A chest X-ray shows the lungs, heart, blood vessels and other structures inside the chest. If a person's chest X-ray is normal, the ribs and spine appear light and the air-filled lungs appear dark, according to the National Heart, Lung, and Blood Institute.
Chest X-rays are used to determine the cause of symptoms such as chest pain, trouble breathing, persistent coughing and coughing up blood, reports MedlinePlus. They are also used to diagnose or rule out conditions such as lung disease and tuberculosis. There are many causes of an abnormal chest X-ray. A physician is able to diagnose pneumonia, lung tumors, collapsed lung, scarring of the lung tissue and other respiratory problems using this test. If the heart is an abnormal size or shape, a physician is able to see the abnormality on a chest film. Chest X-rays also show problems with the position and shape of the large arteries. Because the ribs and spine are visible on a chest film, this type of X-ray is also used to diagnose osteoporosis, rib fractures and spine fractures.
Chest X-rays use a small amount of radiation. In fact, a person receives a similar amount of radiation from a chest X-ray as he would from 10 days of natural radiation exposure, reports the National Heart, Lung, and Blood Institute.