Oblique incidence reflectometry: optical models and measurements using a side-viewing gradient index lens-based...

Area of Science:

• Biomedical Optics
• Medical Imaging
• Optical Physics

Background:

• Accurate optical property measurement is crucial for diagnosing tissue pathologies.
• Existing endoscopic techniques may lack the precision for detailed optical analysis.
• Turbid biological tissues present challenges for light-based diagnostic tools.

Purpose of the Study:

• To design and validate a novel side-viewing reflectometry endoscope.
• To enable in-situ measurement of tissue optical properties (absorption and scattering).
• To assess the endoscope's efficacy in differentiating diseased from normal colon tissue.

Main Methods:

• Development of a 2.3-mm diameter oblique incidence reflectometry endoscope.
• Utilizing gradient index (GRIN) lens optics for oblique light delivery.
• Employing a 30,000-element fiber bundle for 2D diffuse reflectance imaging.
• Fitting the acquired reflectance profiles to theoretical models for property extraction.

Main Results:

• The endoscope successfully acquired diffuse reflectance profiles from tissue phantoms and in vivo mouse colon.
• Optical properties, including the effective attenuation coefficient, were accurately measured.
• The system demonstrated capability in distinguishing between normal and diseased colon tissues.

Conclusions:

• The developed oblique incidence reflectometry endoscope is a viable tool for in-situ optical property measurement.
• This technology holds potential for improved endoscopic diagnostics and disease characterization.
• Further validation in clinical settings is warranted to explore its full diagnostic potential.