Oblique-incidence reflectometry and spectroscopy

This research proposes to build an optical-fiber reflectometer using a light source and an optical fiber bundle. This device will be able to measure tissue optical properties and detect skin cancers ("optical biopsy") in vivo non-invasively and quickly. In vivo experimental evidence has shown that cancerous skin lesions have different optical properties than non-cancerous lesions or normal skin. Therefore, cancerous skin lesions may be differentiated from non-cancerous skin lesions by comparing the optical properties of the skin lesions with those of the surrounding normal skin sites, where the optical properties of the normal skin sites are used to account for different types of skin or different areas of skin.

Skin cancer is the most frequently occurring cancer of all cancers. Each year over 500,000 new cases of skin cancer are detected. A high percentage of skin cancers are diseases in which fatalities can be all but eliminated and morbidity reduced if detected early and treated properly. These skin lesions are distinguished generally by subjective visual inspection and their definitive diagnosis requires time-consuming expensive histopathological evaluation of excisional or incisional biopsies. The proposed devices, which improve the abilities of the physician's eye, can facilitate early screening and detection of skin cancers to maximize cure and reduce or even avoid unnecessary biopsies. Furthermore, these devices are portable and relatively inexpensive. Therefore, they can be used in remote rural areas and the diagnostic results can be easily transferred to metropolitan diagnostic centers via modems or even via the information superhighway in the near future (telemedicine) for expert prognosis if needed.

For the optical-fiber reflectometer, an optical beam will be delivered to the skin surface through a source optical fiber, and the light reflectance pattern will be recorded through a fiber bundle to a computer. The computer will deduce the reduced scattering coefficient and absorption coefficient of the skin area quickly at multiple wavelengths based on our patented oblique incidence reflectometry technique. The optical-fiber reflectometer is easy to use, inexpensive, and has the potential to be used with endoscopes for gastrointestinal applications.

The following graph shows the anisotropy in the optical properties of chicken breast tissue measured using oblique incidence reflectometry.

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