Fig. 8.

Pressure-induced optical parameter deviations. (a) Map of [$\beta$-carotene] concentration of the layered phantom with a two region slab [high scattering low beta, low scattering low beta (center region)]. Likewise, (b) shows the wavelength averaged ${\mu }_{\mathrm{s}}^{\prime }$ (${\mathrm{cm}}^{-1}$) and reveals a similar trend as the center region has a slightly reduced ${⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ (7 to 6.2). (c) Shows the amount of compression during the experiment with the phantom diagrammed in the plot; yellow represents the adipose layer, red the center region, and orange the remaining cancer slab. (d) Shows the $[\beta \text{-carotene}]/{⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ trend for the center region indicated by the box labeled 1. The yellow line represents the expected value. (e) Similarly shows the trend for the region indicated by box 2 and not influenced by the center region. Note the distinct drop in the $[\beta \text{-carotene}]/{⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ ratio beyond 15 mm Hg; this is due to the highly scattering nature of the cancer slab, having a ${⟨{\mu }_{\mathrm{s}}^{\prime }⟩}_{\lambda }$ of $15{\mathrm{cm}}^{-1}$.