Phantom experiments were used to achieve four objectives: (1) characterize the linearity of response to PpIX concentration for both fluorescence channels, (2) determine the minimum detectable concentration of PpIX for both fluorescence channels, (3) determine the accuracy of the white light reflectance analysis in estimating scattering parameters and chromophore concentrations, and (4) examine the stability of the fluorescence measurements to background optical properties with and without correction. Phantoms were constructed using Intralipid (20% Frenius-Kabi, Bad Homburg, Germany), bovine whole blood (7200811 Lampire Biological Inc., Pipersville, Pennsylvania), and PpIX (P8293, Sigma-Aldrich, St. Louis, Missouri). All phantoms were composed of 5% Tween20 (P1379, Sigma-Aldrich) to mitigate aggregation. To explore linearity of response and minimum detection limits of PpIX fluorescence, measurements were acquired in phantoms composed of 1% Intralipid, and 1% BVF, and over a range of . To examine accuracy of white light reflectance analysis and stability to changes in optical properties, measurements were acquired in phantoms prepared using volume fractions of Intralipid [1, 2, 3] % and whole blood [0.5, 1, 2, 3] %. This resulted in 12 phantom combinations, each of which was sampled using serial dilutions of PpIX to achieve . For each phantom composition, white light reflectance, and blue- and red-excited fluorescence measurements were acquired, and measurements were repeated three times. To determine the lower limit of detection for each fluorescence metric (), the data were fit to a line forced through zero, and the lower limit was identified as the highest [PpIX] at which the metric deviated from the fit. Estimated optical parameters were compared with known phantom properties (i.e., BVF and ) using the Pearson correlation coefficient () to show linearity, and the mean residual was calculated as .