NPL is presently implementing state of the art computational models of light propagation in tissue suitable for processing scattering profiles obtained from Optical Coherence Tomography (OCT) images. At present, monochromatic Mie scattering models are used to understand the backscattered light present in OCT images. However, OCT is inherently broadband and tissue is not a collection of randomly arranged spherical scattering particles. In fact, tissue is a quasi-random matrix of scatters contained within a layered cellular structure. There is also extra-cellular material that can be both birefringent and optically scattering. Therefore, the spherical scattering model often assumed does not represent that which is physically present in tissue and hence cannot be reliably used for quantitative assessment. Our light propagation models seek to simulate some of the structural complexity of tissue and its wavelength dependence, enabling more robust measurement of optical properties from OCT images.

OCT image data of real tissue is being used to constrain tissue model parameters. In turn, these parameters can then be used to feed into the development of physical tissue phantoms