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Figure 5c.   Anatomic coverage. (a, b) The coverage for multisection CT (a) can be eight times longer than for single-section helical CT (b) at the same pitch and section thickness. (c, d) To scan the same volume in the same time with single-section helical CT, one must increase the pitch (c) or section thickness (d), thereby degrading image quality. (e) To achieve the same image quality with single-section helical CT, the scanning time would have to be lengthened eightfold.