[Study on the Determination System of Tissue Optical Properties Based on Diffuse Reflectance Spectrum]

Area of Science:

• Biomedical Optics
• Tissue Optics
• Spectroscopy

Background:

• Accurate determination of tissue optical properties (absorption and scattering coefficients) is fundamental in biomedical optics.
• These properties provide insights into tissue physiology, structure, and disease mechanisms, aiding non-invasive detection, diagnosis, and photodynamic therapy.
• Current methods may lack speed, flexibility, or simplicity for clinical applications.

Purpose of the Study:

• To develop a flexible and rapid method for extracting absorption and reduced scattering coefficients from diffuse reflectance spectra of turbid media like human tissue.
• To utilize Artificial Neural Networks (ANN) for modeling non-linear forward and inverse relationships in diffuse reflectance spectroscopy.
• To evaluate the accuracy and robustness of the developed method for potential clinical use.

Main Methods:

• A system comprising a white light source, spectrometer, and fiber optic probe was used to measure diffuse reflectance spectra.
• An empirical forward model and a non-linear inverse model, both based on Artificial Neural Networks (ANN), were developed.
• Principal Component Analysis (PCA) was employed within the inverse model to reduce data dimensionality and suppress spectral noise.
• The method involved generating training spectra, training the ANN models, measuring sample spectra, and predicting optical properties.

Main Results:

• The developed ANN-based method accurately extracted absorption and scattering coefficients from diffuse reflectance spectra measured at a single source-detector distance.
• Mean Root Mean Square (RMS) percentage errors were 4.58% for absorption and 7.92% for scattering coefficients.
• The method demonstrated validity across a wide range of optical properties, showing robustness and accuracy.
• The approach is suitable for extracting chromophore concentrations if their absorption peaks are within the measurement wavelength range.

Conclusions:

• A rapid and flexible method using diffuse reflectance spectroscopy and ANNs enables accurate extraction of tissue optical properties.
• The system setup is simple, and measurements are fast, making it highly suitable for clinical applications.
• This technique advances non-invasive tissue analysis, improving diagnostic capabilities and therapeutic interventions.