Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Radionuclide Scanning (Nuclear Scan)


The Manual's Editorial Staff

Last full review/revision Oct 2019| Content last modified Oct 2019
Click here for the Professional Version
Get the full details

What is a radionuclide scan?

A radionuclide is a chemical that is radioactive. Doctors give you a small dose of the radionuclide. The radionuclide gives off radiation that's picked up by a scanner placed over a certain area of your body. The scanner makes a picture of where the radiation is and how strong it is. This helps show doctors what's going on in the tissue they're testing.

Doctors can give you a radionuclide as:

  • An injection

  • Something to swallow

  • A gas to breathe in

Different radionuclides go to different parts of your body. Doctors pick which radionuclide to use depending on what they need a picture of. A radionuclide scan can help doctors find problems in many parts of your body:

  • Thyroid gland

  • Liver

  • Gallbladder

  • Lungs

  • Urinary tract

  • Bones

  • Brain

  • Certain blood vessels

Why would I need a radionuclide scan?

Doctors usually use this test to find problems such as:

  • Blocked blood flow to your heart

  • Cancer that has spread to your bones or liver

  • Inflammation (swelling and pain) or infection inside organs

  • Bleeding, such as in your intestine

Sometimes, doctors will use the test to see how well a part of your body is working. For example, doctors may see how your heart works when it’s pumping hard by doing the test while you walk or run on a treadmill. If you’ve had a heart attack, doctors may do this test to see how well your heart is recovering.

What happens during a radionuclide scan?

Before the test

  • You may be asked to not eat or drink for several hours before the scan

  • Doctors usually inject the radionuclide in a vein but sometimes have you swallow or breathe it

  • You’ll wait a few minutes or up to several hours while the radionuclide travels through your body

During the scan

  • You’ll lie still on a table while a scanner takes pictures, usually for about 15 minutes

  • Sometimes you’ll need to get another scan after waiting for some more time, possibly hours later

After the scan

Doctors will have you drink lots of water or other liquids to help flush the radionuclide out of your body.

What are the risks of radionuclide scanning?


You'll be exposed to much more radiation than a plain x-ray. Doctors try to limit the total amount of radiation you are exposed to over your lifetime. Getting too much radiation can raise your chance of getting cancer.

If you’re pregnant or could be pregnant, tell doctors before you get radionuclide scanning.

Radionuclides stay in your body for a few days. If you plan to fly on an airplane within a few days after getting this test, you may set off radioactivity alarms in the airport. Get a doctor’s note to have at the airport.

Other problems

  • The test can take a long time, up to several hours

  • Radionuclide scans aren't as detailed as pictures from other imaging tests, such as x-rays, CT scans, or MRIs

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Test your knowledge

Loss of Smell
Anosmia is the total loss of smell. Most people with anosmia can taste sweet, sour, salty, and bitter substances but cannot distinguish among specific flavors. This is because the sense of smell makes it possible to distinguish among flavors, not taste receptors as many people erroneously believe. Which of the following is NOT a common cause of anosmia?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID