Development of GATE Monte Carlo simulation for a dual-head gamma camera.

GATE is a simulation code which is based on the Geant4 Monte Carlo code. This code was developed for simulation of nuclear medicine imaging systems. Our aim in this study was to use and validate GATE for simulating a Siemens E.Cam gamma camera. A dual-head gamma camera was used for modeling with GATE. Each head consisted of a collimator, aluminum layer, crystal, and head shielding. The back compartment consisted of photomultiplier tubes and electronic circuits behind the crystal. The photoelectric effect and Compton and Rayleigh scatter were included in the gamma transport process. The simulation validity was examined by comparison of measured parameters with calculated data including the energy spectrum, energy, spatial resolution, and sensitivity. To evaluate the imaging system, we compared the simulated and experimental images of a phantom. The simulated and measured energy spectra agreed well with regard to the position and height of the photopeak at 140 keV. The FWHMs at 140 keV were calculated to be equal to 14.10 and 13.37 keV, respectively. The energy resolutions were 10.07 and 9.55%, and the sensitivities were 8.68 × 10(-5) and 8.69 × 10(-5) cps/MBq, respectively, for the simulated and measured results. The spatial resolution and imaging tests for a point, line, and node phantom showed good agreement between the simulated and measured results. Overall, the results showed good agreement between the measured and the simulated data. There was also excellent agreement between computational and actual images. This study demonstrated the flexibility and accuracy of GATE in SPECT simulation.