Reactive Oxygen Species Explicit Dosimetry for pleural PDT

Photodynamic therapy (PDT) relies on the interactions between light, photosensitizer, and tissue oxygen to produce cytotoxic reactive oxygen species (ROS). Accurate dosimetry accounting for all three components is crucial for predicting and optimizing PDT outcomes. Explicit dosimetry of light fluence, photofrin concentration, and tissue oxygenation concentrations were integrated into the ROSED model to calculate [ROS]rx across multiple sites inside the pleural cavity and among different patients. Large inter- and intra-patient heterogeneities in [ROS]rx were observed despite identical 60 J/cm2 light doses, with mean [ROS]rx, meas of 0.56 ± 0.26 mM for 13 patients with 21 sites and [ROS]rx, calc1 of 0.48 ± 0.23 mM for 20 patients with 76 sites. This is the first comprehensive analysis of clinical ROSED in pleural patients, providing valuable data on future ROSED based PDT that can potentially produce uniform ROS and thus improve the PDT efficacy for photofrin-mediated pleural PDT.