Ultrasonic transducers for medical diagnostic imaging

Abstract

Over the past decades, ultrasound imaging technology has made tremendous progress in obtaining important diagnostic information from patients in a rapid, noninvasive manner. Although the technology has benefited from sophisticated signal processing technology and imaging system integration, much of this progress has been derived from the development of ultrasonic transducers that are in direct contact with patients. An overview of medical ultrasonic imaging transducers is presented in this review that describes their structure, types, and application fields. The structural components of a typical transducer are presented in detail including an active layer, acoustic matching layers, a backing block, an acoustic lens, and kerfs. The types of transducers are classified according to the dimensions of ultrasound images: one-dimensional array, mechanical wobbling, and two-dimensional array transducers. Advantages of each transducer over the other and the technical issues for further performance enhancement are described. Application of the transducers to various clinical imaging fields is also reviewed.

Keywords: 1D array; 2D array; Mechanical wobbling transducer; Ultrasonic transducer; Ultrasound image.

Fig. 1

Photograph of ultrasonic transducers [5]

Fig. 2

Schematic structure of a 1D array transducer

Fig. 3

2D ultrasound image of a uterus using the 1D array transducer [5]

Fig. 4

Schematic of the 1D array transducer: a linear array, b convex array, and c phased array

Fig. 5

3D ultrasound image of a fetus using the 3D imaging transducer [5]

Fig. 6

Schematic structure of a mechanical transducer

Fig. 7

Schematic structure of a 2D array transducer