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Propagation of fluorescent light
Author(s) -
Welch A. J.,
Gardner Craig,
RichardsKortum Rebecca,
Chan Eric,
Criswell Glen,
Pfefer Josh,
Warren Steve
Publication year - 1997
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/(sici)1096-9101(1997)21:2<166::aid-lsm8>3.0.co;2-o
Subject(s) - monte carlo method , fluorescence , wavelength , optics , photon , absorption (acoustics) , molecular physics , materials science , physics , computational physics , chemistry , mathematics , statistics
Background and Objective In general, the remitted fluorescence spectrum is affected by the scattering and absorption properties of tissue. Other important factors are boundary conditions, geometry of the tissue sample, and the quantum yield of tissue fluorophores. Each of these factors is examined through a series of Monte Carlo simulations. Study Design/Materials and Methods Monte Carlo modeling is used to simulate the propagation of excitation light and the resulting fluorescence. Remitted fluorescence is determined for semi‐infinite single and multiple layer geometries and for cubic geometries representing small tissue samples. Monte Carlo results are compared to approximations obtained with a heuristic model. Results Remitted fluorescence as a function of (1) the depth of fluorescence generation and (2) radial escape position is presented for semi‐infinite single and multiple layer geometries. Fluorescence from a small tissue sample is simulated in terms of a cubic geometry, and losses from the sides and bottom are presented as a function of cube dimensions in terms of optical depth of the excitation wavelength. Monte Carlo results for a homogeneous semi‐infinite layer are compared to a simple, fast heuristic model. Conclusion Both Monte Carlo simulations and the heuristic model clearly detail the volume of tissue interrogated by fluorescence. Since ∼ 35–40% of the remitted fluorescence is due to photons originally directed away from the surface, distal layers affect the remitted fluorescence. Fluorescence spectra from small biopsy samples may not produce the correct line shape owing to wavelength dependent losses. Lasers Surg. Med. 21:166–178, 1997. © 1997 Wiley‐Liss, Inc.