Multiple-source cone-beam scanning is a promising mode for dynamic volumetric CT/micro-CT. The
first dynamic CT system is the Dynamic Spatial Reconstructor (DSR) built in 1979. The pursuance for
higher temporal resolution has largely driven the development of CT technology, and recently led to
the emergence of Siemens dual-source CT scanner. Given the impact and limitation of dual-source
cardiac CT, triple-source cone-beam CT seems a natural extension for future cardiac CT. Our work
shows that trinity (triple-source architecture) is superior to duality (dual-source architecture) for helical
cone-beam CT in terms of exact reconstruction. In particular, a triple-source helical scan allows a
perfect mosaic of longitudinally truncated cone-beam data to satisfy the Orlov condition and yields
better noise performance than the dual-source counterpart. In the (2N+1)-source helical CT case, the
more sources, the higher temporal resolution. In the N-source saddle CT case, a triple-source scan
offers the best temporal resolution for continuous dynamic exact reconstruction of a central volume.
The recently developed multi-source cone-beam algorithms include an exact backprojection-filtration
(BPF) approach and a "slow" exact filtered-backprojection (FBP) algorithm for (2N+1)-source helical
CT, two fast quasi-exact FBP algorithms for triple-source helical CT, as well as a fast exact FBP
algorithm for triple-source saddle CT. Some latest ideas will be also discussed, such as multi-source
interior tomography and multi-beam field-emission x-ray CT.