title: A Comparison of Singlet Oxygen Explicit Dosimetry (SOED) and Singlet Oxygen Luminescence Dosimetry (SOLD) for Photofrin-Mediated Photodynamic Therapy.
abstract: Accurate photodynamic therapy (PDT) dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED) model has been developed for in vivo purposes. It involves the measurement of the key components in PDT-light fluence (rate), photosensitizer concentration, and ground-state oxygen concentration ([³O₂])-to calculate the amount of reacted singlet oxygen ([¹O₂]rx), the main cytotoxic component in type II PDT. Experiments were performed in phantoms with the photosensitizer Photofrin and in solution using phosphorescence-based singlet oxygen luminescence dosimetry (SOLD) to validate the SOED model. Oxygen concentration and photosensitizer photobleaching versus time were measured during PDT, along with direct SOLD measurements of singlet oxygen and triplet state lifetime (τΔandτt), for various photosensitizer concentrations to determine necessary photophysical parameters. SOLD-determined cumulative [¹O₂]rxwas compared to SOED-calculated [¹O₂]rxfor various photosensitizer concentrations to show a clear correlation between the two methods. This illustrates that explicit dosimetry can be used when phosphorescence-based dosimetry is not feasible. Using SOED modeling, we have also shown evidence that SOLD-measured [¹O₂]rxusing a 523 nm pulsed laser can be used to correlate to singlet oxygen generated by a 630 nm laser during a clinical malignant pleural mesothelioma (MPM) PDT protocol by using a conversion formula.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA. mickim@sas.upenn.edu.|Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA. mickim@sas.upenn.edu.
authors.forename: Michele M
authors.initials: MM
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA. Rozhin.Penjweini@uphs.upenn.edu.
authors.forename: Rozhin
authors.initials: R
authors.lastname: Penjweini
authors.affiliation: Department of Electronic and Nanoscale Engineering, University of Glasgow, Glasgow G12 8LT, UK. Nathan.Gemmell@glasgow.ac.uk.
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Gemmell
authors.affiliation: Princess Margaret Cancer Centre, University of Toronto, ON M5G 1L7, Canada. israel.veilleux@uhnresearch.ca.
authors.forename: Israel
authors.initials: I
authors.lastname: Veilleux
authors.affiliation: Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK. A.McCarthy@hw.ac.uk.
authors.forename: Aongus
authors.initials: A
authors.lastname: McCarthy
authors.affiliation: Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK. g.s.buller@hw.ac.uk.
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Buller
authors.affiliation: Department of Electronic and Nanoscale Engineering, University of Glasgow, Glasgow G12 8LT, UK. Robert.Hadfield@glasgow.ac.uk.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Hadfield
authors.affiliation: Princess Margaret Cancer Centre, University of Toronto, ON M5G 1L7, Canada. wilson@uhnresearch.ca.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Wilson
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA. tzhu@mail.med.upenn.edu.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Zhu
keywords: Photofrin; oxygen; photodynamic therapy; singlet oxygen explicit dosimetry (SOED); singlet oxygen luminescence dosimetry (SOLD)