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MED009: Carbon release study from BN

This study focuses on the production of intense 11C ion beams for carbon-based hadron therapy. It explores target developments, dose delivery localization, range uncertainties, and PET-imaging for dose verification. The study also examines the production of 11C ion beams and target materials such as boron nitride (BN).

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MED009: Carbon release study from BN

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  1. MED009: Carbon release studyfrom BN S. Stegemann July – October 2018

  2. Outline 11C based hadron therapy Production of intense 11C ionbeams Target developments MED009

  3. External beam radiation therapy Particle beam: Photon, proton, carbon

  4. More localized dose delivery Dose is spread out over healthy tissue as well B R A G G P E A K Depends on incident energy of protons X-ray Protoncarbon E. Sterpin. MEDICIS-Promed Summer school. CNAO, Pavia. (2017)

  5. Why11C based hadron therapy?

  6. Range uncertainties due to… Image conversion to stopping powers • Uncertainties • Image noise • Tissue assignment? (Fat, bone, muscle, skin…) • Tissue composition • Conversion of a known composition to stopping powers • Total uncertainty of a few % ! Map of stoppingpowers Hounsfield Units (photon attenuation) Breathing of the patient From Lomax Day 0 Day 35 Anatomical changes throughout the treatment fractions E. Sterpin. Treatment planning optimization and validation‘ MEDICIS-Promed Summer School, Pavia (2017)

  7. PET-imaging for dose verification 12C 12C 11C 1 1 Dose Dose 20 Fluence [particle/cm2] as % of primary keV T1/2 = 20.4 min 0 z [cm] Dose [Gy] Dose [Gy] Fluence [particle/cm2] as % of primary Depth in H2O 10-4 10-4 11C -20 107 107 20 β+activity β+activity Events Events 0 z [cm] 103 103 0 0 x [cm] 40 x [cm] 40 Depth in H2O -20 FLUKA simulation of dose and β+ activity distributions with a 12C and 11C primary beam, courtesy of R. Augusto (*) R.S. Augusto et al., NIM B 376 (2016) 374-378 11C beam combines therapy with on-line PET-imagingOn-line dose verification, treatment validation

  8. Production of intense 11C ion beams

  9. 11C based hadron therapy facility (MEDICIS-Promed) ISOL methodIsotope Separation On-Line 11CO1+ Beam cooler p Electron Beam Ion Source 11C4/6+ Injection into Medical Accelerator

  10. Target developments

  11. Target material Boron nitride (BN) 11B(p,n)11C 14N(p,α)11C Calculated in-target production yield 11B(p,n)11C 14N(p,α)11C

  12. Isotope release Diffusion: (Arrhenius eq.) D: Diffusion coefficient μ : Diffusion time λ : Decay constant G:Grain size Control microstructure to enhance release properties Proton +/- 8V 500 A Pulsed Protons 1. Production (Nuclear Reactions) +/- 9 V Ion Source 1000 A 2. Diffusion 3. Effusion 4. Ionization J.-P. Ramos. EMIS Xlll, CERN, Geneva, 2018.

  13. Target processing • 100 °C/min heating rate • 1700 °C final sintering-temperature • Sintering-pressure 25 MPa at1700 °C for 5 min • ρbulk= 1.3(1) g cm-3 • Φtot = 0.40(1) total porosity • Φopen= 0.21(2) open porosity Spark Plasma Sintering • High pulsed DC currents into powder compact • High heating/cooling rates • Minimizes grain growth at low T • Maintaining of micro,- (nano-) structures

  14. Heat management Equilibrium calculation P = 10-6mbar YProd= I·Nt·

  15. High-temperaturemeasurements Modest dissociation kinetics, even at 1500 °C CO2(HBO?) • 2BN = 2B + N2(g) • Low dissociation rate! • BN can ce applied with 1500 °C! N2 N

  16. Increasing [C]  Increasing O2 uptake • But: No conclusive information from MS data • C enhances O2 uptake, but CO could not be measured

  17. MED009

  18. MED009 Sc. Detector • Produce 11C at MEDICIS • Retrieve active target material • Measure 11C activity • Fast & short heat treatment • Measure remaining 11C activity BN target T1/2(11C) = 20.4 min  minimize timing! Sc. Detector Release efficiencystudy

  19. Furnace @ 1500 ֯C Detector Tube containing active target O2 leak

  20. Data analysis progressing Preliminary

  21. Acknowledgements Thierry Stora Joao-Pedro Ramos JochenBallof ErmannoBarbero Bernard Crepieux Nhat-Tan Vuong MEDICIS Team ISOLDE Team Joao Guilherme Martins Correia Juliana Schell Thomas Cocolios OleksiiPoleshchuk

  22. Thank you. Questions, comments? This research project has been supported by a Marie Skłodowska-Curie Innovative Training Network Fellowship of the European Commission’s Horizon 2020 Programme under contract number 642889 MEDICIS-PROMED.

  23. Backup

  24. Sintering atom flux [J-1s-1]D: diffusion coefficient [m2s-1]C: concentration [m-3] densification rate (e.g. lattice diffusion) grain growth rate Densification&Grain growth P: Porosity G : Grain size Limit grain growth, since Note the time dependence! • Mechanism: Diffusion • Sintering:

  25. G : grain size r : pore size Sintered BN powder pellet

  26. Combining therapy with on-line PET-imaging 11C beam for treatment

  27. γ p E. Sterpin. MEDICIS-Promed Summer school. CNAO, Pavia. (2017)

  28. Ionization • Essential process for the beam purification with magnets • Surface ion source • Laser ion source • Plasma ion source • Electron Cyclotron Resonance (ECR) ion source • Short ionization time • No hot metal surfaces (retention)

  29. Treatment plan assumes that images acquired are a faithful representation of the anatomy during the entire course of treatment • Not true: • Patient not positioned all the time the same way • Breathing motion not stable • Position of targets and the organs at risk may change one relative to another (organ filling) • Morphology of the patient may change (weight loss, tumor shrinkage)

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