What are the three fundamental factors in radiation safety that reduce exposure dose?

• A. Time (Min Exposure), Ventilation, Shielding (Barriers)
• B. Distance From Source, Shielding (Barriers), PPE
• C. Time (Min Exposure), Distance From Source, Shielding (Barriers)
• D. Time (Min Exposure), Distance From Source, PPE

Answer: (C)

Reducing radiation dose relies on three practical controls: Time, Distance, and Shielding. If you spend less time near the source, you accumulate less dose because exposure is proportional to how long you’re exposed. Increasing your distance from the source dramatically lowers dose due to the inverse square relationship: doubling the distance makes the dose rate drop to one-quarter. Shielding adds a barrier between you and the radiation, attenuating the radiation so less reaches you; the effectiveness depends on the material and its thickness for the radiation type involved.

PPE and ventilation play supportive roles in specific situations but don’t reduce the external exposure as reliably as these three controls. PPE (like lead aprons) protects parts of the body but doesn’t lower the overall dose rate from the source, and ventilation mainly affects inhalation of airborne contaminants rather than external radiation dose.