Illustration of FSCT concept for arbitrarily selected parameters. (a) Scanner phase ϕrot as a function of time for a 2.0 Hz rotation frequency, with 25 projections acquired per rotation as indicated by numbered asterisks. Projections are numbered according to chronological order of acquisition. Subject phase ϕsub as a function of time for a 13.13 Hz periodic motion cycle. Subject phase is labeled according to 3 equally sized bins, indicated by color (red, orange, yellow). (b) Standard CT reconstruction is performed on sequentially acquired projections, averaging together variable subject phase acquired throughout one scanner rotation. (c) FSCT reconstruction is performed on phase-binned subsets of projections, each containing a limited range of subject phase.