Thickness Compensation Adjustment - GE Alpha RT 32551 Installation Instructions Manual

32551-IMG rev 6
5.2.17

Thickness compensation adjustment

1 Notice the exposure time,which has the correct O.D. from the
previous O.D vs. exposure time graph.
Exposure time _______________
2 Notice the O.D. for the shorter exposure time (for example the 20
mm Acrylic exposure time) from the above graph. Divide the desired
O.D. with this value.
3 Notice the O.D. for the longer exposure time (for example the 60 mm
Acrylic exposure time) from the graph. Divide the desired O.D. with
this value.
4 Enter the #64 AEC program. Press kV+ until the thickness
compensation parameter 'c' is reached. Press autorel to scroll 'P' in
the kV display.
5 Enter the exposure time, which has the correct O.D. from the
calculation to 'P' for 'rotation Point' by pressing Den+/-. This is the
exposure time which is not affected by thickness compensation (=the
rotation point).
6 Press Autorel to scroll the 'r1' parameter in the kV display. Use Den+/
- buttons to change the value. This parameter gives the amount of
rotation at exposure times shorter than the rotation point 'P'. For
example if the short exposure has 12% too dark, a density enter 0.88
for 'r1'.
7 Press Autorel for the 'r2' parameter. Use Den+/- buttons to change
the value. This parameter gives the amount of rotation at exposure
times longer than the rotation point 'P'. For example, if the long
exposure has 12% too light a density enter 1.12 for 'r2'.
CAUTION!
Perform the thickness compensation with both filters (Mo/Rh) and all
cassette tunnels (Bucky/cassette holder/magnification tunnel) separately.
DO NOT change the gain parameter anymore. Use the density correction
(in Pr mode) to bring O.D. to same level with other filter/cassette holder
combinations.
Fine tuning of the thickness compensation
NOTE!
Fine tuning is optional and may only have minor effect to compensation.
GE Healthcare
5 Setups, alignments and adjustments
This value is 'P'
This value is 'r1'
This value is 'r2'
85