What is the maximum velocity limit for a 3 MHz CW Doppler unit operating at a depth of 4 cm?

What is the maximum velocity limit for a 3 MHz CW Doppler unit operating at a depth of 4 cm?

• A. 40 cm/s
• B. 200 cm/s
• C. 2.5 m/s
• D. None of the above

Answer: (D)

In continuous-wave Doppler, the velocity you measure comes from the Doppler frequency shift, given by f_D = 2 f_0 v cos θ / c. That means velocity is determined by the carrier frequency, the speed of sound, and the angle between the flow and the ultrasound beam. Depth does not enter this relationship, because CW Doppler does not provide range information and there’s no range-based constraint like in pulsed Doppler. Since the maximum velocity you can display or measure depends on the receiver’s bandwidth and how large a Doppler frequency shift the system can process, there isn’t a fixed, depth‑dependent limit you can derive from 3 MHz and 4 cm alone. Therefore none of the provided numeric options can be asserted as the maximum velocity for this setup. The key takeaway is that depth doesn’t set a velocity limit in CW Doppler; the limit is determined by the instrument’s bandwidth and display.

In continuous-wave Doppler, the velocity you measure comes from the Doppler frequency shift, given by f_D = 2 f_0 v cos θ / c. That means velocity is determined by the carrier frequency, the speed of sound, and the angle between the flow and the ultrasound beam. Depth does not enter this relationship, because CW Doppler does not provide range information and there’s no range-based constraint like in pulsed Doppler.

Since the maximum velocity you can display or measure depends on the receiver’s bandwidth and how large a Doppler frequency shift the system can process, there isn’t a fixed, depth‑dependent limit you can derive from 3 MHz and 4 cm alone. Therefore none of the provided numeric options can be asserted as the maximum velocity for this setup. The key takeaway is that depth doesn’t set a velocity limit in CW Doppler; the limit is determined by the instrument’s bandwidth and display.