GE Healthcare Senographe DS
Revision 1 Service Information and Procedures Class A 2385072-16-8EN
Job Card CAL A041 - Bad Pixel Calibration
Page no. 1693 Chapter 9
JC-CAL-A-041.fm
Job Card CAL A041 - Bad Pixel Calibration Chapter 9
1SUPPLIES
None
2TOOLS
Flat field phantom
!
Notice:
The acrylic must be clean and free from scratches. This is essential to avoid incorrect detection
of dead pixels.
3 REQUIRED EFFORT
Personnel: 1 Field Engineer
Time: 20 minutes
4 SAFETY PRECAUTIONS
WARNING
This procedure requires the use of X–rays; take all due precautions.
5 PREREQUISITES
• It is strongly recommended to perform bad pixel calibration when the detector has not been used for
a while and when Flat Field test fails.
• The temperature of the detector must be stabilized and within the specified range before commenc-
ing and during bad pixel calibration.
• The Senographe must be in the Medical Application menu.
6 BAD PIXEL CALIBRATION
6-1 Description
A Bad Pixel is an Image Receptor cell which has a response curve very different from that of other cells
subject to the same dose, even after flat field correction. It thus provides no useful information, and
appears as a white or black pixel on the image. Bad Pixel Calibration is a process which uses a number
of acquisitions to identify such cells and store their positions in a Bad Pixel Map. The bad pixel correction
process, applied to acquired images, uses the map to replace the level read from each bad pixel with the
mean level of neighboring cells.
!
Notice:
It is important that the phantom used in these procedures, and all surfaces in the beam (detector,
tube, etc.) are very clean and free from imperfections, which can affect the calibration.
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