The History of Ultrasound in Medicine

Ultrasound refers to sound waves above the human range of hearing, 20,000 or more vibrations per second. Ultrasonic devices are used for measuring distance and detecting objects, but it’s in the realm of medical imaging that most people are familiar with ultrasound. Ultrasonography, or diagnostic sonography, is used to visualize structures inside the human body, from bones to organs, tendons, and blood vessels, as well as the fetus in a pregnant woman. 

Ultrasound was developed by Dr. George Ludwig at the Naval Medical Research Institute in the late 1940s. The physicist John Wild is known as the father of medical ultrasound for imaging tissue in 1949. In addition, Dr. Karl Theodore Dussik of Austria published the first paper on medical ultrasonics in 1942, based on his research on transmission ultrasound investigation of the brain; and Professor Ian Donald of Scotland developed practical technology and applications for ultrasound in the 1950s.

Ultrasound is used in a large array of imaging tools. A transducer gives off the sound waves that are reflected back from organs and tissues, allowing a picture of what is inside the body to be drawn on a screen. 

The transducer produces sound waves from 1 to 18 megahertz. The transducer is often used with a conductive gel to enable the sound to be transmitted into the body. The sound waves are reflected by internal structures in the body and hit the transducer in return. These vibrations are then translated by the ultrasound machine and transformed into an image. The depth and strength of the echo determine the size and shapes of the image.

Ultrasound can be very useful during pregnancy. Ultrasound can determine the gestational age of the fetus, its proper location in the womb, detect ​the fetal heartbeat, determine multiple pregnancies, and can determine the sex of the fetus. While ultrasonic imaging can change temperature and pressure in the body, there is little indication of harm to the fetus or mother through imaging. Nonetheless, American and European medical bodies urge ultrasonic imaging to be performed only when medically necessary.