Optimization of source-detector separation for enhanced spatially resolved fluorescence from epithelial layer

Epithelial cancers, constituting the majority of human cancer cases, can be identified by alterations in the biochemical and morphological characteristics of the thin epithelial layer (ranging from 100 μm to 500 μm), serving as an initial indication of the disease. Many researchers have utilised spatially resolved fiber optic probes and fluorescence spectroscopy technique to detect subtle variations in the optical properties of the epithelium layer of tissue. This study explores the impact of the incident and different collection configurations on epithelium layer sensitivity for spatially resolved fluorescence. Monte Carlo simulation reveals that a fiber probe with illumination-collection at 45-degree beveled angle in parallel configuration provides maximum fluorescence from the epithelium layer. This configuration is suitable for both in vitro and in vivo settings for epithelial precancer diagnosis. The efficacy of the 45-degree beveled angle fiber probe for measuring spatially resolved sensitivity has also been validated experimentally using two layer solid tissue-mimicking phantoms which demonstrates strong agreement with the results generated from Monte Carlo simulation. These findings suggest that employing an optimum source detector configuration enables the collection of enhanced spatially resolved fluorescence from the epithelium layer.