As low as reasonably achievable (ALARA)

Last revised by Calum Worsley on 25 Jan 2024

As low as reasonably achievable (ALARA) is a principle of radioprotection stating that whenever ionizing radiation has to be applied to humans, animals or materials exposure should be as low as reasonably achievable while still maintaining a suitable image quality for diagnosis 1. It is fundamental to the principles of radiation protection.


A variant of ALARA used in the UK and some other countries is as low as reasonably practicable (ALARP), which is said to aim to emphasize the trade-off between dose and image quality, though in practice the two mean substantially the same thing 2.

ADVERTISEMENT: Supporters see fewer/no ads