Chest X-Ray

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What is the test?

Doctors have used x-rays for over a century to see inside the body in order to diagnose a variety of problems, including cancer, fractures, and pneumonia. During this test, you usually stand in front of a photographic plate while a machine sends x-rays, a type of radiation, through your body. Originally, a photograph of internal structures was produced on film; nowadays, the image created by the x-rays goes directly into a computer. Dense structures, such as bone, appear white on the x-ray films because they absorb many of the x-ray beams and block them from reaching the plate (see Figure 16). Hollow body parts, such as lungs, appear dark because x-rays pass through them. (In some other countries, like the United Kingdom, the colors are reversed, and dense structures are black.)

Back x-rays and chest x-rays are among the most common conventional x-ray tests. You should not have an x-ray if you're pregnant, because radiation can be harmful to a developing fetus.

A chest x-ray provides black-and-white images of your lungs, ribs, heart, and diaphragm.

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How do I prepare for the test?

You are usually asked to remove all clothing, undergarments, and jewelry above your waist, and to wear a hospital gown.

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What happens when the test is performed?

Chest x-rays usually are taken while you are standing. A technician positions you against the photographic plate (which looks like a large board) to obtain the clearest pictures. He or she takes pictures from the front and from one side while asking you to take in a deep breath just before each picture. The technician leaves the room or stands behind a screen while the x-rays are taken.

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What risks are there from the test?

The amount of radiation from x-ray tests is too small to be likely to cause any harm. However, if you're pregnant, talk to your doctor. Radiation may be harmful to a developing fetus.

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Must I do anything special after the test is over?

No.

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How long is it before the result of the test is known?

Although digital images may be available immediately, it will take additional time for a doctor to examine and interpret them. You'll probably get the results later in the day.

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