The effect of radiation therapy on the heart depends mainly on the site of the tumor. Chemotherapy often affects tumors in these sites: left breast cancer, left lung cancer, mediastinal masses, and esophageal cancer. It depends mainly on the dose and duration of exposure to the heart, the dose being the cumulative dose. To effectively avoid its impact, you can choose intensity-modulated conformal radiotherapy, or TOMO, which are radiotherapy methods with strong targeting effect to the lesion, which can effectively avoid the heart from radiation exposure. In addition, it is important to pay attention to the toxic effects of simultaneous radiotherapy on the heart and avoid using chemotherapy drugs that have toxic effects on the heart. Cardiac damage caused by radiotherapy can be manifested as coronary artery damage, myocardial cell damage or heart valve damage or pericardial damage. It is common to see acute pericarditis after irradiation, and the patient has particularly severe chest pain, when electrocardiography and myocardial enzymology can be performed. Troponin and BNP are sensitive indicators and need to be taken seriously by clinicians, patients and families when they become abnormal.