Which method creates the triangular-shaped image format by electronically steering the beam with most elements fired for each pulse-echo sequence and small time differences?

Which method creates the triangular-shaped image format by electronically steering the beam with most elements fired for each pulse-echo sequence and small time differences?

• A. Mechanical steering
• B. Electronic steering with elements fired in small groups
• C. Electronic steering with most elements fired for each pulse-echo sequence and short time differences steering the beam
• D. Curved lens

Answer: (C)

The key idea is electronic steering with a phased-array transducer. By applying precise, small time delays across nearly all of the elements for each pulse-echo sequence, the emitted wavefront is steered to a chosen angle. Repeating this with different delays sweeps the beam across the field, producing a fan- or sector-shaped image. Using most elements in the aperture gives wide steering capability and good lateral resolution, while the small time differences control the exact direction of the beam. Mechanical steering relies on moving the transducer, which isn’t what's described here. Firing elements in small groups reduces the active aperture and changes the beam pattern, not the full electronic steering with a wide aperture. A curved lens shapes the beam statically through its geometry, not by electronic delays, so it doesn’t describe steering via time-delayed excitation.

The key idea is electronic steering with a phased-array transducer. By applying precise, small time delays across nearly all of the elements for each pulse-echo sequence, the emitted wavefront is steered to a chosen angle. Repeating this with different delays sweeps the beam across the field, producing a fan- or sector-shaped image. Using most elements in the aperture gives wide steering capability and good lateral resolution, while the small time differences control the exact direction of the beam.

Mechanical steering relies on moving the transducer, which isn’t what's described here. Firing elements in small groups reduces the active aperture and changes the beam pattern, not the full electronic steering with a wide aperture. A curved lens shapes the beam statically through its geometry, not by electronic delays, so it doesn’t describe steering via time-delayed excitation.