1. A method of imaging at least a part of a region of interest (ROI) comprising: moving a source relative to the ROI in a trajectory; collecting data from at least one sensor as the source moves relative to the ROI; and generating a reconstruction of the ROI based on the data collected, wherein the reconstruction is derived from a mathematically exact transformation from data space into image space; wherein generating the reconstruction is using only a subset of the data collected; wherein the ROI exhibits periodic motion with an object temporal cycle; and wherein the source moves relative to the ROI such that the source trajectory motion is not synchronized with the object temporal cycle.