An X-ray is a quick, painless test that produces images of the structures inside your body — particularly your bones.

X-ray beams can pass through your body, but they are absorbed in different amounts depending on the density of the material they pass through. Dense materials, such as bone and metal, show up as white on X-rays. The air in your lungs shows up as black. Fat and muscle appear as varying shades of gray.

For some types of X-ray tests, a contrast medium — such as iodine or barium — is introduced into your body to provide greater detail on the X-ray images.

Why it's done Risks How you prepare What you can expect Results

X-ray technology is used to examine many parts of the body.

Bones and teeth

  • Fractures and infections. In most cases, fractures and infections in bones and teeth show up clearly on X-rays.
  • Arthritis. X-rays of your joints can reveal evidence of arthritis. X-rays taken over the years can help your doctor determine if your arthritis is worsening.
  • Dental decay. Dentists use X-rays to check for cavities in your teeth.
  • Osteoporosis. Special types of X-ray tests can measure the density of your bones.
  • Bone cancer. X-rays can also reveal tumors in your bones.


  • Lung infections or conditions. Evidence of problems such as pneumonia, tuberculosis or lung cancer can show up on chest X-rays.
  • Breast cancer. Mammography is a special type of X-ray test used to examine breast tissue.
  • Enlarged heart. One of the signs of congestive heart failure is an enlarged heart, which shows up clearly on X-rays.
  • Blocked blood vessels. Injecting a contrast material that contains iodine can help highlight sections of your circulatory system so that they can be seen on X-rays.


  • Digestive tract problems. Barium, a contrast medium delivered in a drink or in an enema, can help reveal problems anywhere in your digestive system.
  • Swallowed items. If your child has swallowed something like a key or a coin, an X-ray can show the location of that object.

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