Article

Medical and Biological Engineering and Computing

, Volume 42, Issue 5, pp 669-673

First online:

Influence of illumination-collection geometry on fluorescence spectroscopy in multilayer tissue

  • T. J. PfeferAffiliated withCenter for Devices & Radiological Health, US Food & Drug Administration Email author 
  • , L. S. MatchetteAffiliated withCenter for Devices & Radiological Health, US Food & Drug Administration
  • , R. DrezekAffiliated withDepartment of Bioengineering, Rice University

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Abstract

Device-tissue interface geometry influences both the intensity of detected fluorescence and the extent of tissue sampled. Previous modelling studies have often investigated fluorescent light propagation using generalised tissue and illumination-collection geometries. However, the implementation of approaches that incorporate a greater degree of realism may provide more accurate estimates of light propagation. In this study, Monte Carlo modelling was performed to predict how illumination-collection parameters affect signal detection in multilayer tissue. Using the geometry and optical properties of normal and atherosclerotic aortas, results for realistic probe designs and a semi-infinite source-detection scheme were generated and compared. As illumination-collection parameters, including single-fibre probe diameter and fibre separation distance in multifibre probes, were varied, the signal origin deviated significantly from that predicted using the semi-infinite geometry. The semi-infinite case under-predicted the fraction of fluorescence originating from the superficial layer by up to 23% for a 0.2 mm diameter single-fibre probe and over-predicted by 10% for a multifibre probe. These results demonstrate the importance of specifying realistic illumination-collection parameters in theoretical studies and indicate that targeting of specific tissue regions may be achievable through customisation of the illumination-collection interface. The device- and tissue-specific approach presented has the potential to facilitate the optimisation of minimally invasive optical systems for a wide variety of applications.

Keywords

Fibre-optic probe Fluorescence spectroscopy Light-tissue interaction Monte Carlo modelling Optical diagnostics