Ultrasonic transducers for medical volumetric imaging

Three-dimensional (3D) ultrasound imaging allows physicians to use ultrasound to view pathology as a volume in order to enhance the comprehension of a patient's anatomy. In this paper, the modality of 3D ultrasound imaging is described in accordance with the development of transducer technology. Two representative types of 3D imaging transducers are reviewed with description of the concept and operation principle of each type: mechanical transducer and matrix array transducer. Mechanical transducers are further divided into free-hand scanning and sequential scanning types. Matrix array transducers are also detailed into piezoelectric (single-unit and module-assembly type) transducers and capacitive micromachined ultrasound transducers. Advantages of each transducer and technical issues for further performance enhancement are discussed.