Design of rotating aperture cones for radiographic scatter reduction

A new multiple�scanning�slit or scanning�grid scatter�reduction geometry consisting of coaxial rotating aperture (RA) cones is described and compared with other RA assemblies such as the rotating aperture wheel (RAW) device. A unique feature of the new design is that the geometric and rotational axes of the conical RA surfaces coincide and are collinear with the x�ray focal spot. This arrangement of axes should provide the potential for greatly improved mechanical rigidity, higher rotational velocities, and the capability for static slit�pattern alignment. The common rotational axis of the cone assembly is angled obliquely to the central x�ray beam such that the intersections of the irradiated portion of the RA surfaces with the plane formed by the x�ray central beam and cone axes are straight lines parallel to the film plane. This geometry is compatible with the standard source�patient�image�receptor radiographic relationship and allows for variable source�to�image�receptor distance.