An X-ray uses a small amount of radiation to make images of your bones and organs. X-rays are most often used to look for bone or joint problems, or to check the heart and lungs (chest X-ray). They are also used to look for any hard deposits of minerals or salts in your body, such as kidney stones. You may also have an X-ray to check for problems in the bowel, such as a blockage or free air in the belly (abdomen). X-rays are also used to look for a foreign object in your body, such as metal. This can be from an injury or a swallowed object.