Axial Resolution

• separates interfaces that lie along the beam axis

• depends on the spatial pulse length (SPL)

• = SPL/2

• is constant with depth

• typical value is 0.5 mm 

Lateral Resolution

• separates interfaces that lie across the beam axis

• depends on beam width

• = beam width

• varies with depth

• controlled by electronic focusing

• best in the focal zone

• typical value is 1.0 mm 

Slice thickness Resolution

• also called elevation axis or Z axis resolution

• separates interfaces that lie perpendicular to the plane of section

• depends on the slice thickness

• = slice thickness

• varies with depth

• controlled by mechanical focusing in a conventional array

• controlled by electronic focusing in a 1 1/2D or 2D array

• A typical value is 1.5 mm 

Axial resolution is typically the best.  Therefore, when making measurements you should use axial resolution whenever possible.

See diagram below...