Fig. 1. Diagram of Carlson model(a) Hot zone cold rod, (b) Cold rod and spherical plugs, (c) Linear/uniform cross-section plugs, (d) Main cylinder of the Carlson model container and three plugs

Fig. 2. Diagram of PET/CT model

Fig. 3. Diagram of Hoffman 3D brain model

Fig. 4. Scene photo of Hoffman 3D brain model ²²³Ra SPECT/CT scanning

Fig. 5. Comparison of Carlson model linear images (a) and homogeneity images (b) between ⁹⁹Tc^m SPECT/CT (left) and ²²³Ra SPECT/CT (right) (color online)

Fig. 6. Comparison of Carlson model hot zone images (a) and cold zone images (b) between ⁹⁹Tc^m SPECT/CT (left) and ²²³Ra SPECT/CT (right) (color online)

Fig. 7. Comparison of PET/CT model ⁹⁹Tc^m SPECT/CT (left) and ²²³Ra SPECT/CT (right) coronal images (two aluminum tubes visible) (a) and cross-sectional images (the top, middle and bottom images are respectively CT, SPECT and SPECT/CT fusion images) (b) (color online)

Fig. 8. Comparison of PET/CT model ⁹⁹Tc^m SPECT/CT (a) and ²²³Ra SPECT/CT (b) attenuation-corrected images (the top, middle and bottom images are CT, SPECT and SPECT/CT fusion images, respectively) (color online)

Fig. 9. Hoffman 3D brain model ⁹⁹Tc^m SPECT/CT (a) and ²²³Ra SPECT/CT (b) images (color online)