Nuclear Medicine Scans for Cancer

Nuclear medicine scans can be used to find cancer or plan further cancer treatment. You might hear these called nuclear imaging, radionuclide imaging, or nuclear scans.

What are nuclear scans?

Nuclear scans are imaging tests that make pictures based on your body’s chemistry, such as its metabolism. This is different from other common imaging tests, which make pictures based on physical shapes and forms.

Nuclear scans can help doctors:

• Find tumors
• Determine the amount of cancer in the body and where it is located (staging)
• See if treatment is working
• Look at your heart function while you are being treated for cancer

Nuclear medicine also includes using radioisotopes for treatment of certain cancers.

Types of nuclear scans

The type of nuclear scan you have will depend on the part of your body that your healthcare team wants to look at. Some of the nuclear medicine scans used for cancer are:

• Bone scans
• PET (positron emission tomography) scans
• Thyroid scans
• MUGA (multigated acquisition) scans
• Renal scans
• Gallium scans

This page discusses thyroid, MUGA, and gallium scans. See Bone Scan for Cancer and PET Scan for Cancer to learn more about those tests.

What do nuclear scans show?

Nuclear scans create pictures of your body with the help of liquid substances that release low levels of radiation. These substances are called radiotracers or radiopharmaceuticals.

When body tissues are affected by certain diseases like cancer, they may absorb more or less of the tracer than normal tissues. Special cameras pick up the pattern of radioactivity. This creates pictures that show where the tracer travels and where it collects.

If cancer is present, the tumor might show up on the picture as a hot spot. This is an area of increased cell activity and tracer uptake. Depending on the type of scan, the tumor might instead show up as a cold spot. This is an area of decreased uptake and less cell activity.

How do nuclear scans work?

When you get a nuclear scan, you are usually given a radioactive tracer that sends out small doses of radiation. Some tracers are swallowed. Others are put into a vein or inhaled as a gas.

Over time, the tracer collects in the part of the body that’s being tested. This can take from a few seconds to several days.

The collected tracer sends out gamma rays that are picked up by a special camera, such as a gamma camera. The signals are processed by a computer, which turns them into 2-dimensional (2D) or 3-dimensional (3D) pictures. Color is sometimes added for extra clarity.

A doctor who specializes in nuclear medicine, called a radiologist, interprets the pictures and sends a report to your healthcare team.

How do I get ready?

How you prepare for a nuclear scan will depend on the type of test you need and the tissue being studied. Your healthcare team will give you specific instructions for your scan.

Most of the time, they are done on an outpatient basis, but they can also be done in the hospital. You might get the radioactive material anywhere from a few minutes to many hours before the test. The tracer for a gallium scan is given a few days before the test.

To get ready for your scan, you might be asked to:

• Stop eating or drinking for 2 to 12 hours before the test.
• Take a laxative or use an enema.
• Avoid some prescription and over-the-counter medicines before the test.
• Avoid caffeine or tobacco 24 hours before the test.

Tell your care team everything you take. This includes over-the-counter medicines, vitamins, and herbs. Also let them know if you have any allergies or if you’ve had problems with nuclear scans in the past.

What is it like having a nuclear scan?

Nuclear scans are usually painless. In most cases, you will be given a tracer that sends out small doses of radiation. You might get the tracer by:

• Inhaling a gas
• An IV injection
• Swallowing a capsule or liquid dose

Special materials and equipment are needed for these scans, so they are usually done in the radiology or nuclear medicine department of a clinic or hospital.

You may be asked to:

• Undress and put on a gown.
• Remove all jewelry or metal items that could interfere with the scan.

The scanner used for most nuclear medicine tests has a hole in the middle and looks like a large doughnut. You lie on a padded table, which moves back and forth through the hole in the scanner. You will need to be very still while the scans are done. The technician (tech) might ask you to change positions so different views can be taken. The table may become uncomfortable after a while.

Thyroid scan: Your thyroid gland is in the front of your neck, so for this test you might sit in a chair that faces the scanner. The scanner is placed right in front of your neck.

MUGA scan: You will lie on a flat table with a large camera above your chest.

How long does it take?

A nuclear scan usually takes about 30 to 60 minutes, plus the waiting time after the radioactive tracer is given. The exact time depends on the scan.

• Thyroid scan: The scan itself takes less than 30 minutes. You will take the radioactive tracer as a liquid or pill about 24 hours before the scan. IV injections are given up to 30 minutes before.
• MUGA scan: The scan itself usually takes 15 to 30 minutes, but it can take longer if more pictures are needed.
• Gallium scan: This scan takes 30 to 60 minutes. You will need to wait several days between the injection and the actual scan. Sometimes, people are scanned more than once after the injection.

Results of nuclear scans are usually available within a few days.

Will I be radioactive after the scan?

The radiation exposure from a nuclear scan comes from the radioactive material used in the tracer. The scanner itself does not put out radiation. The radioactive material in your body will naturally decay and lose its radioactivity over time. It might also leave your body through your urine or stool (poop) within a few hours or days.

Ask your healthcare team whether you need to take precautions before having sex or being close to children or people who are pregnant for a period of time after your test.

You will be asked to drink a lot of water to flush out the radioactive material.

You should also put the lid down and flush the toilet right after you use it. This lowers the risk of being exposed to radioactive material in your urine after a scan.

What are the possible risks and side effects?

For the most part, nuclear scans are safe. The doses of radiation are very small, and the radiotracers have a low risk of being toxic or causing an allergic reaction.

• Some people might have pain or swelling where the material is put into a vein.
• Some people develop a fever or allergic reaction when given a monoclonal antibody. This is rare.

Children can safely get nuclear scans with special care. Parents and children can work with the healthcare team to make a plan for these scans.

Can I get a nuclear scan if I’m pregnant or breastfeeding?

If you are pregnant or plan to become pregnant: Talk to your healthcare team to decide the best plan for you. A pregnant person can get certain nuclear scans if the benefit outweighs the risk. Special care will be taken.

If you are breastfeeding: Talk to your healthcare team to decide the best plan for you. You might need to pump breast milk and discard it until the radiotracer is gone from your system.

Learn more

• Exams and Tests for Cancer