An optical method to detect tissue scattering: theory, experiments and biomedical applications

摘要

In vivo physiological sensing is typically done either by imaging thin tissues or by examining changes in the attenuationcoefficient. One known technique for thin tissue in vivo applications is the optical coherence tomography (OCT).However, deep tissue methods are usually based on diffusion reflection (DR), which correlates the optical properties tothe reflected light intensity. The attenuation coefficient is composed of tissue absorption and scattering. We present anoninvasive nanophotonics technique, the iterative multi-plane optical property extraction (IMOPE) for extracting thescattering properties from a turbid medium.The reflectance-based IMOPE is most relevant for in vivo applications, hence, in this research we suggest a newtheoretical description of phase accumulation in deep tissue, which is rarely mentioned in the literature, using a modifiedDR theory that represents the phase based on the effective pathlength.The IMOPE records multiple intensity images, reconstructs the phase using Gerchberg-Saxton (GS) algorithm. Thisalgorithm is usually being used for beam shaping or phase reconstruction. We propose to calculate the phase secondorder moment to estimate the scattering. IMOPE experiments were conducted with tissue-like phantoms for calibrationpurposes, as well as ex vivo and in vivo measurement.The suggested technique was applied both in transmission and reflection mode. The transmission based IMOPE detectedorganic nanoparticles within tissues and the quantitative signature of milk components. The reflectance-based IMOPEwas applied for tissue viability test and in vivo gold nanorods and blood flow detection.