GE Healthcare
Senographe DS
Revision 1
Service Information and Procedures Class A 2385072-16-8EN
Job Card ELE A032 – IQ Tools Flat Field Test
Page no. 701
Chapter 7
JC-ELE-A-032.fm
9
CORRECTIVE ACTIONS IN CASE OF FAILURE
9-1
Brightness Non Uniformity test fails
Typical causes are:
1.
The flatfield phantom does not cover the full FOV;
check the position of the flatfield phantom.
The flat-
field phantom must exceed the detector field of view
in every direction.
2.
A collimator blade is within the FOV;
make an acquisi-
tion in the Medical application in the same conditions
as the flatfield test (flatfield phantom, MoMo, 26 kV,
200 mAs) and verify in the raw image that the X-ray
beam field covers the detector field of view by adjust-
ing the contrast such that window width is less than
200. If collimator blades are visible at the borders,
check tube tilt, centering and collimator format calibra-
tions. If necessary redo these calibrations.
3.
The gain map is no longer valid
; calibrate gain in the MoMo/no grid configuration, move the phantom
slightly and run the test again.
9-2
High Frequency Modulation test fails
Typical causes are:
1. The detector temperature is not stabilized; check that the
system has not been powered on too recently.
2. The gain map is no longer valid; calibrate gain in the
MoMo/no grid configuration, and run the test again.
Brightness
non-uniformity:
Significant signal
variation detected
in the image
High frequency
modulation:
High noise detected
within a ROI