Simulations in Medical Physics Y. TOUFIQUE*, R.CHERKAOUI EL MOURSLI*, M.KACI**, G.AMOROS**, *Université Mohammed V –Agdal, Faculté des Sciences de Rabat, Maroc ** Instituto de Física Corpuscular, Universitat de València/CSIC, Spain

Introduction TOUFIQUE Yassine workshop Valencia 2012

GATE is an advanced opensource software developed by the international OpenGATE collaboration and dedicated to numerical simulations in medical imaging and radiotherapy. It currently supports simulations of Emission Tomography (Positron Emission Tomography - PET and Single Photon Emission Computed Tomography - SPECT), Computed Tomography (CT) and Radiotherapy experiments. # W O R L D # /gate/world/geometry/setXLength 400. cm /gate/world/geometry/setYLength 400. cm /gate/world/geometry/setZLength 400. cm # E C A T E X A C T H R + P E T S C A N N E R /gate/world/daughters/name ecat /gate/world/daughters/insert cylinder /gate/ecat/setMaterial Air # R E P E A T P M T /gate/PMT/repeaters/insert cubicArray /gate/PMT/cubicArray/setRepeatNumberX 1 /gate/PMT/cubicArray/setRepeatNumberY 2 /gate/PMT/cubicArray/setRepeatNumberZ 2 GATE : Geant4 Application for Tomographic Emission OPET scannerSPECT CylindricalPET Ecat PET Radiotherapy TOUFIQUE Yassine workshop Valencia 2012

PET:(Positron tomographic emission )  now a well established diagnostic modality that is extensively used in oncology for tumour diagnosis.  is based on the detection, in coincidence, of two 511 keV photons emitted, at 180º from each other. TOUFIQUE Yassine workshop Valencia 2012

The NEMA NU Test Protocol NEMA scatter fraction phantom Line Source Polyethylene A sensitivity measurement phantom: (a) schematic diagram, (b) actual phantom viewed end-on. The NEMA NU protocol has been designed for the performance evaluation of whole-body PET measurements with scanners acquiring data in 3-D mode. This protocol includes a number of tests to check the different aspects of scanner performance, which comprises : - Spatial resolution - Scatter fraction, count losses, and random measurements - Sensitivity - Accuracy of corrections for count losses and random - Image quality, accuracy of attenuation, and scatter corrections The National Electrical Manufacturers Association TOUFIQUE Yassine workshop Valencia 2012

Description of the ECAT HR+ PET Scanner ParametersEcat exact HR+ Detector MaterialBGO Crystal Dimension (mm 3 )4,05x4,39x30 Detector Ring Diameter (cm)82,4 Transverse Field of View (cm)58,3 Axial Field of View (mm)155 Coincidence Time Windows (nsec)12 ECAT Exact HR+ PET scanner is a commercial Siemens scanner consisting in consists of 4 block rings of 72 detector blocks each. Each block is constructed of an 8×8 BGO crystal array. The dimensions of each crystal element are 4.05mm×4.39mm×30 mm. The detector ring diameter is 82.4 cm while the axial FOV is 155mm. PMTs Crystals TOUFIQUE Yassine workshop Valencia 2012

Parameters and digitizer for the simulation of ECAT HR+ PET Signal processor chain Geant4 Hits Pulses Readout/ block Energy resolution efficiency deadtime/ block Energy Window 511keV 88% 5000ns Paralysable 300/650keV Singles Gate Coincidences deadtime 500ns Paralysable Final Coincidences Parameters Lowenergy models for Compton and Rayleigh Energy cuts: delta-ray 10 keV, X-rays 10 keV, Electron range cut 2 mm Coincidence time window 12 nsec Energy window (in spectra) keV TOUFIQUE Yassine workshop Valencia 2012

Schematic representation of a LOR within a transaxial plane. True ScattedRandommultiple Line of Response and Detected events in PET Representation of a sinogramme 2D TOUFIQUE Yassine workshop Valencia 2012

Results of PET simulation TOUFIQUE Yassine workshop Valencia 2012

Results 1 TOUFIQUE Yassine workshop Valencia 2012

Results 2 TOUFIQUE Yassine workshop Valencia 2012

Results : Comparisons MEASUREDSIMULATED SCATTER FRACTION 46 %44 % MEASUREDSIMULATED SENSITIVITY T.O.P = 0 cm6650 cps/MBq6877 cps/MBq T.O.P = 10 cm7180 cps/MBq7235 cps/MBq Ratio (0 cm/10 cm) T.O.P : Transaxial Offset Position Energy window (keV) The SCATTER FRACTION is the ratio of scattered events to total events (at low counting rate). The SENSITIVITY of a scanner represents its ability to detect annihilation radiations. TOUFIQUE Yassine workshop Valencia 2012

Activity (MBq) Nb Jobs Success Time (h) Results: using GATE on the Grid We need to perform a simulation with 528 MBq source activity. We test GATE on the Grid. Execution time of simulations is limited by the Proxy duration : 48 h

brachytherapy the internal radiation treatment achieved by implanting radioactive material directly into the tumor or very close to it. Catheter Water Phantom Experience: TOUFIQUE Yassine workshop Valencia 2012

brachytherapy TOUFIQUE Yassine workshop Valencia 2012

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TOUFIQUE Yassine workshop Valencia 2012  Follow up the present study Conclusion