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PET scan

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 2 minutes read

PET stands for positron emission tomography, a way of creating 3D images of the inside of your body and showing how well certain parts of the body are working. During the scan, a slightly radioactive substance (known as a radiotracer) is injected into your bloodstream. It can then be detected as it moves around your body and is taken up by different cells or parts of your body. It shows which cells are more active and which are less. It is usually used with CT or MRI scanning to provide detailed images.

Your body then excretes the radiotracer over the course of a couple of hours after the scan, so it does not stay in your system. PET scanning is particularly useful for helping diagnose cancer, looking at its spread or response to treatment, and looking at conditions that affect the brain.

What is the machine like?

The scanner is large and white, with a hole in the middle where the bed (and patient) passes through. You are laid on the bed for a PET scan, and the bed will move you through the scanner. The radiotracer will be injected into your arm and should not be painful. The scan usually takes up to an hour to complete, and you must lie as still as possible.

What about the radioactive tracer?

The amount of radiation from the radioactive tracer is very small, and your body will excrete the substance over the course of a couple of hours. Still, it can give an extremely small increased risk of developing cancer in the future. It is also best avoided in pregnant people unless it is an emergency.

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Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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