Ultrasonic medical imaging, current techniques and future developments

A review is given of a theoretical frame work, that is pre-eminently suited for both narrowband and broadband acoustic echo-techniques as used in seismic exploration, medical imaging and nondestructive inspection. It is shown that conventional focussing represents a simplified acoustic inversion process. A discussion is given on practical aspects of vertical and lateral resolution. Ultimate limits are indicated for the medical situation. It is argued that the new generation of medical imaging systems will consist of digital 'workstations' under full software control. By those workstations advanced data gathering, image reconstruction, image processing as well as tissue characterization will be handled.