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FIGURE 4. Contrast recovery coefficient (CRC) (A and C) and variability (B and D) for image-quality torso phantom for varying acquisition times. Ratio of activity concentration in hot spheres to background is 8:1 (A and B) and 4:1 (C and D). CRC was similar for all acquisition times except at 1 min. Results from 9-min acquisition are shown in CRC plot. Average error bars in variability plots were 6% (B) and 8.5% (D). Dotted vertical line in all 4 plots marks separation between large cold spheres on its right and small hot spheres on its left.
