The use of two-dimensional, focused, anti-scatter-grids (ASGs) in computed tomography is one essential solution to
reduce the scatter radiation for large area detectors.
A detailed analysis of the requirements and related image quality aspects lead to the specification of the two-dimensional
focused geometry of the X-ray absorbing grids. Scatter simulations indicated trade-off conditions and provided
estimations for the expected scatter reduction performance.
Different production technologies for focused two-dimensional structures have been evaluated. The presented
technology of Tomo Lithographic Molding (TomoTM) shows good fulfilment of the specifications. TomoTM is a synthesis
of lithographic micromachining, precision stack lamination, molding, and casting processes with application-specific
material systems. Geometry, material properties, and scatter performance have been investigated. Different analysis
methods will be presented and results of the investigations demonstrate the performance capability of this two-dimensional
Material composition of the tungsten-polymer composite, homogeneity of wall thickness, and precision of the focusing
have the biggest influence on the X-ray behavior. Dynamic forces on the anti-scatter-grid during CT operations should
not lead to dynamic shadowing or intensity modulation on the active pixel area. Simulations of the wall deformation
have been done to estimate the maximum position deviation.
Prototype two-dimensional ASGs have been characterized and show promising results.