User's Manual

120
2852 A EN 20070205
DRYSTAR AXYS
Performing the Annual QC tests for mammography
application (DT 2 Mammo) (optional)
Geometric Consistency Test
To be able to notice fluctuations in image size and aspect ratio, you must per-
form this procedure once a year.
Procedure
1 First, perform the daily test.
2 Measure the distances A and B of the geometric square on the QC mammogra-
phy test image. Refer to “Establishing the image geometry reference values for
mammography application (DT 2 Mammo) (optional)” on page 112.
3 Record these values as measured distances A and B on Chart 4 (‘Drystar AXYS
Geometric Consistency Control Chart’). Refer to “Charts for mammography QC
(optional)” on page 155.
4 Compare the measured A and B dimensions with the reference dimension val-
ues, Aref and Bref on Chart 4 (‘Drystar AXYS Geometric Consistency Control
Chart’). Refer to “Charts for mammography QC (optional)” on page 155.
The differences between the measured dimensions of A and B and the reference val-
ues A ref and B ref should be less than or equal to 1.0%.
5 Check for image distortion.
6 Calculate the aspect ratio by dividing A by B.
The result must be 1 +/- 0.01
WARNING: Make sure to measure distance A from the left edge of
the left line to the right edge of the right line and distance B from
the upper edge of the upper line to the lower edge of the lower
line.
WARNING: We strongly recommend using a 30 cm (12-inch)
machinist scale with 0.5 mm divisions (1/64 inch).
WARNING: If the image size or distortion values are outside of
limits, contact Agfa service to resolve the problem.