Patent ID: 7756242

Claim:
An X-ray computed tomography (CT) apparatus for performing contrast imaging by performance of a helical shuttle scan on a region of interest in a subject, said X-ray CT apparatus comprising: a scan device configured to set a plurality of X-ray doses and perform a helical shuttle scan, said helical shuttle scan comprising: a plurality of helical scan paths, each helical scan path at least partially defined by travel of a region of interest along a predetermined distance along a one-way travel stroke; and a first helical scan of said region of interest emitting an X-ray of a first X-ray dose and a second helical scan of said region of interest emitting an X-ray of a second X-ray dose, said second X-ray dose greater than said first X-ray dose, said first helical scan performed along at least one of said plurality of helical scan paths until a predetermined threshold value of change of CT numbers is exceeded while said region of interest travels along a first one-way travel stroke, said second helical scan comprising a single helical scan performed immediately and automatically thereafter, wherein said region of interest travels along a second one-way travel stroke opposite to the first one-way travel stroke; and an image reconstruction device configured to reconstruct images corresponding to each of said plurality of helical scan paths.