Simulation of the Singlet Oxygen distribution for Photofrin-Mediated Photodynamic Therapy Using Patient-Specific Modeling

Photodynamic therapy (PDT) is employed following surgical resection to address microscopic residual malignant pleural mesothelioma. The generation of singlet oxygen during PDT induces the death of cancer cells. Precise dosimetry plays a pivotal role in ensuring treatment efficacy. This study sought to model the distribution of reacted singlet oxygen ([1O2]rx) on the surface of the pleural cavity using patient-specific data acquired in a clinical setting for Photofrin-mediated PDT. Cavity geometry was obtained using an infrared camera-based navigation system during surgery, and Photofrin concentration was measured using a multi-fiber contact probe. Light fluence was calculated based on the cavity geometry and the position of the treatment wand. The COMSOL Multiphysics software simulated the distribution of [1O2] rx using the measured geometry, Photofrin concentration, and light fluence data. Models comparing homogeneous and heterogeneous Photofrin uptake were examined, revealing that [1O2] rx increased proportionally to the Photofrin concentration in both scenarios. The aim of this research is to account for heterogeneity and optimize treatment outcomes by incorporating real patient data into the model. Monitoring under- and over-exposed regions could potentially enhance treatment efficacy. The findings demonstrate the feasibility of employing explicit dosimetry for pleural PDT. Future investigations will concentrate on real-time modeling through the integration of patient data obtained during treatment. Explicit dosimetry holds the potential to provide accurate dosing, thereby maximizing treatment effectiveness and improving patient outcomes. This patient-specific modeling approach could be extended to PDT in other anatomical locations where a reconstructed treated cavity is available.