The dead zone is the region closest to the transducer face where the ultrasound system cannot display accurate images. This occurs because the transducer is still transmitting its pulse during this very brief time period and cannot simultaneously listen for returning echoes. The dead zone is typically only a few millimeters deep but can affect the visualization of very superficial structures. Sonographers can minimize the impact of the dead zone by using a standoff pad, which is a gel-filled cushion placed between the transducer and the skin to move the area of interest deeper into the imaging field, or by selecting a transducer with a shorter pulse length.
Sonography Term