Inclusion Criteria:  lung tumor patients; 18-80 years old; will be treated by stereotactic body radiotherapy  Exclusion Criteria:  Prior radiotherapy; ACS; heart failure (NYHA III-IV); arrhythmia requiring intervention; echocardiographic images that could not be satisfactorily obtained; significant valvular heart disease (defined as more than mild valvular regurgitation or stenosis).