The present invention provides methods of using current but incomplete data to
prepare an approximated complete image of a patient potentially undergoing radiation
therapy. A complete image of the patient is fused or aligned with a limited patient
image using image registration techniques. The aligned image is converted to sinogram
data. This sinogram data is compared to sinogram data corresponding to the limited
patient image to determine what data exists beyond the scope of the limited sinogram.
Any additional data is added to the limited data sinogram to obtain a complete
sinogram. This complete sinogram is then reconstructed into an image that approximates
the complete image that would have been taken at the time the limited image was obtained.