Medical imaging and what to expect

Learn more about the medical imaging process at Monash Health.

Types of scans

To learn more about your imaging test, visit one of the pages below on the Inside Radiology website:

PET scans

What is a PET (Positron Emission Tomography) scan?

This is a highly sensitive imaging technique which uses small amounts of radioactive tracers to help in the diagnosis of disease.

These tracers are given by injection, usually into a vein in the arm.

A PET/CT scanner is used to obtain an image showing the distribution of the tracer within the body.

The PET scan routinely involves a low level CT scan performed at the same time.

What happens during a PET/CT scan?

Most appointments are completed within 2 hours, however due to the complex nature of PET scanning unforeseen delays can occasionally occur. Please allow at least 3 hours.

Upon arrival a Technologist will explain the test and answer any questions. A needle is inserted into a vein in the arm and for FDG PET scans your blood sugar is tested.

The radiotracer is injected and for most PET scans you rest for a period of 30-90 minutes prior to scanning.

The scan then begins and normally takes between 15 and 30 minutes.

You may drive after a PET scan unless you have had sedation.

Type of PET scans


The most common PET scan performed uses 18F-FDG (a glucose/sugar analogue) to map glucose metabolism.


A brain imaging agent that looks at amino acid transport and protein synthesis.

68Ga-PSMA (Prostate Imaging Tracer)

This tracer accumulates on the Prostate Specific Membrane Antigen which is overexpressed with prostate cancer cells.

68Ga-DOTA (Neuroendocrine/Carcinoid Imaging Tracer)

This tracer identifies areas of increased somatostatin receptors within the body, such as Neuroendocrine and Carcinoid tumours.

18F-NaF (Bone Scan)

This tracer is a bone imaging agent.

Patient preparation

18F-FDG Day Prior
  • No vigorous exercise (running, weights, gym classes, bike riding) for 24hr prior
  • High protein – low carbohydrate/ low sugar diet for 24 hours prior
  • Foods to eat: Meats, eggs, leafy vegetables, broccoli, cauliflower, tofu, avocado, hard cheeses
  • Foods to avoid: Breads, pastas, cereals, potatoes, corn, sweets, deserts, sweet drinks, alcohol
Day of scan
  • Fast for 6 hours. No food or drink other than plain tap water is allowed (this includes no lollies, gums, mints, coffee/tea, or flavoured water).
  • Also no IV solutions that contain any dextrose (please check if anything other than normal saline is planned)
  • It is important to stay warm – please dress warmly in the lead up to your scan as this impacts scan image quality – even in summer (long top and long pants).
  • If there is a chance you may be pregnant or if you are breast feeding – tell reception or a technologist when your appointment is booked.
  • You MUST NOT attend your appointment with pregnant women or children.
What if I have diabetes?

Your blood glucose level ideally needs to be below 10mmol/L, and due to the need to fast it is best for you to have a morning appointment.

Please bring all insulin/diabetic medications with you to your appointment.

For people with diabetes on insulin, you must fast from midnight and must not take your morning insulin on the day of your scan.  If you have been given or require an afternoon appointment or if you are unsure about any instructions then please contact us.

Note: If you are coming from a long distance – it may be worthwhile to check your blood sugar before leaving home and informing us of the result if it is above 8mmol/L.

For people with diabetes on oral medications, cease the following Metformin/Metformin analogues for 48 hours prior to your scan:

  • Metformin
  • Diabex
  • Diaformin
  • Metex
  • Formet
  • Metforbell
  • Glucohexal
  • Glucomet
  • Glucophage
  • Genrx

Other oral diabetic medications: don’t take on the day of your scan until after it is completed.

Information about radiation

To learn more about radiation, visit one of the pages below on the Inside Radiology website:

Learn more about medical imaging

For further information about radiation safety and medical imaging, you can visit the following sites:

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