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GEANT4 Target Simulations for Low Energy P roton Accelerators

GEANT4 Target Simulations for Low Energy P roton Accelerators. By Naomi Ratcliffe Supervisor Prof Bob Cywinski. C ontents. Project 1 BNCT Target Simulations for Neutron Production Introduction Simulation Results Conclusion Project 2 Medical Isotope Production Introduction

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GEANT4 Target Simulations for Low Energy P roton Accelerators

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  1. GEANT4 Target Simulations for Low Energy Proton Accelerators By Naomi Ratcliffe Supervisor Prof Bob Cywinski

  2. Contents • Project 1 BNCT Target Simulations for Neutron Production • Introduction • Simulation • Results • Conclusion • Project 2 Medical Isotope Production • Introduction • Simulation • Results • Further work

  3. BNCT (Boron Neutron Capture Therapy) • BNCT is a developing, two stage form of radiation cancer therapy for head and neck glioblastoma • First stage: patient is injected with a boron enhanced drug which is readily taken up by tumour tissue • Second stage: the patient undergoes full head and neck neutron radiation therapy • The neutrons are absorbed by the boron to produce alpha, a harmful but short range radiation

  4. Neutron Production • Previous BNCT trials have used neutrons produced from nuclear reactors • Not the most practical method for a larger scale to make this an available treatment • Leading to developing accelerator based methods that appear to be safer and more practical Beryllium nucleus Lithium nucleus proton neutron Other light particles e.g. e-γ

  5. GEANT4 Simulations • Simulation of neutron production targets • Initial benchmarking of Li and Be targets • Simple disc target geometries for benchmarking of neutron production for given reaction • Studies carried out using different models to find the best physics to apply to the situation

  6. Using version GEANT4.9.4.p01 with physics model QGSP_BERT_HP Different shape shown between experimental and simulated results Different values obtained by simulation and experimental results Results - Li

  7. Using version GEANT4.9.5.p01 with physics model QGSP_BERT_HP with process.mac Similar shape shown between experimental and simulated results Similar values obtained by simulation and experimental results Results - Be

  8. Conclusions – Part 1 • Significant difference in trend and value of Li results even with best model • Some agreement can be found with the Be target with some modifications • To improve results new data driven models of proton interactions are being developed

  9. Medical Isotopes • Many medical isotopes are currently produced by research reactors • There are several disadvantages to this method of production, the main focus being on: • Reliability • Safety • Logistics • Main isotope used is Tc-99m which comes from the reactor as Mo-99 its generator form

  10. Accelerator based production methods are being developed using both proton and electron beams • e.g in Canada the government commissioned two main labs to come up with a working accelerator based method of production • Canadian Light Source – working on photo-neutron based production • TRIUMF – have succeeded in working through the whole cycle from target production, proton based isotope production, suitable drug production and target recycling

  11. Exploring the potential of a low energy proton accelerator for medical isotope production • Several different reaction chains can be utilised from either proton or neutron incident beam. Direct production Generator production 100Mo(p,2n)99mTc 100Mo(p,pn)99Mo 98Mo(p,γ)99mTc 98Mo(n,γ)99Mo • Neutron beam can be created from the same target reactions as for BNCT

  12. Using version GEANT4.9.5.p01 with physics model QGSP_BERT_HP Slight variations on the same simulation using the full stacked target geometry, one simple disc section of the geometry, two extremes of the Moly deposit thickness Simulation results follow similar trends to each of the experimental results in different energy ranges Results 100Mo(p,pn)99Mo

  13. Conclusions– Part 2 • Initial benchmarking shows reasonable correlation between simulation and experimental results • Other reactions to be looked at to increase confidence in the standard of the results • With few modifications the same simulation can be used to look into other suitable isotopes

  14. Further Work • Looking at the other Mo reactions for direct and generator production • Looing at other possible useful isotopes to replace/supplement 99mTc • Obtaining a working model for low energy protons • Or using direct neutron production to study geometry effects and other reactions

  15. Acknowledgements • Prof Bob Cywinski • Prof Roger Barlow • Dr C Bungau • Dr A Bungau

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