Dependency of crossover point on absorption changes in bilayer diffusion reflection measurements.

Area of Science:

• Biomedical Optics
• Photonics
• Medical Imaging

Background:

• Diffusion reflection (DR) is crucial for noninvasive medical diagnostics and treatments.
• Understanding DR behavior in complex structures like bilayer substances is essential for advancing these applications.

Purpose of the Study:

• To investigate the dependency of the diffusion reflection crossover point ( $$ ) on absorption changes in different layers of a bilayer substance.
• To determine the relationship between the $$ and the absorption coefficients of the layers, keeping scattering and top layer thickness constant.

Main Methods:

• Fabrication and measurement of monolayer and bilayer optical tissue-like phantoms using a DR system.
• Comparison of experimental DR data with Monte Carlo simulations for validation.

Main Results:

• Experimental results showed strong agreement with Monte Carlo simulations.
• The $$ was found to correlate with the square root of the ratio of the lower layer's absorption coefficient to the top layer's absorption coefficient.

Conclusions:

• The study validates the theoretical prediction of the $$ dependency on the ratio of absorption coefficients.
• A secondary breaking point in DR was experimentally suggested, potentially indicating the noise area threshold.