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What Is a Chest X Ray?

A chest x ray is a painless, noninvasive test that creates pictures of the structures inside your chest, such as your heart, lungs, and blood vessels. "Noninvasive" means that no surgery is done and no instruments are inserted into your body.

This test is done to find the cause of symptoms such as shortness of breath, chest pain, chronic cough (a cough that lasts a long time), and fever.


X rays are electromagnetic waves. They use ionizing radiation to create pictures of the inside of your body.

A chest x ray takes pictures of the inside of your chest. The different tissues in your chest absorb different amounts of radiation.

Your ribs and spine are bony and absorb radiation well. They normally appear light on a chest x ray. Your lungs, which are filled with air, normally appear dark. A disease in the chest that changes how radiation is absorbed also will appear on a chest x ray.

Chest X Ray

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Figure A shows a cross-section of a chest. Figure B shows an x-ray image of a chest.

Figure A shows a cross-section of a chest. Figure B shows an x-ray image of a chest. Roll your mouse over the terms on right side of the x-ray image to highlight the internal structures of the chest on both figures.

Chest x rays help doctors diagnose conditions such as pneumonia (nu-MO-ne-ah), heart failure, lung cancer, lung tissue scarring, and sarcoidosis (sar-koy-DO-sis). Doctors also may use chest x rays to see how well treatments for certain conditions are working. Also, doctors often use chest x rays before surgery to look at the structures in the chest.

Chest x rays are the most common x-ray test used to diagnose health problems.


Chest x rays have few risks. The amount of radiation used in a chest x ray is very small. A lead apron may be used to protect certain parts of your body from the radiation.

A chest x ray gives out a radiation dose similar to the amount of radiation you're naturally exposed to over 10 days.

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Last Updated: August 1, 2010