Siemens MAMMOMAT Novation DR, Руководство по установке, Страница: 63 / 104

Image Quality 9 - 3
Siemens AG SPB7-250.815.02 Page 3 of 20 MAMMOMAT Novation
DR
Medical Solutions Rev. 02 09.04 CS SD 24 System
Test Criteria
The test will pass if no grid lines are visible in all images.
If grid lines are visible
- continue with "Measuring grid lines" on Page 9 - 3 on the image(s) that didn't pass.
Otherwise
- Record the measured value in the "Startup Protocol " on Page 11 - 1 and
- continue with "Checking Image Quality" on Page 9 - 8.
Measuring grid lines
9
1. Load the image in the syngo Image Viewer and select the first image where
visible grid lines were detected (see Tab. 1).
To do so click on the
Viewing tabcard, load the image with the Patient -> Browser
and select Tools -> Rectangle . Draw an area of approximately 1 sq.cm and
measure the pixel mean value. You have to measure approximately 2 cm above
the chest wall at the center of the detector.
2. Activate magnification (Image -> Magnify by 2.0) .
3. Select Tools -> Rectangle and draw a rectangle on the background according to
Fig. 3 (X) . The rectangle should be approximately 5 cm long.
4. Make a new rectangle on a grid line according to Fig. 3 (Y) . The rectangle should
be approximately 5 cm long.
5. Note the Mean Value result in column Y in Tab. 2.
6. The mean pixel value difference shall be calculated as (X-Y)/X where Y is the
mean value in the grid line and X is the mean value in the background as seen in
Tab. 2.
Note the result in the Tab. 2.
7. Choose the next image that had visible grid lines in the list and start over with step
3 until all images are evaluated.
"
Fig. 3 Measure Grid Lines