7
ELEVATIONAL TESTING (CONTINUED)
1. Two scan surfaces are provided for obtaining slice
thickness measurements. For depths ranging from 8.0
to 22.0 cm scan surface #2 should be used. Scan
surface #4 is used when the scanning depths required
range from 0 to 18.0 cm. Place the phantom on a
clean, flat surface with the proper scan surface
positioned for use.
2. Apply a liberal amount of acoustic coupling gel to the
scanning surface. It is suggested, when evaluating array systems a low
viscosity coupling agent be used to minimize a "snowplowing" affect on the
surface of the phantom. However, transducer faces with a high degree of
curvature, the use of a high viscosity gel is recommended to maintain good
coupling.
3. Adjust the instrument settings (TGC, output, etc.) to establish baseline values
for "normal" liver scanning. If the penetration is such that the bottom of the
phantom is seen, the gain settings should be reduced such that the image
fades and goes entirely black. These setting should be noted on the quality
assurance record and used for subsequent testing.
4. Position the transducer on the scan surface providing the proper depth range.
The image displayed will appear as a band or thick line positioned at a given
depth in an angular plane.