Stair Step Artifacts.— Stair step artifacts appear around the edges of structures in multiplanar and three-dimensional reformatted images when wide collimations and nonoverlapping reconstruction intervals are used. They are less severe with helical scanning, which permits reconstruction of overlapping sections without the extra dose to the patient that would occur if overlapping axial scans were obtained (Fig 28). Stair step artifacts are virtually eliminated in multiplanar and three-dimensional reformatted images from thin-section data obtained with today’s multisection scanners (Fig 29).
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