For a linear array transducer, which resolution is most affected by the mechanical focus?

For a linear array transducer, which resolution is most affected by the mechanical focus?

• A. Lateral resolution
• B. Elevational resolution
• C. Axial resolution
• D. Temporal resolution

Answer: (B)

The effect of focusing is to concentrate energy into a narrower beam at a chosen depth. With a linear array, that narrowing primarily occurs in the elevational direction—the thickness of the beam perpendicular to the image plane. When the beam is focused in this direction, the slice thickness at the focal depth decreases, which directly improves elevational resolution there. Axial resolution, set by pulse length, isn’t really changed by focusing. Temporal resolution (frame rate) depends on imaging speed and depth, not the beam’s cross-sectional thickness. Lateral resolution is mainly about beam width within the imaging plane and is driven more by electronic focusing and aperture than by mechanical focus in the elevational direction. So the resolution most affected by mechanical focus is elevational resolution.

The effect of focusing is to concentrate energy into a narrower beam at a chosen depth. With a linear array, that narrowing primarily occurs in the elevational direction—the thickness of the beam perpendicular to the image plane. When the beam is focused in this direction, the slice thickness at the focal depth decreases, which directly improves elevational resolution there. Axial resolution, set by pulse length, isn’t really changed by focusing. Temporal resolution (frame rate) depends on imaging speed and depth, not the beam’s cross-sectional thickness. Lateral resolution is mainly about beam width within the imaging plane and is driven more by electronic focusing and aperture than by mechanical focus in the elevational direction. So the resolution most affected by mechanical focus is elevational resolution.