Radiation Safety Practice Exam

What does the biological half-life of an isotope refer to?

1. The time required for half of the isotopes to leave the body

2. The time required for an isotope to fully decay

3. The time it takes for an isotope to start showing biological effects

4. The time required for biological systems to become immune to the isotope

The correct answer is: The time required for half of the isotopes to leave the body

The biological half-life of an isotope is the duration it takes for half of the radioactive substance to be eliminated from a biological system or organism through natural processes, such as metabolism or excretion. This measure is crucial in radiation safety and medicine because it helps in understanding how long an isotope remains active within the body and the potential risks associated with exposure. This understanding is particularly significant when assessing the health impacts of radioactive materials. If an isotope has a long biological half-life, it means that it will remain in the body longer, potentially leading to greater biological effects due to longer exposure to radiation. Thus, the correct answer highlights the relationship between the biological half-life and the elimination of isotopes from living organisms, leading to better informed decisions in medical treatments and safety protocols in handling radioactive materials.