6
DISTANCE (CONT)
4. Align the probe so that all the vertical targets are displayed at their maximum
intensity level.
5. Freeze the image and obtain a hard copy.
6. Using electronic calipers, measure the distances between two wires at various
depths or align the echoes to the display markers for comparison.
7. Record these measurements.
8. Compare the measured values with the recorded baseline distances.
The horizontal target group is used to determine the accuracy of measurements
made perpendicular to the beam axis. The figure and table on page 9 provide a wire
target map that can be used to find the position of horizontal wire target. Testing is
performed as follows.
1. Fill the water trough with tap water.
2. Position the transducer in a vertical plane. (The wires should appear as dots,
not lines).
3. Adjust the instrument settings (gain, TGC, output, etc.) as for a “normal”
technique. Record these settings for use on subsequent testing.
4. Align the probe so that all the horizontal targets are displayed at their maximum
intensity level.
5. Freeze the image and obtain a hard copy.
6. Using electronic calipers, measure the distances between two wires along the
horizontal plane.
7. Record these measurements.
8. Compare the measured values with the known distances between the targets.
PERIMETER, AREA AND VOLUME MEASUREMENTS
Ultrasound imaging systems may detect differences in echogenicity of tissue struc-
tures and determine the dimensions of those structures through boundary detec-
tion. Spatial measurement data collected will give an indication of the accuracy that
the system is capable of. For more information see “Standard Methods for Calibra-
tion of 2-Dimensional and 3-Dimensional Spatial Measurement Capabilities of Pulse
Echo Ultrasound Imaging Systems.” AIUM: 2004.
Using the 2D shapes shown in the taget diagram on page 9, areas and perimeters
may be determined by connecting lines between the filament targets. Linear mea-
surements are taken from an image which is on a plane perpendicular to the line
targets.