What is a chest X-ray?

A chest X-ray is a test that uses a small amount of radiation to create an image of the structures within the chest, including the heart, lungs, blood vessels and bones. During an X-ray, a focused beam of radiation is passed through your body, and a black-and-white image is recorded on special film or a computer. The X-ray image that is created looks like a negative from a black and white photograph.

X-rays work because the body's tissues vary in density (thickness). Each tissue allows a different amount of radiation to pass through and expose the X-ray-sensitive film, which results in a shadow image of the organ. Bones, for example, are very dense, and most of the radiation is prevented from passing through to the film. As a result, bones appear white on an X-ray. Tissues that are less dense––such as the lungs, which are filled with air––allow more of the X-rays to pass through to the film and appear on the image in shades of gray.

Why is a chest X-ray used?

A chest X-ray may be used to help diagnose and plan treatment for various conditions, including:

  • Lung disorders such as pneumonia, emphysema, tuberculosis and lung cancer
  • Heart disorders such as congestive heart failure (which causes the heart to enlarge)
  • Fractures (breaks) of the bones in the chest, including the ribs and collarbone, as well as breaks in the bones of the upper spine
  • Reasons for shortness of breath, a bad or persistent cough, or chest pain

Who performs the test?

A radiology technologist, a skilled medical professional who is trained in X-ray procedures, will perform the test. A radiologist, a doctor who specializes in evaluating X-rays and other radiology procedures, will interpret the X-rays and report the test results to your doctor.

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