X-Rays

  • Medical Author:
    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

What Is a Chest X-Ray?

A chest X-ray is most commonly used to detect abnormalities in the lungs. However, it also can detect abnormalities in the heart, aorta, and the bones of the thoracic area. Chest X-rays are used to help diagnose:

  • Cysts
  • Tumors
  • Asthma
  • Cancers
  • Heart failure
  • Fractures
  • Lung diseases and conditions

X-ray definition and facts

  • X-rays are a form of electromagnetic radiation that can pass through solid objects, including the body. X-rays penetrate different objects more or less according to their density. In medicine, X-rays are used to view images of the bones and other structures in the body.
  • X-rays were first discovered by Wilhelm Conrad Roentgen, a German physics professor. Roentgen also studied X-rays and their ability to pass through human tissues to produce images of the bones and metals visible on developed film.
  • To obtain an X-ray image of a part of the body, a patient is positioned so the part of the body being X-rayed is between the source of the X-ray and an X-ray detector. As the X-rays pass through the body, images appear in shades of black and white, depending on the type of tissue the X-rays pass through.
  • For example, the calcium in your bones makes them denser, so they absorb more radiation and appear white on X-rays. Thus when a bone is broken (fractured), the fracture line will appear as a dark area within the lighter bone on an X-ray film.
  • Less dense tissue such as muscle or fat absorbs less, and these structures appear in shades of gray on X-ray film. Air absorbs little of the X-rays, so the lungs and any air-filled cavities appear black on an X-ray film. If pneumonia or tumors are present in the lungs, they are denser than the air-filled areas of the lungs and they will appear as whiter spots on X-ray film.

What are uses of X-rays?

The most common form of X-ray used is X-ray radiography, which can be used to help detect or diagnose:

Medically Reviewed by a Doctor on 7/22/2016

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