All patients receive intensity-modulated radiotherapy (IMRT). The prescription dose of PTV is 60-70Gy，Troponin I, troponin T, hypersensitive troponin, brain natriuretic peptide and NT-proBNP are detected before radiotherapy, at the end of radiotherapy (day 15), at the end of radiotherapy and at 1 month after radiotherapy. Echocardiography was performed before radiotherapy, in the middle of radiotherapy (day 15) and at the end of radiotherapy to obtain global longitudinal strain value. Cardiac magnetic resonance imaging is used to measure the blood flow of the anterior descending coronary artery before and at the end of radiotherapy.
Calculating which cardiac substructure accepting with the highest radiation dose by conventional radiotherapy, then to investigate the relationship between the changes of global longitudinal strain or cardiac magnetic resonance imaging and cardiac biomarkers and the certain cardiac substructure for stage N2-3 non-small cell lung cancer