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X-ray

Definition

X-rays are a type of electromagnetic radiation, just like visible light.

An x-ray machine sends individual x-ray particles through the body. The images are recorded on a computer or film.

  • Structures that are dense (such as bone) will block most of the x-ray particles, and will appear white.
  • Metal and contrast media (special dye used to highlight areas of the body) will also appear white.
  • Structures containing air will be black, and muscle, fat, and fluid will appear as shades of gray.

Alternative Names

Radiography

How the test is performed

The test is done in a hospital radiology department or in the health care provider's office. How you are positioned depends on the type of x-ray being done. Several different x-ray views may be needed.

You need to stay still when you are having an x-ray. Motion can cause blurry images. You may be asked to hold your breath or not move for a second or two when they image is being taken.

How to prepare for the test

Before the x-ray, tell your health care team if you are pregnant, may be pregnant, or if you have an IUD inserted.

Metal can cause unclear images. You will need to remove all jewelry and may need to wear a hospital gown.

How the test is done depends on the specific type of x-ray.

How the test will feel

X-rays are painless. However, some body positions needed during an x-ray may cause temporary discomfort.

Why the test is performed

Normal Values

What abnormal results mean

What the risks are

X-rays are monitored and regulated so you get the minimum amount of radiation exposure needed to produce the image.

For most conventional x-rays, the risk of cancer or defects is very low. Most experts feel that benefits of appropriate x-imaging greatly outweight any risks.

Young children and babies in the womb are more sensitive to the risks of x-rays. Tell your health care provider if you think you might be pregnant. 

For more information, see the specific x-ray topics:

Special considerations

References

Mettler FA. Introduction: an approach to image interpretation. In: Mettler FA, ed. . 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2005:chap 1.

Goldstone K, Yates SJ. Radiation issues governing radiation protection and patient doses in diagnostic imaging. In: Adam A, Dixon AK, eds. . 5th ed.New York, NY: Churchill Livingstone; 2008:chap 9.

Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.