Distance-weighted reflectance for arbitrary source-detector geometries from a single pencil-beam Monte Carlo...

Area of Science:

• Biomedical Optics
• Computational Physics
• Spectroscopy

Background:

• Modeling light reflectance in biological tissues often requires complex Monte Carlo simulations.
• Explicitly defining source and detector areas in simulations is computationally intensive.
• Existing methods struggle with diverse source-detector geometries.

Purpose of the Study:

• To develop an efficient, generalizable method for calculating reflectance.
• To simplify modeling for various source-detector configurations.
• To validate the new method against established simulation techniques.

Main Methods:

• A novel distance-weighted formulation was developed.
• Reflectance is calculated from a single, localized Monte Carlo simulation.
• The method accounts for source-detector separation distributions and numerical apertures.

Main Results:

• The distance-weighted method accurately computes reflectance for overlapping, concentric, and non-overlapping geometries.
• Validation shows agreement with full source-detector simulations for reflectance and pathlength distributions.
• The framework extends to non-uniform illumination and detection.

Conclusions:

• This distance-weighted formulation offers a general and efficient framework for reflectance modeling.
• It significantly reduces computational cost compared to traditional methods.
• The approach is particularly relevant for fiber-based reflectance spectroscopy in laterally homogeneous media.