An ARX model for light propagation in biological tissue

Area of Science:

• Biomedical Engineering
• Biophotonics
• Medical Physics

Background:

• Precise measurement of light absorption and scattering in biological tissues is vital for applications like photodynamic therapy (PDT).
• Current endoscopic methods using backscattering cannot independently determine these optical coefficients.
• Accurate dosimetry in PDT requires separating absorption and scattering for effective treatment planning.

Purpose of the Study:

• To develop a novel model capable of separately quantifying light absorption and scattering coefficients in biological tissues.
• To address the limitations of existing endoscopic techniques in distinguishing between absorption and scattering phenomena.
• To enhance the precision of optical measurements in biomedical applications.

Main Methods:

• A new model was derived from Kubelka-Munk theory, a well-established framework for describing light propagation in scattering and absorbing media.
• The Auto Regressive with eXternal input (ARX) model, a signal processing algorithm, was applied to determine the optical coefficients.
• Validation was performed using both numerical simulations and experimental measurements with tissue phantoms.

Main Results:

• The proposed model, integrating Kubelka-Munk theory and the ARX algorithm, successfully determined absorption and scattering coefficients separately.
• Numerical simulations demonstrated the model's capability to accurately differentiate between the two optical properties.
• Experimental validation using phantoms confirmed the reliability and effectiveness of the developed method.

Conclusions:

• The novel model provides a reliable and effective solution for precisely measuring separate absorption and scattering coefficients in biological tissues.
• This advancement has significant implications for improving dosimetry in photodynamic therapy and other biomedical applications requiring accurate optical characterization.
• The combined approach of Kubelka-Munk theory and ARX modeling offers a robust tool for optical diagnostics in tissue.