Date of Completion

12-9-2015

Embargo Period

12-7-2018

Keywords

Imaging systems; Illumination design; Light delivery system; Photoacoustic imaging; Image processing; Tomography; Ultrasound; Transvaginal probe; Ovarian cancer detection

Major Advisor

Prof. Quing Zhu

Associate Advisor

Prof. Rajeev Bansal

Associate Advisor

Prof. Patrick Kumavor

Field of Study

Electrical Engineering

Degree

Doctor of Philosophy

Open Access

Campus Access

Abstract

Ovarian cancer ranks fifth as the cause of cancer death in women. Due to nonspecific associated symptoms as well as lack of efficacious screening techniques at the disposal of patients, the survival rate for ovarian cancer has not significantly improved over the last two decades. Therefore, ovarian cancer has the highest mortality rate of all gynecologic cancers. As a result, there is an urgent need to improve the current diagnostic techniques to detect early malignancies in the ovary.

In this dissertation, the research work has been primarily focused in investigating the potential of photoacoustic/ultrasound (PAT/US) imaging as a future screening modality for ovarian cancer detection and characterization. A hand-held fiber-array transvaginal probe suitable for non-invasive PAT/US imaging of ovarian tissue was designed, implemented and evaluated. The probe was optimized for the highest light delivery output and best beam uniformity on tissue surface, by simulating the light fluence and power output for different design parameters. The laser fluence profiles were experimentally measured through chicken breast tissue and calibrated intralipid solution at various imaging depths. In ex vivo studies, porcine ovaries were imaged beneath a porcine vaginal muscle tissue, mimicking a non-invasive imaging condition. The co-registered PAT/US images clearly showed blood vasculature on the surface and inside the ovaries. In order to miniaturize the light coupling optics of the imaging system, a novel lens-array based illumination scheme for a compact co-registered PAT/US transvaginal probe was designed and tested. The lens array consists of four cylindrical lenses that couple the laser beams into four 1-mm-core multi-mode optical fibers with numerical aperture (NA) of 0.48 and optical coupling efficiency of ~87%. To verify the lens-array design, spatial distribution of hemoglobin oxygen saturation (sO2) of a mouse tumor was imaged in vivo using photoacoustic measurements. Furthermore, wavelength selection for multispectral PAT/US tomography was optimized to obtain accurate images of hemoglobin oxygen saturation (sO2) in vivo. These results highlight the clinical potential of the PAT/US system for early stage cancer detection and diagnosis. In the last part of this dissertation, reflection-mode acoustic-resolution photoacoustic microscopy (AR-PAM) for obtaining high resolution PAM images was designed and investigated.

Available for download on Friday, December 07, 2018

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