GATE (Geant4 Application for Tomographic Emission): a PET/SPECT general-purpose simulation platform

G.Santin (ESA/ESTEC, Noordwijk, The Netherlands),

D.Strul, C.Morel (University of Lausanne, Lausanne, Switzerland),

D.Lazaro, V.Breton (LPC, IN2P3-CNRS, Clermont-Ferrand, France)

C. Morel (University of Lausanne, Switzerland)

(on behalf of the OpenGATE Collaboration)

ABSTRACT

Since many a couple of decades, accurate Monte Carlo (MC) simulations are widely used in parallel to analytical computations or experimental studies for a large range of positron emission tomography (PET) and single positron photon emission computed tomography (SPECT) applications such as scanner design, statistical image reconstruction, scatter correction, or protocol optimization.

GATE (Geant4 Application for Tomographic Emission), the simulation tool for emission tomography new PET/SPECT MC tool described here, combines the advantages of the general-purpose simulation codes (such as wide community of developers and users, code and physics validation, documentation and support) and those of dedicated software packages (such as the implementation of the most common Nuclear Medicine specific options specific to emission tomography). Actually, GATE takes advantage, in fact, of the physics models, geometry description, visualisation tools of the Geant4 simulation toolkit, and on top of that itfurthermore integrates a large set of specific components to facilitate its use in the PET/SPECT domain.

One distinctive and original feature of the GATE tool is the modelling of time-dependent processes: the description of movements or other changes with time in the geometry description is kept synchronized with the source time-dependent intensities activities and spatial distributions. Moreover, GATE includes a coherent management of parallel multiple sources (whose type can vary from radio-isotopes, with a modified version of the Geant4 Radioactive–Decay-Module, to standard Geant4 source description) with independent time-profiles and locations (see Fig.2).

Many options for the simulation output are provided, both for the detail description level (from the application summary to a complete event history report) and for the output format (ASCII, ROOT, or a dedicated binary format). A graphical histogram plotter allows the on-line visualization of all the recorded information.

A wide use of the GATE tool has been allowed by the creation of a dedicated scripting mechanism for geometry modelling, sources description, and output options:, i.e. all the geometry volumes and movements (rotations, translations, helical movements, etc.),as well as the source type and properties definition, or the output selection. This allows to the user to create interactively the interactive creation at run-time,without the need of specific coding, of very complicated geometries or sources via macro files or single commands typing (see Fig.1 and 2), without the need of specific coding.

The software consists of in several hundreds of C++ classes. A particular attention is paid to the Object Oriented Analysis and Design phases and is giving important results in terms of code comprehension, validation and support, and of extension of the tool functionalities.

All the features presented have allowed an impressive and continuous growth of the GATE developers and users communities, the OpenGATE Collaboration, that includes already academic and research institutes, medical imaging centres, hospital research departments, spread all around the world (see