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Positron Emission Tomography (PET) provides physicians with information
about the body's chemistry not available through any other procedure.
Unlike CT or MRI, which look at anatomy or body form, PET studies
metabolic activity or body function. PET has been used primarily in
cardiology, neurology, and oncology. In particular, it has been used to
assess the benefit of coronary artery bypass surgery, identify causes of
childhood seizures and adult dementia, and detect and grade tumors.
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In PET the patient receives a short
half-lived radiopharmaceutical (produced by a cyclotron or a generator).
Because the radioisotope used in a PET scan is short-lived, the amount of
radiation exposure the patient receives is about the same as from two
chest X-rays. The radiopharmaceuticals discharge positrons from wherever
they are used in the body. As the positrons encounter electrons within the
body, a reaction producing gamma rays occurs.
The patient lies on a table that slides into the middle of the
scanner. Within the scanner are rings of detectors containing special
crystals that produce light when struck by a gamma ray. The scanner's
electronics record these detected gamma rays and map an image of the area
where the radiopharmaceutical is located. Since the radiopharmaceutical
contains a chemical commonly used by the body, PET enables the physician
to see the location of the metabolic process. For example, glucose (or
sugar, which the body uses to produces energy) combined with a
radioisotope will show where glucose is being used in the brain, the heart
muscle, or a growing tumor.
More information on PET
You can go to our links
page or use these external
resources.
UCLA's Brochure Positron Emission Tomography (PET) - The Power of
Molecular Imaging
UCLA's Let's Play PET on-line tutorial, which provides a detailed
explanation of the physical and medical basis of Positron Emission
Tomography
Institute for
Clinical PET
Society of Nuclear
Medicine |
