Objective To investigate the changes of ambulatory electrocardiography( AECG),QT dispersion( QTd),and heart rate variability( HRV) in patients with nasopharyngeal carcinoma( NPC) after radiotherapy. Methods Before and after 3 stages of radiotherapy with different doses( 15-25 Gy,35-45 Gy,and 55-65 Gy,respectively),40 cases with NPC underwent AECG monitoring and were observed the changes of AECG,QTd,corrected QT dispersion( QTcd),and HRV indices of time domain and frequency domain caused by radiotherapy. Res...