What are the cardinal principles for controlling external radiation exposure?

The cardinal principles for controlling external radiation exposure are indeed time, distance, and shielding. These principles are foundational in radiation safety practices and are essential for minimizing the risk to individuals who may be exposed to ionizing radiation.

The principle of time refers to the duration of exposure; limiting the amount of time spent near a radiation source reduces the total dose received. The distance principle emphasizes maximizing the distance between oneself and the radiation source. As the distance from the source increases, the exposure to radiation decreases significantly, following the inverse square law. Lastly, shielding involves using materials that can absorb or deflect radiation, such as lead or concrete, to protect individuals from exposure.

These three principles work together effectively to reduce radiation dose and ensure safety. Understanding and applying these principles is crucial for anyone working with or near radiation sources to maintain a safe working environment and protect health.