Patent ID: 7173997

Claim:
An X-ray CT imaging method for conducting a helical scan for collecting projection data while making relative rotation of at least one of an X-ray tube and a multi-row detector around a subject to be imaged and making relative rectilinear motion of them with respect to the subject to be imaged, said method comprising the steps of: defining a relative rectilinear motion start point and a relative rectilinear motion end point within a region of interest (ROI) for which a CT image is to be created; collecting projection data from said relative rectilinear motion start point to said relative rectilinear motion end point; producing a CT image at a desired image position in said region of interest using the collected projection data; and generating a first distance between the relative rectilinear motion start point and the relative rectilinear motion end point, wherein the relative rectilinear motion starts at the relative rectilinear motion start point and ends at the relative rectilinear motion end point; and generating a second distance between an ROI front end position and an ROI back end position, wherein the ROI starts at the ROI front end position and ends at the ROI back end position, and wherein the first distance is less than the second distance, wherein the X-ray tube generates an X-ray beam, wherein the relative rectilinear motion start point is located at a distance from the ROI front end position, wherein the distance is measured in a direction of the relative rectilinear motion and is equal to half of a thickness of the X-ray beam, and wherein the thickness is at a center of rotation of the X-ray tube and the multi-row detector.