What is the equation for PRF? PRF (Hz) = 77,000 cm/s / imaging depth (cm)

What is the equation for PRF? PRF (Hz) = 77,000 cm/s / imaging depth (cm)

• A. PRF (Hz) = imaging depth (cm) / 77,000 cm/s
• B. PRF (Hz) = imaging depth (cm) * 77,000
• C. PRF (Hz) = 77,000 s / cm * imaging depth (cm)
• D. PRF (Hz) = 77,000 cm/s / imaging depth (cm)

Answer: (D)

PRF is the number of ultrasound pulses emitted per second, and it depends on how long it takes for sound to travel to the deepest point and back. The pulse repetition frequency is the inverse of the round-trip travel time: t = (2 × depth) / c, so PRF = 1/t = c / (2 × depth). Using c/2 as 77,000 cm/s (since c is about 154,000 cm/s in tissue), PRF becomes 77,000 cm/s divided by the imaging depth in cm, giving PRF in Hz. This is exactly the form shown. The other options misplace depth in the equation or mix units, which would not yield a rate in Hz.

PRF is the number of ultrasound pulses emitted per second, and it depends on how long it takes for sound to travel to the deepest point and back. The pulse repetition frequency is the inverse of the round-trip travel time: t = (2 × depth) / c, so PRF = 1/t = c / (2 × depth). Using c/2 as 77,000 cm/s (since c is about 154,000 cm/s in tissue), PRF becomes 77,000 cm/s divided by the imaging depth in cm, giving PRF in Hz. This is exactly the form shown. The other options misplace depth in the equation or mix units, which would not yield a rate in Hz.