The Effect of Computed Tomography Viewer Controls on Anatomical Measurements

Newer computed tomography (CT) scanners provide a means for direct measurement of the size of normal and abnormal body structures from the viewing screen. Because tissue densities within the brain tend to fall in a narrow range, viewer control settings (window width and window center) are used in a relatively stereotyped fashion when studying head scans. In contrast, CT body scan images usually include tissues of widely different densities and require much broader use of the control settings for complete examination. Studies of the effect of changing the control settings have uncovered wide differences in how these controls should be set when measuring structures directly from the CT scan.