What describes the Doppler effect in ultrasound?

• A. A change in amplitude of sound waves
• B. A change in frequency of sound waves in relation to movement
• C. A change in wavelength irrespective of movement
• D. A change in sound quality due to equipment malfunctions

Answer: (B)

The Doppler effect in ultrasound is characterized by a change in frequency of sound waves in relation to movement. This phenomenon occurs when the source of sound or the observer is moving relative to each other. In clinical ultrasound, the Doppler effect is utilized to assess blood flow dynamics; when a blood cell moves towards the ultrasound transducer, the frequency of the reflected sound waves increases, resulting in a higher pitch. Conversely, if the blood cell is moving away from the transducer, the frequency decreases, leading to a lower pitch. This frequency shift is essential for evaluating the velocity and direction of blood flow, which can assist in diagnosing various cardiovascular conditions. The change in frequency is what makes Doppler ultrasound an invaluable tool in clinical practice.