Research Papers: Therapeutic

Explicit dosimetry for 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a-mediated photodynamic therapy: macroscopic singlet oxygen modeling

[+] Author Affiliations
Rozhin Penjweini, Baochang Liu, Michele M. Kim, Timothy C. Zhu

University of Pennsylvania, School of Medicine, Department of Radiation Oncology, 3400 Civic Center Boulevard TRC 4W, Philadelphia, Pennsylvania 19104, United States

J. Biomed. Opt. 20(12), 128003 (Dec 24, 2015). doi:10.1117/1.JBO.20.12.128003
History: Received July 23, 2015; Accepted November 18, 2015
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Abstract.  Type II photodynamic therapy (PDT) is based on the photochemical reactions mediated through an interaction between a photosensitizer, ground-state oxygen ([O32]), and light excitation at an appropriate wavelength, which results in production of reactive singlet oxygen ([O12]rx). We use an empirical macroscopic model based on four photochemical parameters for the calculation of [O12]rx threshold concentration ([O12]rx,sh) causing tissue necrosis in tumors after PDT. For this reason, 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH)-mediated PDT was performed interstitially on mice with radiation-induced fibrosarcoma (RIF) tumors. A linear light source at 665 nm with total energy released per unit length of 12 to 100  J/cm and source power per unit length (LS) of 12 to 150  mW/cm was used to induce different radii of necrosis. Then the amount of [O12]rx calculated by the macroscopic model incorporating explicit PDT dosimetry of light fluence distribution, tissue optical properties, and HPPH concentration was correlated to the necrotic radius to obtain the model parameters and [O12]rx,sh. We provide evidence that [O12]rx is a better dosimetric quantity for predicting the treatment outcome than PDT dose, which is proportional to the time integral of the products of the photosensitizer concentration and light fluence rate.

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© 2015 Society of Photo-Optical Instrumentation Engineers

Citation

Rozhin Penjweini ; Baochang Liu ; Michele M. Kim and Timothy C. Zhu
"Explicit dosimetry for 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a-mediated photodynamic therapy: macroscopic singlet oxygen modeling", J. Biomed. Opt. 20(12), 128003 (Dec 24, 2015). ; http://dx.doi.org/10.1117/1.JBO.20.12.128003


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