Positron Emission Tomography Scan

In this Article

What are the risks and/or side effects?

PET scans are considered safe. Even though they use radioactive materials, the amounts are small. In some cases, your child would be exposed to the same amount of radiation for an x-ray. However, a PET-CT scan uses more radiation than either one by itself.

The risk of radiation exposure is very low compared to the benefits, such as finding cancer or another disease in its early stages. Nuclear medicine scans have been done on babies and children for over 50 years, and doctors have not found any long-term adverse effects related to them.

Some children are allergic to the tracers used in nuclear medicine scans. This kind of an allergy is rare, and the reaction is usually mild. Be sure to inform the doctor running the scan:

  • If your child has an allergy to the tracer
  • If any other problems have happened during past nuclear medicine scans

If your child is diabetic, their blood sugar levels will need to be watched closely. The tracer with glucose will not affect the diabetes, but it’s important to let the doctor know that your child is diabetic.

What are the benefits?

A PET scan can reveal information that other imaging studies can’t. It can show problems at the cellular level of your child’s body. That means it is a very useful tool in finding diseases in their early stages and then guiding the treatment of those diseases.

Doctors use PET scans to check the size, shape, and function of organs. Unlike exploratory surgery, a PET scan is not invasive.

A combined PET-CT scan gives more detail and is more accurate. Instead of having 2 scans done at different times, your child can have both done at once.

How do I prepare?

Your child’s doctor will tell you specific things to do or not to do before the PET scan. If your child has diabetes, you may want to ask about the fasting and diet needed before the scan.

Your child’s doctor will tell you about the PET scan and what to expect. Some common ways to prepare include:

  • Asking questions. If you have questions or concerns about the procedure, be sure to talk to your doctor or healthcare provider.
  • Informing your doctor. Before the scans are done, you should verify that the doctor running the scan knows what medicines, vitamins, supplements, or patches your child uses as well as your child’s medical conditions, allergies, and recent illnesses. The doctor can make sure that these things will not interfere with your child’s safety, the test, or its results.
  • Following instructions. You may receive instructions about eating and drinking before the scan. You may also be asked to stop using certain medicines.
  • Talking to your child about the scan. If your child is old enough to understand, you can tell them about the test so they know what to expect. An injection of the tracer might hurt like getting a shot. The scanner itself might make them feel closed in and uncomfortable. Most of the time, a parent will be allowed to stay in the room with them during the scan. (Pregnant women cannot stay.) If the scan will take a long time, they will be given breaks.
  • Wearing loose, comfortable clothes. Your child might be asked to change into a gown for the test. They should not wear jewelry or metal during the scan.

How is it done or administered?

Before the Scan
Before the scan, your child will need to have the tracer injected. This might hurt like getting a shot, but the pain should go away quickly. If your child is getting a tracer mixed with glucose, your child’s blood sugar level may need to be checked first.

The tracer needs about an hour to move through your child’s body to where it is designed to go. Your child will be in a warm, dimly lit room during this time. Your child will need to hold still, be quiet, and rest. They won’t be allowed to play games. Any activity affects the tracer and the pictures that will be taken.

When the tracer’s uptake time is over, your child will be asked to use the bathroom.

During the Scan
When it is time to start the scan, your child will be placed on an exam table while the gamma camera does its work. The gamma camera does not put off any radiation. Instead, it detects radiation from the tracer and then sends information to a computer. Using the camera’s data, the computer makes detailed pictures of the structure of an organ, how an organ is working, or the spread of diseased tissue.

A tracer that is mixed with glucose (sugar) might be used to find the extent of cancer growth. Cancer cells will pick up the glucose faster than regular cells. This test can find cancer in the body because the radioactive material that was absorbed with the sugar will light up in the pictures.

For a PET-CT scan, your child might need an IV that will inject a contrast material into your child’s bloodstream throughout the scan. The contrast material might feel warm in your child’s body. That goes away as soon as the IV is taken out.

Your child will need to hold still while the camera is on. Sometimes they will be asked to do things that stimulate the brain or cause another effect that the PET scan will pick up. Most of the time, the scanning will take less than an hour.

If your child is having lots of trouble holding still, the doctor running the scan may consider sedating your child to make them sleepy.

After the Scan
Before you go, the doctor running the scan will want to check all the pictures. You’ll have to wait for a short time while they make sure that no more pictures are needed.

The tracer will naturally disappear from your child’s body after the scan in a process called radioactive decay. This usually takes less than a day, and your child should drink plenty of water to help flush the tracer out of their body.

Unless the doctor says not to, your child will be able to go back to their usual routine and activities after the scan. If your child was sedated, the doctor will give you specific instructions to follow.


When will I know the results?

After the PET scan is done, the pictures will be studied by a specialist who will write a report. That report and the pictures are then sent to your child’s doctor who will explain them to you.

What are follow-up requirements and options?

Your child’s doctor will explain the results of the scan during a follow-up appointment.

Support and Resources

RadiologyInfo.org (Radiological Society of North America): https://www.radiologyinfo.org/en/info.cfm?pg=pet

MedLine Plus: https://medlineplus.gov/nuclearscans.html

National Institute of Biomedical Imaging and Bioengineering: https://www.nibib.nih.gov/science-education/science-topics/nuclear-medicine

A PET or positron emission tomography [PAH-zih-TRAWN ee-MIH-shun tuh-MOG-ruh-fee] scan makes pictures of organs and tissues inside your child’s body. The scan can help show how well parts of the body are functioning or show abnormal changes. PET scans can find disease in its earliest stages, see how well treatment is working, see if cancer has returned, measure blood and oxygen use in the body, and check for problems in the brain. The scan uses small amounts of a radioactive substance called a tracer that is injected into your child. The procedure takes about an hour and can be used to diagnose or observe many diseases and conditions. The scan is sometimes combined with a CT scan to make a PET-CT scan with even more detail.

What is Positron Emission Tomography Scan?

A positron emission tomography [PAH-zih-TRAWN ee-MIH-shun tuh-MOG-ruh-fee] scan or PET scan is a kind of nuclear [NOO-klee-er] medicine scan. Like all nuclear medicine scans, it uses a small amount of radioactive material called a tracer that can be detected by a special gamma camera and computer.

For a PET scan, the tracer is mixed with something that the body uses such as sugar or oxygen and is designed to go to the part of the body that is being studied. The tracer is usually injected 45 minutes to 1 hour before the procedure so it has time to travel through the body. The tracer uses very low amounts radioactive material and is considered safe for use in the body.

The tracer is detected and tracked by a special camera and computer, which then make images showing parts of the body and how well they’re working. The scans can help diagnose cancers, injuries, infections, and other problems, especially those that can’t be seen with other imaging studies such as an x-ray, CT scan, or MRI.

In a child, a PET scan might be done to:

  • Check for cancer
  • See how a treatment, such as chemotherapy, is working
  • Measure blood flow
  • Measure oxygen use
  • Measure glucose metabolism (how your child’s body is using sugar)
  • Check for problems in the brain and nervous system
  • Look at normal function of organs, such as the brain or heart

The scan doesn’t hurt and usually takes 30 minutes to 1 hour to complete. Your child will need to hold very still while the pictures are taken. Some children need to be sedated with medicine to make them sleepy and help them hold still.

A PET scanner is often combined with a CT scan to provide even more detail in the pictures it makes. This is called a PET-CT scan. The PET scan can also be combined with an MRI.