title: Performance measurement of the microPET focus 120 scanner.
abstract: The microPET Focus 120 scanner is a third-generation animal PET scanner dedicated to rodent imaging. Here, we report the results of scanner performance testing.
  
  
  METHODS
  A (68)Ge point source was used to measure energy resolution, which was determined for each crystal and averaged. Spatial resolution was measured using a (22)Na point source with a nominal size of 0.25 mm at the system center and various off-center positions. Absolute sensitivity without attenuation was determined by extrapolating the data measured using an (18)F line source and multiple layers of absorbers. Scatter fraction and counting rate performance were measured using 2 different cylindric phantoms simulating rat and mouse bodies. Sensitivity, scatter fraction, and noise equivalent counting rate (NECR) experiments were repeated under 4 different conditions (energy window, 250 approximately 750 keV or 350 approximately 650 keV; coincidence window, 6 or 10 ns). A performance phantom with hot-rod inserts of various sizes was scanned, and several animal studies were also performed.
  
  
  RESULTS
  Energy resolution at a 511-keV photopeak was 18.3% on average. Radial, tangential, and axial resolution of images reconstructed with the Fourier rebinning (FORE) and filtered backprojection (FBP) algorithms were 1.18 (radial), 1.13 (tangential), and 1.45 mm full width at half maximum (FWHM) (axial) at center and 2.35 (radial), 1.66 (tangential), and 2.00 mm FWHM (axial) at a radial offset of 2 cm. Absolute sensitivities at transaxial and axial centers were 7.0% (250 approximately 750 keV, 10 ns), 6.7% (250 approximately 750 keV, 6 ns), 4.0% (350 approximately 650 keV, 10 ns), and 3.8% (350 approximately 650 keV, 6 ns). Scatter fractions were 15.9% (mouse phantom) and 35.0% (rat phantom) for 250 approximately 750 keV and 6 ns. Peak NECR was 869 kcps at 3,242 kBq/mL (mouse phantom) and 228 kcps at 290 kBq/mL (rat phantom) at 250 approximately 750 keV and 6 ns. Hot-rod inserts of 1.6-mm diameter were clearly identified, and animal studies illustrated the feasibility of this system for studies of whole rodents and mid-sized animal brains.
  
  
  CONCLUSIONS
  The results of this independent field test showed the improved physical characteristics of the F120 scanner over the previous microPET series systems. This system will be useful for imaging studies on small rodents and brains of larger animals.
authors: Department of Nuclear Medicine, Seoul National University College of Medicine, 28 Yungun-Dong, Chongno-Gu, Seoul 110-744, Korea.
authors: Jin Su
authors: JS
authors: Kim
authors: Jae Sung
authors: JS
authors: Lee
authors: Ki Chun
authors: KC
authors: Im
authors: Su Jin
authors: SJ
authors: Kim
authors: Seog-Young
authors: SY
authors: Kim
authors: Dong Soo
authors: DS
authors: Lee
authors: Dae Hyuk
authors: DH
authors: Moon
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000000981:diagnostic imaging; D001921:Brain / Q000000981:diagnostic imaging; D002415:Cats; D005240:Feasibility Studies; D005462:Fluorine Radioisotopes; D005857:Germanium; D006321:Heart / Q000000981:diagnostic imaging; D051379:Mice; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D011868:Radioisotopes; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005462:Fluorine Radioisotopes; D011868:Radioisotopes; D005857:Germanium