title: Characterization and standardization of tissue-simulating protoporphyrin IX optical phantoms.
abstract: Optical devices for measuring protoporphryin IX (PpIX) fluorescence in tissue are routinely validated by measurements in optical phantoms. Yet there exists limited data to form a consensus on the recipe for phantoms that both mimic the optical properties found in tissue and yield a reliable and stable relationship between PpIX concentration and the fluorescence remission intensity. This study characterizes the influence of multiple phantom components on PpIX fluorescence emission intensity, using Intralipid as the scattering source, bovine whole blood as the background absorber, and Tween as a surfactant to prevent PpIX aggregation. Optical measurements showed a linear proportionality (r > 0.99) between fluorescence intensity and PpIX concentration (0.1 to 10 μg/mL) over a range of Intralipid (1 to 2%) and whole blood (0.5 to 3%) for phantoms containing low surfactant (≤ 0.1%), with fluorescence intensities and scattering and absorption properties stable for 5 h after mixing. The role of surfactant in PpIX phantoms was found to be complex, as aggregation was evident in aqueous nonturbid phantoms with no surfactant (0% Tween), and avoided in phantoms containing Intralipid as the scattering source with no additional or low amounts of added surfactant (≤ 0.1% Tween). Conversely, phantoms containing higher surfactant content (>0.1% Tween) and whole blood showed interactions that distorted the fluorescence emissions.
authors.affiliation: Polytechnique Montreal, 2500 Chemin de Polytechnique, Montreal, Quebec H3T 1J4, CanadabDartmouth College, 14 Engineering Drive, Hanover, New Hampshire 03755, United States.
authors.forename: Mikael
authors.initials: M
authors.lastname: Marois
authors.affiliation: Polytechnique Montreal, 2500 Chemin de Polytechnique, Montreal, Quebec H3T 1J4, Canada.
authors.forename: Jaime
authors.initials: J
authors.lastname: Bravo
authors.affiliation: Dartmouth College, 14 Engineering Drive, Hanover, New Hampshire 03755, United StatescNorris Cotton Cancer Center, Dartmouth Hitchcock Medical Center, 1 Medical Center Drive, Lebanon, New Hampshire 03766, United States.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Davis
authors.affiliation: Dartmouth College, 14 Engineering Drive, Hanover, New Hampshire 03755, United StatescNorris Cotton Cancer Center, Dartmouth Hitchcock Medical Center, 1 Medical Center Drive, Lebanon, New Hampshire 03766, United States.
authors.forename: Stephen Chad
authors.initials: SC
authors.lastname: Kanick
mesh_terms: D008954:Models, Biological; D061848:Optical Imaging / Q000295:instrumentation*; D019047:Phantoms, Imaging; D011524:Protoporphyrins / Q000032:analysis*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D013501:Surface-Active Agents
chemical_list: D011524:Protoporphyrins; D013501:Surface-Active Agents; C028025:protoporphyrin IX