%0 Journal Article %T RESEARCH ON THE ABSOLUTE MEASUREMENT AND CALIBRATION METHODS OF (250–450) KV X-RAY AIR KERMA AT NIM %A Zhao, Rui %A WU, Jin-Jie %A XU, Yang %A REN, Guo-Yue %A DU, Hai-Yan %A YU, Ji-Li %A CHE, Wei-Na %J Radiation Protection Dosimetry %V 192 %N 4 %P 444-452 %@ 0144-8420 %D 2020-12-30 %I Oxford University Press %~ DeepDyve