples. Threedimensional imaging of mummified remains was demonstrated, with sufficient contrast and resolution within the soft tissue to capture microanatomical details; blood vessels, skin layers, fingerprints and remains of adiposecells were visualised in the hand of an ancient Egyptian mummy. Virtualhistology was also performed on paraffin-embedded excised tumours foranalysis of the resection margin, and on rat bones for mapping the vascularcanals.For imaging with micrometre resolution, a nano-CT system was builtand characterised. Photoreceptor imaging in unstained compound eyes ofbumblebees was demonstrated, and light- and electron microscopy wereused to verify the results. Comparisons with conventional attenuationmicro-CT and synchrotron radiation tomography, with both unstained andstained samples, showed the advantage of using phase contrast instead ofstaining the samples