Ultrasonic Medical Images.

Spectacular progress were made in recent years in the use of ultrasounds for medical images. This success is due to the fact that the organs are transparent to ultrasonic radiation of a few MHz. The first ultrasonic images produced by the Russian physicist Sokolov in 1929 used a set-up imitating the method by which ordinary optical images are produced. More recently, many research workers tried to apply the new techniques of coherent optics to ultrasonic waves. As the same time since the fifties, other systems were devised for producing echograph pictures analogous to sonar images. Although ordinary image techniques have not yet been used much for medical applications, echography on the other hand is proving to be a very effective investigation technique, used increasingly by doctors.