TRINITY: A three-dimensional time-dependent radiative transfer code for in-vivo near-infrared imaging

We develop a new three-dimensional time-dependent radiative transfer code, TRINITY (Time-dependent Radiative In Near-Infrared TomographY), for in-vivo diffuse optical tomography (DOT). The simulation code is based on the design of long radiation rays connecting boundaries computational domain, which allows us to calculate light propagation with little numerical diffusion. parallelize Message Passing Interface (MPI) using domain decomposition technique and confirm high parallelization efficiency, so that simulations spatial resolution ∼1 millimeter can be performed in practical time. As first application, we study pulse collimated within θ∼15∘ phantom, uniform medium made polyurethane mimicking biological tissue. show spreads all forward directions over ∼ few millimeters due multiple scattering process photons. Our successfully reproduce time-resolved signals measured eight detectors phantom. also introduce effects reflection refraction at boundary different refractive index demonstrate faster photons an air hole analogue respiratory tract.