Department of Cardiology, Beijing Chao-Yang Hospital, Captial Medical University, 8 Gongti Nanlu Road, Chaoyang District, Beijing, 100020, NO, China. xiaotaozhao926@sina.com. Department of Internal Medicine, General Political Department Hospital of Chinese PLA, Beijing, China. National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Chinese Center for Medical Response to Radiation Emergency, No. 2 Xinkang Street, Deshengmenwai, Beijing, 100088, China. qingjieliu@yahoo.com.