title: Determination of tissue optical properties in PDT treated Head & Neck patients.
abstract: Determination of optical properties (absorption (μa) and scattering (μs') coefficients) in human tissue is important when it comes to accurate calculation of fluence rate in and around tissue area. ALA application to the tissue induces production of protoporphyrin IX when activated by red light. Changes in the tissue optical properties can send information such as treatment outcome and tissue drug concentration. Patients in this study were treated with PDT for head and neck mucosal dysplasia. They were enrolled in a phase I study of escalating light doses and oral ALA with 60mg/kg. Red light at 630nm was administered to the tumor from a laser. The light dose was escalated from 50-200J/cm2with a measured fluence rate at tissue surface of 100mW/cm2. We developed a light detection device for the purpose of determining optical properties in vivo using the semi-infinite method. The light detection device consists of two parallel, placed 5mm apart. In one of the catheters a 2 mm long linear diffusing light source is placed while in the second catheter, a calibrated isotropic detector is placed. The detector is scanned along the length of the light source containing catheter. Scans are done with the device placed on the treatment area (tumor) and on the normal tissue. Optical properties were measured in-vivo before and after PDT delivery for both normal tissue and tumor.
authors.affiliation: Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Andreea
authors.initials: A
authors.lastname: Dimofte
authors.affiliation: Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Jarod C
authors.initials: JC
authors.lastname: Finlay
authors.affiliation: Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Anna V
authors.initials: AV
authors.lastname: Sharikova
authors.affiliation: Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Cengel
authors.affiliation: Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Peter
authors.initials: P
authors.lastname: Ahn
authors.affiliation: Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Busch
authors.affiliation: Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Zhu
keywords: ALA; Optical properties; head and neck; photodynamic therapy