Defect Correction; Defect Map Editor; Calibration Maintenance - Varex Imaging Azure 3131Z Manual

Azure 3131Z - 4131Z Reference Manual
18.1.1

Defect Correction

The X-ray detectors are provided with a defect correction map to correct defective pixels/lines.
The map used by the detector is composed by two parts: a base map and auxiliary map.
The base map is created during the X-ray detector production test and is used in combination
with the auxiliary map, which is updated automatically every time a gain calibration is
performed.
18.1.2

Defect Map Editor

Viva Pro includes a Defect Map Editor tool to allow editing of the defect map. If defective pixels
are not marked in the defect map after the gain calibration the tool can be used to mark specific
pixels defective. In this tool, both maps are shown but only the auxiliary one can be edited. More
information can be found in the Viva Pro User Manual.
19.0

Calibration Maintenance

In principle, the X-ray detector is maintenance-free, however; it is important that all
calibrations are regularly performed and used for image processing. In some applications, it is
advantageous to run the Offset Calibration before each acquisition sequence.
Although the X-ray detectors are resistant to X-rays they can exhibit degradation over time when
exposed to high X-ray dose environments. Sensitivity and uniformity may change depending on
the weekly exposure duration and X-ray dose.
The pixel correction maps need to be updated regularly to identify and
update the defect map. Gain calibration should be performed at regular
Note
intervals, typically once every 6 months or whenever the central beam of the
X-ray source moves relative to the X-ray detector.
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