Siemens AG SPB7-250.815.06.02.02 MAMMOMAT Novation DR
12.05 CS SD 24
Collimator Adjustment 49
Page 49 of 116
Medical Solutions
8-
7Collimator Adjustment
Automatic collimator 0
The automatic collimator unit limits the radiation/illumination field on the object table
(detector) depending on the combination of the object table, compression paddle and
focus.
At start-up or reset, a self-test is carried out to check that the collimator lamellae are mov-
ing in both directions, from their outer end positions (from now on called the reference
position(s)) into and passing the positions for maximum collimation.
After the self-test has passed, collimation is carried out according to the combination of
object table and compression paddle. During standby the collimation is always made to
the focus of the field light bulb, i.e. to get the illumination field. This field will correspond to
the radiation field during the exposure. When the exposure preparation is started, the col-
limator lamellae are adjusted to the currently selected anode focus, i.e. to get the radiation
field.
Exposure will not be allowed as long as collimation is not ready or an invalid object table
and compression paddle combination has been selected.
The maximum time to change the size of the field is 7s in standby and 1.9s when the initi-
ation of the exposure preparation has been received. If the maximum time has elapsed,
error 816 is generated.
Collimator reference axis 0
Collimator calibration is used to get the offset values to two reference axes, y and x.
• The y-axis is orthogonal to the chest wall side edge in the center of the object table.
• The x-axis is located at the object table chest wall side edge.
Fig. 32: Collimator calibrations
• Moving the collimator OUT is done by INCREASING the YC value and DECREASING
the YS, XL and XR values.
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