The Spatial Response of Source-Collimator-Detector Systems

Although the tomographic reconstruction technique assumes that the projections correspond to sets of line integrals, the measurements are, in fact, made with beams having a finite width and height. This has important implications for the design of tomography systems. Artifacts may be generated by variations in the beam profile across the slice [1]. Furthermore, the spatial resolution that can be achieved with a given beam geometry is limited to the full-width at half-maximum (FWHM) of the beam profile [1]. (Image restoration can improve spatial resolution but only at the expense of contrast discrimination [2].) Therefore, a detailed knowledge of the spatial response associated with various beam geometries is essential for the design of tomography scanners.