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Nuclear Scans
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Diagnostic Tests

Nuclear Scans

Nuclear scans utilize small amounts of radioactive material to visualize how organs and tissues are functioning at a cellular level.

What is a nuclear scan?

A nuclear scan is a type of medical imaging test that uses a small amount of radioactive material, called a radiotracer. This scan shows how organs and tissues are working, not just what they look like.

After the radiotracer is given, a special camera detects the radiation coming from inside the body. This allows your health care provider to see organ function, blood flow, or tissue activity, which can help diagnose conditions and check how well treatment is working.

Who needs a nuclear scan?

Nuclear scans may be used to find disease, target certain cells, and monitor response to treatment. They are commonly used to:

  • Check how organs such as the heart, lungs, or kidneys are working
  • Find disease early, sometimes before changes can be seen on other imaging tests
  • Perform bone scans
  • Evaluate the thyroid
  • Check how well cancer treatment is working

How do you prepare for a nuclear scan?

Before the scan, you will receive a small amount of radiotracer. This may be given as:

  • An injection
  • A pill or liquid to swallow
  • A gas to inhale

The radiotracer travels to the part of the body being examined. How much of the tracer is absorbed can help show how well an organ or tissue is functioning. Always tell your provider if you are pregnant, think you may be pregnant, or are breastfeeding.

How is a nuclear scan done?

You may be asked to change clothes and remove jewelry or other items that could interfere with the scan. Ask your provider if there are any special instructions before your scan. Depending on the type of nuclear scan, you may:

  • Lie on a table
  • Sit in a chair
  • Stand
  • Walk on a treadmill or ride a stationary bike (for some heart scans)

You will be asked to stay as still as possible, unless movement is part of the test. A special imaging device, such as a gamma camera, single-photon emission computed tomography (SPECT) scanner, or positron emission tomography (PET) scanner, detects radiation from the tracer and creates images. The length of the scan depends on the type of test and the area being examined.

What should you expect after a nuclear scan?

Most people can return to normal activities right away. Drinking fluids may help your body clear the radiotracer. A specialist called a radiologist reviews the images and shares the results with your provider.

Frequently Asked Questions

Yes, most nuclear scans are safe with pacemakers because the camera detects emitted radiation, not magnetic fields. However, inform the technologist about any implants; they may adjust positioning or use a different tracer if needed.
Tell the imaging center before the appointment. Most radiotracers have very low transfer into breast milk, but many facilities ask you to pump and discard milk for 24‑48 hours after the study to minimize infant exposure.
The radiotracer’s half‑life is usually measured in minutes to hours, and most of it is eliminated via urine or stool within 24‑48 hours. The radiation dose is comparable to a few months of natural background exposure and is considered safe for diagnostic purposes.
Repeat scans are generally allowed as long as the cumulative radiation dose stays within recommended limits. For most adults, a few scans per year are acceptable, but your physician will weigh the benefit of monitoring against the small incremental radiation risk.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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