A barium meal test can detect tumors that are growing in the esophageal or gastrointestinal cavity and are of a certain size. Barium meal examination is commonly used to diagnose malignant tumors of the gastrointestinal tract, especially those of the esophagus and gastrointestinal tract. Tumors that grow to a certain size appear as filling defects in the barium meal examination film. By using information such as the size, location and shape of the filling defects, the radiologist can determine that tumors may exist here, but smaller tumors are often difficult to be detected due to certain limitations in the sensitivity of barium meal development. In addition, tumors that grow inside the gastrointestinal wall or grow from inside the gastrointestinal wall to outside the gastrointestinal cavity cannot be detected because barium cannot be visualized. In view of this, with the use of more sensitive and comprehensive examination equipment such as CT and MRI for tumor diagnosis, barium meal examination is gradually eliminated, and at present, barium meal examination is rarely used to diagnose tumors in clinical practice.