An aften ignored setting during sonography:

One of the most prominent settings control on any ultrasound machine is the gain knob. Yet, this happens to be one of the most unused. This knob in conjunction with the TGC or Depth gain is very useful. A good example is the female child. Here, transabdominal ultrasound to image the ovaries and small uterus can be a real pain. But lower the gain or Depth gain, and you should be able to see the ovaries, even if very small. It works in most cases.


Observe the images of the thyroid here:
With high gain settings, the margins of the thyroid and fine detail are lost. With too low gain, most of the thyroid becomes poorly visible. Optimal gain settings show both internal and marginal details. Another observation: when Color Doppler imaging is switched on, the overall gain goes down.. the gain has to be increased to compensate for this.