title: Quantitative monitoring of radiation induced skin toxicities in nude mice using optical biomarkers measured from diffuse optical reflectance spectroscopy.
abstract: Monitoring the onset of erythema following external beam radiation therapy has the potential to offer a means of managing skin toxicities via biological targeted agents - prior to full progression. However, current skin toxicity scoring systems are subjective and provide at best a qualitative evaluation. Here, we investigate the potential of diffuse optical spectroscopy (DOS) to provide quantitative metrics for scoring skin toxicity. A DOS fiberoptic reflectance probe was used to collect white light spectra at two probing depths using two short fixed source-collector pairs with optical probing depths sensitive to the skin surface. The acquired spectra were fit to a diffusion theory model of light transport in tissue to extract optical biomarkers (hemoglobin concentration, oxygen saturation, scattering power and slope) from superficial skin layers of nude mice, which were subjected to erythema inducing doses of ionizing radiation. A statistically significant increase in oxygenated hemoglobin (p < 0.0016) was found in the skin post-irradiation - confirming previous reports. More interesting, we observed for the first time that the spectral scattering parameters, A (p = 0.026) and k (p = 0.011), were an indicator of erythema at day 6 and could potentially serve as an early detection optical biomarker of skin toxicity. Our data suggests that reflectance DOS may be employed to provide quantitative assessment of skin toxicities following curative doses of external beam radiation.
authors.affiliation: Department of Physics, Ryerson University, Ontario, Canada ; These authors contributed equally to this work.
authors.forename: Darren
authors.initials: D
authors.lastname: Yohan
authors.affiliation: Department of Medical Physics, Odette Cancer Centre, Sunnybrook Health Sciences Centre Canada ; These authors contributed equally to this work.
authors.forename: Anthony
authors.initials: A
authors.lastname: Kim
authors.affiliation: Department of Medical Biophysics, University of Toronto and Ontario Cancer Institute / Campbell Family Institute for Cancer Research Canada.
authors.forename: Elina
authors.initials: E
authors.lastname: Korpela
authors.affiliation: Department of Medical Biophysics, University of Toronto and Ontario Cancer Institute / Campbell Family Institute for Cancer Research Canada ; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Stanley
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Medical Biophysics, University of Toronto and Ontario Cancer Institute / Campbell Family Institute for Cancer Research Canada.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Niu
authors.affiliation: Department of Medical Biophysics, University of Toronto and Ontario Cancer Institute / Campbell Family Institute for Cancer Research Canada.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Wilson
authors.affiliation: Department of Physics, Ryerson University, Ontario, Canada ; Department of Medical Physics, Odette Cancer Centre, Sunnybrook Health Sciences Centre Canada ; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Lee Cl
authors.initials: LC
authors.lastname: Chin
keywords: (170.4580) Optical diagnostics for medicine; (170.6510) Spectroscopy, tissue diagnostics