1. A method for creating a four-dimensional image of a patient exhibiting periodic motion with a C-arm imaging system, comprising: generating positioning information related to the periodic motion of the patient utilizing external position or motion sensors; acquiring a series of projected images, wherein the acquisition of each of the series of projected images is associated with the generated positioning information; storing the acquired series of projected images in an image data set with position information; constructing a three-dimensional image from images in the data set for a particular position; repeating the construction of three-dimensional images from images in the data set for each position based on the position information collected, thereby forming a three-dimensional image set; and combining the images of the three-dimensional image set into the four-dimensional image.