In this paper we present two-dimensional phantom measurements of fluorescence light distribution in the frequency
domain and reconstruction of three-dimensional fluorophore distribution. An experimental set-up was built up with two
dimensional laser scanning, intensity modulation with frequencies up to 1 GHz, and two-dimensional imaging of
modulated fluorescence light. Stable phantoms were developed simulating mammary tissue to perform measurements in
a backscattering geometry for a variety of cylindrical fluorescence sources with different diameters, fluorophore
concentrations, and surface distances at different modulation frequencies. At first calculated fluorescence light
distributions from Monte-Carlo simulations was compared to measured data. In a second step from tomographic data sets
of calculated fluorescent light, three-dimensional tomographic reconstructions of fluorophore distribution were
performed. Finally three-dimensional tomographic reconstructions of fluorophore distribution were performed from
tomographic fluorescence measurements. We found good concurrence between measured and calculated fluorescence
distribution. Synthetic and real tomographic reconstruction showed good localization but underestimated the depth of
fluorophore distribution.
Raman signals of biological tissues are distorted by the influence of tissue absorption and scattering properties, which
significantly challenges signal quantification. We investigated the influence of the tissue optical properties on the
resonance Raman signal of β-carotene with tissue phantom measurements and Monte Carlo simulations. Both methods
show that the Raman signal drops roughly proportional to 1/μa for absorption coefficients (μa) in the range of 0.1-4mm-1.
The influence of the reduced scattering coefficient in the range of 0.1-8mm-1 is less strong, but not negligible. We
introduce combined Raman and spatially resolved reflectance measurements to measure both Raman signals and tissue
optical properties. The optical properties were deduced from the spatially resolved reflectance measurements by a Monte
Carlo-based lookup table (LUT). For the signal correction we applied correction functions derived from the Monte Carlo
simulations. We corrected in vivo resonance Raman measurements of carotenoids in caucasian skin (n=9) with respect to
the mean optical properties of the group. The magnitude of the average correction effect was found to be 18±11% on the
minimal pigmented palm.
An experimental set-up is presented for wavelength and spatially resolved reflectance measurements (SRR) via optical
fibers and imaging optics. In order to characterize the set-up, we made a set of silicone rubber phantoms with different
absorber and scatterer concentrations. The remission profiles gained from the phantoms are the input for a look-up table
(LUT) based "inverse Monte-Carlo simulation" to deduce absorption μa and reduced scattering coefficients μs'. As an independent method for determination of μa and μs' we also made measurements with an 'integrating sphere
spectrometer' (ISS). Our normalization procedure of the SRR measurements is presented and the validity of this method
is discussed.
With a cardanically mounted micromirror a confocal laser scanning microscope for in vivo imaging was built. A
resolution of 0.6 μm laterally and 10 μm axially allows to image tissue and cells in good quality. Samples of skin and
adhered cells are imaged either in reflection or in fluorescence with an excitation wavelength of 682 nm. Fluorescence
of Indocyanine Green is detected in the wavelength range above 730 nm.
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