An X-ray examination uses electromagnetic radiation to make images of your bones, teeth and internal organs. An X-ray allows your doctor to take pictures of the inside of your body.

One of the oldest forms of medical imaging, an X-ray is a painless medical test that can help your doctor in diagnosis and treatment — even in emergency situations. It’s a fast, easy and safe way for your doctor to view and assess conditions ranging from broken bones to pneumonia to cancer. Many different types of X-rays exist, such as bone or chest X-rays. The type your doctor uses depends on what part of your body is being examined and for what purpose.

The amount of radiation you’re exposed to during an X-ray is so small that the risk of any damage to cells in your body is extremely low. For most X-ray examinations, the benefits of a medically indicated examination are thought to far outweigh the small risk. In addition, great care is taken to use the lowest radiation dose needed to produce the best images for the radiologist to evaluate. No radiation remains after an X-ray examination.  However, if you’re pregnant or suspect that you may be pregnant, inform your doctor before having an X-ray. Though the risk of most diagnostic X-rays to an unborn baby is small, your doctor may consider whether it’s better to wait or to use another imaging test, such as ultrasound.

X-rays are effective for people of all ages, even young children. X-rays are particularly useful for examining the chest, bones, joints and abdomen. Your doctor may recommend an X-ray for many different reasons. For example, an X-ray exam may be used to:

  • Determine whether a bone is chipped, dislocated or broken (fractured)
  • Evaluate joint injuries and bone infections
  • Diagnose and monitor the progression of degenerative conditions, such as arthritis and the bone-thinning disease osteoporosis
  • Screen for heart and lung diseases
  • Find and treat artery blockages
  • Diagnose the cause of persistent coughing or chest pain
  • Check for broken ribs or a punctured lung
  • Evaluate abdominal pain
  • Locate objects that may have been accidentally swallowed by a child
  • Determine whether you have injured a bone or disk in your spine
  • Detect scoliosis, an abnormal curvature of the spine, and other spinal defects
  • Evaluate infection of the sinuses (sinusitis)
  • Locate dental problems such as cavities, abscessed teeth, and other tooth and jaw abnormalities

X-ray exams also play an important role in the detection and diagnosis of cancer. In fact, one use of X-ray in diagnosing cancer is to see whether you have lung cancer or whether cancer from another part of the body has spread (metastasized) to your lungs. Cancer may appear lighter in color on an X-ray than does normal, healthy lung tissue. X-rays may also be used to examine cancers of the intestines, stomach, liver, spleen, kidneys and breasts.

Different types of X-rays require different preparations.

In general, you undress the area of your body that needs examination. You may wear a gown to cover yourself during the exam, depending on which area is being X-rayed. You may also be asked to remove jewelry, eyeglasses and any metal objects or clothing that may obscure the X-ray image, because these objects can show up on an X-ray. You may be asked to wear a lead apron to shield your sex organs from exposure to the X-rays. At very high doses, radiation can damage a woman’s eggs or a man’s sperm. Because you’re exposed to a small amount of radiation during most X-rays, the lead apron is used as a precaution.

Before some types of X-rays you’re given a liquid called contrast medium. Contrast mediums, such as barium and iodine, help outline a specific area of your body on X-ray film. You may swallow the contrast medium, or receive it as an injection or an enema. The contrast medium appears opaque on X-ray film, providing clear images of structures such as your digestive tract or blood vessels. If you’re to receive a contrast medium before an X-ray, tell your doctor if you have a history of allergy to X-ray dye, such as iodine.

An X-ray machine produces an X-ray beam using a tube that is carefully focused on the body part being examined. The machine produces a tiny burst of radiation, at a safe level, that passes through your body and records an image on film or on a specialized plate. As X-rays pass through your body, different tissues absorb different amounts of the radiation. This creates varying levels of radiation exposure on the X-ray film. For example, your bones are dense and absorb radiation well. So bones appear light on the film. But soft tissues, such as your skin, fat, muscles and organs, allow more radiation to pass through them, which makes them appear in varying shades of gray. Structures containing air, such as your lungs, appear dark.

An X-ray procedure may take only a few minutes for a bone X-ray, or more than an hour for more involved procedures, such as those using a contrast medium.

After an X-ray, you generally can resume normal activities. Routine X-rays usually have no side effects. However, if you receive an injection of contrast medium before your X-rays, call your doctor if you experience pain, swelling or redness at the injection site. Ask your doctor about other signs and symptoms to watch for pertaining to your specific X-ray procedure.

X-rays are recorded on film or are recorded digitally. They can be viewed on-screen within minutes. A radiologist typically views and interprets the results and sends a report to your doctor, who then explains the results to you. In an emergency, your X-ray results can be made available to your doctor in minutes.