ALARA (as low as is reasonably achievable)

ALARA (as low as is reasonably achievable) is defined in US Nuclear Regulatory Commission regulations (10 CFR 20.1003) as making every reasonable effort to maintain radiation exposures as far below the dose limits in 10 CFR Part 20 as is practical, taking into account the state of technology, the economics of improvements in relation to that technology and to benefits for public health and safety, and other societal and socioeconomic considerations, all in the context of using nuclear energy and licensed materials in the public interest. It is not itself a numeric dose limit; it is an operating principle that sits below the hard limits and requires continual effort to reduce doses further wherever reasonably practical.

10 CFR 20.1101 requires every licensee to develop, document and implement a radiation protection programme that is commensurate with the scope and extent of licensed activities and sufficient to ensure compliance, with ALARA as its guiding principle for both occupational and public exposure. In a nuclear medicine or radiopharmacy setting this translates into concrete practice: shielding (lead or tungsten syringe shields, L-blocks, hot-cell walls), distance (using tongs or automated dispensers rather than close manual handling), time (minimising time spent near unshielded sources), workflow design that keeps the highest-activity work furthest from staff and the public, and engineering controls such as ventilated hoods for volatile radiopharmaceuticals.

ALARA is distinct from, but complementary to, the specific dose limits in Part 20 (for example, 100 mrem/year for members of the public, or 2 mrem in any one hour in unrestricted areas) and the training-and-equipment requirements of Part 35 for medical use of byproduct material; a facility can be within all numeric limits and still be found non-compliant if it has not made the reasonable further efforts ALARA demands, particularly during periodic radiation safety programme reviews and inspections.