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Propagation of fluorescent light
A J Welch1, C Gardner, R Richards-Kortum
1Biomedical Engineering Program, University of Texas, Austin 78712, USA.
Lasers in Surgery and Medicine
|January 1, 1997
Summary
Monte Carlo simulations reveal that tissue optical properties and geometry significantly impact remitted fluorescence. Distal tissue layers influence fluorescence, and small samples may yield inaccurate spectra due to wavelength-dependent losses.
Area of Science:
- Biomedical Optics
- Photonic Spectroscopy
- Tissue Optics
Background:
- Remitted fluorescence spectra are influenced by tissue scattering, absorption, boundary conditions, sample geometry, and fluorophore quantum yield.
- Understanding these factors is crucial for accurate interpretation of fluorescence-based tissue diagnostics.
Purpose of the Study:
- To investigate the impact of tissue optical properties and geometry on remitted fluorescence using Monte Carlo simulations.
- To compare simulation results with a heuristic model for validating findings.
Main Methods:
- Monte Carlo modeling was employed to simulate excitation light propagation and fluorescence emission.
- Simulations covered semi-infinite single/multiple layer and cubic geometries representing small tissue samples.
- Remitted fluorescence was analyzed as a function of fluorescence generation depth and radial escape position.
Main Results:
- Detailed presentation of remitted fluorescence based on depth and radial escape for various geometries.
- Analysis of fluorescence losses from small cubic samples as a function of dimensions and optical depth.
- Comparison of Monte Carlo results with a heuristic model for homogeneous semi-infinite layers.
Conclusions:
- Monte Carlo simulations and the heuristic model delineate the interrogated tissue volume for fluorescence.
- Approximately 35-40% of remitted fluorescence originates from photons directed away from the surface, highlighting the influence of deeper tissue layers.
- Wavelength-dependent losses can distort fluorescence spectra from small biopsy samples, potentially affecting diagnostic accuracy.