GE Discovery LS, Руководство по обслуживанию системы

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IRECTION
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YSTEM
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ERVICE
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Page 250 Chapter 8 - System QC, Calibration and Functional Tests
Service personnel should ignore these messages and proceed to mechanical realignment in
Section 8.1.1.6 .
Image Alignment Table
The Image Alignment Table shows the accuracy of alignment between PET and CT images. The
alignment results are calculated for the phantom landmarks in the center of FOV and 20 cm from
the center of FOV.
The Specs column of the table shows the user-acceptable limits in each direction (in-plane X, Y,
and slice offset Z):
• 1.3 mm at the center of FOV
• 2.0 mm at 20 cm from the center of FOV
NOTICE The above limits are User (Operator) limits. Mechanical system calibration should provide
image alignment within the following Service Limits:
• 0.5 mm at the center of the FOV
• 1.0 mm at 20 cm from the center of FOV
The calculated X, Y, Z deltas (misalignments in mm) between PET and CT images are presented
in the
Delta table columns. The out-of-user limit values are RED in color. The system should be
mechanically calibrated until all the deltas are inside the Service Limits .
Gantry Alignment Table
If all the deltas are within the user limits, this section of the screen will not immediately display.
Proceed as follows:
Click [ Options ], and select Show Gantry Alignment from the drop-down menu. The Gantry
Alignment Table and the [Update CT Recon Center] and [Update Plane Offset] buttons for software
realignment display.
NOTICE The [Update CT Recon Center] and [Update Plane Offset] buttons are for User (Operator) use
only. Please do NOT use these buttons. Proceed to the mechanical PET Gantry Alignment in
Section
8.1.1.6 .
The Gantry Alignment Table displays the linear shifts in millimeters for X, Y, and Z directions and
the angular rotations in degrees required for the PET gantry registration and table calibration. These
values are calculated for the PET gantry center of rotation and may differ from the values in the
Image Alignment table.