Medically reviewed on Jan 6, 2018
An X-ray is a quick, painless test that produces images of the structures inside your body — particularly your bones.
X-ray beams pass through your body, and 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 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 images.
Why it's done
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 signs 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 take pictures of the teeth and jaw and check for cavities.
- Osteoporosis. Special types of X-ray tests can measure bone density.
- Bone cancer. X-rays can reveal bone tumors.
- Lung infections or conditions. Evidence of 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. This sign of heart failure shows up clearly on X-rays.
- Blocked blood vessels. Changes in blood flow to the lungs and heart can be seen on chest X-rays.
- Digestive tract problems. Barium, a contrast medium delivered in a drink or an enema, can help reveal problems 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.
Knee arthritis can affect one side of the joint more than the other. This X-ray image shows how the cushioning cartilage has worn away, allowing bone to touch bone.
A chest X-ray helps detect problems with your heart and lungs. The chest X-ray on the left is normal. The image on the right shows a mass in the right lung.
X-rays can locate metal objects your child has swallowed, such as this jack.
Some people worry that X-rays aren't safe because radiation exposure can cause cell mutations that may lead to cancer. The amount of radiation you're exposed to during an X-ray depends on the tissue or organ being examined. Sensitivity to the radiation depends on your age, with children being more sensitive than adults.
Generally, however, radiation exposure from an X-ray is low, and the benefits from these tests far outweigh the risks.
However, if you're pregnant or suspect that you may be pregnant, tell 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 another imaging test, such as ultrasound.
In some people, the injection of a contrast medium can cause side effects such as:
- Feeling of warmth or flushing
- Metallic taste
Rarely, severe reactions to a contrast medium occur, including:
- Severe low blood pressure
- Anaphylactic shock
- Cardiac arrest
How you prepare
How you prepare depends on the type of X-ray you need. Ask your doctor or nurse to provide you with specific instructions.
What to wear
In general, you undress whatever part of your body needs examination. You may wear a gown during the exam, depending on which area is being X-rayed. You may also be asked to remove jewelry, eyeglasses and any metal objects because they can show up on an X-ray.
Before some types of X-rays, you're given a liquid called contrast medium. Contrast mediums, such as barium and iodine, help highlight a specific area of your body on the X-ray image. You may swallow the contrast medium or receive it as an injection or an enema.
This X-ray using contrast reveals a kidney stone at the junction of the kidney and the tube that connects the kidney to the bladder (ureter).
The X-ray tube is focused on the man's abdomen. X-rays will pass through his body and produce an image on the specialized plate below.
What you can expect
During the X-ray
X-rays are performed at doctors' offices, dentists' offices, emergency rooms and hospitals — wherever an X-ray machine is available. The machine produces a safe level of radiation that passes through your body and records an image on a specialized plate. You can't feel an X-ray.
A technologist positions your body to obtain the necessary views. Pillows or sandbags may be used to help you hold the position. During the test, you must stay still (and sometimes hold your breath to avoid moving) to prevent blurry images.
An X-ray procedure may take from a few minutes for a bone X-ray to more than an hour for more-involved procedures, such as those using a contrast medium.
Your child's X-ray
Restraints or other techniques may be used to keep a young child still during an X-ray. These won't harm your child. They will prevent the need for a repeat procedure, which may be necessary if your child moves during the X-ray exposure.
You may be allowed to stay with your child during the test. If you do, you'll likely be asked to wear a lead apron to shield you from unnecessary exposure.
After the X-ray
After an X-ray, you generally can resume normal activities. Routine X-rays usually have no side effects. However, if you receive contrast medium before the test, drink plenty of fluids to help rid your body of it.
Call your doctor if you have pain, swelling or redness at the injection site. Ask your doctor about other signs and symptoms to watch for.
X-rays are saved digitally on computers, which 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.