User Guide

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0.5 dB Area 0.7 dB Area
Figure 5 - Top View of the Anechoic Stepped Cylinders Arrangement
Low Attenuation Zone
High Attenuation Zone
In the second method, the anechoic cylinders are used as simulated focal lesions
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 the anechoic cylinder, taking care to
adjust the tilt so that the cylinders are lined up in a vertical column.
4. Freeze the image and save a copy.
5. At each depth, record the smallest detectable cylinder diameter.
CONTRAST RESOLUTION
Machines have a tendency to represent low-contrast structures smaller than they
actually are and with irregular rather than smooth borders. This is referred to as ll-
in. Ideally, the ll-in effect will be minimal.
The Model 040GSE has 12 anechoic stepped cylinders at various depths with mul-
tiple diameters. This design provides a better range of steps for assessment of the
anechoic void perception and the response of the system for small cysts. The rst
two cylinders have smaller-sized cysts than the four deeper cylinders. (See Table 1,
page 16, for the size and depth of each cylinder.)
By design, the ratio of cross-sectional areas for any two adjacent steps has been
xed at 1.5. In other words, the ratio of the cross sectional area of 2.00 mm diam-
eter mass divided by the cross sectional area of the next 1.33 mm diameter mass is
1.49, and so on. This feature provides even increments for assessing the response
of the system to small cysts.
The anechoic stepped cylinders are arranged in parallel pairs and ipped 180
degrees to each other, allowing all diameters in both the low attenuation zone back-
ground and the high attenuation zone to be available. See Table 1, page 16, and
Figure 5 for location and arrangement of the cystic masses.