Experimental method to assess depth sensing limits of inelastic scattering measurements using spatial-offset Raman...

Area of Science:

• Spectroscopy
• Biomedical Optics
• Chemical Analysis

Background:

• Spatial offset Raman spectroscopy (SORS) is a promising technique for subsurface biochemical analysis.
• The relationship between spatial offset and sensing depth in SORS is not well understood, limiting clinical applications such as breast cancer surgery margin assessment.

Purpose of the Study:

• To develop an experimental method to establish a relationship between spatial offset in SORS and sampling depth.
• To enable detection of subsurface biochemical composition for improved clinical translation of SORS.

Main Methods:

• Utilized a custom hyperspectral line-scanning imaging system for SORS detection.
• Employed bilayer phantoms (PDMS/Nylon) with varying optical properties and thicknesses.
• Developed a technique using the spectral angle mapper metric to predict sensing depth based on spatial offset.

Main Results:

• Demonstrated detectability of an underlying Nylon layer through up to 3 mm of PDMS.
• Showcased detection of protein-rich tissue through 3 mm of Intralipid and 2 mm of porcine fat.
• Established correlation curves between spatial offset and probed depth based on top-layer optical properties.

Conclusions:

• Feasibility of using bilayer phantoms to correlate spatial offset with probing depth was demonstrated.
• The developed technique can facilitate clinical translation of SORS for tumor detection and margin assessment.