Taboo before examination: (1) Do not take iron, iodine, sodium, bismuth, silver and other drugs for 2 days before examination. (2) It is not advisable to eat more fiber and indigestible food 1 day before filming. (3) Eat a diet with less residue, such as soybean milk, noodles and porridge. On the night of 1 day, before radiography. (4) Avoid wearing clothes with more metal patterns on the day of inspection. Before inspection, please remove jewelry, belts, coins, keys and other items that may produce artifacts. (5) Fasting on the morning of radiography, including boiling water and medicine. (6) Before radiography, patients need to have an iodine allergy test. Requirements during examination: Patients only need to follow the guidance and cooperation of doctors. Improper population: (1) esophageal varices or stenosis. (2) allergic to contrast agent (lipiodol). (3) Acute attack of acute pancreatitis or chronic pancreatitis. (4) Patients with severe cardiovascular diseases with cardiac insufficiency or frequent angina pectoris. (5) Viral hepatitis, hepatitis B surface antigen positive (Australian antibody positive). (6) Persons who are mentally abnormal and unable to cooperate. (7) Acute biliary tract infection.