Which of the following is a method to control external exposure in radiation?

The method of controlling external exposure in radiation, known as "time, distance, shielding," is a fundamental principle in radiation safety. This approach is widely adopted to minimize exposure to radiation for both patients and healthcare professionals.

The concept of time entails reducing the duration of exposure to the radiation source; the less time spent near the source, the lower the dose received. Distance involves maximizing the space between the individual and the radiation source; radiation intensity decreases with increased distance from the source, helping to further diminish exposure. Shielding involves using materials that absorb or attenuate radiation, such as lead for x-rays or concrete for gamma rays, thus protecting individuals from harmful radiation.

By applying these three principles, radiation safety protocols effectively reduce the risk of harmful effects associated with ionizing radiation. This structured approach is critical in protecting not only patients but also medical staff involved in the delivery of radiological procedures.

While changing protocols may influence exposure indirectly and reducing personnel or using personal protective equipment is certainly relevant, they do not encapsulate the primary methods of controlling external radiation exposure as comprehensively as the time, distance, and shielding principle does.