Ultrasonic medical imaging: past, current and future

Ultrasonic imaging began, like life, in the sea, with the development of sonar for detecting submarines after World-War 1. However, to begin to image soft tissues the ranging time of ocean sonars needed to be reduced, and the electronics speeded up, by a factor of about the ratio between nautical miles and centimeters. This was only possible after the electronic developments made for radar in World-War 2. The rest of our technical history closely follows the developments in semiconductors and fabrication methods that led to modem electronics. This is a largely personal story of a recently graduated engineer with radar experience, who began with fabricating equipment to be used in the hospital to diagnose breast cancer, and continued with involvement the development of echocardiography and Doppler devices. Along the way many others have contributed to the field, including work in other countries that is not covered here. In future, ultrasonic imaging may hold the key to understanding some fundamental questions in human health if adopted for screening studies. It alone offers a relatively inexpensive imaging method that is free of known hazards.