Tissue optical properties correction of multispectral singlet oxygen luminescent dosimetry (MSOLD) for Photofrin-mediated Photodynamic Therapy

Photodynamic therapy (PDT) is a promising cancer treatment modality that involves the administration of a photosensitizing agent followed by light activation at a specific wavelength. Upon activation, the photosensitizer generates reactive oxygen species, including singlet-state oxygen ([1O2]), which causes cellular damage leading to cancer cell death. Direct detection of singlet-state oxygen constitutes the holy grail dosimetric method for type II PDT, a goal that can be quantified using multispectral singlet oxygen dosimetry (MSOLD). The optical properties of tissues, specifically their scattering and absorption coefficients, play a crucial role in determining how light interacts within a medium. Variations in these optical properties can significantly impact various aspects, including the distribution of treatment laser, the generation of singlet oxygen, and the detection of singlet oxygen signals using the MSOLD device. In this study, we have investigated the influence of optical properties variation on the spatial distribution of treatment laser energy in tissue simulated phantom and the distribution of generated singlet oxygen signals using Monte Carlo simulations (MC). Additionally, we conducted a comparative analysis by examining singlet oxygen signals generated by Photofrin in MeOH, as detected by an InGaAs spectrometer in vitro, and compared these results to our Monte Carlo simulations. The experimental findings validate the accuracy of our Monte Carlo simulations, further affirming the robustness of our research. Our research advanced the comprehension of singlet oxygen generation and enhanced the accuracy of singlet oxygen detection using the MSOLD device, especially when optical properties undergo changes.