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New high lutetium content Lu1.8Gd0.2SiO5:Ce (LGSO) scintillators with promising physical properties for PET, but also for SPECT and X-ray counting CT applications, have recently been developed. The new crystals have a high density (7.3 g/cc), high light output (>90% of NaI(Tl)), suitable emission wavelength for APD readout (420, 480 nm), and fast decay time that can be adjusted from 34 to 45 ns by varying Ce-doping concentration. Three different LGSO species with 0.025 mol% Ce (34.2 ¿¿ 0.3 ns), 0.15 mol% Ce (38.3 ¿¿ 0.3 ns) and 0.75 mol% Ce (44.8 ¿¿ 0.3 ns) were investigated. Photoelectron yields measured with a high performance UV-enhanced APD readout were respectively 12380 ¿¿ 570, 14250 ¿¿ 570 and 17690 ¿¿ 760 phe/MeV. Energy spectra of 68Ge (511 keV, PET), 99mTc (140 keV, SPECT) and 241Am (60 keV, CT) sources were obtained with the crystals coupled to the APD. FWHM energy resolutions at 511, 140 and 60 keV reached 10.5%, 17.6% and 32.2%, respectively. Timing resolution was measured in reference to a fast PMT-plastic detector and yielded 1.3-1.5 ns. It is concluded that APD-based detectors using these new high lutetium content LGSO scintillators are very promising candidates for multimodality medical imaging applications.