Functional Brain Tomography using a Time-Gated ICCD Camera

The mean penetration depth of diffusely reflected photons is dependent on the arrival time t of photons, but not on the source-detector distance. Thus, all photons collected at the same t have the same depth sensitivity, and can be used for the reconstruction. Following this concept, we have implemented a system for 3D tomography using a single injection fiber and a time-gated ICCD camera. The feasibility of the novel approach to reconstruct a local perturbation was demonstrated both with simulations and phantom measurements. Finally, preliminary measurements were performed in vivo following a standard protocol of motor cortex activation.