Article Figures & Data
Figures
- Figure 1.
Graphical depiction of the BSF calculation process: the distribution of the scattered photons ksc(z,ρ,τ) is a product of the spatial distribution h(z,ρ,τ) and the temporal dispersion distribution G(z,τ) (Eq. 1). The time-dependent distribution is integrated over time to obtain the intensity values ksc(z,ρ), and added to the distribution of the unscattered photons kusc(z,ρ) for the total distribution k(z,ρ) (Eq. 4), called the BSF. Note that the equations also include absorption effects that were omitted from the figure for simplicity.
- Figure 2.
a, Simulation procedure: the 1st stage is the calculation of a 3D pencil-beam response, the 2nd stage is the angular convolution of the pencil beam response, and the 3rd stage is a spatial convolution with the fiber tip area. b, Simulation outcomes of the various simulation steps. For better visualization, all of the figures are in log scale. c, Illustration of the experimental setup cross-section.
- Figure. 3.
Comparisons of MC and BSF methods for two different tissue-scattering parameter settings: µs =168.6 cm−1 (top; from Al-Juboori et al. 2013) and µs =120 cm−1 (bottom; from Yaroslavsky et al. 2002). a, Contour maps of the light distribution in the tissue, created using the MC method. b, Contours created using the BSF method. The iso-intensity lines are at 50, 20, 5, and 1% of maximum. c, Light transmission curves along the z-axis.
- Figure. 4.
Transmission of light along the z-axis, comparing published experimental results (red dotted curves) with BSF method (blue curves). a, Best-fit curves to measured data from Aravanis et al. (2007). b, Experimental data from Al-Juboori et al. (2013) measured from the peduncopontine tegmental nucleus; the optical parameters used for the BSF curve are explained in the text.
- Figure. 5.
Experimental results: light transmission in a mouse cortex along the z-axis (a) and the radial axis (b) at 300 μm (blue) and 600 μm (red). The solid lines are the best fit of the BSF model. c, Surface plot of the simulated light distribution in the slice, obtained with BSF model using the experimentally estimated parameters (µs = 211 cm−1, g = 0.86), with overlaid experimental measurements (colors matched to a and b). Light transmission is in log scale. d, Contour map of the simulated light distribution.
Tables
Source Brain sample Wavelength, nm Scattering coefficient, cm−1 Anisotropy factor Our experiment Adult mouse cortex, (5 months old) 473 211 0.86 Aravanis et al. (2007) Mouse cortex 473 60.7 0.885 Al-Juboori et al. (2013) Mouse subcortical, (6–8 weeks old) 453 168.6 — Azimipour et al. (2014) Rat cortex 532 ∼170 ∼0.9 Yaroslavsky et al. (2002) Human gray matter 480 120 0.88 Fiber properties Volume illuminated (10−3 
mm3), %NA Diameter, µm >50 >20 >5 >1 0.1 25 0.02 0.04 0.09 0.20 0.22 50 0.06 0.14 0.34 0.79 0.22 105 0.29 0.68 1.48 3.28 0.22 200 1.07 2.56 5.53 13.7 0.22 365 3.62 8.71 19.5 61.7 0.37 200 1.05 2.52 5.52 14.3 0.39 200 1.05 2.51 5.50 14.4 0.39 300 2.39 5.75 12.7 38.1 0.39 400 4.30 10.4 23.3 79.4 0.48 400 4.76 10.3 23.1 79.0 Threshold is in percentage of maximal illumination.
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