At what angle relative to the velocity of a red blood cell should the transducer be held during Doppler ultrasound to most accurately determine blood velocity?

The answer is 0º

Explanation:

The options are;

A. 0º

B. 30º

C. 45°

D. 90°

The answer is A - 0º (Zero degree)

Cosine θ is applied as a correction for the angle between the ultrasound beam and the direction of blood flow. Cos θ = 1 if the beam is parallel to the direction of blood flow, which allows the Doppler ultrasound measure maximum and accurate velocity.