Treatments and tests

PET scan – positron emission tomography

What is a PET scan?

A PET scan uses a special camera and a computer to take pictures of the organs in your body. Most PET scans also use a low radiation dose CT scan so the areas of the body are more accurately identified. 

You will be given a radioactive liquid into a vein in your hand, arm, or foot.

The scanner has a round opening in the centre and a flat bed for you to lie on. While you are lying on the bed, it will slowly move you into the opening where the pictures are taken. The movement is controlled by the staff.

A PET scan may be used to show:

  • cancer and what stage it is at
  • diseases of the heart or brain.

Benefits of a PET scan

  • Shows all the organs of the body in 1 image.
  • May show changes before CT or MRI scans.
  • Can show if you have cancer and how far it has spread.
  • Can be used to look at the response of your cancer treatment.
  • Generally painless.

Risks of a PET scan

Your doctor knows the risks of having a PET scan. Your doctor will consider the risks before recommending you to have a PET scan.

PET scans are not recommended for pregnant or breastfeeding women.

Possible risks include:

  • very small chance you could develop cancer in the long term from the radiation
  • infection, bleeding or bruising at the site of an intravenous injection.


  • Bring your referral letter or request form and all X-rays taken in the last 2 years with you.
  • Leave the X-rays with the staff, as the doctor may need to look at them.
  • These will be returned to you before you leave or you will be told when these are ready to be picked up.
  • Leave all jewellery and valuables at home.
  • You may be asked not to eat or drink for 6 to 8 hours before the PET scan.
  • If you have diabetes, you will be given special instructions.

Just before the PET scan:

  • You may be given a gown to wear.
  • You may be asked to remove any metal objects.
  • You may request or be asked to take a tablet to help you relax (sedative).

Tell your doctor before the scan

  • If you are or may be pregnant.
  • If you are breastfeeding.
  • If you have any allergies.
  • If you have diabetes.
  • If you have eaten anything in the last 6 to 8 hours.

What happens during a PET scan

Staff will put a needle into a vein in your hand or arm ready for the injection. Staff will prick your finger with a small needle and use a special machine to measure the amount of sugar in your blood.

The staff will inject a small amount of radioactive liquid into a vein in your hand, arm or foot. You will then wait around an hour while the liquid moves through your body.

Staff will then ask you to go to the toilet to empty your bladder before you have your PET scan.

For the PET scan, you will be asked to lie on a bed. The staff will set up the camera and leave the room while the pictures are taken. They can see, hear and speak to you at all times. You will be able to speak to them at all times. They will tell you what is happening and when to hold still. If you get stiff, need to move or are feeling closed in (claustrophobic), tell the staff.

The camera may pass over your body while it is taking the pictures. A PET scan takes 1 to 2 hours including time taken to get ready. The scan itself takes about 20 minutes.

When the scanning is finished you will be asked to wait while the staff check the pictures.


You have the right to refuse an examination and may do so if you wish. You may be asked to fill in a consent form.

When will I get the results?

The amount of time it takes for you to get your results will differ depending on where you get your scans done. The imaging specialist will look at the pictures and write a report. The pictures may be on films or on a CD.

Ask whether you should wait to take the pictures and report with you, or whether they will be sent to your doctor.

Your doctor will need to discuss the report with you. You will need to make an appointment to do this.

After a PET scan

You will be able to go soon after the PET scan has finished and can continue with normal activities.

  • Staff will need to take out the needle if it is still in your hand, arm or foot.
  • Staff will give you any special instructions.
  • The radioactive liquid will disappear from your body with only a very small amount remaining after 2 to 4 hours.
  • Drink plenty of fluid to help get rid of the radioactive liquid.

If you had a sedative

  • You must not drive a car or take public transport for 24 hours afterwards.
  • You must have someone with you for 24 hours afterwards.
  • You must not operate machinery for the rest of the day.

Costs of a PET scan

For an Australian patient in a public hospital in Western Australia:

  • public patient – no cost to you unless advised otherwise
  • private patient – costs can be claimed through Medicare and your health insurance provider

For a patient in a private hospital or private imaging site in Western Australia – ask your doctor or the staff where you are having your test done.

Where to get help

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.

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