Hologic DISCOVERY A, Техническое руководство

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Discovery QDR Series Technical Manual
3-54
4. At the CARM$$$$> prompt, type
CALIBRATE<Enter>
(be patient, this
procedure takes several minutes to start).
3.4.7 Check Laser Positioning Offset
Center the table and arm using Center Table button on the Control Panel or the Utilities|
AP Reposition feature in the software.
1. Turn on the laser and set the point of a sharp metal object to the right of, and at a
45º angle to, the crosshair.
2. At the Discovery Main Menu screen, click the Perform Exam button, create a
test patient biography, and select AP Lumbar as the scan type.
3. Uncheck the Use Default Scan Mode check box and click Next.
4. Start the scan.
5. After scan starts and you can see the object, click the Reposition Scan button.
6. Using the mouse, move the image so that the tip of the object is horizontally in
the center and touching the bottom edge of the scan area.
7. Click the Restart Scan button and let the arm reposition.
8. At the Start Scan screen, click the Cancel button.
9. Turn on the laser. Locate the 3 laser adjustment screws (small Phillips) under the
C-arm. Adjust these screws to tilt the assembly until the laser crosshair is on the
tip of the pointed object.
10. Run another scan to check your adjustments.
3.5 A/D Gain Control Adjustment
An A/D gain adjustment potentiometer ensures that all systems have the same input to the
A/D converter regardless of slight variations in X-ray flux. The location of the
potentiometer depends on the system configuration:
• On systems with a separate A/D Converter board, the adjustment is the only potenti-
ometer on the A/D Converter board.
• On systems without a separate A/D Converter board, the adjustment is the only poten-
tiometer on the X-Ray Detector assembly.
Caution:Any adjustment of this potentiometer affects the QC highs and lows. You must
run detector flattening after adjusting the A/D gain. DO NOT ADJUST THE A/
D GAIN UNLESS ABSOLUTELY NECESSARY AS DEFINED BY “Check
and Verify the A/D Gain” on page 3-54.
3.5.1 Check and Verify the A/D Gain
1. Install all system covers that are normally in the X-ray beam.
2. Install the table pad onto the table.