Polarization and terahertz imaging for functional characterization of biological tissues

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Remote connection: https://oulu.zoom.us/j/64193836537

Topic of the dissertation

Polarization and terahertz imaging for functional characterization of biological tissues

Doctoral candidate

Master of Science Mariia Borovkova

Faculty and unit

University of Oulu Graduate School, Faculty of Information Technology and Electrical Engineering, Optoelectronics and Measurement Techniques

Subject of study

Electrical engineering

Opponent

Professor Ronald Sroka , Ludwig-Maximilians-University, Munich

Custos

Docent Aliaksandr Bykau, University of Oulu

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Polarization and terahertz imaging for functional characterization of biological tissues

New methods for the functional characterization of biological tissues based on optical sensing and imaging techniques have been developed in recent decades. These advanced optical methods enable the quantitative scoring of tissue optical properties and give rise to the optical biopsy, which shows high potential for implementation in clinical practice in the near future.

The present thesis describes the methods for the functional characterization of biological tissues based on the polarized light of the visible range and terahertz radiation. The use of polarized light in biomedical diagnostics is especially advantageous due to its high sensitivity to the morphological structure of the examined biological tissues. In particular, such tissue structural alterations as variations in size, shape, and/or density of light scattering inclusions, changes in fibrous structures organization, presence of chiral aggregates, and other could be detected with the aid of polarized-light-based techniques. The changes in the structural composition of a biological tissue often correlate with the changes in water level within the tissue. Techniques utilizing terahertz radiation enable effective sensing of hydration level of biological tissues. In the thesis, the considered approaches, enhanced by methods of mathematical and statistical analysis, were applied to differentiate various conditions of biological tissues that affect their morphological structure and water content. Polarized light imaging techniques, in particular, Stokes vector polarimetry based on circularly polarized illumination and multi-wavelength Mueller matrix imaging, were used for the label-free analysis of changes in tissue polarimetric characteristics caused by different conditions such as cancer, beta-amyloidosis in Alzheimer’s disease, skin tissue stretching, and dystrophic changes of cardiac tissue. Terahertz time-domain spectroscopy was utilized to non-invasively monitor tissue dehydration in transmission- and reflection-based measurement configurations. The fundamentals of the considered methods of optical tissue characterization, their limitations, and recent advances are overviewed.

The present work aims for the improvement of the considered optical imaging and characterization techniques, as well as for discovering their potential to achieve better diagnostic efficiency and for facilitating their transfer from the laboratory to clinical use.
Last updated: 6.4.2021