Effects of Partial-body, Continuous/Pulse Irradiation at Dose Rates from Flash to Conventional Rates on the Level of Surviving Blood Lymphocytes: Modeling Approach. III. Lymphocyte Survival Is a Biomarker of Flash Sparing Effects.

Experimental data on magnitudes of sparing effects of whole-abdominal pulse irradiation, whole-brain pulse irradiation, and bilateral thorax pulse/continuous irradiation at high doses and dose rates from conventional to FLASH irradiation rates (> 40 Gy/s) on normal intestinal, brain, and lung tissues in mice, which were reported in the literature, are analyzed by making use of recently developed mathematical models. These models are capable of predicting the fractions of surviving blood lymphocytes in mice after the exposures. Results of juxtaposing those experimental data with the respective modeling results suggest a possible relationship between them. Recent experimental findings confirming this relationship are presented. Finally, an algebraic formula to predict FLASH dose rate thresholds for the exposures is derived and verified, providing a tool for future experimental design.