ALARAprincippet

ALARAprincippet, often referred to in English as the ALARA principle, is a guideline in radiation protection that exposures to ionizing radiation should be kept as low as reasonably achievable, taking into account economic and social factors. The principle embodies the idea that radiation risk can be minimized not by fixed limits alone but through an ongoing optimization process; the concept is usually applied alongside justification of practices and dose limits.

Origin and development: The approach emerged in the mid-20th century in the nuclear industry and medical research community and was formalized by the International Commission on Radiological Protection (ICRP) and later incorporated into IAEA safety standards and national regulations. It emphasizes that there is no zero-risk threshold, but that exposures should be reduced as far as practicable given available technology and resources.

Implementation: In practice, ALARAprincippet requires a systematic optimization process. First assess the potential exposure and associated risk; then apply protective measures such as reducing time near sources, increasing distance, improving shielding, and using engineering controls. Administrative measures, training, procedural changes, and equipment optimization are also used. Doses are monitored with reference levels and dose constraints, and protection plans are reviewed regularly.

Applications: It is central to radiology, interventional imaging, nuclear medicine, radiotherapy planning, industrial radiography, and occupational exposure management. It guides equipment design, procedure protocols, and safety culture.

Limitations: Because it weighs economic and social factors, the definition of what is "reasonably achievable" can vary, leading to inconsistencies. It is not a fixed dose limit and does not guarantee zero exposure; it requires careful justification, ongoing measurement, and governance.