Other Film/Screen Combinations - Siemens MOMMOMAT 1000 Installation And Start-Up Instructions Manual

Start-up and functional test of the IONTOMAT

Other film/screen combinations

In case the customer uses another film/screen combination than those the correction
curves are optimized for, see table 1 of correction curves on page 11 - 1, proceed as fol-
lows:
1.
2.
3.
4.
5.
NOTICE
Siemens-Elema AB
Solna, Sweden
Begin with curve C, speed H, and make test exposures using a grid table at 25 kV
(Mo/Mo), 2 and 6 cm plexi (5 cm if limit (ER550) or ER 013 occurs, due to
insufficient dose rate). If the image from 6 cm plexi (O.D.-6 cm) is lighter than one
from 2 cm plexi (O.D.-2 cm), choose correction curve A or B (A makes images
from thick objects darker than B does, i.e. A corrects more than B). On the other
hand, if O.D.-6 cm is darker than O.D.-2 cm, choose curve D. Repeat the test with
the chosen curve. The difference between O.D.-6 cm and O.D.-2 cm (∆ Ο.D.)
should be less than 0.30 O.D.
Now test 27 kV, 2 and 6 cm. Try even 30 and 35 kV if these kV´s are of interest for
the customer. If this ∆ Ο.D. is ≤ 0.30 O.D., go to 3. If not, it is necessary to test
another curve (choose between A, B, C and D) at 27 kV. Choose the best one and
repeat the test at 25 kV. Continue in this manner until the result is as good as
possible for the kV´s of interest for the customer. Diagrams 1, 3, 5 and 7 on the
following pages can be of help. Note that the steeper the curve is, the more the
thicker objects are corrected (they will be darker).
Check also the correction with 2 cm plexi between the different kV values of
interest. If this ∆ Ο.D. is ≤ 0.30 O.D., an acceptable curve has been chosen. It may
not be possible to reach the specified O.D. corrections, choose then the best
compromise for the customer´s needs.
Do the same tests with magnification table, but use 2 and 5 cm plexi instead. The
permissible ∆ Ο.D. for magnification tables is ≤ 0.40 O.D. If the result is not
satisfactory, try another curve with speed button D. Choose between correction
curves A, B, C and D. Diagrams 2, 4, 6, and 8 on the following pages can be of
help. Normally, the magnification tables and the contact exposures tables function
properly with the same curve family, which means that the other speed button can
be used for another film/screen combination.
Test the chosen curve/curves with the other anode/filter combinations as well.
The film density levels may vary from cassette to cassette.
Therefore, be sure to use one and the same cassette for all test
exposures.
Register 3 SP B7-230.033.07
Rev. 03 11.99
Page 3 of 12 Mammomat 1000/3000
SPS-UD Installation and Start-Up
11 - 3
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