Which control is used to compensate for signal loss with depth to keep brightness uniform?

• A. TGC
• B. Overall gain
• C. Output power
• D. Depth

Answer: (A)

Attenuation of ultrasound signals increases with depth, so to keep image brightness uniform you need depth-specific amplification. This is achieved with Time Gain Compensation (TGC), which applies more gain to echoes from deeper locations by using a depth-dependent amplification curve. That way, echoes from far tissue aren’t dimmed by attenuation as much, resulting in a consistently bright image across depths.

The other controls don’t provide this targeted compensation: overall gain amplifies all echoes equally, so it can brighten near regions but won’t correct for depth-dependent loss; output power changes the transmitted intensity but doesn’t adjust the received signal’s brightness by depth; depth control simply sets how deep the image displays, not how the echoes are compensated.