title: The ratio of the spherical and flat Detectors at tissue surfaces during pleural photodynamic therapy.
abstract: An isotropic detector-based system was compared with a flat photodiode-based system in patients undergoing pleural photodynamic therapy. Isotropic and flat detectors were placed side by side in the chest cavity, for simultaneousin vivodosimetry at surface locations for twelve patients. The treatment used 630nm laser to a total light irradiance of 30 J/cm2(measured with the flat photodiodes) with photofrin® IV as the photosensitizer. Since the flat detectors were calibrated at 532nm, wavelength correction factors (WCF) were used to convert the calibration to 630nm (WCF between 0.542 and 0.703). The mean ratio between isotropic and flat detectors for all sites was linear to the accumulated fluence and was 3.4±0.6 or 2.1±0.4, with or without the wavelength correction for the flat detectors, respectively. The μeffof the tissues was estimated to vary between 0.5 to 4.3 cm-1for four sites (Apex, Posterior Sulcus, Anterior Chest Wall, and Posterior Mediastinum) assuming μs' = 7 cm-1. Insufficient information was available to estimate μeffdirectly for three other sites (Anterior Sulcus, Posterior Chest Wall, and Pericardium) primarily due to limited sample size, although one may assume the optical penetration in all sites to vary in the same range (0.5 to 4.3 cm-1).
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, PA.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Zhu
authors.affiliation: Department of Surgery, Thomas Jefferson University, PA.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Friedberg
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, PA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Dimofte
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, PA.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Miles
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, PA.
authors.forename: James
authors.initials: J
authors.lastname: Metz
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, PA.
authors.forename: Eli
authors.initials: E
authors.lastname: Glatstein
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, PA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Hahn
keywords: diffuse reflectance; effective attenuation coefficient; pleural PDT; ratio of spherical-to-flat detectors