System specific modeling for absolute quantification of 99mTc and 177Lu with SPECT/CT

In this study, quantitative SPECT was evaluated for a Symbia Intevo 6 (Siemens Medical Solutions, Germany) SPECT/CT with
¹⁷⁷
Lu and
^99m
Tc. The aim of this study was to assess the accuracy of quantitative SPECT images from absolute activity concentrations (kBq/ml) and as a SUV by using CT-based scatter and attenuation correction for
^99m
Tc with dead time, sensitivity, and scatter measurements. The activity concentration images of the IEC body phantom filled with
^99m
Tc and
¹⁷⁷
Lu showed 0.3% differences from the true concentrations. The ratio of the SUV value in hot spheres and the background 6.9:1 on the quantitative image also matched to the true activity ratio of 7.2:1. A previously published quantitative SPECT/CT methodology was adapted and validated for
^99m
Tc and
¹⁷⁷
Lu with a phantom to generate an absolute activity image in kBq/ml.