The depth of the reflector determines the depth at which the reflection focus occurs.

• A. Surface
• B. Depth of the reflector
• C. Height
• D. Distance to transducer

Answer: (B)

In ultrasound imaging, where a reflection shows up along the depth axis is determined by how deep the reflecting interface is. The transducer sends a pulse, it travels to the reflector and back, and the system converts that two-way travel time into a display depth using the known speed of sound. The deeper a reflector is, the longer the round-trip time and the deeper the echo appears on the image. So the depth of the reflector directly sets the depth position of the reflection focus in the image.

The surface would primarily produce shallow echoes, but it doesn’t regulate deeper reflections. Height isn’t the depth axis used for showing where reflections lie, and while the distance to the transducer is related to the setup, it’s the reflector’s actual depth that fixes where the reflection is displayed.