Biomedical optical imaging using frequency domain photon migration measurements: Experiments and numerical image reconstructions

Tamara Lynn Troy, Purdue University

Abstract

Although the implementation of conventional x-ray mammography is efficient for the detection of breast cancer in postmenopausal women, the quality of mammograms in younger women is compromised due to radiative scatter from increased tissue cellularity. This dissertation investigates the development of a novel optical imaging technique which utilizes scattered light for image formation of diseased tissues. The success of frequency domain biomedical optical imaging depends on the ability to measure changes in photon migration due to differences in the optical properties of normal and diseased tissues. However, the work presented here suggests that differences between normal and diseased breast tissue may not be consistently large enough for sufficient detection. Consequently, the prospect of employing exogenous optical contrast agents for detecting diseased tissue volumes was investigated using single pixel measurements of photon migration. The results from the single pixel studies show that fluorescent agents offer improved contrast over those that only absorb light. In order to obtain spatial information for image reconstruction within clinically realistic data acquisition times, a multi-pixel frequency domain apparatus was also developed. The implementation of this apparatus shows the ability to detect perfectly absorbing and fluorescing heterogeneities embedded in a tissue-mimicking scattering medium. From these rapid measurements, successful reconstructions of interior optical property maps may now be possible. Clinically, optical property maps of interior tissue volumes are needed for accurate diagnosis. A reconstruction algorithm was developed in order generate interior maps from the exterior multi-pixel measurements. Although the algorithm was tested only using simulated data, the ultimate goal is to couple experimental multi-pixel measurements to the inversion scheme.

Degree

Ph.D.

Advisors

Sevick-Muraca, Purdue University.

Subject Area

Chemical engineering|Biomedical research

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