Schematic of the gain-modulated intensified CCD imaging system using a breast-shaped tissue phantom. Frequency-domain experiments are performed using 100 MHz modulated light source, launched via optical fibers. The different components in the schematic include: (a) breast-shaped tissue phantom; (b) laser diode (source); (c) collecting optical fibers; (d) interfacing plates; and (e) intensified CCD camera lens.
Flowsheet of the two-stage image reconstruction algorithm.
Three-dimensional iso-surface plots of fluorescence absorption distributions for (a) Case 1, (b) Case 2, and (c) Case 3. The reconstructed target (solid region inside breast phantom) was differentiated from background phantom at iso-surface cutoff values of 30% of the maximum reconstructed in each case. The true 1 cc volume target is shown by a black wire frame.
Normalized convergence plots for (a) Stage-1 and (b) Stage-2 reconstructions, and for all three experimental cases.
Four views of the 3D fluorescence lifetime reconstructions for Case 3. (a) 3D iso-surface plot of the lifetime distribution (iso-surface cutoff at 30% of the maximum lifetime value with respect to background lifetime), (b)–(d) orthogonal contour slices through the true centroid location (shown by white crosshairs).
Bar plot of the Stage 2 reconstructed (maximum value of) T:B lifetime contrast for Cases 1, 2, and 3, imposing three different levels of rescaled contrast in the true fluorescence absorption structure.
Generic pseudocode for a computationally efficient version of the approximate extended Kalman filter (AEKF) algorithm.
Experimental case studies performed using a single 1 cc target located at various depths, under varying T:B contrasts in fluorescence absorption and lifetime .
Background optical absorption and reduced scattering coefficients of 1% Liposyn solution in tissue phantoms at excitation (subscript ) and emission (subscript ) wavelengths due to fluorophore (subscript ) and nonfluorescing chromophore (subscript ), for the different experimental cases studied. All the units are in .
Mean and/or variance of model mismatch and measurement errors for the three experimental cases (using measurements above noise floor).
Reconstructed T:B contrast values of fluorescence absorption and lifetime for all experimental cases. Max(T):B corresponds to maximum reconstructed value of the optical parameter in the target relative to the background.
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