A PET scan uses low-dose radiation to check the activity of cells in different parts of the body. It may be used to give more detailed information about cancer or abnormal areas seen on X-rays or scans.

What is a PET scan?

A PET uses low-dose radioactive glucose (a type of sugar) to measure the activity of cells in different parts of the body. It may help find out if  a tumour is cancerous (malignant) or non-cancerous (benign). They can also find out if it has spread to other parts of the body.

PET scans can also be used to examine any lumps that remain after treatment to see if they are scar tissue or whether cancer cells are still present.

What happens during a PET scan?

A very small amount of a mildly radioactive substance is injected into a vein, usually in your arm. A scan is then taken a couple of hours later.

Cancer cells are usually more active than surrounding tissue, and show up on the scan. Not all hospitals have PET scanners, so if you need one you may have to travel to another hospital.

SPECT (single photon emission computerised tomography) scan

This test is similar to a PET scan. It looks at blood flow through the brain.

You are given an injection of a very mild radioactive substance, usually in your arm. This substance travels in the blood to the brain. Then, in the scanning room, pictures (scans) of the brain are taken.

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