Infographics / Ultrasound Physics

Time-gain compensation (TGC)

Three aligned panels for five reflectors of equal reflectivity at increasing depth. Panel one: received echo amplitude falls with depth because of attenuation. Panel two: time-gain compensation applies progressively increasing receiver gain with depth. Panel three: the displayed result, received amplitude multiplied by gain, is uniform brightness at all depths.

Time-gain compensation equalises echo brightness with depth Three aligned panels for five reflectors of equal reflectivity at increasing depth. Panel one: received echo amplitude falls with depth because of attenuation. Panel two: time-gain compensation applies progressively increasing receiver gain with depth. Panel three: the displayed result, received amplitude multiplied by gain, is uniform brightness at all depths. Time-gain compensation (TGC): equalising echo brightness with depth Five reflectors of equal reflectivity, sampled at increasing depth 1 · received echo amplitude echo amplitude attenuation amplitude falls exponentially with depth 2 · TGC receiver gain applied receiver gain gain rises with time-of-flight (depth) — more gain for deeper echoes 3 · displayed brightness (received × gain) brightness uniform brightness at all depths increasing depth (superficial → deep)
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