Which term is also known as depth of penetration or penetration depth?

Which term is also known as depth of penetration or penetration depth?

• A. Fundamental frequency
• B. Half value layer
• C. Dispersion
• D. Duty factor

Answer: (B)

Attenuation of the ultrasound beam in tissue governs how far it can travel before becoming too weak to image. The half-value layer is the thickness of tissue required to reduce the beam’s intensity by 50%. This directly links distance traveled to a specific drop in energy, making it a practical measure of penetration depth. Since attenuation increases with frequency, higher-frequency beams have smaller half-value layers and shallower penetration, while lower-frequency beams have larger half-value layers and deeper penetration. The other terms describe frequency, dispersion, or timing, not how far the beam penetrates, so the half-value layer best matches depth of penetration.

Attenuation of the ultrasound beam in tissue governs how far it can travel before becoming too weak to image. The half-value layer is the thickness of tissue required to reduce the beam’s intensity by 50%. This directly links distance traveled to a specific drop in energy, making it a practical measure of penetration depth. Since attenuation increases with frequency, higher-frequency beams have smaller half-value layers and shallower penetration, while lower-frequency beams have larger half-value layers and deeper penetration. The other terms describe frequency, dispersion, or timing, not how far the beam penetrates, so the half-value layer best matches depth of penetration.