@article{3115306,
    title = "Comparative evaluation of two commercial PET scanners, ECAT EXACT HR+
and Biograph 2, using GATE",
    author = "Karakatsanis, N. and Sakellios, N. and Tsantilas, N. X. and Dikaios, N. and and Tsoumpas, C. and Lazaro, D. and Loudos, G. and Schmidtlein, C. R. and and Louizi, K. and Valais, J. and Nikolopoulos, D. and Malamitsi, J. and and Kandarakis, J. and Nikita, K.",
    journal = "NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION
A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT",
    year = "2006",
    volume = "569",
    number = "2, SI",
    pages = "368-372",
    publisher = "ELSEVIER SCIENCE BV",
    doi = "10.1016/j.nima.2006.08.110",
    keywords = "GATE; PET; HR; biograph; Monte Carlo simulations; validation",
    abstract = "Geant4 application for tomographic emission (GATE) is a generic Monte
Carlo simulation platform based on a general-purpose code GEANT4 and
designed to simulate positron emission tomography (PET) and single
photon emission tomography systems. Monte Carlo simulations are used in
nuclear medicine to model imaging systems and develop and assess
tomographic reconstruction algorithms and correction methods for
improved image quantification. The purpose of this study is to validate
two GATE models of the commercial available PET scanner HR+ and the
PET/CT Biograph 2. The geometry of the system components has been
described in GATE, including detector ring, crystal blocks, PMTS etc.
The energy and spatial resolution of the scanners as given by the
manufacturers have been taken into account. The GATE simulated results
are compared directly to experimental data obtained using a number of
NEMA NU-2-2001 performance protocols, including spatial resolution,
sensitivity and scatter fraction. All the respective phantoms are
precisely modeled. Furthermore, an approximate dead-time model both at
the level of single and coincidence events was developed so that the
simulated count rate curve can satisfactorily match the experimental
count rate performance curve for each scanner In addition a software
tool was developed to build the sinograms from the simulated data and
import them into the software for tomographic image reconstruction where
the reconstruction algorithm of FBP3DRP was applied. An agreement of
less than 0.8 mm was obtained between the spatial resolution of the
simulated system and the experimental results. Also the simulated
scatter fraction for the NEMA NU 2-2001 scatter phantom matched the
experimental results to within 3% of measured values. Finally the ratio
of the simulated sensitivities with sources radially offset 0 and 10 cm
from the central axis of each of the two scanners reaches an agreement
of less than 1 % between the simulated and experimental values. This
simulation code will be used in a second phase in order to study scatter
phenomena and motion artifacts. The simulation results will be used to
optimize image reconstruction algorithms, with emphasis on dynamic PET
studies. (c) 2006 Published by Elsevier B.V."
}