Computed tomography scanning systems and methods using a field emission x-ray source are disclosed. An exemplary micro-computed tomography scanner comprises a micro-focus field emission x-ray source, an x-ray detector, an object stage placed between the x-ray source and the detector, an electronic control system and a computer that control the x-ray radiation and detector data collection, and computer software that reconstructs the three dimension image of the object using a series of projection images collected from different projection angles. Exemplary methods obtain a computed tomography image of an object in oscillatory motion using the micro computed tomography scanner.