PET scans

Positron emission tomography (PET) is a non-invasive nuclear medicine technique that allows the evaluation of metabolic processes and the disturbance of these processes by disease

It allows the identification of metabolically active cancer cells and provides excellent information on the staging of the disease and the impact of treatment.

What preparation will I need?

Depending on what type of PET/CT scan you’re having there will be specific preparation instructions you need to follow. All instructions will be on your appointment letter – please read it carefully.

For FDG PET/CT scans you will not be able to eat anything six hours before your appointment. During this time you can drink as much still/tap water as you like - you do not need to have a full bladder for your scan.

It is essential that you contact the Nuclear Medicine Department on receipt of your appointment to let us know about any medication that you may be taking, if you have diabetes, are pregnant or breast-feeding. 

What happens when I come for a scan?

When you come for your appointment it is advisable to wear clothing without metal fastenings. Alternatively, we can provide a hospital gown or pyjamas.

A locker will be provided for your valuables but you must give the key to a radiographer/technologist as it is magnetic.

Who will I see when I have my scan?

As well as meeting reception staff, you will also meet radiographers/technologists who are trained to carry out the scans.

You may also see a Radiologist - a specialist doctor who is trained to interpret the results and carry out some of the more complex examinations.

Does the scan hurt?

No, the scan isn’t painful. However, you will have to lie still for up to one hour on a table which is quite hard. The radiographers/technologists will do their best to make you comfortable.

If you have any pain or discomfort that could lead to difficulties with the scan, please tell the radiographer/technologist before your scan.

What happens during the scan?

When you arrive in the department we will ask you to change into a hospital gown and remove all jewellery. You will then be taken to a preparation room where we will give you a small injection of radioactive tracer into a vein and ask you to remain lying down for about one hour before your scan.

After an hour, we will ask you to move into the scanning room. You will be scanned with your arms raised above your head. Occasionally we may also scan you with your arms by your sides.

If you are worried about any aspects of your scan, please speak to your radiographer/technologist before you come in. During the scan, the radiographer/technologist will be able to see you from the control room and you can talk to each other through an intercom.

How long will the scan take?

Scans can take between 90 and 120 minutes. If your scan is going to take longer you will be told when your appointment is made.

What happens afterwards?

Once the scan is completed you will be able to leave the department immediately.

You will be able to eat and drink what you like, and go anywhere you wish but you should avoid prolonged close contact with children for the rest of the day to avoid exposing children to unnecessary radiation.

The tracer that we inject will not produce any side effects. You can continue with your usual daily activities, it will not make you drowsy and will not prevent you from driving a car.

When will I know the results?

Although the radiographer/technologist can see parts of your body on the screen, the images must be carefully interpreted by a Radiologist/Nuclear Medicine physician who is an expert in this field.

He or she will prepare a report and send it to your doctor within 24 hours of completion. Your doctor will tell you the results and discuss them with you.

What if I can’t keep my PET/CT appointment?

If you can’t keep your appointment, please contact the PET/CT department straight away on 020 8661 3762 (Sutton) or 020 7808 8537 (Chelsea). If you are admitted to hospital before your appointment, please tell the ward staff that you have a PET/CT appointment booked.

Where can I get help?

The staff in the PET/CT department will be happy to answer any questions you may have. Please ask at the time of your appointment or call the department at any time on the numbers above.