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Fig. 6 | EJNMMI Physics

Fig. 6

From: 166Holmium–99mTechnetium dual-isotope imaging: scatter compensation and automatic healthy-liver segmentation for 166Holmium radioembolization dosimetry

Fig. 6

Quality analysis for the 166Ho images, reconstructed using several k-factors, as function of the 99mTc activity in the phantom during the 166Ho–99mTc dual-isotope acquisition. Coefficient of variation and contrast recovery coefficients for hot sphere S1 and S2 are depicted as function of effective 99mTc activity in the phantom, for 166Ho reconstructions using three different k-factors. Panel A shows the coefficient of variation, measuring the level of inhomogeneity, computed on the 166Ho images within the healthy-liver compartment VOI. Panels B and C depict the contrast recovery coefficients for sphere S1 and S2, respectively. Ideally, these image-quality metrics for 166Ho are independent of 99mTc activity if scatter from 99mTc is sufficiently corrected for. The impact of the choice of k-factor can be observed by the dependence on 99mTc activity, causing an offset of counts in the phantom background. The depicted k-factors are the lowest, the highest and the k-factor leading to the lowest dependency on 99mTc for the considered metric

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