Why is gel used in Ultrasonography?
Gel is applied between the transducer and skin to displace air and minimize large reflections that would interfere with ultrasound transmission from the transducer into the patient and vice versa. Reflections tend to occur at tissue interfaces where there are large differences in the speed of propagation of ultrasound waves, such as at air/soft tissue and bone/soft tissue interfaces. Gel decreases such reflections at the skin surface by matching the acoustic impedances of the transducer surface and skin surface.
