If sound did not attenuate with increasing depth, what system control would you no longer need?

• A. Reject
• B. TGC
• C. Dynamic range
• D. Frame averaging

Answer: (B)

The concept being tested is how depth-related signal loss is compensated in ultrasound imaging. As sound travels through tissue, it weakens with depth, so echoes from deeper structures come back fainter. To keep brightness consistent from near to far, the system uses a gain that increases with depth—Time Gain Compensation. If attenuation did not occur with depth, there would be no need to boost deeper echoes, so this depth-specific gain adjustment would not be required. Other controls address different image quality aspects: rejecting low-level noise, adjusting the overall dynamic range to map echoes to gray levels, and frame averaging to reduce speckle. These would still be useful for image quality, but they don’t compensate for depth-related loss, so they aren’t the control you’d drop in this scenario.