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The parameters used to evaluate the variability were: Background Activity Concentration (BAC) (evaluated in the UQP and in the IQ phantoms), Ratio spheres to background (SBR) (defined as the ratio between activity concentration of the larger sphere and the BAC), Recovery coefficient (RC) (calculated as the ratio between measured maximum and actual activity concentration in each sphere).
The scanners were considered calibrated if difference between the theoric activity and the one measured in the ROI inside the UQP phantom was less than 10%. With the value obtained by the ROI placed on the hot spheres of the NEMA phantom’s image, the RC were calculated and compared with the value imposed by the European guidelines (Boellaard et al., 2014).
RESULTS
Seventy-seven Italian sites equipped with 85 PET/CT scanners participated in the 18F phantom CTQ program. Sixty-four out of 85 (75%) scanners fulfilled the CTQ requirements with the 18F, 17 (20%) did not, while CTQ is still ongoing on 4 (5%) scanners. For qualified scanners the CTQ was reached at the first round in 34% of the cases, while in 31%, 17%, 11%, 3% and 3% two, three, four, five or more than five iterations, were required, respectively. For the PET/CT scanners fulfilling the CTQ the difference between measured and expected BAC in the uniformity phantom was -1.3±5.4% (CI 95%: % -11.9 - +9.3%, ISV=21.2%). The difference between measured and expected BAC in the IQ phantom was -4.2±17.3% (CI 95%: -38.1% - +29.7%, ISV=67.8%). The difference between measured versus expected SBR in the IQ phantom was 7.0±12.9% (CI 95%: - 18.3% to +32.3%, ISV=50.6).
Twenty-five Spanish sites equipped with 25 PET/CT scanners participated in the 18F phantom CTQ program. Eighteen out of 25 (72%) scanners fulfilled the CTQ requirements with the 18F, 4 (16%) did not, while CTQ is still ongoing on 3 (12%) scanners. For qualified scanners the CTQ was reached at the first round in 33% of the cases, while in 44%, 17%, 0% and 6% two, three, four or iterations, were required, respectively. For the PET/CT scanners fulfilling the CTQ the difference between measured and expected BAC in the uniformity phantom was -1.9±5.7% (CI 95%: -13.9% to +8.0%, ISV=21.9%). The difference between measured and expected BAC in the IQ phantom was -1.0±16.4% (CI 95%: -35.4% to +33.4%, ISV=68.8%). The difference between measured versus expected SBR in the IQ phantom was -0.7±10.1% (CI 95%: -21.9% to +20.5%, ISV=42.4). Twenty-five worldwide sites equipped with 28 PET/CT scanners participated in the 18F phantom CTQ program. Sixteen out of 28 (58%) scanners fulfilled the CTQ requirements with the 18F, 6
(21%) did not, while CTQ is still ongoing on 6 (21%) scanners. For qualified scanners the CTQ was 25
Tesi di Specialità