Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring a feasibility study E. Testa 1 , D. Dauvergne 1 , G. Dedes 1 , N. Freud 2 , P. Henriquet 1 , J. Krimmer 1 , J.M. L´ etang 2 , C. Ray 1 , M.-H. Richard 1 , 2 , F. Sauli 3 1 IPNL, France 2 CREATIS, France 3 TERA Foundation, Italy ICTR-PHE 2012 Geneva, Switzerland Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 1 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Outline 1. Ion range verification 2. Interaction Vertex Imaging principles 3. Simulation tools 4. Results Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 2 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Rationale Typical 12 C therapy treatment Ideal control • 3D real-time dose control Dose 1 GyE Current challenge 120 cm 3 Irradiated volume No. of energy slices 39 • 1D real-time ion-range control 7 × 10 8 Total • an energy-slice basis No. of C ions ∼ 2 × 10 7 AVG per energy slice • or on a pencil-beam basis ∼ 10 5 AVG per pencil beam M. Kraemer et al. 2000 Proton / carbon therapy • Beam intensities • Nuclear reactions Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 3 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Physical principles Measurement of β + activity (200 MeV/u 12 C in PMMA) Correlation between • ion range • nuclear reaction depth profile Simulation of prompt radiations Two kinds of radiations of 12 95MeV/u C, PMMA target, GEANT4.9.4 counts/ion/mm 0.03 γ relevance n p 0.025 α • β + activity nuclear reactions 0.02 • Prompt radiations ( γ , p) 0.015 0.01 0.005 0 0.5 1 1.5 2 2.5 3 Target depth [cm] Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 4 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives 5 modalities β + activity (PET) Prompt radiations • Clinical use • Collimated • off-beam (HIT, NIRS...) camera • in-beam (GSI) • Slit-hole camera • Compton • Current research camera • Radioactive beams • TOF • Interaction Vertex Imaging Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 5 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Principle and rationale Principle • Detection of secondary protons emitted from incident ions • Reconstruction of nuclear reaction positions (“vertex”) • Comparison of measured and simulated distributions of “reconstructed” vertices Rationale • ++ Intrinsic detection efficiency ∼ 1 • ++ “High” proton emission yield with 12 C ion: 10 − 1 Proton yield ∼ γ -ray yield ∼ incident 12 C • - - Attenuation and straggling in particular: low-energy protons emitted at the end of incident ion ranges Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 6 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives 2 imaging techniques Imaging techniques • “Single-proton” imaging (SP-IVI) Intersection of a secondary-proton trajectory with the incident-ion trajectory • “Double-proton” imaging (DP-IVI) Intersection of 2 secondary-proton trajectories Detectors • Tracker + beam hodoscope (in coincidence) Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 7 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Simulated setups Cylindrical target Tool 100 mm • Geant4 9.1 20° 12 C • Nuclear models QMD (Quantum Molecular Dynamics) Targets Head phantom Tracker 200 mm • Cylindrical 20° • Head phantom 12 C p Projectile-like fragment 2 trackers 250 mm • 10 × 10 cm 2 pixelized detectors 50 mm (CMOS) Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 8 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Reconstruction Basic reconstruction • Line intersection • Segment S : the smallest distance between trajectories • Vertex location: middle of S "Single-proton" imaging 12 Incident C (beam hodoscope) Future reconstruction Reconstructed vertex • Most Likely Path Segment S "Double-proton" imaging Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 9 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Simulation validations: nuclear reactions Experimental setup Results Experimental setup 210 mm Detection angle 12 C 128 mm Beam Target energy thickness (MeV) (mm) • Good overall agreement Our GSI 310 210 experiments GANIL 95 50 for E ≤ 200 MeV Gunzert-Marx et al. 200 128 Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 10 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Depth profile of generated vertices 100 mm PMMA target 12 200 MeV/u C • Secondaries Important contribution • Contrast Relatively low: 1.3 Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 11 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Depth profile of reconstructed vertices Cylindrical target 100 mm 20° 12 C • Imaging technique “Single proton” ⇒ higher statistics • Contrast Promising ( ∼ 5) Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 12 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Ion-range influence Vertex Yield vs ion-range • Strong dependence Fit function • y = a + b erf ( x − IPP ) • IPP : Inflection-Point Position Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 13 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Ion-range resolution Standard deviation of IPP 3.5 (mm) Counts Entries Entries 1000 1000 100 Mean Mean 54.73 54.73 3 RMS RMS 1.809 1.809 ± ± 0.04046 0.04046 IPP 2.5 50 Standard deviation of 2 0 1.5 45 50 55 60 65 Position IPP (mm) 1 • Homogeneous target 0.5 • Millimetric resolution 3 10 × 0 on a pencil-beam basis ( 10 5 ions) 0 200 400 600 800 1000 Number of incident ions (Beam energy: 200 MeV/u) Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 14 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Conclusion Feasibility study • Geant4 9.1 (validated against experimental data) • Elementary vertex reconstruction Main results • “Single-proton” imaging choice • Real-time ion range verification (on a pencil-beam basis) Henriquet et al. , submitted to PMB Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 15 / 16
Ion range verification Interaction Vertex Imaging principles Simulation tools Results Conclusion and perspectives Perspectives Detailed study of inhomogeneity influences • IVI sensitivity to inhomogeneities at the end of ion path (low probabilibity of proton escape) • Inhomogeneities in the “exit channel material” In-beam tests with CMOS detectors • Low and high energies • GANIL (95 MeV/u) • HIT (200-300 MeV/u) • Analysis in progress Interaction Vertex Imaging (IVI) for carbon ion therapy monitoring 16 / 16
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