The macroscopic singlet oxygen model has been used for singlet oxygen explicit dosimetry in photodynamic therapy
(PDT). The photophysical parameters for commonly used sensitizers, HPPH and BPD, have been investigated in
pre-clinical studies using mouse models. So far, studies have involved optimizing fitting algorithms to obtain the
some of the photophysical parameters (ξ, σ, g) and the threshold singlet oxygen dose ([1O2]rx,sh), while other
parameters such as the low concentration correction, δ, has been kept as a constant. In this study, using
photobleaching measurements of mice in vivo, the value of δ was also optimized and fit to better describe
experimental data. Furthermore, the value of the specific photobleaching ratio (σ) was also fine-tuned using the
photobleaching results. Based on literature values of δ, σ for photosensitizers can be uniquely determined using the
additional photobleaching measurements. This routine will further improve the macroscopic model of singlet
oxygen production for use in explicit dosimetry.
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