Tomographic phosphorescence lifetime multiplexing.

We present a tomographic reconstruction algorithm for recovering distributions of multiple phosphorescent dyes within turbid media from time-resolved measurements, using either point or spatially patterned sources and detectors. The algorithm employs a multi-exponential analysis of time-resolved data, followed by tomographic inversion of the decay amplitudes to recover independent yield distributions for each lifetime present in the medium. Using Monte Carlo simulations, we computationally demonstrate that this two-step inversion approach provides several-fold improvement in quantitative and localization accuracy compared to a direct inversion of the time domain phosphorescence. We also demonstrate the tomographic reconstruction of up to three phosphorescent lifetimes embedded in thick tissue. The proposed algorithm can allow quantitative multiplexed tomography of luminescent and phosphorescent dyes for a wide range of in vivo applications.