ORIGINAL ARTICLE Performance of the new generation of whole-body PET/CT scanners: Discovery STE and Discovery VCT M. Teräs & T. Tolvanen & J. J. Johansson & J. J. Williams & J. Knuuti Received: 29 March 2007 / Accepted: 14 May 2007 / Published online: 28 July 2007 # Springer-Verlag 2007 Abstract Purpose The new GE Discovery STE and Discovery VCT respectively combine 16-slice and 64-slice CT with PET. The PET scanner has a new BGO detector block of 8×6 matrix (6.3×4.7×30 mm 3 ). The aim of this study was to test the performance of the new scanner. Methods The PET performance evaluation was done using NEMA methodology. Owing to improved front-end elec- tronics, the system was tested with different energy window and coincidence timing settings. Results Transaxial resolution FWHM for 2D(3D) mode at 1 cm offset from the centre of the field of view (R1) was 4.87 mm (5.12 mm) and at 10 cm off centre (R10) radially 5.70 mm (5.89 mm) and tangentially 5.84 mm (5.47 mm). The axial resolutions were 4.4 mm (5.18 mm) (R1) and 5.99 mm (5.86 mm) (R10). The sensitivities were 2.3 cps/ kBq (8.8 cps/kBq) (R0, centre of field of view) and 2.3 cps/ kBq (8.9 cps/kBq) (R10). The system scatter fraction was 21.4% in 2D at an energy of 375 keV (33.9% in 3D mode at a higher energy of 425 keV). Peak noise equivalent count rates (k=1) were 84.9 kcps at 43.9 kBq/ml (2D) and 67.6 kcps at 12.1 kBq/ml (3D). In image quality measurement the hot sphere to background contrast with 10- to 22-mm diameter spheres varied from 14% to 68%, being slightly better in 3D than in 2D mode. Cold sphere contrast was 67% in 2D and 59% in 3D mode. Conclusion GE’ s new STE and VCT PET/CT systems have improved spatial resolution without loss in sensitivity. When compared with the LYSO crystal-based GE Discov- ery RX, the resolution and scatter fraction are comparable, the count rate capability is lower but the sensitivity is higher. Keywords Positron emission tomography . Multidetector computed tomography . NEMA Introduction Current trends in positron emission tomography (PET) imaging are increased use of combined PET and multislice computerised tomography (CT), respiratory gating (4D CT and 4D PET), and applications in radiation therapy planning and fields other than oncology, e.g. neurology and cardiol- ogy. These trends have led to several new scanner require- ments, such as better spatial resolution, high sensitivity, a larger patient port, improvements in acquisition and recon- struction features and also ECG and respiratory gating possibilities. The new features and scanning protocols often require routine list mode acquisition. Until recently, the standard scintillator material was bismuth germanate (BGO) [1, 2]. In the new scanners, lutetium oxyorthosilicate (LSO) [3, 4], lutetium yttrium oxyorthosilicate (LYSO) [5] and gadolinium oxyorthosili- cate (GSO) have also been used owing to some favourable characteristics [6]. However, the performance of a scanner depends not only on the scintillating material but also on the scanner design as a whole, and this includes the collection of the light, the performance of the photo- multiplier tube, the block detector design and the electronic architecture [7, 8]. Eur J Nucl Med Mol Imaging (2007) 34:1683–1692 DOI 10.1007/s00259-007-0493-3 M. Teräs (*) : T. Tolvanen : J. J. Johansson : J. Knuuti Turku PET Centre, Turku University Central Hospital, PO Box 52, 20521 Turku, Finland e-mail: mika.teras@tyks.fi J. J. Williams Functional Imaging, GE healthcare, Waukesha, WI, USA