Advantage of pulsed light irradiation in photodynamic therapy of solid tumors: numerical simulation and experimental in VIVO study

In this study, we investigated the effect of pulsed mode light irradiation on the effectiveness of photodynamic therapy (PDT) for solid tumors. Our aim was to optimize PDT by addressing tumor tissue hypoxia. Using a macroscopic model we developed, which considers oxygen consumption and influx, photosensitizer photobleaching, and diffuse light scattering,  we performed numerical simulations of singlet oxygen generation in tumor tissue in vivo. To verify these simulation results and assess the in vivo effectiveness of the pulsed mode, we compared PDT in continuous and pulsed modes using a mouse model of AKATOL colon adenocarcinoma (Balb/c). We showed that the pulsed irradiation mode provides improved tumor oxygenation and leads to a more pronounced cytotoxic effect, resulting in greater suppression of tumor growth and increased animal survival compared to the continuous mode. Our results confirm the potential of using the pulsed mode to enhance the effectiveness of PDT for solid tumors.