Macroscopic singlet oxygen model incorporating photobleaching as an input parameter

Michele M. Kim; Jarod C. Finlay; Timothy C. Zhu

doi:10.1117/12.2079046

2 March 2015 Macroscopic singlet oxygen model incorporating photobleaching as an input parameter

Michele M. Kim, Jarod C. Finlay, Timothy C. Zhu

Proceedings Volume 9308, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXIV; 93080V (2015) https://doi.org/10.1117/12.2079046
Event: SPIE BiOS, 2015, San Francisco, California, United States

Abstract

A macroscopic singlet oxygen model for photodynamic therapy (PDT) has been used extensively to calculate the reacted singlet oxygen concentration for various photosensitizers. The four photophysical parameters (ξ, σ, β, δ) and threshold singlet oxygen dose ([¹O₂]_r,sh) can be found for various drugs and drug-light intervals using a fitting algorithm. The input parameters for this model include the fluence, photosensitizer concentration, optical properties, and necrosis radius. An additional input variable of photobleaching was implemented in this study to optimize the results. Photobleaching was measured by using the pre-PDT and post-PDT sensitizer concentrations. Using the RIF model of murine fibrosarcoma, mice were treated with a linear source with fluence rates from 12 - 150 mW/cm and total fluences from 24 – 135 J/cm. The two main drugs investigated were benzoporphyrin derivative monoacid ring A (BPD) and 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH). Previously published photophysical parameters were fine-tuned and verified using photobleaching as the additional fitting parameter. Furthermore, photobleaching can be used as an indicator of the robustness of the model for the particular mouse experiment by comparing the experimental and model-calculated photobleaching ratio.

Citation Download Citation

Michele M. Kim, Jarod C. Finlay, and Timothy C. Zhu "Macroscopic singlet oxygen model incorporating photobleaching as an input parameter", Proc. SPIE 9308, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXIV, 93080V (2 March 2015); https://doi.org/10.1117/12.2079046

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