Singlet oxygen explicit dosimetry to predict local tumor control for HPPH-mediated photodynamic therapy

Rozhin Penjweini; Michele M. Kim; Yi Hong Ong; Timothy C. Zhu

doi:10.1117/12.2251011

8 February 2017 Singlet oxygen explicit dosimetry to predict local tumor control for HPPH-mediated photodynamic therapy

Rozhin Penjweini, Michele M. Kim, Yi Hong Ong, Timothy C. Zhu

Proceedings Volume 10047, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVI; 1004710 (2017) https://doi.org/10.1117/12.2251011
Event: SPIE BiOS, 2017, San Francisco, California, United States

Abstract

This preclinical study examines four dosimetric quantities (light fluence, photosensitizer photobleaching ratio, PDT dose, and reacted singlet oxygen ([¹O₂]_rx)) to predict local control rate (LCR) for 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated photodynamic therapy (PDT). Mice bearing radiation-induced fibrosarcoma (RIF) tumors were treated with different in-air fluences (135, 250 and 350 J/cm²) and in-air fluence rates (50, 75 and 150 mW/cm²) at 0.25 mg/kg HPPH and a drug-light interval of 24 hours using a 1 cm diameter collimated laser beam at 665 nm wavelength. A macroscopic model was used to calculate ([¹O₂]_rx)) based on in vivo explicit dosimetry of the initial tissue oxygenation, photosensitizer concentration, and tissue optical properties. PDT dose was defined as a temporal integral of drug concentration and fluence rate (φ) at a 3 mm tumor depth. Light fluence rate was calculated throughout the treatment volume based on Monte-Carlo simulation and measured tissue optical properties. The tumor volume of each mouse was tracked for 30 days after PDT and Kaplan-Meier analyses for LCR were performed based on a tumor volume ≤100 mm3, for four dose metrics: fluence, HPPH photobleaching rate, PDT dose, and ([¹O₂]_rx)). The results of this study showed that ([¹O₂]_rx)) is the best dosimetric quantity that can predict tumor response and correlate with LCR.

Citation Download Citation

Rozhin Penjweini, Michele M. Kim, Yi Hong Ong, and Timothy C. Zhu "Singlet oxygen explicit dosimetry to predict local tumor control for HPPH-mediated photodynamic therapy", Proc. SPIE 10047, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVI, 1004710 (8 February 2017); https://doi.org/10.1117/12.2251011

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