Monte Carlo simulations are increasingly used in scintigraphic imaging to
model imaging systems and to develop and assess tomographic reconstruction
algorithms and correction methods for improved image quantitation. GATE (GEANT
4 Application for Tomographic Emission) is a new Monte Carlo simulation
platform based on GEANT4 dedicated to nuclear imaging applications. This paper
describes the GATE simulation of a prototype of scintillation camera dedicated
to small animal imaging and consisting of a CsI(Tl) crystal array coupled to a
position sensitive photomultiplier tube. The relevance of GATE to model the
camera prototype was assessed by comparing simulated 99mTc point spread
functions, energy spectra, sensitivities, scatter fractions and image of a
capillary phantom with the corresponding experimental measurements. Results
showed an excellent agreement between simulated and experimental data:
experimental spatial resolutions were predicted with an error less than 100 mu
m. The difference between experimental and simulated system sensitivities for
different source-to-collimator distances was within 2%. Simulated and
experimental scatter fractions in a [98-182 keV] energy window differed by less
than 2% for sources located in water. Simulated and experimental energy spectra
agreed very well between 40 and 180 keV. These results demonstrate the ability
and flexibility of GATE for simulating original detector designs. The main
weakness of GATE concerns the long computation time it requires: this issue is
currently under investigation by the GEANT4 and the GATE collaboration
