1. A method for creating a four-dimensional image of a, subject comprising: from a subject exhibiting uninterrupted periodic external motion, detecting position information representing the uninterrupted periodic external motion of the subject utilizing external position or motion sensors, said external periodic motion comprising successive phases; with a C-arm imaging system, acquiring a series of projected images independent of said phases at successive respective known times in all phases of the uninterrupted external periodic motion represented in the generated positioning information; storing the acquired series of projected images in an image data set with position information; constructing a three-dimensional image, defined by three orthogonal spatial directions from images in the data set for a particular position of the subject in said uninterrupted external periodic motion; repeating the construction of three-dimensional images from images in the data set for each position of the subject in the uninterrupted periodic motion represented in the generated position information, thereby forming a three-dimensional image set; and combining the images of the three-dimensional image set into a four-dimensional image using said three orthogonal spatial directions as three of the four dimensions and using said uninterrupted external periodic motion as a running variable for a fourth of the four dimensions.