Fig. 6

(A) The first two normalized components of the OD spectra obtained using PCA (n = 5 components). (B) The graph of the first PCA component plotted versus the second PCA component for the parathyroid gland (orange) and other tissue types (blue). (C) Effective optical density spectra of the thyroid under different probe pressures on the inspected tissue site. For panels (B,C) the black-to-red gradient indicates the data obtained by varying the probe pressure on the inspected tissue site. The graph of the water index (green) and \(\:\text{H}\text{b}{\text{O}}_{2}^{{\prime\:}}\) (orange) plotted versus relative probe pressure is shown in the inset.