Higher frequency sound results in a ____ half-value layer.

Higher frequency sound results in a ____ half-value layer.

• A. Thick
• B. Thin
• C. Medium
• D. None

Answer: (B)

In ultrasound physics, the half-value layer is the thickness of tissue needed to reduce the sound intensity by half. Higher frequency sound is attenuated more quickly in tissue because attenuation increases with frequency. Because of that stronger attenuation per unit length, a smaller thickness is enough to halve the beam’s intensity. So the half-value layer becomes thinner as frequency rises. A thicker or unchanged HVL would imply less attenuation, which isn’t the case with higher frequency. So the correct description is thin.

In ultrasound physics, the half-value layer is the thickness of tissue needed to reduce the sound intensity by half. Higher frequency sound is attenuated more quickly in tissue because attenuation increases with frequency. Because of that stronger attenuation per unit length, a smaller thickness is enough to halve the beam’s intensity. So the half-value layer becomes thinner as frequency rises. A thicker or unchanged HVL would imply less attenuation, which isn’t the case with higher frequency. So the correct description is thin.