A Monte Carlo simulator dedicated to a time-resolved optical tomographic modality based on the Henyey-Greenstein phase function

The current work focuses on the Time-Resolved Optical Tomographic (TROT) modality and mainly studies the scattering process that takes place in a diffusing medium like tissue when Near-Infrared radiation propagates through it. Additionally, it handles the time filtering which is necessary to be performed on the detected photons in order to gain the anatomical information of an area under investigation. The Near-Infrared radiation that is utilized in this type of imaging technique is mainly followed by Mie (forward peaked) type of scattering which causes the majority of the photons to get diffused. A small fraction of those photons remain forward scattered and only by proper time filtering can be resolved; they provide the correct anatomical information of the medium. In order to investigate this mechanism, a Monte Carlo simulator program, named PHOSIM, has been developed. This software package is based on the Henyey-Greenstein phase function which in a macroscopic way can undoubtedly approximate the microscopic character of the process that gives rise to Mie type of scattering.