A shielding device constructed with a thickness equivalent to 1 half-value layer (HVL) will reduce the quantity of radiation to:

A shielding device constructed with a thickness equivalent to 1 half-value layer (HVL) will reduce the quantity of radiation to:

• A. 75% of the original quantity
• B. 50% of the original quantity
• C. 25% of the original quantity
• D. 12.5% of the original quantity

Answer: (B)

One half-value layer is the thickness of shielding that reduces the beam intensity by 50%. Attenuation through shielding is exponential, so each HVL halves the transmitted radiation. Therefore, a shield thickness equal to one HVL leaves 50% of the original radiation.

One half-value layer is the thickness of shielding that reduces the beam intensity by 50%. Attenuation through shielding is exponential, so each HVL halves the transmitted radiation. Therefore, a shield thickness equal to one HVL leaves 50% of the original radiation.