A wavefront intersection algorithm for time-of-flight non-contact diffuse optical tomography of fluorescent inclusions in thick turbid media

Abstract

In previous work, we have introduced a numerical constant fraction discrimination (NCFD) technique for processing time-resolved optical signals. It allows to extract, in a stable manner, the arrival time of early photons emitted by a fluorescent inclusion embedded in a scattering medium. We showed experimentally that these arrival times correlate quasi-linearly with inclusion depth. We now exploit this arrival time vs depth relationship for inferring the inclusion position by way of a time of flight algorithm. The algorithm uses the relative arrival times measured at several detector positions around the scattering medium with respect to a reference detector position. The latter is chosen as that detector position for which the arrival time is shortest. Our approach provides accurate inclusion localization, showing the potential of direct time-of-flight fluorescence diffuse optical tomography.