Light propagation for time-domain fluorescence diffuse optical tomography by convolution using lifetime function

Abstract

Time-domain light propagation in biological tissue is studied by solving the forward problem for fluorescence diffuse optical tomography using a convolution of the zero-lifetime emission light and the exponential function for a finite lifetime. We firstly formulate the fundamental equations in a time-domain assuming that the fluorescence lifetime is equal to zero, and then the solution including the lifetime is obtained by convolving the emission light and the lifetime function. The model is a two-dimensional (2-D) 10 mm-radius circle with the optical properties simulating biological tissue for the near infrared light, and contains some inclusions with fluorophores. Temporal and spatial profiles of excitation and emission light are calculated and discussed for several models with different inclusions. The results are physically reasonable and will be used for the inverse problem of fluorescence diffuse optical tomography.