摘要Radiological or nuclear accidents can lead to serious outcomes for individuals exposed to ionizing radiation,with health effects that are either acute or delayed,deterministic or stochastic,depending on the effective dose of exposure.Mechanistically,ionizing radiation can inflict damage either directly on DNA or through oxidative stress,which may trigger a cascade of damages to tissues and organs.The development of effec-tive radiation medical countermeasures is an unmet need and should be a top priority in preparing for radiation emergencies.This paper aims to address the critical ques-tions of whether current countermeasures are available,what additional measures are needed,and what actions can be taken to enhance the development of radiation medical countermeasures from a systematic perspective.