Radiation Protection Glossary

A radiation protection glossary for Radiation Protection Supervisors (RPS), Radiation Protection Advisers (RPA) and anyone else interesting in radiation safety terms and definitions. The glossary is a mixture of health physics , phrases related to radiation protection legislation, transport, practical safety, technical terms and similar.

Search the Glossary by either clicking on a letter or typing a keyword into the search box. This glossary is relational so when looking at one term you can click through to other related terms as required.

For formal advice, see our Radiation Protection Adviser pages. 

016External Hazard_600by400

External Radiation


The external radiation (hazard) exists where an absorber (typically a person) is being exposed to a source of Ionising Radiation external to the body. Examples would include exposures to Sealed Sources, dental X-Rays and Cosmic Rays. One feature of this hazard is that moving the absorber away from the source (usually) results in a reduction in the Dose of ionising radiation to that absorber, which is not the case for Internal Radiation hazards.

Imagination is more important than knowledge

– Albert Einstein -