title: A gate evaluation of the sources of error in quantitative90Y PET.
abstract: OBJECTIVE
  Accurate reconstruction of the dose delivered by90Y microspheres using a postembolization PET scan would permit the establishment of more accurate dose-response relationships for treatment of hepatocellular carcinoma with90Y. However, the quality of the PET data obtained is compromised by several factors, including poor count statistics and a very high random fraction. This work uses Monte Carlo simulations to investigate what impact factors other than low count statistics have on the quantification of90Y PET.
  
  
  METHODS
  PET acquisitions of two phantoms-a NEMA PET phantom and the NEMA IEC PET body phantom-containing either90Y or18F were simulated using gate. Simulated projections were created with subsets of the simulation data allowing the contributions of random, scatter, and LSO background to be independently evaluated. The simulated projections were reconstructed using the commercial software for the simulated scanner, and the quantitative accuracy of the reconstruction and the contrast recovery of the reconstructed images were evaluated.
  
  
  RESULTS
  The quantitative accuracy of the90Y reconstructions were not strongly influenced by the high random fraction present in the projection data, and the activity concentration was recovered to within 5% of the known value. The contrast recovery measured for simulated90Y data was slightly poorer than that for simulated18F data with similar count statistics. However, the degradation was not strongly linked to any particular factor. Using a more restricted energy range to reduce the random fraction in the projections had no significant effect.
  
  
  CONCLUSIONS
  Simulations of90Y PET confirm that quantitative90Y is achievable with the same approach as that used for18F, and that there is likely very little margin for improvement by attempting to model aspects unique to90Y, such as the much higher random fraction or the presence of bremsstrahlung in the singles data.
authors.affiliation: IMIV, U1023 Inserm/CEA/Université Paris-Sud and ERL 9218 CNRS, Université Paris-Saclay, CEA/SHFJ, Orsay 91401, France.
authors.forename: Jared
authors.initials: J
authors.lastname: Strydhorst
authors.affiliation: Department of Nuclear Medicine, Centre Hospitalier Universitaire de Nantes and CRCNA, Inserm U892, Nantes 44000, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Carlier
authors.affiliation: Department of Nuclear Medicine, Hôpital Beaujon, HUPNVS, APHP and Inserm U1149, Clichy 92110, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Dieudonné
authors.affiliation: Siemens Healthcare Molecular Imaging, Knoxville, Tennessee, 37932.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Conti
authors.affiliation: IMIV, U1023 Inserm/CEA/Université Paris-Sud and ERL 9218 CNRS, Université Paris-Saclay, CEA/SHFJ, Orsay 91401, France.
authors.forename: Irène
authors.initials: I
authors.lastname: Buvat
mesh_terms: D000465:Algorithms; D002138:Calibration; D003198:Computer Simulation; D005462:Fluorine Radioisotopes / Q000008:administration & dosage; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D011874:Radiometry / Q000295:instrumentation / Q000379:methods; D012542:Scattering, Radiation; D015021:Yttrium Radioisotopes / Q000008:administration & dosage*
chemical_list: D005462:Fluorine Radioisotopes; D015021:Yttrium Radioisotopes
keywords: 
  gate
  ; Applications; Biological material, e.g. blood, urine; Haemocytometers; Biomedical modeling; Cancer; Coupled channel methods; Digital computing or data processing equipment or methods, specially adapted for specific applications; Dose-volume analysis; Dosimetry/exposure assessment; Image data processing or generation, in general; Image reconstruction; Image scanners; Measuring half-life of a radioactive substance; Medical image contrast; Monte Carlo methods; PET/CT simulation; Photon scattering; Photons; Positron emission tomography; Positron emission tomography (PET); Positrons; Radiation therapy; Reconstruction; Scintigraphy; bremsstrahlung; cancer; cellular biophysics; dosimetry; image reconstruction; medical image processing; phantoms; positron emission tomography; quantification; yttrium; yttrium-90