A procedure that uses x-rays to take a series of pictures of the esophagus, stomach, and duodenum (the first part of the small intestine). The x-ray pictures are taken after the patient drinks a liquid that contains barium (a silver-white metallic compound). The barium coats and outlines the inner walls of the esophagus, stomach, and duodenum so they can be seen on the x-ray pictures. Photographs are then taken of the x-ray images and made into a short film to make the organs easier to see. This makes it possible to see the motion of the organs and exposes the patient to less radiation.