Find us on Social Media:

Positron Emission Tomography
What is it? Overview Usage Side Effects and Warnings

Positron Emission Tomography Overview

Written by FoundHealth.


This test makes images that show activity in body tissues. A substance that gives off a tiny amount of radiation is put into your body. This substance goes to the part of you body that is most active. A machine can then detect where that substance is. PET can be done for many body parts, including:

  • Whole body
  • Brain
  • Lungs
  • Breast
  • Heart

PET Scans of the Brain
PET Scans of the Brain
© 2009 Nucleus Medical Media, Inc.

If you are allergic to the radioactive substance given for a PET scan, you may be at risk for complications. Talk to your doctor.

What to Expect

Prior to Test

  • Wear comfortable clothes.
  • Do not eat or drink anything, except water, for at least four hours before the scan.
  • Check with your doctor about taking your regular medicines.
  • If you have diabetes , ask the doctor for specific diet recommendations for the test day, since this can affect your results.
  • Tell your doctor if you are or might be pregnant.

Description of Test

A nurse or technologist will give you a radioactive substance. This may be done through an injection, or in some cases, you will be asked to breathe in a gas. It will travel through your blood to the area of the body being studied. It takes 30-90 minutes for the substance to be absorbed by the tissue. Once the substance has been absorbed, the scan can take place.

You will lie on a table and be moved into a machine that looks like a large, square doughnut. This machine detects and records the energy levels from the substance that was injected earlier. The images are viewed on a computer monitor. The scan lasts about 30-45 minutes. You may be asked to perform specific tasks before or during the test. For example, during a heart PET scan, you may be asked to walk on a treadmill.

After Test

Drink plenty of fluids to help the radioactive substance pass from your body.

How Long Will It Take?

At least two hours

Will It Hurt?

Except for the pinprick from the injection, a PET scan is a painless procedure. People who are claustrophobic (uncomfortable in closed or tight spaces) may have some anxiety .


The images will show activity levels as different colors or degrees of brightness. A radiologist will review the images and send the results to your doctor. It may take a few days for your doctor to receive the report.




Society of Nuclear Medicine


The College of Family Physicians of Canada

Health Canada


Goroll AH, Mulley AG. Primary Care Medicine. 4th ed. Boston, MA: Lippincott, Williams, and Wilkins; 2000.

National Institutes of Health website. Available at: . Accessed July 22, 2009.

Positron emission tomography (PET) scan. Mayo Clinic website. Available at: . Updated June 2009. Accessed July 22, 2009.

Radiological Society of North America website. Available at: . Accessed July 22, 2009.



No one has made any comments yet. Be the first!

Your Comment