Which artifact is caused by a high PRF setting?

Which artifact is caused by a high PRF setting?

• A. Lateral displacement
• B. Range ambiguity
• C. Shadowing
• D. Speckle

Answer: (B)

High PRF means the pulses are sent very close together in time, so the time available for echoes to return before the next pulse is issued is short. If echoes from deeper structures don’t return before the next pulse, their depth information gets mixed up, causing range ambiguity—echoes can be assigned to incorrect, often shallower, depths or even appear duplicated. This is the artifact produced by a high PRF setting. Lateral displacement comes from beam geometry and steering, not the timing between pulses. Shadowing results from attenuation behind dense tissues, unrelated to PRF. Speckle is the grainy texture from coherent interference of scattered waves, also not due to PRF.

High PRF means the pulses are sent very close together in time, so the time available for echoes to return before the next pulse is issued is short. If echoes from deeper structures don’t return before the next pulse, their depth information gets mixed up, causing range ambiguity—echoes can be assigned to incorrect, often shallower, depths or even appear duplicated. This is the artifact produced by a high PRF setting.

Lateral displacement comes from beam geometry and steering, not the timing between pulses. Shadowing results from attenuation behind dense tissues, unrelated to PRF. Speckle is the grainy texture from coherent interference of scattered waves, also not due to PRF.