A PET/CT (Positron Emission Tomography Computed Tomography) scan combines a CT scan and a PET scan into one. The scan uses X-ray technology together with a radioactive tracer to produce a detailed three-dimensional picture of your internal anatomy and function.
What is a PET/CT Scan?
A PET/CT scan is a precise diagnostic imaging technique that combines a PET scan and a CT scan to create detailed 3D images of the inside of your body to help identify the location of your cancer.
The PET (proton emission tomography) scan detects the radiation given off by a radioactive drug (a radiotracer) that is injected into your arm and accumulates in parts of the body where the cancerous cells are. The radiotracer has been modified to seek out and specifically attach to proteins that are found on the outside of cancer cells. It can even find cancer cells that have spread to other parts of the body that can’t be seen on other imaging scans. When the radiotracer attaches to and accumulates around a tumour, it shows up on your PET scan as a hot spot of radioactivity that can be easily seen by your radiographer.
The CT (computed tomography) scan uses X-ray radiation to take a series of X-rays from different angles around your body. Each X-ray image is called a ‘slice’. A computer analyses each slice and combines them together to create a detailed 3D image of the inside of your body.
We use PET/CT scans for many types of cancer and during different parts of your cancer journey. It is more accurate in diagnosing cancer than a PET scan or CT scan alone.
Why do I need a PET/CT scan?
Your consultant may suggest you undergo a PET/CT scan so we can:
- Diagnose your cancer
- Stage your cancer (find out its size and see if it has spread)
- Determine if you can have surgery to remove your cancer
- Choose your treatment options
- Plan radiotherapy treatment
- See how well your cancer is responding to treatment or if it has come back
A 68Gallium PET/CT is also routinely used as part of our ‘seek and destroy’ Theranostics treatment. Your consultant may suggest Theranostics if you have either advanced prostate cancer or neuroendocrine tumours which have spread elsewhere in your body and other treatments haven’t worked or are not suitable.
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What happens at a PET/CT scan?
Your radiographer may ask you to stop eating for four to six hours before your PET/CT scan but you can drink water during this time. They might also advise you to avoid strenuous exercise for 24 hours before your scan. We’ll discuss this in more detail with you beforehand.
Once you’ve arrived at your appointment, your radiographer will ask you to change into a gown and remove any jewellery or other metal objects which may interfere with the scanner. A private changing area and locker for your personal items is provided for your use during the scan.
Before your PET/CT scan, your radiographer will inject a radioactive tracer into your arm, hand or occasionally foot, through a small plastic tube (cannula). The tracer will only remain in your body for a few hours and will not produce any side effects.
Once you’re ready to have your scan, your radiographer will take you into the scanning room. They’ll ask you to lie down on your back on the couch and will help you into the correct position.
Your radiographer will leave the room, but they’ll be able to see you on a screen for the duration of the scan. You’ll be able to talk to one another through an intercom system and they may give you some specific instructions during the scan.
The couch will slowly move backwards and forwards through the hole of the scanner. The machine looks like a big ring and takes images as you move through.
Depending on which area you’re having scanned, you may be in the room for 20 to 45 minutes. The scan itself won’t cause you any pain but you may find that lying in the same position causes you a little discomfort. Once your scan has finished, your radiographer will come back in the room and help you off the couch.
You shouldn’t experience any side-effects from your PET/CT scan and can usually go home soon as soon as your cannula has been removed. You’ll need to drink plenty of fluids to flush the radiotracer out of your system and you can eat as normal.
Because of the radioactivity in your system, your radiographer will advise you to avoid prolonged contact with children or pregnant women for a couple of hours after your scan as a precaution. We’ll discuss this in more detail with you on the day. The radiotracer will eventually pass out of your body in your urine.
Your results will be sent to the doctor who requested the scan, usually within 24-48 hours of the scan being completed.
Should I be worried about radiation from a PET/CT scan?
A PET/CT scan is a low risk procedure and the amount of radiation you’ll receive from it is equivalent to about five years of naturally occurring (‘background’) radiation. The decision to perform a PET/CT scan is always made by a qualified member of our team who ensures that the radiation exposure is justified.
Your PET/CT scan will provide us with important information and it’s considered that the benefit for you is much greater than the risk from radiation. If you have any concerns or want some more information about the risks of a PET/CT scan, you can speak to your radiographer or visit:
If you’re breast-feeding, pregnant, or know there is chance that you might be, please inform the department where you’ll be having your PET/CT scan ahead of your appointment.
How much does a PET/CT scan cost?
We’re recognised by all major private medical insurers and also offer a range of self-payment options. A GP referral is not always necessary and the cost for a PET/CT scan starts from £1,400. Find your nearest centre offering PET/CT scanning to book an appointment.