PET scan



A positron emission tomography (PET) scan is a medical imaging test that is used to assess cancers, neurological (brain) diseases and cardiovascular (heart) disease.

Your PET scan is performed by a healthcare professional called a nuclear medicine scientist who works with a doctor.

How does a PET scan work?

A PET scan involves the patient being given a simple and painless injection of a small amount of a positron-emitting radioactive material called a radiopharmaceutical.


A camera in the PET scanner detects emissions coming from this injected radiopharmaceutical to take two and three-dimensional images of the body.

The areas where the injected radiopharmaceutical gathers - for example, fast-growing cancer cells - appear 'brighter' on the images than normal tissue.

In most cases where a PET scanner is used, a CT scanner is also used.

A CT scan is used for taking pictures of virtually any part of the body.


When is a PET scan used?

There are a number of occasions when a PET scan proves to be extremely helpful.

These include the early detection and monitoring of cancer, as many cancers can be detected using PET before they can be 'seen' using other medical imaging techniques.

A PET scan can also be used to see if tumours are malignant (cancerous) and to tell the difference between an active tumour and scar tissue.

PET scans be used in neurological diseases to provide information about the biochemical function of the brain, and in assessing conditions such as Alzheimer's disease and Parkinson's disease.

This is because the images can show areas of the brain that are functioning differently to normal.

Cardiovascular (heart-related) diseases can be assessed by a PET scanner to assess both the blood flow to the heart and how the heart is working.

Before having a PET scan

Your doctor will tell you what to expect from a PET scan and so will the nuclear medicine scientist.

You may need to fast (not eat or drink) for a set amount of time before having the scan.

Tell the receptionist or nuclear medicine staff if you have diabetes when you make your booking, so that appropriate arrangements can be made.

You must also inform your doctor and the nuclear medicine staff if you are pregnant, think you may be pregnant or if you are breastfeeding.

Having the scan

The small injection of radioactive material does not cause any symptoms and you will feel no different after having it.

After you have the injection the PET scanner will start taking a series of images. The nuclear medicine team may decide to wait at least 60 minutes after the injection before the scan begins.

In most cases, you will need to rest before and after the injection of the radioactive material and then once enough amount of time has passed, you will be asked to lie on the imaging bed which has rests for your legs, arms and head to help keep them still and comfortable.

You must lie quietly and still as the scanning table moves through the scanner 'ring' and imaging generally takes around 30 minutes. It is completely painless.

After the PET scan

After your PET scan, you can go home and carry on with your normal activities straight away as the injection does not make you feel any different or drowsy and no anaesthetic is used.

The scan results will not be available immediately so before you leave.

The nuclear medicine scientist will tell you when your doctor will have the results and when a follow-up appointment with your doctor is needed.

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