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This page describes programmer level details about the Slat Collimator. If you are looking for general user-level information go to the Collimator Page within the User Guide.
The slat collimator code is implemented in the source file "ColSlat.c". It is a sub-module of the Collimator module. The data structure (i.e. run time parameter structure) is defined in the file "ColTypes.h" along with all of the other collimator specific structures.
The slat collimator is special in the sense that it is very tightly coupled with the dual headed planar detector module. Not only does use of the slat collimator require the use of the DHCI detector, but the slat collimator module also receives information from the detector module. This tight data coupling has been avoided as much as possible throughout the PHG. In this case it was allowed to decrease design and implementation features. A result of this is that the parameters for the slat collimator are few and non-redundant with the detector module.
Tracking through the collimator is done in an almost identical way as within the planar detector module. The primary difference is that in the detector module a boundary crossing in the Y or Z dimension automatically signals an exit, while a crossing in the X dimension signals a layer crossing which may or may not indicate an exit from the detector. In the slat collimator there is only one layer so boundary crossings in X and Y indicate automatic exits. Crossings in Z however, indicate a change from slat to gap or gap to slat. In which case, attenuation factors must be adjusted for and then tracking continues.
The other major difference between the detector and the collimator is that interactions are handled as if the tracking were being done in the object. No list of interactions is maintained and no centroid is computed.
Last revised by: Steven Vannoy Revision date: July 22 1999
