Ultrasonography is a medical imaging technique that uses high frequency sound waves to see inside of your body. The ultrasonography technique is similar to echolocation, which is used by bats, whales and dolphins. It’s also similar to the SONAR technique used by submarines.

What it’s used for

Ultrasonography is used by doctors to look inside of your body. The technique has a wide variety of uses in the medical field. It can show doctors how fast blood is moving through a heart valve, how a baby is developing in the womb, and even detect stones inside the kidneys or gall bladder.

How it Works

The ultrasound machine transmits high-frequency (1-5 MHz) sound pulses into your body using a probe that the ultrasound technician manipulates. The sound waves then travel into your body and hit a boundary between tissues. These boundaries can be between fluid and soft tissue or between soft tissue and bone.

Some of the sound waves get echoed back to the probe, while some continue traveling until they reach another boundary and get echoed. The echo waves are picked up by the probe and transmitted to the machine.

The machine analyzes the distance from the probe to the boundaries (signifying a tissue or organ) using the number for the speed of sound in tissue and the time of each echo’s return. This is a very small amount of time, usually millionths of a second. The machine shows the distances and intensities of the echoes on the screen. This forms a two dimensional image like the ones shown on this page.

Typically, millions of pulses and echoes are sent and received each second. The technician can manipulate the probe along the surface of the body to get different views of the tissues.