Which is the best example of a cardinal principle of radiation protection?

Minimizing exposure time is a fundamental principle of radiation protection because reducing the time a person is exposed to radiation directly decreases the dose received. This principle is rooted in the concept that exposure to radiation is cumulative; the longer the time spent near a source of radiation, the higher the total dose will be. By limiting the duration of exposure, individuals can significantly lower their risk of potential radiation-related health effects.

In contrast, the other options do not align with the primary objectives of radiation safety. Decreasing the distance from the source, while it can reduce exposure, is not a cardinal principle since increasing distance is typically the recommended practice for minimizing exposure—not decreasing it. Increasing the intensity of the radiographic image is not relevant to radiation protection principles, as it focuses on image quality rather than safety. Finally, maximizing the effective dose during imaging runs counter to the basic tenets of radiation protection, which strive to keep doses as low as reasonably achievable.