Siemens MAMMOMAT NovationDR, Руководство по установке, Страница: 82 / 95

Maintaining Image Quality
February 5, 2004
6-3
Table 6-2. Random Artifacts
Problem Cause Recommended Action
Increase in Defective Pixels
and Lines Defective pixel fi le requires updating. Contact Direct Radiography Corp. Support
for information on bad pixel correction.
Table 6-3. Structured Artifacts
Problem Cause Recommended Action
Appearance of 24 “256 blocks”
of different Densities or
Counts Gain calibration not turned on.
Detector not calibrated properly.
Follow calibration procedure.
Image not appearing in One or
More “256 blocks” Detector defective. Replace Detector.
Image not appearing in one or
more quarters of Detector Detector defective. Replace Detector.
Garbled, scrambled, or
truncated (from edges of long
axis in) images Poor cable connection.
Electronic interference with or along cable.
Check pins and Detector connection to
PXCM.
Identify and isolate sources of interference;
examine the cable pathway.
Fine Linear Pattern, Parallel to
Long Axis, in One or More
“256 Blocks” (usually more
pronounced on an edge) Electromagnetic noise interfering with
Detector Read Out. Shield Motors, power sources, and so on,
located in proximity to the DirectRay
Detector.
Table 6-4. Other Artifacts
Problem Cause Recommended Action
Density Image is too dark or light. Verify LUT curves are properly set.
No Image or Very High
Exposure Required to Obtain
an Image HV setting incorrect.
HV contact failed.
Check pac.cfg for correct setting.
Replace DirectRay Detector.
High Contrast Objects Appear
as Ghost Image DirectRay Detector erase not working
correctly. Check pac.cfg for correct settings.
Check for DirectRay Detector component
failure.
White lines towards the center
of panel (Bar Code) DirectRay Detector defective. Replace DirectRay Detector.
Dark lines / weak lines Lines need to be mapped out. Perform a procedure with X-ray and submit
the
fi le to Direct Radiography Corp. Support
for mapping.
Poor image quality DirectRay Detector not calibrated to optimal
operating temperature. Allow proper warm-up time to normal
operational temperature.
Distorted image with 256
blocks DirectRay Detector defective. Replace DirectRay Detector.