In-vivo outcome study of HPPH mediated PDT using singlet oxygen explicit dosimetry (SOED)

Rozhin Penjweini; Michele M. Kim; Timothy C. Zhu

doi:10.1117/12.2076441

2 March 2015 In-vivo outcome study of HPPH mediated PDT using singlet oxygen explicit dosimetry (SOED)

Rozhin Penjweini, Michele M. Kim, Timothy C. Zhu

Proceedings Volume 9308, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXIV; 93080N (2015) https://doi.org/10.1117/12.2076441
Event: SPIE BiOS, 2015, San Francisco, California, United States

Abstract

Type II photodynamic therapy (PDT) is based on the use of photochemical reactions mediated through an interaction between a tumor-selective photosensitizer, photoexcitation with a specific wavelength of light, and production of reactive singlet oxygen. However, the medical application of this technique has been limited due to inaccurate PDT dosimetric methods. The goal of this study is to examine the relationship between outcome (in terms of tumor growth rate) and calculated reacted singlet oxygen concentration [¹O₂]_rx after HPPH-mediated PDT to compare with other PDT dose metrics, such as PDT dose or total light fluence. Mice with radiation-induced fibrosarcoma (RIF) tumors were treated with different light fluence and fluence rate conditions. Explicit measurements of photosensitizer drug concentration and tissue optical properties via fluorescence and absorption measurement with a contact probe before and after PDT were taken to then quantify total light fluence, PDT dose, and [¹O₂]_rx based on a macroscopic model of singlet oxygen. In addition, photobleaching of photosenitizer were measured during PDT as a second check of the model. Changes in tumor volume were tracked following treatment and compared to the three calculated dose metrics. The correlations between total light fluence, PDT dose, reacted [¹O₂]_rx and tumor growth demonstrate that [¹O₂]_rx serves as a better dosimetric quantity for predicting treatment outcome and a clinically relevant tumor growth endpoint.

Citation Download Citation

Rozhin Penjweini, Michele M. Kim, and Timothy C. Zhu "In-vivo outcome study of HPPH mediated PDT using singlet oxygen explicit dosimetry (SOED)", Proc. SPIE 9308, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXIV, 93080N (2 March 2015); https://doi.org/10.1117/12.2076441

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