Modeling subdiffusive light scattering by incorporating the tissue phase function and detector numerical aperture.

Area of Science:

• Biomedical Optics
• Tissue Optics
• Optical Sensing

Background:

• Optical techniques require small sampling volumes for detecting small-scale tissue changes.
• Diffusion approximation inadequately describes reflectance at short source-detector separations.
• Existing phase function parameters (? and ?) show limitations in predicting subdiffusive reflectance, especially at lower numerical apertures (NAs).

Purpose of the Study:

• To derive and evaluate a new parameter, R p NA, for improved subdiffusive reflectance prediction.
• To incorporate detector numerical aperture (NA) and phase function integrals into reflectance modeling.
• To enhance the accuracy of deriving optical properties from subdiffusive measurements.

Main Methods:

• Monte Carlo simulations were conducted for overlapping source/detector geometries.
• Simulations covered a range of phase functions, reduced scattering coefficients, NAs, and source/detector diameters.
• The predictive capability of R p NA was compared against existing parameters (? and ?).

Main Results:

• The R p NA parameter demonstrated improved prediction of measured reflectance compared to ? and ?.
• The new parameter effectively accounts for the detector's numerical aperture.
• R p NA's accuracy was validated across various optical and geometric conditions.

Conclusions:

• R p NA offers superior prediction of subdiffusive reflectance, especially under conditions where diffusion approximation fails.
• The incorporation of NA and phase function integrals enhances the model's physical relevance.
• R p NA is expected to significantly improve the derivation of tissue optical properties from reflectance measurements.