Siemens SOMATOM Spirit Operator's Manual page 404

Constancy Test
Performing the homogene-
ity test
F.3-20
With this test, you measure the homogeneity of the CT values in
five regions of the water phantom.
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Press the Start key on the control box.
✧
Scanning is started.
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i
After the previous test has been completed, the Homogeneity
. 3 F
test is started automatically.
An image of the water phantom is recorded. 5 ROIs are marked
in the image, one central and four peripheral.
In addition to the ROIs, the mean values and standard deviations
of the CT values are displayed.
The difference between the mean values of the central ROI and
the peripheral ROIs is displayed.
Quality Assurance
SOMATOM Spirit
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