Boots WebMD Partners in Health
Return To Boots

PET scan

A positron emission tomography (PET) scan is used to give doctors a three-dimensional view inside a person's body.

The PET scan shows the part of the body being scanned and how well it is working.

Uses of PET scans include identifying part of the brain that is causing seizures in a person with epilepsy, or problems in the brain caused by dementia.

A PET scan may be performed to plan an operation, such as heart surgery, or to monitor cancer, or other treatment.


How a PET scan works

The PET scan is done by injecting a small amount of radioactive material, called tracer, into a vein, usually in the arm.

Positively charged particles called positrons in the tracer interact with negatively charged particles called electrons in the body.

The PET scanner uses this interaction to form an image.

Not all hospitals will have PET scanners, so a referral to a specialist centre may be made.

Before having a PET scan

Before having a PET scan, the medical team will make sure they know about existing health conditions and medication taken.

Although the amount of radiation involved in a PET scan is at safe levels, it is important for women to say whether they might be pregnant or are breastfeeding, as there are risks in these cases.

The PET scanner will usually have a flat bed to lie on, with the circular scanner at the end.

It is important to stay still and not speak during the scan. You will be monitored from a control room, and will be able to let the operator know if you are distressed or are experiencing discomfort.

The scanner may upset people with a fear of enclosed spaces (claustrophobia), and sedation may be recommended in some cases.

Specific instructions will be given before leaving the scanning centre on drinking fluids to help flush out the tracer.

If sedation has been given, the person will not be able to drive home.

The results of the PET scan will usually be given through the doctor who requested them some days or weeks later.

WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on September 21, 2017

Stay informed

Sign up for BootsWebMD's free newsletters.
Sign Up Now!

Popular slideshows & tools on BootsWebMD

How to help headache pain
rash on skin
Top eczema triggers to avoid
boost your metabolism
Foods to lower LDL (bad) cholesterol
Tips to support digestive health
woman looking at pregnancy test
Is your body ready for pregnancy?
sick child
Dos and don'ts for childhood eczema
Treating your child's cold or fever
bucket with cleaning supplies in it
Cleaning and organising tips
adult man contemplating
When illness makes it hard to eat
woman holding stomach
Understand this common condition
cold sore
What you need to know