September 2005

EEEL Researchers Measure Scattering Dispersion Using Optical Coherence Tomography

Researchers in the Optoelectronics Division of EEEL have used Optical Coherence Tomography (OCT) to make sensitive measurements of the dispersion of light scattered from microspheres with diameters ranging from 19 μm to 60 μm. The project's goal is to use scattering dispersion from cell nuclei (measured via OCT) as a sensitive indicator of nuclear refractive index and diameter. Nuclear size can vary significantly - healthy nuclei have a characteristic diameter of 4 to 7 μm, while dysplastic nuclei can be as large as 20 μm. Because dysplastic changes are often associated with precancerous conditions, this OCT technique could have future applications in early cancer detection.

In this first step, researchers have measured dispersion signatures for various diameters of polystyrene and glass microspheres in air and collagen suspensions. Measurement results agree qualitatively with theoretical predictions of dispersion based on phase-sensitive Mie scattering theory developed by Thomas Germer of the Physics Lab. Currently, work is proceeding to refine both theory and experimental procedures to enable better agreement and to demonstrate similar measurements on cell nuclei.

Researchers outside of NIST have shown promising results using intensity scattering as an indicator of nuclear size. However, there are indications that dispersion measurements may be a more sensitive approach with possible immunity to some noise sources seen in intensity measurements.

Contact:

Shellee Dyer, (303) 497-7463