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ALARA stands for “As Low As Reasonably Achievable”.
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- It is a fundamental principle of radiation protection, recommended by ICRP (International Commission on Radiological Protection), aimed at minimizing radiation doses and releases of radioactive materials while still achieving the required medical/technical purpose.
The ALARA (As Low As Reasonably Achievable) principle in radiation protection
Najjar R (July 10, 2023) Radiology's Ionising Radiation Paradox: Weighing the Indispensable Against the Detrimental in Medical Imaging. Cureus 15(7): e41623. doi:10.7759/cureus.41623
Rationale
Based on the Linear No-Threshold (LNT) model:
- Any radiation dose, no matter how small, carries a risk of biological harm (e.g., stochastic effects like cancer).
- Therefore, exposures must be kept well below regulatory dose limits whenever reasonably possible.
Implementation
Applied through three cardinal principles of radiation protection:
Time
- Minimize time spent near a radiation source.
- Example: reduce fluoroscopy screening time, pulsed fluoro.
Distance
- Radiation intensity follows the inverse square law (I ∝ 1/d²).
- Doubling distance reduces exposure by ~75%.
- Example: staff standing farther from patient during exposure.
Shielding
- Use barriers (lead aprons, thyroid shields, lead glass, wall shielding) to absorb scatter.