Which principle of radiation safety is addressed by keeping exposure time as short as possible?

• A. Distance
• B. Time
• C. Shielding
• D. Dosimeter badges

Answer: (B)

Shortening exposure time directly lowers the total radiation dose because dose is the product of the exposure rate and the time the source is active near you. This idea is a practical part of the ALARA mindset, which encourages reducing exposure by controlling time (along with distance and shielding). In practice, keeping beam-on time as brief as possible—using pulsed or intermittent exposure, prepared techniques, and efficient workflow—minimizes the amount of radiation you and the patient receive.

The other approaches still affect dose but don’t address time itself. Increasing distance reduces exposure through the inverse-square relationship, and shielding blocks some of the radiation. Dosimeter badges measure the amount of exposure you’ve received but do not reduce it.