Using radiation in medicine - PET scanning

PET scanning stands for

positron emission tomography

PET scanning

• A medical imaging technique that uses radioactive isotopes to visualise organ function and diagnose medical conditions.

• It can identify active cancer tumours by showing metabolic activity in tissue as cancer cells have much higher metabolism than healthy cells because they’re growing a lot

how PET scans work step 1

Inject patient with a substance used in the body (e.g. glucose), containing a positron-emitting radioactive isotope with a short half-life is injected into the patient's bloodstream so it acts as a tracer. Tracers then spread throughout body.

how PET scans word step 2

Positrons emitted by the isotopes meet electrons in an organ and annihilate, emitting high-energy gamma rays in opposite directions.

how PET scans work step 3

• the patient will lie in a PET scanner which will detect where the gamma radiation is being emitted from

• the doctors can use this to see where the tracers are concentrated & to diagnose medical conditions

• The distribution of radioactivity matched up with metabolic activity because more of the radioactive glucose is used by cells that are doing more work (cells with increased metabolism)

Tracers must be made nearby

The radioactive isotopes have short half lives(to minimise harm to patient) + means they have to be made near the hospital as they would decay before being used