X-rays are a form of energy, just like visible light. In the health care setting, an X-ray machine sends X-rays through the body. For most typical X-rays, the chance of harm is very low.

A computer records the images the X-ray machine creates. Structures that are dense (such as bone) will block most of the X-rays, and will appear white. Metal and contrast media (a special dye used to highlight areas of the body) will also appear white. Air will appear black, and muscle, fat and fluid will appear as shades of gray.

Accordion Block v2

Frequently asked questions

  • The test is done in a radiology department by a trained X-ray technologist. How the test is done will depend on what part of the body needs to imaged. You may be able to stand, or you might need to lie down.

    The technologist may ask you to hold your breath or hold still for a short while. Just like with a photo, moving can blur the image.

  • If you're a woman, let your doctor know if you're pregnant (or could be pregnant) or have an IUD.

    In some cases, the test may need to be delayed. For example, if you’re scheduled for abdominal X-rays and you’ve:

    • Had a barium contrast study (such as a barium enema, upper GI series, or barium swallow)
    • Taken medicines with bismuth (such as Pepto-Bismol) in the last four days

    For the test, you'll need to wear a hospital gown and remove all jewelry. Metal and certain clothing can block the images.

  • You can't feel the X-rays from the test. You might need to stay still in awkward positions for a short period of time.

  • Most experts say X-rays have a low chance of causing harm. And, X-rays can give your doctor a great deal of useful information to help care for you.

    There are very strict rules about how X-rays are used. Health care providers must use the smallest amount of X-rays needed to produce the image. Young children and unborn babies are more sensitive to the risks of X-rays than adults. Women should tell their doctors if they think they are pregnant so the child can be protected.