positron emission tomography scan PET

Positron emission tomography (PET) scan



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A PET scan produces three-dimensional, colour images of your body using radiation. It can be used to diagnose a health condition, or find out more about how a condition is developing. It can also be used to evaluate the results of a particular treatment.

What is a PET scan used for:

Diagnose a cancer

Stage a cancer

Show whether a lump is cancerous or not

Show whether a cancer has spread to other parts of the body

Decide the best treatment for your cancer

Show how well chemotherapy is working

Show the difference between scar tissue and active cancer tissue

What having a PET scan involves:

Since only a few hospitals have the PET scanner you may have to travel to another hospital. For some PET scans you may need to eat nothing for 4 to 6 hours before your appointment time and only drink water. For other scans there will be no preparation at all. Your appointment card should give you details about what to do to prepare for your scan. Unless you are told otherwise, always take any prescribed medications as usual.

Before a PET scan is performed you will be injected with a glucose solution containing a very small amount of a radioactive drug (tracer) which helps to show a clearer picture of the part of your body that needs to be examined. The level of radiation is very small, so it doesn't damage your body. However, you should speak with your doctor or specialist if you are pregnant or breastfeeding, as the level of radiation used could damage your baby unless special precautions are taken.

After you have the injection you rest for about an hour. This allows the radioactive tracer to spread through the body. The scan itself can take up to an hour. It is important that you lie as still as possible while the scan is being done. The test should not be painful. In case you need some assistance, you will have a buzzer that you can press to get attention. The staff doing the scan will be able to see you at all times.

After your scan you should feel fine and be able to resume your normal diet and activities. A PET scan is a painless procedure. You should be able to return home on the same day without any side effects.

When do patients get the results?

It usually takes a couple of weeks for the results to come through. Usually, the scan is examined by a specialist in radiology or nuclear medicine and a report is written. The report then goes to your specialist, who gives the results to you.
If your doctor needed the results urgently, it would have been noted on the scan request form and the results will be ready sooner than that. Try to remember to ask your doctor how long you should expect to wait for the results when you are first asked to go for the test.

Further general information Your doctors and specialist nurses are in an ideal position to give you relevant information on your disease and treatment as they know your individual circumstances. Cancerbackup has a help line (0808 800 1234) and a prize winning video available in English, Italian, Urdu, Bengali, Gujarati & Hindi explaining Radiotherapy & Chemotherapy. Cancernet.co.uk has over 500 pages describing cancer, its management, practical tips and tool which patients, their carers and their doctors have found helpful during the cancer journey.