Author: Robert H Hadfield, Madelyn Johnson, Baozhu Lu, Hongjing Sun, Vikas Vikas, Brian C. Wilson, Weibing Yang, Timothy C. Zhu 👨🔬
Affiliation: University of Glasgow, University of Toronto, University of Pennsylvania 🌍
Purpose:
Multispectral Singlet Oxygen Luminescent Dosimetry (MSOLD) has been developed as a real-time in vivo dosimetry technique for Photodynamic Therapy (PDT). This study investigates the feasibility and accuracy of MSOLD in monitoring singlet oxygen (1O₂) generation in mice bearing RIF (radiation-induced fibrosarcoma) tumors undergoing benzoporphyrin derivative (BPD)-mediated PDT. The correlation between MSOLD signals and Singlet Oxygen Explicit Dosimetry (SOED) is evaluated to assess its potential as a treatment-guidance tool.
Methods:
RIF tumor-bearing mice were used for in vivo PDT studies with BPD as the photosensitizer. BPD was administered via intravenous injection 3 hours prior to light irradiation to allow for optimal tumor uptake. PDT was performed using a 690 nm laser with an appropriate fluence rate. The luminescence signals were recorded in real time and analyzed with an appropriate spectral basis. Comparisons between MSOLD and SOED were performed to assess dosimetry accuracy. Variations in MSOLD signals were examined concerning tissue optical properties, photosensitizer concentration, and PDT fluence rates. Tumor response and histological analysis were performed post-treatment to assess PDT efficacy.
Results:
MSOLD successfully detected singlet oxygen signals in vivo during BPD-PDT. The MSOLD signals exhibited a strong correlation with SOED dosimetry, confirming its capability for real-time PDT monitoring. The system demonstrated high sensitivity in detecting weak singlet oxygen signals, validating its feasibility for dosimetric applications. However, signal variability in regions with heterogeneous optical properties and abrupt curvature changes suggests the need for further calibration and correction strategies.
Conclusion:
This study demonstrates the feasibility of MSOLD for real-time dosimetry in BPD-mediated PDT of RIF tumors. The multispectral approach enhances 1O₂ detection specificity and enables quantitative correlation with explicit dosimetry models. Future work will focus on optimizing calibration strategies, refining signal interpretation, and integrating MSOLD into clinical PDT applications to improve treatment accuracy and patient outcomes.