Elastic light scattering spectroscopy for the detection of early cancer and pre-cancer

We have investigated elastic scattering spectroscopy in large-scale clinical studies for several organ areas, including multi-center studies for Gl diseases. The method of elastic-scattering spectroscopy (ESS) has a simple fiber geometry that is sensitive to the sub-cellular morphology and architectural changes, such as nuclear grade and nuclear to cytoplasm ratio, mitochondrial size and density, etc., which correlate with features used by pathologists when performing histological assessment. Most cancers arise in the epithelium, which is the superficial tissue layer of an organ, with a thickness, typically, of 100-500 micrometers. Hence, sensitivity to the optical properties of the epithelial layer requires superficial measurement techniques. In several of our studies, the two fibers typically have a core diameter of 200 microns, with a center-to-center separation of around 250 microns. Thus, most of the elastically-scattered light is collected from the epithelial layer. The theoretical underpinnings of elastic light scattering in tissue, based on Mie theory, will be reviewed, and Monte Carlo methods for computational simulation will be illustrated.