Fig. 7.

Contrast in tissue. (a) Possible $[\beta \text{-carotene}]/{⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ values for a line scan ($\chi$) across a rectangular volume ($l\times w\times h=0.25\times 0.25\times 3\mathrm{mm}$) with cancer-like optical properties surrounded by a semi-infinite adipose slab (the geometry is shown in Sec. 2.8), shown as a function of $\mathrm{\Delta }s$. Similarly, (b) and (c) represent possible $[\beta \text{-carotene}]/{⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ values for perturbations in increasing size (0.75 and 1.5 mm, respectively). The center position of the simulated photodiode is represented by $\chi$. The gray plane represents the threshold for which the heterogeneity would be correctly classified as “likely cancer.” In (d) through (f), the possible $[\beta \text{-carotene}]/{⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ estimates are condensed in box-and-whisker plot format. The blue line represents the true $[\beta \text{-carotene}]/{⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ value for the cancer-like heterogeneity and the expected median value for the lower row of boxes. The dashed red line indicates the threshold for which the heterogeneity would be correctly diagnostically classified. The orange line represents the true $[\beta \text{-carotene}]/{⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ value for the adipose slab and the expected median value for the upper row of boxes.