In the advanced CT equipment, the more effective diagnoses are determined by how precise and fast the measurement systems are (speed and resolution),
as well as their cost effectiveness. Irrespective of whether spiral, helical or dual source apparatus is used, the requirements are continuing to increase.
In particular, this also concerns the length measurement equipment for the horizontal reclined position. In order to obtain the best possible overall image of the target, the individual  X-ray  sections,  which  normally  travel  through the object, have to be measured with smaller and smaller spacing.  To  do  this,  the  sections  are  compiled  in  a  3D reconstruction  to  obtain  voxels  (volumetric  and  pixel). Based on this complete volume data set, any 3D views or sectional planes can be produced (see 3D image). In order to correctly assign the sections, the horizontal position of the couch has to be measured precisely. Therefore, a measuring system with very high resolution and long measuring range is required.