Time-Resolved Imaging of Solid Tissue Phantoms Using a Perturbation Model

Measurements of the time-dependent intensity of transmitted light through a highly scattering tissue phantom have been compared with an analytical model which describes the sensitivity of that intensity to localized changes in optical properties. A least-squares fitting procedure is employed to investigate the accuracy with which the model can predict the true displacement between a single embedded inhomogeneity and the line-of-sight across the phantom. The embedded object has twice the scatter and absorption coefficient of the surrounding medium. A further fitting procedure was used to derive the amplitudes of the measurement perturbations as the line-of-sight is translated towards the inhomogeneity. Results show that the diffusion perturbation amplitude provides inherently greater spatial resolution than the absorption perturbation amplitude.