Positron Emission Tomography (PET) 1973 – Three-Dimensional Medical Imaging

In Star Trek, fictional spacecraft were powered by antimatter–matter reactions. Today, however, real antimatter–matter reactions have a practical application in the three-dimensional medical imaging technique called positron emission tomography (PET). 

Unlike other scanning methods such as CAT (computerised axial tomography) or MRI (magnetic resonance imaging), which use X-rays and magnetism, PET provides detailed information about body and tissue function. 

• In preparation for a PET scan, a radioactive substance produced in a cyclotron (particle accelerator), such as  the sugar fluorodeoxyglucose (FDG), which contains a radioactive fluorine atom,  may be injected into the patient. 
• Cancer  cells are examples of metabolically active cells that absorb more  FDG than less active cells and tissues.
• When the fluorine atom decays, it emits a  positron, the antimatter form of an electron with a positive electric charge.
• The positron collides with an ordinary electron, creating a burst of energy in the form of gamma rays (high-energy radiation). 
• These gamma rays are then detected by circular detectors surrounding the patient, helping to locate high concentrations of FDG. 

Today, PET scanners are often integrated with CAT scanners to show metabolic and anatomical information in better alignment. The patient's radiation dose may be low because radioactive fluorine is short-lived. 

Many technology specialists contributed to developing PET. For example:

• In 1953, American physicist Gordon Brownell conducted early research into using positrons for medical imaging of the brain.
• In 1973, American biophysicist Michael E. Phelps invented a PET device. He then worked on later generations of PET scanners that served as prototypes for today's systems.

Although PET images are not as sharp as CAT and MRI images, PET scans may be useful for detecting tumours and cancer spread, determining the effectiveness of cancer treatment, examining blood flow in heart muscle, assessing seizures and epilepsy, and predicting the course of disease. 

They have also contributed to identifying the onset of Alzheimer's disease and distinguishing it from other conditions such as Parkinson's disease, Huntington's disease and vascular dementia.

Description of the article image: A PET scan “slice” of the brain after the patient has been injected with the tracer FDG. Red areas show accumulated high concentrations of FDG. Blue areas show regions with very little tracer accumulation.

Historical figures mentioned in the article: Gordon L. Brownell (1922–2008), Michael E. Phelps (b. 1939)

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