Interstitial optical parameter quantification of turbid medium based on CW radiance measurements

CW radiance measurements examine the light intensity at a single source-detector location from different detection directions to recover absorption coefficient and reduced scattering coefficient of the turbid medium which is important in treatment planning of minimally invasive laser therapies. In this paper, P9 approximation for radiance is used as the forward model for fitting by considering the balance between computational time and the correctness of the forward model at low albedo and small source detector separation (SDS). By fitting P9 approximation for radiance to the angular radiance Monte Carlo (MC) simulations used as the angular radiance measurements, optical parameters are recovered over a wide range of reduced albedo between 0.69 and 0.99 at small SDS 2mm. The recovery errors of absorption coefficient and reduced scattering coefficient are less than 11.96% and 2.63%, respectively. The effects of the maximum angle used for fitting on optical parameter recovery have been further studied. The results show that the recovery errors of absorption coefficient and reduced scattering coefficient are less than 12% and 3% respectively when the maximum angle is greater than 70 degree.