Comprehensive and Detailed Explanation From Exact Extract:
Continuous wave (CW) Doppler utilizes two separate crystals: one constantly transmitting and one constantly receiving. This setup allows CW Doppler to measure very high velocities without aliasing, but at the cost of losing range specificity (no depth resolution).
According to sonography instrumentation reference:
“Continuous wave Doppler uses two separate elements for continuous transmission and reception of sound waves, allowing for detection of very high velocities but without depth specificity.”
Therefore, the correct answer is D: Dedicated transmit and receive crysta
82
What artifact is indicated by the arrows in the image below?
An ultrasound image of a fetus
Description automatically generated
A. Ring down
B. Grating lobe
C. Enhancement
D. Refraction
Answer: A
Comprehensive and Detailed Explanation From Exact Extract:
The image shows a bright, continuous, vertical band extending from a gas-containing structure (seen at the top). This is characteristic of ring down artifact, which occurs when multiple small gas bubbles resonate and create continuous echoes below the structure.
According to sonography instrumentation reference:
“Ring down artifact results from resonance of gas bubbles, producing a continuous series of echoes distal to the source. It appears as a bright, vertical band that does not fade with depth.”
Therefore, the correct answer is A: Ring down.
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