Lung enhancement CT requires fasting. This is because enhancement CT requires the injection of a contrast agent, which may cause certain adverse reactions in patients, such as nausea and vomiting. If the patient eats a meal before the test and has stomach contents in the stomach. When this test is done, the injection of contrast agent may cause nausea and vomiting in the patient, which may lead to accidental aspiration or choking. Because the patient is lying flat on the examination bed, lung enhancement CT requires the patient to have an empty stomach. Patients with poor liver and kidney function, poor cardiac circulation, and patients with weak constitution also need to consider carefully whether they can undergo enhanced CT.