title: Effect of the positron range of 18F, 68Ga and 124I on PET/CT in lung-equivalent materials.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of positron range on visualization and quantification in (18)F, (68)Ga and (124)I positron emission tomography (PET)/CT of lung-like tissue.
  
  
  METHODS
  Different sources were measured in air, in lung-equivalent foams and in water, using a clinical PET/CT and a microPET system. Intensity profiles and curves with the cumulative number of annihilations were derived and numerically characterized.
  
  
  RESULTS
  (68)Ga and (124)I gave similar results. Their intensity profiles in lung-like foam had a peak similar to that for (18)F, and tails of very low intensity, but extending over distances of centimetres and containing a large fraction of all annihilations. For 90% recovery, volumes of interest with diameters up to 50 mm were required, and recovery within the 10% intensity isocontour was as low as 30%. In contrast, tailing was minor for (18)F.
  
  
  CONCLUSIONS
  Lung lesions containing (18)F, (68)Ga or (124)I will be visualized similarly, and at least as sharp as in soft tissue. Nevertheless, for quantification of (68)Ga and (124)I large volumes of interest are needed for complete activity recovery. For clinical studies containing noise and background, new quantification approaches may have to be developed.
authors.affiliation: Department of Nuclear Medicine, Maastricht University Medical Center, PO Box 5800, 6202 AZ Maastricht, The Netherlands. gerrit.kemerink@mumc.nl
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Kemerink
authors.forename: Mariëlle G W
authors.initials: MG
authors.lastname: Visser
authors.forename: Renee
authors.initials: R
authors.lastname: Franssen
authors.forename: Emiel
authors.initials: E
authors.lastname: Beijer
authors.forename: Mariangela
authors.initials: M
authors.lastname: Zamburlini
authors.forename: Servé G E A
authors.initials: SG
authors.lastname: Halders
authors.forename: Boudewijn
authors.initials: B
authors.lastname: Brans
authors.forename: Felix M
authors.initials: FM
authors.lastname: Mottaghy
authors.forename: Gerrit J J
authors.initials: GJ
authors.lastname: Teule
mesh_terms: D000362:Agar; D004583:Electrons; D005462:Fluorine Radioisotopes; D005710:Gallium Radioisotopes; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007457:Iodine Radioisotopes; D008168:Lung / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D013594:Syringes; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*; D014867:Water
chemical_list: D005462:Fluorine Radioisotopes; D005710:Gallium Radioisotopes; D007457:Iodine Radioisotopes; D014867:Water; D000362:Agar