User Guide

Figure 3 - Combined Axial/Lateral Resolution Target at 10.5 cm depth (top) and a table listing the distances

between them (bottom)

Targets

C1-D1 C2-D2 C3-D3 C4-D4 C5-D5

Axial

Resolution (mm)

1.0 2.0 3.0 4.0 5.0

Targets

C1-C2 C2-C3 C3-C4 C4-C5 C5-C6

Lateral

Resolution (mm)

5.0 4.0 3.0 2.0 1.0

ELEVATIONAL TESTING

A full characterization of system resolution requires measurement of elevational res-

olution, or slice thickness. Slice thickness is typically much coarser than axial and

lateral resolution as most ultrasound transducer arrays are mechanically focused in

the thickness dimensions.

Two methods are described for measuring elevational resolution. The rst method,

rst described by Skolnick

(1)

, uses the vertical wire targets as follows:

1. Apply coupling gel to the scanning surface or ll the water trough with tap

water.

2. Adjust the instrument settings (gain, TGC, output, etc.) as for a “normal” tech-

nique. Record these settings for use on subsequent testing

3. Orient the transducer to image the length of the vertical target wires, taking

care to adjust the tilt so that the wires are lined up in a vertical column.

4. Rotate the transducer 45° so that only a partial length of the wires is now vis-

ible.

5. Freeze the image and measure the length of each wire segment with the elec-

tronic calibers.

6. Record the measurements.

C2C3C4C5C6

Axial Resolution

Lateral Resolution

Edge to

adjacent Edge

3 mm

Edge to

adjacent Edge

2 mm

1.Skolnick, ML. “Estimation of ultrasound beam width in the elevation (section thickness) plane.” Radiology. 1991 Jul;180(1):286-8.