What are three basic means for controlling radiation exposures?

The three basic means for controlling radiation exposures are time, distance, and shielding. This principle is commonly known as the ALARA (As Low As Reasonably Achievable) concept in radiation safety.

Time refers to the duration of exposure to radiation; minimizing the time spent near a radiation source directly reduces the amount of radiation absorbed. The longer a person is exposed, the higher the total dose received, so limiting exposure time is a fundamental practice.

Distance involves maximizing the distance from the radiation source. Radiation intensity decreases with distance due to the inverse square law, meaning as one moves away from the source, the exposure decreases significantly. Therefore, increasing distance is an effective strategy to reduce exposure levels.

Shielding involves using barriers made of lead, concrete, or other materials to absorb or deflect the radiation before it reaches individuals. The effectiveness of shielding depends on the type of radiation and the material used, and selecting appropriate shielding is a key method in protecting against radiation.

In contrast, the other options include terms that do not specifically relate to radiation exposure control. Mass and velocity do not directly influence radiation exposure, while energy, speed, and distance do not coherently address methods of protection against radiation. Thus, the combination of time, distance, and shielding is essential