Examination of cross-calibration and concentration linearity with quantitative gallium-67 single-photon emission...

We evaluated whether scattered radiation should be considered for cross-calibration and concentration linearity with quantitative gallium-67 (⁶⁷Ga) single-photon emission computed tomography (SPECT). The scanned data from cylinder and spherical phantoms were used. They were reconstructed using ordered subset expectation maximization with resolution recovery, scatter, and computed tomography (CT)-based attenuation correction. The standardized uptake values (SUVs) of the cylinder phantom SPECT/CT images were calculated using system planar sensitivity with and without scatter correction, and the results were compared with the theoretical value. To determine concentration linearity, the relationship between the measured SUVs in three different spherical phantoms was evaluated. SUVs calculated by system planar sensitivity without scatter correction were closer to the theoretical values. Furthermore, the 37-mm sphere showed proper radioactive linearity. Our study suggests the utility of the SUV for ⁶⁷Ga SEPCT/CT. Nevertheless, additional studies are required.