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Check of Opdima AEC
The objective is to assess the performance of the AEC (automatic exposure control)
function with different exposure conditions.
In this test, images shall be obtained using different combinations of kVp, anode/filter
material and object thickness. The AEC is designed to control the exposure so that the
mean AD value of the images obtained of homogeneous phantoms shall be close to 800
independently of these parameters. For some combinations of kVp, object thickness and
anode/filter material, the minimum mAs value (12 mAs) or maximum mAs value (560 mAs,
or lower due to MAMMOMAT limits) is the limiting factor for proper AEC functionality.
These combinations are of no clinical relevance and should not be tested, and have been
marked with a gray color in the test report tables (Appendix 2).
120
100
80
60
40
20
0
Fig. 1 Histogram
Procedure
1.
Start a new examination.
2.
Enter Spot mode.
3.
Use the table that will be used by the customer, images shall be taken at normal
resolution, and the mammography unit shall be used with a grid object table.
4.
Initially, place one plate of calibration plexiglas 19 mm on the object table.
5.
The first image shall be obtained using 26 kV and Mo/Mo as exposure
parameters.
6.
Examine the image and measure the mean value. The gray scale parameters
(center and width) are shown in the upper bar of the Opdimar window. The center
value is approximately the mean value and shall be used as such in this test. Note
that these values (gray scale center and width) are automatically set to optimal
when an image is captured, but will be affected by adjustments made to
brightness or contrast in Opdimar. Because of this, no adjustments shall be done
to these parameters before reading the AD center value, in order to get a correct
reading.
Opdimar
Service
Histogram
AD-value
Register 5
SPB7-230.061.11
Rev. 02
Measures after service
Page 2 of 6
07.03
CS PS 24
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10
Siemens AG
Medical Solutions
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