Direct measurement of resolution in volumetric imaging systems

The resolution of 2D imaging systems is frequently described by experimental estimates of the point, line, or edge spread function. It is shown that a response function across the normal to a boundary between two homogeneous volumes can provide a measure of resolution. The set of surface boundary voxels is determined by applying a simple threshold. The normal distance of every voxel to the surface is computed and an accumulator bin is incremented by the voxel´s gray level. This results in an aggregate surface response function, which is related to 3D point, line, and plane spread functions. This method can be applied to general boundary interfaces where precise surface normals are known, such as those on a sphere or plane. Results of applying this method to volumetric cone beam X-ray CT data are shown