ABSTRACT
GATE, which stands for Geant4 Application for Emission Tomography, is an opensource and freely distributed Monte Carlo simulation tool. The origin of GATE can be traced back to a workshop organized in July 2001 by Irène Buvat in Paris, France, and attended by several research groups sharing a
CONTENTS
Overview of GATE .............................................................................................. 131 Basic Architecture of the Code ..................................................................... 131 Mechanism of Macros in GATE ................................................................... 132 Important Concepts in GATE ....................................................................... 133
Systems ....................................................................................................... 133 Sensitive Detectors and Actors ................................................................ 135 Digitizer ...................................................................................................... 135 Data Output ................................................................................................ 137 Time Management ..................................................................................... 138
Physics of GATE .................................................................................................. 138 Radioactive Sources ....................................................................................... 138 Principle of Particle Propagation in GATE ................................................. 139 Physics Models ............................................................................................... 140
Electromagnetic Processes ........................................................................ 140 Hadronic Processes ................................................................................... 141 Optical and Scintillation Processes ......................................................... 141
Designing a GATE Simulation .......................................................................... 142 Building a Macro ............................................................................................ 142 Acceleration Options ..................................................................................... 144
Running a GATE Simulation ............................................................................. 144 Systems Already Modeled and Validated with GATE .................................. 145 Current Applications of GATE .......................................................................... 145 Conclusion ........................................................................................................... 147 References ............................................................................................................. 148
common interest in Monte Carlo simulations. The focus was to brainstorm about the future of Monte Carlo simulations in nuclear medicine. Indeed, the dedicated Monte Carlo codes developed for positron emission tomography (PET) and single photon emission computed tomography (SPECT) suffered from a variety of drawbacks and limitations in terms of validation, accuracy, and support [1] and did not meet users’ requirements. Accurate and versatile general-purpose simulation codes such as Geant3 [2], EGS4 [3], MCNP [4], and Geant4 [5] were available. These codes were quite appealing as they included well-validated physics models, geometry modeling tools, and ef‰cient visualization utilities. However, modeling PET or SPECT acquisitions using these codes required a large effort. After discussions, the need to develop a simulation toolkit that would combine the best of both worlds became clear. The aim was to have a dedicated Monte Carlo platform for emission tomography including speci‰c features relevant in that context (modeling of decay kinetics, of detector dead time, of detector and patient movements), and to bene‰t from the versatility and support of general-purpose simulation tools. At that time, object-oriented technology appeared to be the best choice to ensure high modularity of the code. Therefore, the consensus was to select the simulation toolkit developed in C++ by the Geant4 Collaboration and to warrant long-term support by sharing the developments among many research groups.
