_ X-ray imaging is the original method for looking inside the body without surgery. Because the liver and all internal organs are "soft" objects, x-rays pass directly thru the organs and can only detect solid masses, such as tumors, which are easily detectible with other types of imaging. X-rays are also used for upper and lower GI tests, which show the digestive system in motion. Barium is ingested for these tests. Barium shows up on a "live" x-ray image so the radiologist can watch as the barium passes thru the body.