The 'ALARA' principle in radiation protection stands for 'As Low As Reasonably Achievable.' In practice, which combination of measures best operationalizes ALARA for a diagnostic radiology worker?

• A Wearing a lead apron only when performing fluoroscopy
• B Reducing the number of imaging studies regardless of clinical indication
• C Minimizing exposure time, maximizing distance from the source, and using appropriate shielding ✓
• D Using the highest kV settings to reduce radiation dose per image

Explanation

ALARA is operationalized through three principles: (1) Time — minimize duration of exposure; (2) Distance — dose decreases with square of distance (inverse square law); (3) Shielding — appropriate lead barriers or aprons. Reducing studies regardless of clinical need is inappropriate as it compromises patient care. High kV does reduce patient dose but is only part of the technical optimization; it does not protect the worker from scatter radiation. The time-distance-shielding triad is the classical framework for radiation worker protection.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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