부산대학교 도서관

We report on the NEMA-NU2-2012 performance of a hypothetical Monte Carlo (MC) model, Ex-PET, of the Siemens Biograph Vision positron emission tomography (PET)/CT (Bio-Vis) with sparse detector module rings and extended axial field of view (AFOV). MC simulations were performed with the detector module rings interleaved with 32-mm gaps, equivalent to the axial dimension of each detector module, yielding an AFOV of 48.0 cm (Bio-Vis has 25.6-cm AFOV). 3D-PET acquisition combined with a limited continuous-bed-motion (limited-CBM) was used to compensate for the loss in sensitivity within the gaps’ regions. MC simulations of the Bio-Vis were performed for comparison purposes. All MC simulations were performed using GATE MC toolkit. Ex-PET exhibited 0.49, 0.16, and 0.16 mm deterioration in axial resolution at 1, 10, and 20 cm off-center of the transaxial field of view, respectively, compared to Bio-Vis. Only 1% reduction in system sensitivity and 6% reduction in peak NECR was observed with Ex-PET compared to Bio-Vis. 3D-OSEM image reconstruction, combined with CBM, allowed compensating for the lack of counts within the gaps’ regions. NEMA Image Quality test showed < 6% reduction in contrast recovery with Ex-PET versus Bio-Vis, yet the background variability was increased by up to 8%. The feasibility of PET imaging with an easily adoptable sparse detector configuration was demonstrated. This can lay the pathway for future development of cost-effective PET systems with long and conventional AFOV’s.