What depth yields PRF of 5,000 Hz?

What depth yields PRF of 5,000 Hz?

• A. 7.7 cm
• B. 15.4 cm
• C. 5.0 cm
• D. 10.0 cm

Answer: (B)

Depth and PRF are inversely related: to image deeper, the ultrasound pulse must travel farther and come back later, so fewer pulses can be sent each second. The relationship is PRF = c / (2d), where c is the speed of sound in tissue and d is depth. Solving for depth gives d = c / (2 × PRF). Using c ≈ 1540 m/s in soft tissue and a PRF of 5000 Hz: d = 1540 / (2 × 5000) = 1540 / 10000 = 0.154 m = 15.4 cm. So 15.4 cm is the depth that yields a PRF of 5,000 Hz. Deeper depths would lower PRF, while shallower depths would raise PRF (as the round-trip time shortens or lengthens accordingly).

Depth and PRF are inversely related: to image deeper, the ultrasound pulse must travel farther and come back later, so fewer pulses can be sent each second. The relationship is PRF = c / (2d), where c is the speed of sound in tissue and d is depth. Solving for depth gives d = c / (2 × PRF).

Using c ≈ 1540 m/s in soft tissue and a PRF of 5000 Hz:

d = 1540 / (2 × 5000) = 1540 / 10000 = 0.154 m = 15.4 cm.

So 15.4 cm is the depth that yields a PRF of 5,000 Hz. Deeper depths would lower PRF, while shallower depths would raise PRF (as the round-trip time shortens or lengthens accordingly).