Final answer:
A lead apron that can reduce transmitted exposure to approximately 99.9% of the incident scatter dose typically requires a thickness of 1.5 mm Pb equivalent or greater, with 0.50 mm Pb equivalent offering less protection and 0.25 mm Pb equivalent offering the least protection. Therefore, the correct answer is 1. 1.5 mm Pb equivalent.
Step-by-step explanation:
A person wearing a lead apron with a certain level of lead equivalence will reduce their exposure to scatter radiation during medical procedures that utilize ionizing radiation, such as x-rays. The question asks for the thickness of lead equivalent in a protective apron that would reduce transmitted exposure to approximately 99.9% of the incident scatter dose.
Without a direct citation to confirm, we would refer to general radiation safety guidelines which suggest that a 0.25 mm Pb equivalent apron can provide a reduction in exposure of about 95%, whereas a 0.50 mm Pb equivalent apron offers increased protection, but to achieve approximately 99.9% protection, a 1.5 mm Pb equivalent or greater is typically required.
Therefore, for maximum safety in a high exposure environment, higher lead equivalency in protective aprons is advised.
Factors that influence the effectiveness of radiation shielding include the thickness of the protective material and the type of radiation. For instance, lead aprons in medical settings, such as in dental radiography, protect patients and technicians from scattered radiation.
The effectiveness of this protective measure is crucial for occupational safety in healthcare environments where ionizing radiation is used.