Which phenomenon is produced when echoes are placed too superficially because a second pulse was emitted before all reflections have returned from the first pulse?

• A. Range Ambiguity
• B. ROM Read Only Memory
• C. RAM
• D. Real Time Imaging

Answer: (A)

Range ambiguity occurs when a second pulse is sent before all echoes from the first pulse have returned. In pulsed ultrasound, depth is determined from the time it takes echoes to return, so each echo is assigned to the pulse that produced it. If another pulse is emitted too soon, deeper echoes can be misattributed to the shallower depth of the newer pulse, causing those echoes to appear at incorrect, too-superficial positions. This artifact limits how deep you can reliably image at a given pulse repetition period. To prevent it, extend the time between pulses (increase PRP) or reduce the imaging depth so all echoes from the current pulse return before the next pulse is emitted. The other options are unrelated phenomena or capabilities (memory types, real-time imaging) and do not describe this depth misassignment.