Challenges Facing FLASH Radiotherapy: In View of Safety Licensing and Regulation in China

FLASH radiotherapy (FLASH-RT) delivers ultra-high dose rates that are orders of magnitude above those of conventional radiotherapy. While pre-clinical and early clinical studies suggest therapeutic advantages, its extremely high instantaneous intensities challenge the applicability of existing radiation protection standards. This paper reviews international and national regulatory frameworks with emphasis on dose-rate criteria and shielding requirements, including those of the ICRP, IAEA, the United States, Switzerland, the United Kingdom and China. Particular attention is given to the interpretation of “maximum ambient dose rate” in Chinese standards, which may result in overly conservative shielding designs for FLASH-RT facilities. Comparative analysis indicates that time-averaged or workload-based approaches, as adopted in several countries, remain adequate to ensure compliance with occupational and public dose limits. Optimisation pathways are proposed to harmonise national practice with international recommendations and to facilitate the safe clinical implementation of FLASH-RT.