It is well known in photodynamic therapy (PDT) that there is a large variability between PDT light dose and therapeutic
outcomes. An explicit dosimetry model using apparent reacted 1O2 concentration [1O2]rx has been developed as a PDT
dosimetric quantity to improve the accuracy of the predicted ability of therapeutic efficacy. In this study, this explicit
macroscopic singlet oxygen model was adopted to establish the correlation between calculated reacted [1O2]rx and the
tumor growth using Photofrin-mediated PDT in a mouse tumor model. Mice with radiation-induced fibrosarcoma (RIF)
tumors were injected with Photofrin at a dose of 5 mg/kg. PDT was performed 24h later with different fluence rates (50,
75 and 150 mW/cm2) and different fluences (50 and 135 J/cm2) using a collimated light applicator coupled to a 630nm
laser. The tumor volume was monitored daily after PDT and correlated with the total light fluence and [1O2]rx.
Photophysical parameters as well as the singlet oxygen threshold dose for this sensitizer and the RIF tumor model were
determined previously. The result showed that tumor growth rate varied greatly with light fluence for different fluence
rates while [1O2]rx had a good correlation with the PDT-induced tumor growth rate. This preliminary study indicated that
[1O2]rx could serve as a better dosimetric predictor for predicting PDT outcome than PDT light dose.
Haixia Qiu, Michele M. Kim, Rozhin Penjweini, and Timothy C. Zhu, "Dosimetry study of PHOTOFRIN-mediated photodynamic therapy in a mouse tumor model," Proc. SPIE 9694, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXV, 96940T (Presented at SPIE BiOS: February 14, 2016; Published: 1 March 2016); https://doi.org/10.1117/12.2211169.
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