Radiological risks have to be managed:

• by efficiently using protection resources to reduce exposure to as low a level as is reasonably achievable, and by ensuring that the risk is not transferred to other population groups;
• by ensuring that dose variations within exposed groups also remain reasonable.

To manage risks, three risk levels are usually distinguished: unacceptable, tolerable, and negligible.

The aim of radiation protection is to reduce exposure levels to below the unacceptable risk region. When radiation protection is optimized, the residual risk level becomes acceptable. Any additional measure is ineffective from both the economic and social points of view.

Regulatory limits are an additional means of ensuring that the residual risk levels for any individual remain in the tolerable risk region. Individual exposures below these limits are only regarded as 'acceptable' if they have been optimized.