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Scanning for Medical Purposes

PET Scans

PET (Positron Emission Tomography) is a very high resolution medical imaging technique, capable of identifying tumours in the early stages, as well damage to the heart or the brain.

This kind of examination has the advantage of providing information about the metabolism of the organ being scanned, and not only about its structure as is the case of magnetic resonance, ultra sound or X-rays.

However,  it costs around £4.2 million to set up a full PET scanner.

How does it work?

The PET scan starts with the injection of a tracer solution containing a radioactive element (e.g. Fluorine18).  It is taken up most quickly by parts of the body where there is an exaggerated multiplication of cells (a tumour for example) and does not reach damaged regions of the body where activity is minimal (such as damaged parts of the brain or heart).

The radioactive element has a half-life of a few hours and emits gamma rays as it decays. The source of the gamma rays is precisely located with the help of computers  to generate high resolution images. These are used by doctors to visualize the damaged body structures in a precise way.

PET scans are non-invasive, unfortunately, the use of this kind of exam is limited by its high costs, because it requires the production and storage of radioactive elements.

PET scans are also used in Pharmacology: a medicine can be tagged with a radioactive tracer in order to study its absorption and elimination.


Next: Scanning for medical purposes: NMR scanners


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PET scan image

PET scan image


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