Date of Award

8-31-2014

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Physics, Applied

First Advisor

Chandra Yelleswarapu

Second Advisor

Jonathan Celli

Third Advisor

Stephen Arnason

Abstract

Quantitative phase imaging (QPI) is a rapidly growing optical microscopy technique. It offers unique advantages compared to conventional light imaging methods such as phase contrast and differential interference contrast microscopes. Using interference principles the optical phase delay associated with the samples can be quantified and displayed in 3D. Motivated by the need of versatile QPI method that enables reconstruction of object at video time frames, in this thesis a three-wavelength quantitative Fourier phase contrast microscopy (FPCM) technique is developed. FPCM is a versatile and cost effective microscopy technique that uses a dye doped liquid crystal at the Fourier plane to convert optical phase delays into the amplitude contrast. This qualitative phase imaging technique is converted to a QPI by employing three lasers emitting at different wavelengths. The amount of phase shift that the liquid crystal cell introduces at each wavelength was measured and is used to calculate the thickness of the sample. In addition, in order to demonstrate the utility of QPI in studying the cells that are going on 3D cultures, the growth characteristics and treatment response of PANC-1 cancer cells were studied. Off-axis digital holographic microscopy apparatus is used to record the holograms of the cancer tumor nodules. Unwrapped phase images were obtained, from digitally recorded holograms, to quantify nodule thickness and volume over time under normal growth, and in cultures subjected to chemotherapy treatment. Results show differences in growth inhibition between cultures that were subjected to different chemo concentrations. Furthermore our data suggests that in the early stages, or during the growth inhibition period, the estimated volume (assuming the tumor nodules are spheroidal) may lead to inaccurate conclusions on growth inhibition. As tumor volume is the standard reporter of disease burden, prognosis, and outcome, the ability to measure this important parameter is significant. This work suggests the ability of DHM to quantify changes in 3D structure over time and shows that the further development of this approach for time-lapse monitoring of 3D morphological changes during growth and in response to treatment that would otherwise be impractical to visualize.

Comments

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