Depth information on A-mode is derived from which information?

Depth information on A-mode is derived from which information?

• A. Time-of-flight information
• B. Amplitude
• C. Pulse duration
• D. Frequency

Answer: (A)

Depth in A-mode comes from the time it takes for a ultrasound pulse to travel to a boundary and back. Knowing the speed of sound in tissue, you convert the round-trip travel time into distance, using depth = (speed of sound × round-trip time) / 2. In A-mode, the display uses depth along one axis and the echo amplitude on the other, so the height shows reflectivity while the position of the spike along depth reflects where that boundary lies. Amplitude affects how strong the echo is, not how deep it is; pulse duration and frequency influence pulse characteristics and resolution, not the depth calculation itself.

Depth in A-mode comes from the time it takes for a ultrasound pulse to travel to a boundary and back. Knowing the speed of sound in tissue, you convert the round-trip travel time into distance, using depth = (speed of sound × round-trip time) / 2. In A-mode, the display uses depth along one axis and the echo amplitude on the other, so the height shows reflectivity while the position of the spike along depth reflects where that boundary lies. Amplitude affects how strong the echo is, not how deep it is; pulse duration and frequency influence pulse characteristics and resolution, not the depth calculation itself.