The (68)Ge phantom-based FDG-PET site qualification program for clinical trials adopted by FIL (Italian Foundation on Lymphoma)

The quantitative assessment of Positron Emission Tomography (PET) scans using standardized uptake value and derived parameters proved to be superior to traditional qualitative assessment in several retrospective or mono-centric prospective reports. Since different scanners give different quantitative readings, a program for clinical trial qualification (CTQ) is mandatory to guarantee a reliable and reproducible use of quantitative PET in prospective multi-centre clinical trials and in every-day clinical life. We set up, under the auspices of Italian Foundation on Lymphoma (FIL), a CTQ program consisting of the PET/CT scan acquisition and analysis of (18)F and (68)Ge NEMA/IEC image quality phantoms for the reduction of inter-scanner variability. Variability was estimated on background activity concentration (BAC) and sphere to background ratio (SBR). The use of a (68)Ge phantom allowed reducing the inter-scanner variability among different scanners from 74.0% to 20.5% in BAC and from 63.3% to 17.4% in SBR compared to using the (18)F phantom. The CTQ criteria were fulfilled at first round in 100% and 28% of PET scanners with (68)Ge and (18)F respectively. The (68)Ge phantom proved a reliable tool for PET scanner qualification, able to significantly reduce the potential sources of error while increasing the reproducibility of PET derived quantitative parameter measurement.