An imaging system is provided including a gantry, a detector unit mounted to the gantry, at least one processing unit, and a controller. The at least one processing unit is configured to obtain object information corresponding to an object, and to automatically determine at least one first portion of the object and at least one second portion of the object. The controller is configured to control a rotational movement of the detector unit. The detector unit is rotatable at a sweep rate over a range of view of the object to be imaged, and the controller is configured to rotate the detector unit at an uneven sweep rate. The uneven sweep rate varies during the rotation from the, wherein a larger amount of scanning information is obtained for the at least one first portion than for the at least one second portion.
