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Chest X-ray

What is a chest x-ray?

A chest x-ray is a test that produces images of the organs in your chest, including the heart and lungs. The chest x-ray can show if you have fluid buildup in the lungs or if your heart has become enlarged. In heart failure diagnosis, the chest x-ray is one of the first tests performed to determine the cause of your heart failure symptoms because it can identify or rule out other possible causes of shortness of breath and fluid buildup in the lungs, including lung problems such as pneumonia or emphysema.

How does a chest x-ray work?

A machine beams x-rays that pass through the chest and onto a special film or digital recording plate placed behind your back or to your side, producing a black and white image of the organs inside the chest. Different parts of the body absorb X-rays differently: the more the x-ray is absorbed, the lighter the tissue appears on the final image. Bone is very dense and absorbs most x-rays, so little of the x-ray reaches the film plate, causing bones to appear white on the final image. Softer tissue, such as the heart, is less dense and allows more x-rays to pass through to the film plate, causing the heart to appear gray on an x-ray film. Hollow organs, such as the lungs and the air in them, allow most x-rays to pass through, so they appear black in the final image. If there is fluid buildup in the lungs, more of the x-rays will be blocked, so these areas will appear lighter than normal lungs.

Chest x-ray normal versus heart failure
Left: Chest x-ray of a healthy woman, labeled with general location of the heart and lungs
Right: Chest x-ray of a woman with an enlarged heart and fluid buildup, indicating heart failure


Who might have a chest x-ray?

If you have symptoms typical of heart failure, such as shortness of breath, persistent cough, or chest pain, your doctor may order a chest x-ray to look at your heart and lungs and help find the cause of your symptoms. Doctors can tell from a chest x-ray if you have an enlarged heart or fluid buildup in the lungs, and can rule out other causes of heart failure symptoms such as lung disease.1, 2

How do I prepare for a chest x-ray?

No special preparation is required. However, you may be asked to remove your clothes above the waist and put on a hospital gown. You may also need to remove any jewelry or other metallic objects (for example, eyeglasses) that can interfere with the x-ray images.

What happens during a chest x-ray?

You will be asked to stand in front of a large, board-like box containing the x-ray film or digital recording plate. Two views of the chest are usually done: first, you will stand with your chest against the film box and with your hands on your hips. The technologist will go behind a screen or into another room and ask you to hold your breath before she or he aims a short burst of radiation that will pass from the back to the front of your chest, recording an image of your heart onto the film or digital recording plate. For the picture from the side, you will be placed with your left side to the film box and asked to raise your arms. You will need to stand very still because movement can blur the x-ray images.

If you are unable to stand, you may be asked to lie on a table with the x-ray beam above you and the film box beneath you.

A chest x-ray usually takes about 15 minutes.

What happens after a chest x-ray?

There are usually no restrictions on normal activities after a chest x-ray. However, a chest x-ray alone doesn’t provide enough information to make a diagnosis of heart failure and you will undergo more tests, such as an echocardiogram, to see how your heart is working if the chest x-ray did not identify a different cause of your symptoms.

What do the results of a chest x-ray mean?

A normal chest x-ray will show heart and lungs of normal size and shape. An abnormal result may show an enlarged heart or lungs with fluid buildup, indicating heart failure.

What are the risks of a chest x-ray?

The amount radiation used in one chest x-ray is very small, roughly equal to the amount of background radiation the average person is exposed to in a few days of daily life. You should tell your doctor if you are pregnant, as radiation may be harmful to the developing fetus.

For information on radiation safety, see the Radiological Society of North America’s Radiation Exposure in X-ray Examinations.


  1. Hunt SA. ACC/AHA 2005 Guideline Update for the Diagnosis and Management of Chronic Heart Failure in the Adult: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Update the 2001 Guidelines for the Evaluation and Management of Heart Failure). J Am Coll Cardiol. September 20, 2005 2005;46(6):e1-82.
  2. Heart Failure Society of America. HFSA 2006 Comprehensive Heart Failure Practice Guideline. J Card Fail. Feb 2006;12(1):e1-2.

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