Nonlinear Behavior of the Autofluorescence Intensity on the Surface of Light-Scattering Biotissues and its Theoretical Proofстатья
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Дата последнего поиска статьи во внешних источниках: 20 октября 2021 г.
Аннотация:In the up-to-date medical laser fluorescence spectroscopy
(LFS) in vivo, there is a problem of quantification
of fluorophores concentrations in optically-turbid biotissues
by measurements of the laser induced autofluorescence flux
on the surface of these tissues. One of the main problems is:
whether the flux depends linearly or non-linearly on the concentration
of fluorophores in tissues? The purpose of this work
was both experimental and theoretical study of the character of
dependencies between measured fluorescence intensities and
fluorophores concentrations in optically-turbid media. In the
experimental part of our study, measurements of the superficial
fluorescence on phantoms at various known concentrations of
fluorophores in them were carried out. As a result, experimental
dependencies of registered intensities of the laser-induced
autofluorescence emission were plotted against fluorophore
concentrations. In the theoretical part of the study, the analytical
solution for the fluorescence emission by Kokhanovsky’s
method based on the well-known two-flux Kubelka-Munk approach
(KMA) was used. In addition, in our study the
Kokhanovsky’s method was modified by its association with
our improved KMA, allowing us to receive exact analytical
solutions for boundary intensities collected by optical probes.
As a result, a set of theoretical curves describing the influence
of fluorophore concentrations on the registered autofluorescence
intensities was obtained, as well. Both experimental
and theoretical results show a good qualitative agreement with
each other. Also, these results demonstrate that the dependence
of the fluorescence intensity on tissues’ optical properties and
on the concentration of fluorophores in light-scattering tissues
can be both nonlinear and non-monotonic.