What percentage of a 50-kVp x-ray beam is attenuated by a 0.25-mm lead equivalent apron?

The correct answer indicates that 97% of a 50-kVp x-ray beam is attenuated by a 0.25-mm lead equivalent apron because this level of attenuation is consistent with the known properties of lead as a protective material against radiation. Lead is highly effective in absorbing x-rays due to its high atomic number, which allows it to significantly reduce the intensity of x-ray beams through interactions like photoelectric absorption and Compton scattering.

At 50 kVp, x-rays have relatively low energy. Lead aprons are typically designed to provide adequate protection at such energy levels, and a 0.25 mm thickness is often sufficient to attenuate nearly all of the radiation. The 97% attenuation rate is supported by scientific studies and data showing that lead aprons of this thickness can effectively block the majority of radiation exposure to underlying tissues.

The other options would suggest different levels of attenuation that do not accurately reflect the protective characteristics of lead at this specific thickness and energy level. For example, a 51% or 66% attenuation would imply that a significant portion of the x-ray energy is still transmitted, which is not in alignment with the effectiveness of lead aprons used in practice. The claim of 100% attenuation is also unrealistic