GE Senographe DS Manual page 703

GE Healthcare
Revision 1
9-3-4 The collimator is visible in the field of view
Run the flatfield test, locate the bad ROIs or bad pixels.
If there are bad pixels or bad ROIS, check tube tilt, cen-
tering and collimator format calibrations. If necessary
redo these calibrations.
9-3-5 Detector response is unequal at some rows, columns, or groups of pixels
1. Check that there is no visible group of defective of pixels (a group of defective pixels = 2 pixels or
more which are significantly darker or brighter than the background). Use the mouse middle button to
adjust contrast and brightness such that window width WW is less than 200. If necessary, take an
image in the Medical Application and use the AWS display tools.
2. If there is at least one group: check that the mirror is clean and free from dust (if not, clean it up) and
redo the gain calibration in the configuration of the test which is failing. Move slightly the Flat Field
phantom between each X-ray exposure
3. Redo the Flat Field test in the same configuration
4. If it is not passing, run the bad pixel calibration. Move the Flat Field phantom between each X-ray
exposures.
5. Redo the Flat Field test in the same configuration.
6. If it is still not passing contact OLC.
9-4 Signal–to–Noise Ratio Non uniformity fails
Typical causes are:
1. The X-ray beam is badly centered; carry out the
Job Card CAL A027 - Tube Tilt Calibration on page
1681 and Job Card CAL A029 - Collimator Format
Calibration on page
2. The detector sensitivity is not uniform; locate in the
graphical window the area having a poor SNR (low
mean signal or high standard deviation). Calibrate
gain in the MoMo/no grid configuration, and run the
test again. If the SNR Non uniformity result is still
above the Upper Specification Limit, call your OLC
for a possible detector replacement.
JC-ELE-A-032.fm
Service Information and Procedures Class A 2385072-16-8EN
1683.
Job Card ELE A032 – IQ Tools Flat Field Test
Page no. 703
Senographe DS
Collimator visible in
field of view
Significant
signal-to-noise variation
detected in the image
Chapter 7