Differential NIR technique for tissue diagnosis

Liu Zheng; Hyo Sang Lee

doi:10.1117/12.238804

24 April 1996 Differential NIR technique for tissue diagnosis

Liu Zheng, Hyo Sang Lee

Proceedings Volume 2676, Biomedical Sensing, Imaging, and Tracking Technologies I; (1996) https://doi.org/10.1117/12.238804
Event: Photonics West '96, 1996, San Jose, CA, United States

Abstract

A new NIR technique based on pseudo-random modulation/correlation method is being developed for non-invasive tissue diagnosis applications. Simulation study and preliminary experiment demonstrate the feasibility of the technique applied to tissue oxygenation measurement. Using this technique, two diode lasers emitting at different wavelengths are modulated with orthogonal pseudo-random codes. The output power from these lasers is combined and delivered by an optical fiber to the tissue phantom to be studied. Simultaneous dual-wavelength detection is achieved by using only one detector due to the unique mathematical properties of the pseudo-random code. The system is further capable of rejecting common mode noise and reducing the tissue dependent effect. Preliminary experiments demonstrate 50 ps time resolution with a 200 to 400 MHZ modulation frequency. Prototype sensor performances are demonstrated in tissue phantom experiment and fluorescence lifetime measurement. In tissue phantom experiments, overall tissue deoxygenation is simulated by changing the phantom's optical property globally and a tumor tissue is simulated by a strong absorber embedded in the uniform background phantom. The depth of the absorber was measured up to 6 cm with an accuracy of 5 mm. In the fluorescence lifetime measurement experiment, a dye with a lifetime of 1.25 ns is excited by the 670 nm light and its fluorescence is detected at 760 nm.

Citation Download Citation

Liu Zheng and Hyo Sang Lee "Differential NIR technique for tissue diagnosis", Proc. SPIE 2676, Biomedical Sensing, Imaging, and Tracking Technologies I, (24 April 1996); https://doi.org/10.1117/12.238804

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KEYWORDS

Modulation

Tissues

Absorption

Sensors

Near infrared

Interference (communication)

Luminescence

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