X-ray Do Not Enter ImageX-rays are useful in the detection of pathology of the skeletal system as well as for detecting some disease processes in soft tissue. Some examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer or pulmonary edema, and the abdominal X-ray, which can detect intestinal obstruction, free air and free fluid. X-rays may also be used to detect pathology such as gallstones or kidney stones which are often (but not always) visible.