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FIGURE 12. Cross-sectional diagrams of GE quality assurance phantom (24) illustrating respective sections (inserts) for evaluation of laser-light alignment, image slice thickness, spatial resolution, linearity, and high-contrast contrast resolution (A); low-contrast uniformity (B); and image uniformity and noise (C). Various short black lines in acrylic insert in section shown in A are cavities that fill with water when phantom is filled, providing high contrast between cavities and acrylic; portion of this section outside this insert, although not shown in black, is also water-filled. Diagonally arranged sets of line cavities ranges are 1.6 (lower left), 1.3, 1.0, 0.8, 0.6, and 0.5 (upper right) mm in line width and are used to evaluate spatial resolution. Section shown in B includes polystyrene membrane with series of holes (10, 7.5, 5, 3, and 1 mm in diameter) that also fill with water when phantom is filled, providing low contrast between holes and polystyrene. (D) Side-view diagram (not to scale) of section of phantom in A, showing only 1 of slice-thickness measurement components of insert; these line cavities are air-, not water-, filled. They are staggered (offset) 1 mm apart in longitudinal direction. Also shown in D, as well as in A, is laser-alignment groove around circumference of phantom and 2 corresponding laser-alignment cavities. Boxes indicate pertinent ROIs for different analyses. (See text for details.)
