Which transducer type uses a rotating mechanical element to sweep the ultrasound beam?

• A. Mechanical sector
• B. Linear array
• C. Phased array
• D. Annular array

Answer: (A)

A rotating mechanical element sweeps the ultrasound beam, which is the hallmark of a mechanically scanned sector transducer. In this design, a single crystal or small element is physically driven by a motor to rotate, producing the beam’s arc and creating a wedge-shaped (sector) image on screen. The other transducer types rely on multiple elements and electronic methods to steer and focus the beam rather than moving a single element mechanically. Linear and phased arrays use electronic steering and focusing across many elements, while annular arrays use concentric rings with electronic focusing rather than a rotating part to sweep the beam.