Fig. 5.

Clinical squamous cell carcinoma. (a),(b) White light and LOT image at 0.20mm source-detector separation (inset) of squamous cell carcinoma lesion (metric ruler at left for scale). Yellow dashed line indicates approximate location of histopathology section from superior (S) to inferior (I) margins. (c) 532 nm LOT image showing regions of interest selected for differential contrast measurement. White box = reference region, Blue and green boxes = regions of interest. Red box = normal region. (d) Raw LOT frames taken at 532nm and RGB merged data for 5 source-detector (s-d) separations. Anomalous red structures are highlighted by yellow arrows (and black arrows in (b)). Note that the pink circles in wider separations are a specular reflection caused by the variable position of the articulating arm between imaging and calibration scans [21]. (e),(f) Plots of differential contrast and fit parameters of regions in (c). Error bars show standard deviations of 15 repeated scans. RMS error of fit for the red, green, and blue ROIs were 0.0462, 0.0528, and 0.0622, respectively. Note that the blue and green regions appear to be deeper than the red region (which is off scale to the left, implying a very superficial source of contrast). (g) H&E histopathology section from yellow dashed line. Scale bar 200 microns. Red arrowheads show increased subsurface blood accumulation, black arrowheads show adjacent aggregates of dysplastic keratinocytes.