Abstract
1847
Objectives National Electrical Manufacturers Association (NEMA) provides guidelines to assess the performance of Positron Emission Tomography (PET). A PET/CT scanner, Discovery IQ, GE Medical systems, Milwaukee, USA was installed in our department which has high sensitivity PET component. Total 11252 Bismuth Germanate (BGO) crystal elements are arranged in 5 circular rings providing 260mm axial and 700mm transaxial field of view. We have performed the NEMA NU-2 2012 quality control tests to evaluate this system on site before clinical use.
Methods Performance measurements of the PET scanner were made using the NEMA NU2-2012 procedures for spatial resolution, scatter fraction, sensitivity, count rate loss and random coincidence estimation, Noise Equivalent Count Rate (NECR) and Image quality. As per NU2 2012 spatial resolution was calculated near center, at 10cm and 20 cm off center in tangential, radial and axial directions. Sensitivity was calculated at centre and 10cm off center and system sensitivity was calculated by using these two values. Scatter fractionand NECR measurements. Image quality test was also performed.
Results The tangential, radial and axial FWHM were 4.99mm, 4.20mm and 4.79mm at centre, 5.49mm, 4.69mm and 4.81mm and 10cm off centre and 7.99mm, 5.07mm and 4.95 mm 20cm off centre respectively. The absolute sensitivity of this scanner was found to be 20.1cps/kBq. The scatter fraction calculated from the decay method was 37.94% and NECR was 125kcps. The peak NECR was achieved at activity concentration of 8.7KBq/ml and the count loss below the peak NECR was found to be 0.68%. Image quality test for percentage contrast, background variability and lung error residual mean are shown in table1(Figure1).
Conclusions Overall PET performance of Discovery IQ whole-body scanner was satisfactory and passed the entire NEMA 2012 acceptance test.