For a single-row linear array, elevational focus is achieved primarily through which method?

• A. Transmit focusing
• B. Dynamic receive focusing
• C. Aperture focusing
• D. Mechanical focusing

Answer: (D)

Elevational focus means concentrating the beam in the direction perpendicular to the imaging plane (the slice thickness). With a single-row linear array, there isn’t a second row of elements to steer or focus the beam electronically in that vertical (elevation) dimension, so the elevational focus must come from the physical design of the transducer. Mechanical focusing uses a curved lens or a specially shaped element to bend and converge the ultrasound energy in the elevation direction, creating a thinner, more focused slice at a certain depth. This fixed, lens-based approach is how elevational focusing is achieved in a single-row array. Transmit or receive focus in the imaging plane, and aperture strategies, influence lateral and axial focusing, but they don’t establish elevation focus.