Fig. 1

Illustration of addressed problem and sketch of proposed solution. a Typical 4D CT artifacts stem from inappropriate breathing state definition and/or assignment to projection data (in low-pitch spiral 4D CT) or reconstructed image segments (ciné 4D CT). b To overcome shortcomings of classical phase- or amplitude-based sorting approaches, we extracted a patient-specific reference breathing curve that was used for phase- and breathing signal amplitude-assignment to the acquired projection data. c In addition, an artifactness measure was introduced into and to be minimized during image reconstruction. To retain the range of breathing dynamics represented in the acquired data, uncertainty intervals were defined to restrict the minimization search space