Quantitative assessment of transient hypoxia under high-dose-rate photon irradiation using a yeast-based real-time oxygen monitoring system

Abstract

This study investigates hypoxic effects induced by high-dose-rate photon irradiation using a yeast-based real-time oxygen monitoring system. S.cerevisiae was used to quantify changes in oxygen concentration during photon irradiation at 6.34 Gy/s, 0.23 Gy/s, and 0.07 Gy/s. Oxygen depletion exhibited a significant dose-rate dependency (p < 0.001). At 6.34 Gy/s, oxygen concentration decreased by 49.5 % (p < 0.001), while reductions at 0.23 Gy/s (p = 0.03) and 0.07 Gy/s (p = 0.07, not significant) were smaller. Post-hoc analysis confirmed significant differences between 6.34 Gy/s and both 0.23 Gy/s (p < 0.01) and 0.07 Gy/s (p < 0.001), whereas 0.23 Gy/s and 0.07 Gy/s were not significantly different (p = 0.08). These results demonstrate the impact of dose rate on oxygen depletion, emphasizing its role in transient hypoxia and its potential implications for radiotherapy. While the findings suggest a possible trend toward a dose-rate threshold below which oxygen depletion becomes minimal, this study focused on physical-biological measurements of radiation-induced oxygen dynamics without evaluation of downstream biological endpoints. Future studies with larger sample sizes are needed to confirm the threshold observation, incorporate biological endpoints such as cell viability and DNA damage to elucidate mechanistic relevance, and validate the observed oxygen kinetics in mammalian or clinically relevant systems.