One you have changed into your gown the radiographer will weigh and measure you. Then you have an injection of a very small amount of a radioactive drug called a tracer. This is what shows up on the scan. The drug is usually a form of glucose. Voiceover : After the injection you rest for about an hour.
This allows the tracer to spread through your body. The scan shows up cancer because they use glucose in a different way from normal tissue. When you are ready for the scan the radiographer helps you lie on the couch in the correct position.
Radiographer : I am just going to pop this under your knee, just to help your back stay comfortable. Nothing is going to touch you or anything like that. You must keep very still. Close your eyes, because this light is quite bright. Voiceover : Once you are in position and comfortable the radiographer will leave the room.
You need to lie as still as possible while you are having the scan. If you begin to feel unwell or want some help you will be able to get the radiographers attention. Voiceover : The radiographer control the scan from a separate room, but they will be able to hear and see you all the time you are having the scan and will check you are okay.
Are you okay? You can pop your arms down now. Voiceover : Once the scan is finished you can go home. As a precaution you should avoid contact with pregnant women and small babies for six hours after your scan. Your specialist will give you the results usually within a couple of weeks. The radiation in the radioactive tracer is very small. Drinking plenty of fluids after your scan helps to flush the radiotracer out of your system.
The radioactive tracer gives off very small levels of radiation that go away very quickly. As a precaution, you should avoid close contact with pregnant women, babies and young children for 6 hours after the scan. Most airports have sensitive radiation monitors, which may pick up the trace of radiation following your test. If travelling abroad within a week of your scan, it's a good idea to take your appointment letter with you.
A PET scan is a safe test for most people. But like all medical tests it has some risks. Your doctor and radiographer make sure the benefits of having the test outweigh these risks. Pregnant women should only have the scan in an emergency. Contact the department beforehand if you're or think you might be pregnant. If you're breastfeeding, let the department know a few days before your appointment. They will let you know if you need to stop breastfeeding for a length of time after having the radioactive drug.
You might need to store enough expressed milk for at least one feed. Exposure to radiation from the radiotracer during a PET scan slightly increases your risk of developing cancer in the future.
Talk to your doctor if this worries you. There's is a risk that the radioactive tracer will leak outside the vein. After the test you can carry on with your day as usual, unless your doctor tells you otherwise. You'll need to drink plenty of fluids to help flush the tracer from your body. A doctor specially trained to interpret scan images radiologist will report the findings to your doctor.
Or the PET images may be combined to provide more detail about your condition. Explore Mayo Clinic studies of tests and procedures to help prevent, detect, treat or manage conditions.
Positron emission tomography scan care at Mayo Clinic. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version. This content does not have an Arabic version. Overview Positron emission tomography Open pop-up dialog box Close. Positron emission tomography During a positron emission tomography PET scan, you lie on a narrow table that slides into a doughnut-shaped hole.
PET scan of the heart Open pop-up dialog box Close. PET scan of the heart This PET image shows an area of reduced blood flow from one of the arteries that feeds the heart. Request an Appointment at Mayo Clinic. Share on: Facebook Twitter. Radiological Society of North America. Accessed April 6, What is PET? Society of Nuclear Medicine and Molecular Imaging.
Umterrainer M, et al. Recent advances of PET imaging in clinical radiation oncology. Radiation Oncology. Adam A, et al. It's important you arrive on time because the radiotracer used for your scan only works well for a short time. Your scan may have to be cancelled if you're late. It's a good idea to wear loose, comfortable clothes. It may be possible to wear these during the scan, although sometimes you may be asked to change into a hospital gown.
Avoid wearing jewellery and clothes that have metal parts, such as zips, because these will need to be removed. If you're claustrophobic, ask the hospital staff before the day of the scan about the possibility of having a mild sedative to help you relax.
The radiotracer is injected into a vein in your arm or hand about an hour before your scan, as it takes time for it to reach the right cells in your body. It's important to relax, keep as still as possible, and avoid talking while you wait because moving and speaking can affect where the radiotracer goes in your body. The scan usually takes 30 to 60 minutes. Having the scan is completely painless, but you may feel uncomfortable lying still for this long.
You shouldn't experience any side effects after having a PET scan and can usually go home the same day. The results of your scan won't usually be available on the same day. They'll be sent to your specialist to be discussed at your next appointment.
Any exposure to radiation carries a very small risk of potential tissue damage that could cause cancer at a later date.
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