Modellizzazione DICOM in Geant4 Stéphane Chauvie Santa Croce e Carle Hospital, Cuneo Gruppo italiano MC-INFN

DICOM example in Geant4 Developed in 2002 –L. Archambault, L. Beaulieu, V.-H. Tremblay (Univ. Laval and l'Hôtel-Dieu, Québec) Donated to Geant4 for the common profit of the scientific community –under the condition that further improvements and developments are made publicly available to the community Released with Geant4 5.2, June 2003 in an extended example –with some software improvement by S. Guatelli and M.G. Pia Navigation functionalities –Pedro Arce (CIEMAT, Madrid) Update and maintained –Pedro Arce (CIEMAT, Madrid) –Stéphane Chauvie (Santa Croce e Carle Hospital & INFN, Cuneo & Torino) /examples/extended/medical/DICOM

extended example: Navigation Is the only example in GEANT4 to offer 4 different navigation functionalities: –The 1D optimisation It will be very slow because each time a track exits a voxel it has to loop to all other voxels to know which one it may enter –The 3D optimisation with G4SmartVoxel a 3D grid is built, so that the location of voxels is fast, but it requires a lot of memory –Using G4NestedParameterisation The search is done hierarchically in X, Y and Z. It is fast and does not require big memory –Using G4PhantomParameterisation/G4RegularNavigation A special algorithm to navigate in regular voxelised geometries (see GEANT4 doc). This is the fastest way without any extra memory requirement (and it is the default in this example). It includes an option (default) to skip frontiers between voxels when they have the same material.

Reading image information Transformation of pixel data into densities Association of densities to a list of corresponding materials Defining the voxels –Geant4 parameterised volumes –parameterisation function: material reverse engineering by S. Guatelli extended example: DICOM interface

Interfaccia DICOM Osso: - linearità CT- el - diluizione osso-midollo Polmone: linearità CT- Tessuti molli: - relazione CT-tessuto ICRU HU to material

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F luka Phys. Med. Biol. 52 (2007) 3369–3387 Clinical CT-based calculations of dose and positron emitter distributions in proton therapy using the FLUKA Monte Carlo code K Parodi1,3, A Ferrari2, F Sommerer2 and H Paganetti1 writegolem.f NB: No reading CT of variable thickness 27 HU intervals and materials (Schneider) defined trough elemental composition and nominal mean density (density corresponding to the HU value at the centre of the considered interval) a materiali same compostion but different nominal density UH>1600 come Schneider HU>3600 metallic implants CORRFACT to account for nuclear and electromagnetic interaactions (ratio of stopping power) Journal of Physics: Conference Series 74 (2007) A MC tool for CT-based calculations of dose delivery and β +-activation in proton therapy K Parodi1,3, A Ferrari2, F Sommerer2 and H Paganetti1