Key terms & definitions

A process in which an unstable atomic nucleus emits radiation and changes; the moment at which a particular nucleus decays cannot be predicted.

The process in which an unstable atomic nucleus emits radiation and changes to become more stable.

Radioactive material carried through the environment after a nuclear explosion or accident.

An isotope with unstable nuclei that can decay by emitting radiation.

A radioactive substance used to make the location of a target visible on a scan.

Material containing unstable atoms whose nuclei emit radiation as they decay.

A material containing unstable atomic nuclei that emit radiation as they decay.

A mildly radioactive substance introduced into the body so that its distribution can be detected by a scanner.

A radioactive substance introduced into the body so that its movement or concentration can be detected from outside.

A radioactive substance introduced into the body so that its radiation can be detected to investigate what is happening inside the body.

Waste containing radioactive material that requires secure management and storage to protect people and the environment.

Unwanted radioactive material that must be managed safely because some of it remains dangerous for a long time.

Unwanted material that emits ionising radiation and must be managed safely to protect people and the environment.

The spontaneous decay of unstable atomic nuclei, accompanied by the emission of radiation.

A dating method that uses radioactive carbon-14 in material that was once living.

A method of estimating the age of once-living material by measuring its remaining radioactive carbon-14 and calibrating the result.

A method of estimating the age of suitable material by measuring the decay of radioactive isotopes.

Estimating age using the radioactive decay of isotopes in suitable materials.

An isotope with an unstable nucleus that undergoes radioactive decay.

A radioactive isotope attached to a substance chosen to travel to, or collect in, a particular part of the body.

The treatment of cancer using radiation to destroy cancer cells or reduce tumour growth.

Treatment that uses ionising radiation to destroy tumour cells.

The treatment of unwanted tissue, such as a cancerous tumour, using ionising radiation.

Treatment that uses radiation to kill cancer cells.

A radioactive isotope incorporated into a substance so that its movement or distribution can be detected.

An electromagnetic wave in the lowest-frequency, longest-wavelength region of the electromagnetic spectrum.

An electromagnetic wave that can be produced by electrical oscillations and can induce electrical oscillations when absorbed.

Electromagnetic radiation used to carry signals for broadcasting and other wireless communications.

The distance from the centre of a circle to its edge; it is half the diameter.

The distance from the centre of a sphere or approximately spherical object to its edge.