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

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.

Inclusion Criteria:

1. Patients at TNM stage N2-N3 NSCLC confirmed by histopathology or cytology using IASLC International TNM staging standard (8th edition)
2. KPS score >80; Aged 18 to 75 year-old
3. No contraindications to radiotherapy
4. No history of heart disease before treatment
5. Patients receiving intensity modulated radiation therapy (IMRT)
6. Patients receiving PTV at a prescription dose of 60-70Gy by IMRT
7. Patients receiving radiotherapy alone and concurrent chemoradiotherapy

Exclusion Criteria:

1. Patients with pleural effusion
2. Patients with serious medical illness or infection
3. Patients with acute myocardial infarction within 6 months
4. In patients with NYHA grade 3-4, baseline LVEF before radiotherapy is below 59%
5. Patients with congenital heart diseases, valvular diseases and arrhythmia
6. Patients with pericardial effusion
7. Patients receiving immunotherapy and drug targeted therapy
8. Patients with a history of anthracycline use

patients with stage N2-3 non-small cell lung cancerreceive intensity-modulated radiotherapy (IMRT) from Guizhou medical university affiliated cancer hospital.