GATE Simulations of Preclinical andClinical Scans in Emission Tomography, Transmission Tomography and Radiation Therapy Using GATE Quick tour & Highlights ! GATE Training, INSTN-Saclay, March 2014 Albertine Dubois IMNC – CNRS Orsay, France [email protected] Simon Stute SHFJ – CEA Orsay, France [email protected] Sebastien Jan SHFJ – CEA Orsay, France [email protected] GATE structure Simulation platform for medical applications # CRYSTAL /gate/block/daughters/name crystal /gate/block/daughters/insert box User scripts /gate/crystal/placement/setTranslation 0 0 0 cm /gate/crystal/geometry/setXLength 3.0 cm /gate/crystal/geometry/setYLength 3.0 mm /gate/crystal/geometry/setZLength 3.8 mm Application classes /gate/crystal/setMaterial Air /gate/crystal/vis/setVisible 0 Framework Geant4 - PET - SPECT - CT - Optical - Radiotherapy GATE Geant4 2 Detector and system description • Standard Geant4 volumes • Movement & Time Management • Using every materials Siemens - ECAT EXACT HR+ From simple volumes TO a complete device… Elekta - Precise Philips - Allegro GE - Advance 3 Geometry & Phantom description Whole body - Morphologic description - Voxelized or analytical approach - Realistic material database - Organ motion description Organ motion Clinical Pre-clinical Radiation Therapy: • CT patient images • GATE converts HU values to the Geant4 material composition Brain imaging 4 Data output management List mode oriented ROOT (most general output) ; ASCII LMF (cylindricalPET system) Imaging applications Interfile projection (Optical or SPECT system) ECAT 7 (PET system) RAW sinogram (PET system) RAW projection (CT system) easy to add a dedicated output… Radiotherapy and dosimetry applications “Actors” + Filters based on G4 scorers and G4Filters 3D dose scorer (dose map – Analyze format) Simulation statistic Track killer ….. 5 GATE – Available features Imaging 6 Oncology: Simulation of whole body scan GATE Simulation Simulation set-up - Start acqui. : 264 MBq - 7 bed positions - 7’ per bed position + Tumor volume 22 ml Simulation result Since 2009: new navigator Speed-up factor of 10 to 20 7 Brain: Metabolism & Receptor imaging Protocol [18F]FluoroDOPA : real data against simulation Real scan (Frame 0 to 8) Patlak analysis - Exam LDOPA 3 Uptake Ratio 2,5 2 Cd D /occ Cd G /occ Put D /occ Put G /occ 1,5 1 0,5 0 0 50 100 150 Patlak time - min. GATE Simulation (Frame 0 to 8) Patlak analysis - Simulation LDOPA 3,00 Uptake Ratio 2,50 2,00 Cd D /occ Cd G /occ Put D /occ Put G /occ 1,50 1,00 0,50 0,00 0,00 20,00 40,00 60,00 80,00 100,00 120,00 140,00 Patlak time - min. 8 Molecular and pre-clinical imaging CT scan: attenuation Full numerical phantom [18F]FDG scan simulation - microPET FOCUS 220 system - Injected dose: 200 μCi - Start acquisition: 45 min. after injection - Acquisition time: 15’ GATE simulation Simulation result 9 Molecular and pre-clinical imaging 4D MOBY phantom CT scan simulation - PIXSCAN-XPAD3 developed in CPPM, Marseille - X ray beam 17 keV - Coupled with prototype PET scan - Cluster of 10 CPUs & CPU time : 24h GATE simulation Simulation result 10 Molecular and pre-clinical imaging New Feature : Optical Imaging Optical physics processes in GATE: - Absorption by the bulk - Scattering process (Rayleigh or Mie) - Process at boundary (transmission or reflection) A set of parameters is defined for each tissue type: - refractive index - absorption length - scattering length - anisotropy coefficient A set of parameters is defined for each surface type: - roughness - reflectivity - transmittance (when the medium refractive index is unknown) - specular and diffuse reflection coefficient 11 Molecular and pre-clinical imaging New Feature : Optical Imaging Fluorescence process using GATE Comparison Data/MC Fluorescent photon energy spectrum after a fluorophore was excited by a 400 nm wavelength light GATE accurately reproduces the well-known Rhodamine B and Fluorescein emission spectra 12 Molecular and pre-clinical imaging New Feature : Optical Imaging Simulation of a bioluminescence experiment • Mouse “water” model • An optical probe: wavelenght 560nm and located in the kidney • 2D projection of the optical photons • Displayed it on the anatomical CT image of the mouse 13 GATE – Available features Radiation Therapy 14 Radiotherapy ans Dosimetry • • • • Questions are related to dose distribution Radiotherapy: therapy with photon Hadrontherapy: therapy with hadron Other radiation simulations – Brachytherapy – Dose during X-Ray imaging – Research experiments (biology, physics) – … Simulated with GATE Beam(s) Target (CT) Output = dose distribution Radiotherapy ans Dosimetry Complete beam modelling with GATE: Beam and patient parts 16 Radiotherapy ans Dosimetry Performing Dicom-RT-plan simulation with Gate and comparison with a commercial TPS • Convert dicom plan into Gate simulation • Dose to water vs dose to medium calculation in Gate • Compare with Xio (Elekta) TPS 17 Radiotherapy ans Dosimetry TPS and GATE comparison – patient case1 Dose scoring difference due to gas in the rectum region 18 Radiotherapy ans Dosimetry Hadron-PET : Feasibility test with Gate Monitoring of the deposited dose using PET imaging for a 12C treatment Principle Fragmentation: 12C 15O 11C Simulation Set-Up • Phantom: CT scan • Tumor Head ø 2 cm - segmentation • 1 beam - 9.108 12C • Phantom: CT scan • Real lung tumor • 3 beams - 108 12C / beam Hounsfield number • PET scan simulation – 10 min post-irradiation acquisition – commercial scanner Hounsfield number 19 Radiotherapy ans Dosimetry deposited dose Inverse model 11C PET scan a.u. 12C Depth – pixel unit 12C deposited dose 11C PET scan 15O PET scan Hyper realistic simulation in term of statistic events: Radiation + PET acquisition…20000 hours……2 days with a cluster of 400 processors 20
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