Design of a "3.5th generation" photon counting detector CT architecture for higher spatial resolution and decreased ring artifact.

Abstract

Fourth generation CT was originally conceived to reduce ring artifacts from inhomogeneities in early energy integrating detector (EID) modules. These inhomogeneities are well controlled in modern EID modules but have reappeared in photon counting detector (PCD) modules, where fabrication techniques are not yet mature. Fourth generation CT was abandoned decades ago because of its high cost and scatter. We propose grafting its central insight into 3rd generation CT using a compact, modified X-ray source that operates with a high-speed flying focal spot over a limited range of travel (e.g., 1 cm). The PCD must be modified so that measured data is rebinned on-the-fly, so that data bandwidth requirements across the slip ring are unchanged. In this geometry, data from each PCD pixel is distributed to a several contiguous radial indices. This reduces ring artifacts that stem from pixel inhomogeneities and also allows recovery of missing data that is due to dead pixels or occlusion by the anti-scatter grid. Finally, if the dwell time at each focal spot location is very short (sub-microsecond), the maximum instantaneous surface temperature at the anode is reduced. This could be used to reduce focal spot size while maintaining the thermal limit of the focal track.