Chapter A5: Image Viewer
Definium AMX 700 X-Ray System 5161515-1EN Rev. 6 (10 February 2008) A5-19
Operator Manual © 2008 General Electric Company. All rights reserved.
Figure A5-14 DEI graphical display
Figure A5-15 Examples of graphical DEI displays
For each acquired image, the system provides 3 estimated values:
• Uncompensated Detector Exposure (UDExp): Estimated exposure (µGy) to the detector behind the
patient anatomy with an assumed technique of 80 kV with no anti-scatter grid. This information is
stored in the DICOM header.
• Compensated Detector Exposure (CDExp): Estimated exposure (µGy) to the detector behind the
patient anatomy with the actual kV and use of anti-scatter grid. This information is stored in the
DICOM header.
• Detector Exposure Index (DEI): A relative measure of exposure to the detector, as compared to the
expected exposure for a particular anatomical view. It is a visual indicator on the viewer display.
DEI compensates for the speed setting of the system. For example, if an exposure is taken of an object at
a speed setting of 400 and the resultant DEI was 1.72, then an exposure taken of the same object
(assuming identical technique and positioning) after setting the speed to 200 will also give a DEI of 1.72.
NOTE: A higher DEI indicates a higher exposure to the detector. It should not be confused with system
“speed” which decreases as the exposure increases.
Default DEI lower and upper limits are provided as preliminary guidelines. These guidelines should not be
taken as strict requirements of retakes/re-exposures. DEI read-outs are reference guides to help the
technologist determine that if a re-acquisition of an image is necessary, the indicator can help the user
determine appropriate technique adjustments to provide adequate exposure to the detector.
The specific limits and retake rules should be ultimately determined by the appropriate staff at your
facility.
1. Acceptable DEI range (upper and lower limit)
2. Current DEI for the selected image
First segment (left) colored orange
Low DEI = Image under-exposed
Center segment colored green
Acceptable DEI = Image correctly exposed
Last segment (right) colored orange
High DEI = Image over-exposed
FOR TRAINING PURPOSES ONLY!
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