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1.
Figure 8

Figure 8. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

Results of SVD fitting to representative fluorescence spectra collected from (a) two-layer and (b) three-layer phantoms, with spectra corrected for background and system response. Fit magnitudes shown are not corrected for the effects of fluorescence quantum yield and absorption at 488 nm.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
2.
Figure 1

Figure 1. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

Schematic of the cylindrical diffusing fiber, showing the four regions that are modeled. Photon packets are launched from the fiber core, with the diffusive medium being treated as having negligible absorption, and the cladding being treated as having negligible absorption and scattering. The dielectric reflector is treated as a perfect reflector.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
3.
Figure 3

Figure 3. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

Simulated irradiance profiles along the surface of a 1 cm diffuser, with its proximal end at z = 1 cm, illustrating the effect of changing μs. Simulation parameters are identical in both cases except for the value of μs inside the diffusive region, which was (a) 0.2009 cm−1 and (b) 10 cm−1.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
4.
Figure 2

Figure 2. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

Experimental set-up for measurement of fluorescence in (a) two-layer and (b) three-layer phantoms. The diffuser was inserted such that each layer bordered on an equal length of the diffuser. Only one diffuser is shown for clarity, but experiments used two diffusers inserted in parallel with a separation of 1 cm. One diffuser was used for delivery of an axially homogeneous fluorescence excitation profile, while the other was used for detection of fluorescence.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
5.
Figure 4

Figure 4. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

3D rendering of the fluence distribution around a 1 cm cylindrical diffusing fiber with its proximal end at z = 0.5 cm and an air-tissue boundary at z = 0. Tissue optical properties were set to μa = 2 cm−1, μs = 100 cm−1, and g = 0.9. Voxel size was 0.02×0.02×0.02 cm.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
6.
Figure 7

Figure 7. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

Simulated detected fluorescence by axial position along (a) 1 to 2 cm diffusers with μa = 2 cm−1, (b) 3 to 5 cm diffusers with μa = 2 cm−1, (c) 1 to 2 cm diffusers with μa = 0.2 cm−1, and (d) 3 to 5 cm diffusers with μa = 0.2 cm−1. All simulations used μs = 90 cm−1 and g = 0.82, and placed the diffuser's proximal end at z = 0.5 cm. The arrows indicate the location of the proximal end of the diffusers.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
7.
Figure 5

Figure 5. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

Comparison between linear array of point sources model and our MC model in terms of radial degradation of fluence for μa = 2 cm−1, showing substantial overlap between the two methods. Shown is a cut through the fluence at the axial center of a 1 cm diffuser. Simulation parameters were identical, except for the source model. The arrow indicates the position of the outer radius of the diffuser.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
8.
Figure 6

Figure 6. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

(a) Fluorescence generated in tissue by a 1-cm diffuser with its proximal end at z = 2 cm and an outer radius of 0.05 cm. (b) Origins of fluorescence photons that crossed into the diffuser after being generated in the surrounding tissue. (c) Origins of fluorescence photons that were detected by the diffuser. μa was set to 2 cm−1 in tissue. Planar cuts are shown through the simulated volume at the center of the diffuser. Only the right half of this plane is shown for clarity. The left half is identical.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.
9.
Figure 9

Figure 9. From: New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation.

Comparison between simulated and experimental fluorescence detection using (a) 1 cm and (b) 1.5 cm diffusers. Heights of experimental bars (□) indicate the mean value of (a) n = 6 and (b) n = 4 experiments, with error bars representing standard deviation. Values used were corrected for background, system response, fluorescence quantum yield, and absorption at 488 nm. Heights of simulated bars (■) indicate the mean value of 3 simulations, with error bars representing the standard deviation. The value of μa was set to 2 cm−1 for both simulation and experiment.

Timothy M. Baran, et al. J Biomed Opt. 2011 August;16(8):085003.

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