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.

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For formal advice, see our Radiation Protection Adviser pages. 


Distance, in the context of Radiation Protection, relates to one of the three key principles of protection against External Radiation hazards (i.e. Time, Distance & Shielding). In simple terms, increasing the distance between a static source of Ionising Radiation and the absorbing medium (e.g. a person) will reduce the exposure to that person. For certain defined geometries, (e.g. Point Source), the Inverse Square law can be applied which can be stated as: 'double the distance, quarter the dose'.

In radiation protection I spend most of my time explaining to clients what they do not need to worry about.

– Mark Ramsay -