Comparative Analysis of Multispectral Singlet Oxygen Dosimetry (MSOLD) and Singlet Oxygen Explicit Dosimetry (SOED) in Type II Photodynamic Therapy

Direct detection of singlet-state oxygen (¹O₂) is critical in type II photodynamic therapy (PDT) but remains challenging due to its short lifetime. Our cost-effective and user-friendly Multispectral Singlet Oxygen Dosimetry (MSOLD) system facilitates real-time detection of ¹O₂ with precision and ease, underscoring the importance of validating its accuracy against the established Singlet Oxygen Explicit Dosimetry (SOED) model. A 690 nm laser excited benzoporphyrin derivative (2 - 6 mg/kg) in liquid phantom, Real-time ¹O₂ spectra were recorded for 900 seconds using an Avantes spectrometer. Ground-state oxygen, photosensitizer concentrations, and fluence rates were measured for SOED calculations. Both the MSOLD and SOED signals exhibit decay over the course of the PDT treatment. Instantaneous and cumulative ¹O₂ signals measured with MSOLD showed strong linear correlations with SOED results. This study demonstrates that the ¹O₂ signal detected by MSOLD can be effectively utilized for PDT dosimetry, comparable to the capabilities of SOED.