View larger version (135K)

Figure 6.  Diagram illustrates the effect of adjustments in window width and level with respect to the voxel histogram of a CT data set. Such adjustments alter the attenuation of structures displayed in a reconstructed 3D image. A change in width (slope) alters image contrast, whereas a change in level (shift on the x axis) alters data inclusion and the attenuation of voxels in the resulting image.