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PET, or positron emission tomography, is an imaging technology. Unlike CT or MRI, PET does not image structures inside the body. Instead, PET machines produce images of body functions in 3D. These include blood flow and parts of the brain responsible for specific mental processes. Patients swallow or are injected with safe radioactive materials called ‘tracers’, and are then placed inside the PET machine while detectors scan and track the tracers around the body. Computers process this information into images showing body function.

Georg von Hevesy pioneered radioactive tracers during the 1930s and was awarded a Nobel Prize in 1944 for his work. During the 1950s and 1960s research teams scanned radioactive substances. American scientist Michel Ter-Pogossian and his team at Washington University pioneered the practical use of PET within medicine in the 1970s. Ter-Pogossian was inspired by the number-crunching power of CT scanners, and developed the first computerised PET scanner in 1975.

However, PET is not used in medicine as often as other scanning techniques. PET techniques are complex and expensive. To use a PET machine, hospitals need enormous machines called cyclotrons to produce radioactive tracers on site.


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M Welch and V Kunkler, ‘Michael Ter-Pogossian Obituary Notice’, Physics Today, 49 (1996), pp 100-102


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