A /sup 68/Ge PET hot-sphere phantom with no cold shells

A cylindrical 20 cm by 20 cm /sup 68/Ge PET resolution phantom was created. The phantom contained one cold (non-radioactive) silicone sphere of diameter 32 mm, and nine hot silicone spheres with diameters ranging from 4 to 25 mm in diameter. No shell of non-radioactive material was used to contain the silicone. The ten spheres were arranged on a circular locus 10 cm in diameter, in a background of polyurethane whose specific activity was 4.6 times lower than that of the hot spheres. In a 15-hour PET/CT study of this phantom, all objects were detected.