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USING LOW-COHERENCE INTERFEROMETRY TO MONITOR CELL INVASION IN AN IN-VITRO MODEL SYSTEM
Title
USING LOW-COHERENCE INTERFEROMETRY TO MONITOR CELL INVASION IN AN IN-VITRO MODEL SYSTEM.
Creator
Davoudi Nasab, Behnaz, Dogariu, Aristide, Andl, Claudia, University of Central Florida
Abstract / Description
In an optically random system, such as naturally occurring and man-made media, light undergoes pronounced multiple scattering. This phenomenon has shown a remarkable potential in characterizing complex materials. In this regime, scattering occurs from each individual center of the scattering and independent scattering events lead to multiple light scattering. This phenomenon is often described as a random walk of photons and can be modeled in terms of a diffusion equation based on the...
Show moreIn an optically random system, such as naturally occurring and man-made media, light undergoes pronounced multiple scattering. This phenomenon has shown a remarkable potential in characterizing complex materials. In this regime, scattering occurs from each individual center of the scattering and independent scattering events lead to multiple light scattering. This phenomenon is often described as a random walk of photons and can be modeled in terms of a diffusion equation based on the radiative transfer theory. In this thesis, we used optical path-length spectroscopy (OPS), which is an experimental method to obtain the path-length probability density of the propagating light in multiple scattering media, with a low-coherence optical field to investigate the distribution of photon path lengths in a skin cell model system. This method is capable of measuring the transport mean free path of light in a highly scattering medium and depth-resolved profiles of the backscattered light. Our OPS experimental configuration is based on a fiber-optic Michelson interferometer geometry using single mode optical fibers. We performed OPS based on low-coherence interferometry (LCI) on three-dimensional organotypic models of esophageal cell invasion by measuring the optical path-length distribution of backscattered light in normal and invasive conditions. The optical path-length distribution of light waves inside the cell samples provides information on how a change in the extracellular matrix affects invasiveness of the esophageal cells and induction of signaling pathways. Also, we demonstrated the compatibility to study the structural changes during a two-week period for in vitro cell samples.
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Date Issued
2017
Identifier
CFH2000219, ucf:45955
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH2000219
SYSTEM DESIGN AND OPTIMIZATION OF OPTICAL COHERENCE TOMOGRAPHY
Title
SYSTEM DESIGN AND OPTIMIZATION OF OPTICAL COHERENCE TOMOGRAPHY.
Creator
Akcay, Avni, Rolland, Jannick, University of Central Florida
Abstract / Description
Optical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. A challenge in optical coherence imaging, as in any imaging system towards biomedical diagnosis, is the quantification of image quality and optimization of the system components, both a primary...
Show moreOptical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. A challenge in optical coherence imaging, as in any imaging system towards biomedical diagnosis, is the quantification of image quality and optimization of the system components, both a primary focus of this research. We concentrated our efforts on the optimization of the imaging system from two main standpoints: axial point spread function (PSF) and practical steps towards compact low-cost solutions. Up to recently, the criteria for the quality of a system was based on speed of imaging, sensitivity, and particularly axial resolution estimated solely from the full-width at half-maximum (FWHM) of the axial PSF with the common practice of assuming a Gaussian source power spectrum. As part of our work to quantify axial resolution we first brought forth two more metrics unlike FWHM, which accounted for side lobes in the axial PSF caused by irregularities in the shape of the source power spectrum, such as spectral dips. Subsequently, we presented a method where the axial PSF was significantly optimized by suppressing the side lobes occurring because of the irregular shape of the source power spectrum. The optimization was performed through optically shaping the source power spectrum via a programmable spectral shaper, which consequentially led to suppression of spurious structures in the images of a layered specimen. The superiority of the demonstrated approach was in performing reshaping before imaging, thus eliminating the need for post-data acquisition digital signal processing. Importantly, towards the optimization and objective image quality assessment in optical coherence imaging, the impact of source spectral shaping was further analyzed in a task-based assessment method based on statistical decision theory. Two classification tasks, a signal-detection task and a resolution task, were investigated. Results showed that reshaping the source power spectrum was a benefit essentially to the resolution task, as opposed to both the detection and resolution tasks, and the importance of the specimen local variations in index of refraction on the resolution task was demonstrated. Finally, towards the optimization of OCT and OCM for use in clinical settings, we analyzed the detection electronics stage, which is a crucial component of the system that is designed to capture extremely weak interferometric signals in biomedical and biological imaging applications. We designed and tested detection electronics to achieve a compact and low-cost solution for portable imaging units and demonstrated that the design provided an equivalent performance to the commercial lock-in amplifier considering the system sensitivity obtained with both detection schemes.
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Date Issued
2005
Identifier
CFE0000651, ucf:46527
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000651