Types of Diagnostic Ultrasound Transducers

The transducer is a critical component of any diagnostic ultrasound system because it is responsible for generating the ultrasound pulses that travel into the patient and for converting the received echoes into data used for diagnosis. A variety of different transducers, also called probes, are used to acquire data, and each type is designed to meet the imaging demands of specific clinical applications. Ultrasound probes can be divided into three categories: surface probes used to perform transcutaneous imaging, endocavity probes designed to be inserted into the body, and specialized probes for niche applications.

Herein we describe common types of transducers used to acquire 2D ultrasound images, including the display format and characteristics that make them appropriate for the intended clinical applications. For information about volume (3D and 4D) transducers, please see our report Ultrasound Technology: Volume Rendering in Brief.

A typical handheld ultrasound transducer consists of the probe handle and the probe face (see Figure 1). The probe face is the most delicate portion of the probe, as it contains electronic circuits and the transducer elements that transmit acoustic energy and receive echoes that are returned from the patient's body to create an image or, in the case of Doppler, blood flow data. The portion of the probe face that comes in contact with the patient is referred to as the probe footprint. To optimize image quality, the footprint must be in full contact with the patient.

A probe's operating frequencies, sometimes referred to as output frequencies, determine the spatial resolution and the degree of tissue penetration. Lower-frequency probes have poorer spatial resolution than higher-frequency probes, but greater penetration. This trade-off requires clinicians to choose the probe that will...