All 12 image slices for a phantom with two spheres: 12.4 mm [slices 1–3, bottom (posterior)]; and 15.6 mm (slices 5–8, central). LBRt = 3 for both spheres, and BG concentration = 0.44 kBq/mL. au: arbitrary units.
(Top row) Single slices from three acquisitions at different BG activity levels of the 3.9 mm diameter sphere, with LBRt = 21. (Bottom row) Similar to top row but images of the 7.8 mm sphere with LBRt = 3. BG activity concentration is given at the top of each column. Arbitrary units (au) are consistent across columns.
Measured BG activity concentration and COV versus the true activity in the phantom. The solid gray line is the line of identity. The dotted line is an extrapolation of the linear region (0–2 kBq/mL) of the measured concentration. COV from images generated using full list mode data files and reduced-count files are distinguished by open and solid diamond symbols. The line through COV data connects the 100%-count data points (open diamonds).
Contrast recovery coefficient vs sphere size for sphere ROI max and mean. Error bars represent ± one standard deviation calculated by averaging CRC across BG concentration and LBRt.
Cumulative reader detection sensitivity vs BG concentration and LBRt. Circle markers are measured data points; the mesh grid is an interpolation of measurements.
(a) Symbols show individual reader detection sensitivities vs BG concentration, averaged over all LBR, and separated into two groups: 3.9 mm spheres and all other spheres. The solid lines with error bars represent mean cumulative results and corresponding standard deviation. (b) Cumulative sensitivity vs sphere diameter averaged over all LBR for each BG concentration. Error bars represent standard deviation across readers.
Sphere and background (BG) properties used in phantom image acquisitions.
Expected patient BG activity concentrations.
Comparison of synthetic and single-acquisition images.
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