The three basic radiation safety principles are shielding, distance, and:

The three basic radiation safety principles are shielding, distance, and time. The principle of time refers to minimizing the duration of exposure to radiation. The longer an individual is exposed to a radiation source, the higher the dose they will accumulate. By reducing the time spent near the source of radiation, professionals can effectively lower their dose and reduce the risk of harmful effects.

Shielding involves using barriers to protect against radiation, while distance relates to maintaining a safe physical space between oneself and the radiation source, thus reducing exposure according to the inverse square law. Together, these three principles—shielding, distance, and time—form the foundational strategies for minimizing radiation exposure and ensuring safety in environments where radiation is present.

The other options—radioactivity, prophylaxis, and dosage—do not represent the fundamental principles of radiation safety. Radioactivity refers to the decay of unstable atomic nuclei, prophylaxis generally pertains to preventive measures in health care rather than radiation safety, and dosage relates to the amount of radiation absorbed but does not serve as a principle for protection strategies in the same direct context as time, shielding, and distance.