Jaszczak phantom. The spatial resolution of the system was verified for 123I, using a Jaszczak phantom with hot rods ranging from 0.7 to 1.2 mm. Images were acquired in 32 projections, using 150 s per gantry position. Jaszczak phantom, filled with 75 MBq of 123I-Na, demonstrates the spatial resolution of the system. The red line in the SPECT image (a) represents the area where the count profile curve (b) is captured. The 0.8-mm hot rods are clearly detectable.