Chest x rays show the structures in and around the chest. The test is used to look for and track conditions of the heart, lungs, bones, and chest cavity. For example, chest x-ray pictures may show signs of pneumonia, heart failure, lung cancer, lung tissue scarring, or sarcoidosis.
Chest x rays do have limits. They only show conditions that change the size of tissues in the chest or how the tissues absorb radiation. Also, chest x rays create two-dimensional pictures. This means that denser structures, like bone or the heart, may hide some signs of disease. Very small areas of cancer and blood clots in the lungs usually don't show up on chest x rays.
For these reasons, your doctor may recommend other tests to confirm a diagnosis.