Optimization of physiological parameter for macroscopic modeling of reacted singlet oxygen concentration in an in-vivo model

Ken Kang Hsin Wang, Theresa M. Busch, Jarod C. Finlay, Timothy C. Zhu

Research output: Contribution to journalConference articlepeer-review

9 Scopus citations

Abstract

Singlet oxygen ( 1O 2) is generally believed to be the major cytotoxic agent during photodynamic therapy (PDT), and the reaction between 1O 2 and tumor cells define the treatment efficacy. From a complete set of the macroscopic kinetic equations which describe the photochemical processes of PDT, we can express the reacted 1O2 concentration, [ 1O 2]rx, in a form related to time integration of the product of 1O 2 quantum yield and the PDT dose rate. The production of [ 1O 2]rx involves physiological and photophysical parameters which need to be determined explicitly for the photosensitizer of interest. Once these parameters are determined, we expect the computed [ 1O 2]rx to be an explicit dosimetric indicatorfor clinical PDT. Incorporating the diffusion equation governing the light transport in turbid medium, the spatially and temporally-resolved [ 1O 2]rx described by the macroscopic kinetic equations can be numerically calculated. A sudden drop of the calculated [ 1O 2]rx along with the distance following the decrease of light fluence rate is observed. This suggests that a possible correlation between [ 1O 2]rx and necrosis boundary may occur in the tumor subject to PDT irradiation. In this study, we have theoretically examined the sensitivity of the physiological parameter from two clinical related conditions: (1) collimated light source on semi-infinite turbid medium and (2) linear light source in turbid medium. In order to accurately determine the parameter in a clinical relevant environment, the results of the computed [ 1O 2]rx are expected to be used to fit the experimentally-measured necrosis data obtained from an in vivo animal model.

Original languageEnglish (US)
Article number71640O
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume7164
DOIs
StatePublished - 2009
Externally publishedYes
EventOptical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVIII - San Jose, CA, United States
Duration: Jan 24 2009Jan 25 2009

Keywords

  • Light transport
  • Oxygen diffusion
  • PDT dosimetry
  • Photodynamic therapy
  • Singlet oxygen

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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