The Doppler frequency is determined by the ______.

The Doppler frequency is determined by the ______.

• A. Angle
• B. Transducer
• C. Pulse duration
• D. Sample volume

Answer: (B)

The Doppler frequency is anchored to the frequency emitted by the transducer. The measured Doppler shift scales with the transmitted ultrasound frequency: a higher transmit frequency produces a larger shift for the same blood velocity, described by the Doppler relation fD ∝ f0 · v cosθ / c. While the angle (cosθ) affects how much of the flow velocity is projected along the beam, and pulse duration or sample volume influence resolution and where you measure, they do not set the fundamental frequency shift itself. Therefore, the transducer—by setting the transmitted frequency—determines the Doppler frequency.

The Doppler frequency is anchored to the frequency emitted by the transducer. The measured Doppler shift scales with the transmitted ultrasound frequency: a higher transmit frequency produces a larger shift for the same blood velocity, described by the Doppler relation fD ∝ f0 · v cosθ / c. While the angle (cosθ) affects how much of the flow velocity is projected along the beam, and pulse duration or sample volume influence resolution and where you measure, they do not set the fundamental frequency shift itself. Therefore, the transducer—by setting the transmitted frequency—determines the Doppler frequency.