What is a typical Doppler frequency?

What is a typical Doppler frequency?

• A. 1-10 Hz
• B. 1-10,000 Hz
• C. 100-1000 Hz
• D. 10-100 Hz

Answer: (B)

Doppler frequency in ultrasound is the frequency shift you detect from moving blood cells or tissue. Because the transmitted ultrasound is in the megahertz range and typical blood velocities are modest, the shift ends up in the kilohertz region. Using the standard relation f_d = 2 f0 v cos θ / c, with f0 around 2–5 MHz and v on the order of tens of cm/s, you get shifts from a few hundred hertz up to several thousand hertz, often up to about 10,000 Hz. That makes a range of roughly 1–10,000 Hz the realistic, clinically relevant depiction of a typical Doppler frequency. The smaller ranges (1–10 Hz, 10–100 Hz, or 100–1000 Hz) would not accommodate the shifts produced by ordinary blood flow with standard transducers.

Doppler frequency in ultrasound is the frequency shift you detect from moving blood cells or tissue. Because the transmitted ultrasound is in the megahertz range and typical blood velocities are modest, the shift ends up in the kilohertz region. Using the standard relation f_d = 2 f0 v cos θ / c, with f0 around 2–5 MHz and v on the order of tens of cm/s, you get shifts from a few hundred hertz up to several thousand hertz, often up to about 10,000 Hz. That makes a range of roughly 1–10,000 Hz the realistic, clinically relevant depiction of a typical Doppler frequency. The smaller ranges (1–10 Hz, 10–100 Hz, or 100–1000 Hz) would not accommodate the shifts produced by ordinary blood flow with standard transducers.