Ultrasound and its various modes in use-part I.

This is part I of a two-part discussion of the basic principles and properties of ultrasound and piezoelectric materials. These instruments are designed to perform depth measurements. Various types of conventional diagnostic ultrasound instruments are commonly used in health care: A-scanners are the basic ultrasound machine, useful in examining the brain and the eye. B-scanners, used for rapid recognition of anatomic landmarks, provide a two-dimensional image. Time-motion or M-mode scanning produces a trace of time vs position. Doppler instruments transmit and receive information continuously. In part 2, the author will review real-time scanners, principles and uses, and considerations in designing imaging systems.