Automatic Collimator; Collimator Reference Axis - Siemens MAMMOMAT Novation DR Installation Manual

Collimator Adjustment

Automatic collimator

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 startup 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 a not valid object table
and compression paddle combination has been selected.
Maximum time to change the size of the field is 7s in standby and 1.9s when the initiation
of the exposure preparation has been received. If the maximum time is elapsed, error 816
is generated.
NOTE

Collimator reference axis

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. 1 Collimator calibrations
•
Moving the collimator OUT is done by INCREASING the YC value and DECREASING
the YS, XL and XR values.
Siemens AG
Medical Solutions
The calibration procedure has to be performed for detector wing
only.
SPB7-250.815.02
Rev. 02
Page 1 of 6
09.04 CS SD 24
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DR
MAMMOMAT Novation
System