Nuclear Medicine Scan

Medically Reviewed by Sabrina Felson, MD on November 11, 2022
4 min read

A nuclear medicine scan uses small amounts of radiation to create pictures of tissues, bones, and organs inside the body.

The radioactive material collects in certain areas of your body, and special cameras find the radiation and make images that help your medical team diagnose and treat cancer and other illnesses.

Other terms your doctor might use for a nuclear medicine scan are:

  • Nuclear scan
  • Nuclear imaging
  • Radionuclide imaging

Most scans don’t take more than an hour or so, though you may have to wait a few hours as health care workers prep you for the test.

These scans are usually done at a nuclear medicine or radiology department at a hospital. A little bit of radioactive material will go into your body. Doctors call this material a radioactive “tracer,” radionuclide, or radiopharmaceutical.

Hospital staff may inject this tracer or give it to you to swallow in a pill or inhale as a gas.

It can take from a few seconds to several days for the tracer to collect in the part of the body that will get scanned.

Before the scan, you’ll remove all jewelry and metal that could interfere with the images. Medical staff may ask you to wear a hospital gown, though in some cases you can wear your own clothes.

You’ll lie on a table or sit on a chair for the scan. Technicians use a special camera, or “scanner,” on the appropriate parts of your body to detect gamma rays from the tracer. Technicians might ask you to change positions to get different angles as the scanner works.

The scanner sends the information to computer software that creates pictures, sometimes in three dimensions (3D) and with color added for clarity.

A specialized doctor called a radiologist will review the pictures and talk to your doctor about what they show.

Nuclear medicine scans are especially useful for cancer because they show tumors and track if they spread inside the body. They’re also a way to check how well treatment is working.

These scans have some limits. For example, a scan might show areas that could be cancer. But your doctor will need more focused pictures (X-ray, CT scan, MRI) of those areas and to look for tumors that may not show up on the nuclear scan. To know for sure if there’s cancer, you may need a biopsy, when a surgeon removes a small piece of a tumor to check under a microscope.

Doctors also use nuclear medicine scans for conditions other than cancer, including:

The nuclear medicine scans most commonly used for cancer are:

PET scans. Here, your medical team injects a radioactive sugar into your body. Your doctor can then tell where cancer might be because those cells tend to absorb more sugar than normal cells. Your medical team might ask you to avoid sugar and especially sugary drinks in the hours before the scan.

PET/CT scans. This scan finds general areas of possible cancer activity with the PET scan and then zeroes in for more detail in those areas with the CT scan. But it’s a tradeoff: It gives your doctor more information but exposes you to more radiation.

Bone scans. These can often detect changes in bones that might suggest cancer much earlier than other imaging. After injection, the radioactive tracer collects in the bones over a few hours before the scan starts.

Thyroid scans. You swallow radioactive iodine, which goes through your blood to collect in your thyroid gland, where it helps find thyroid cancer. Tell your doctor if you take anything with iodine such as supplements, cough medicines, seaweed, or heart medications.

Gallium scans. This test uses the tracer gallium-67 to scan the whole body or to look specifically at organs for signs of cancer. In places where the scanner finds gallium gathered, it might be a sign of inflammation, infection, or cancer.

MUGA: This scan uses a radioactive liquid tracer to track how well your heart moves blood back out into your body. It helps your doctor decide whether your heart is strong enough for certain types of chemotherapy (a cancer treatment). Some specialists might also use it to test for possible heart problems.

Nuclear medicine scans are generally safe and have been around in some form for about 50 years. The radiation dose that you get is usually very low and doesn’t pose serious health risks.

Some people have an allergic reaction to the tracer material. But it’s usually mild and doesn’t last very long.

Tell your doctor if you’re pregnant or breastfeeding because they may need to take certain safety precautions or change the timing and type of scan.