PHOTON MIGRATION IN THE PRESENCE OF A SINGLE DEFECT - A PERTURBATION ANALYSIS

We present an analytical perturbation analysis for studying the sensit ivity of diffusive photon flux to the addition of a small spherical de fect object in multiple-scattering media such as human tissues. As a f irst simple application of our perturbation method, we derive analytic ally the photon migration path distributions and the shapes of the so- called banana regions in which the photon migration paths are concentr ated. We then derive analytically the sensitivity of detected photon f lux densities to the inclusion of small spherical defects in the multi ple-scattering medium for both single-source and two-source configurat ions, at both steady-state (dc) and frequency-modulation conditions, a nd compare the results with Monte Carlo simulations.