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Study of a DD compact neutron generator for BNCT

Study of a DD compact neutron generator for BNCT. Elisabetta Durisi Lorenzo Visca. Collaborations. The research activity is performed in the mainframe of :

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Study of a DD compact neutron generator for BNCT

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  1. Study of a DD compact neutron generator for BNCT Elisabetta Durisi Lorenzo Visca durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  2. Collaborations The research activity is performed in the mainframe of: "Terapie oncologiche innovative basate sulla cattura di neutroni (NCT) con nuove tipologie di sorgenti di neutroni e di molecole-target a base di Boro e Gadolinio" supported by Azienda Ospedaliera San Giovanni Battista A.S. (dipartimento Oncologia) and included in the Oncology Program financed by Compagnia di San Paolo. • Lawrence Berkeley National Laboratory (Accelrator & Fusion division) • Experimental Physics Department, University of Turin • S. Giovanni Battista Hospital Torino, Italy – Molinette Hospital Torino, Italy • INFN section of Turin, Italy • ENEA (Frascati - Bologna) • EUROSEA, Turin • Nuclear Energy Department, Polytechnic of Milan • Chemistry Department, University of Turin durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  3. Within patient’s body fast neutrons epithermal neutrons slow neutrons Cell-killing 10B-Capture in Tumour Neutron sources Moderator Material Tissue (moderator) Neutron Sources • Epithermal neutron (0.4 eV - 10 keV) beams are availablefrom existing nuclear reactors. Charged-particle accelerators, compact neutron generators and hospital radiotherapy facilities for BNCT (PHONES, INFN project)arenow under development. • Epithermal neutrons lose energy in the patient body and become capturable slowneutrons while proceeding to the tumour. durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  4. DD compact neutron generator developed by LBNL - accelerator and fusion division • A 13.56 MHz radio frequency (RF) discharge is used to produce deuterium ions. • The ion beam is accelerated to energy of 120 kV. • The beam impinges on a titanium coated aluminum target where neutrons are generated through D-D fusion reaction: • D+D  3He + n (2.45 MeV) 45 cm High Voltage Shield Target Water Manifold Al2O3 High Voltage Insulator Target Cylinder gas in Secondary Electron Filter Electrode 60 cm Ion Source RF-Induction Antenna RF-Induction Antenna Vacuum Chamber RF-Antenna Guide Vacuum Pump durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  5. Water cooling (2 lines: 1- Low conductance water for target 2- standard water for void system, RF system, HV power supply system. HV power supply 120 kV – 300 mA HV relay Turbo pumping system Roughing pump (up to 2 10-3 mbar) Turbo pump (<10-10 mbar) Pressure gauge controllers RF power supply and matching network (freq. 13.56 MHz, max. transfer power 5000 W) Deuteriumgas flow system

  6. High voltage flange and target assembly Al3O2 insulator Vacuum pumping chamber Installation December 2004 The compact neutron generator has been installed in the former irradiation room of the synchrotron laboratory at the Physics Institute • TEST: • low neutron flux, • GOAL: • maximum neutron flux for BNCT application, • final moderator design. Minimum neutron yield(from agreement with LBNL) > 1011 s-1 durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  7. Gamma shielding REFLECTOR DELIMITER MODERATOR GOAL - Final moderator design: Beam Shaping Assembly (BSA) • Neutrons produced from DD fusion reaction (2.45 MeV) need to be moderated to lower energies for use in BNCT: • maintaining adequate beam flux, • minimizing undesired dose to the patient’s body and other non-tumour locations. The major components of BSA are: durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  8. Assessment of a “good” BSA and comparison between different configurations Evaluation of FIGURES OF MERIT IN-PHANTOM FIGURES OF MERIT: calculation of depth dose profiles in healthy and tumour tissue FREE BEAM PARAMETERS durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  9. Lithiated polyethylene= 5 cm Copper Plasma chamber + water cooling Air RF antenna: quartz outside, water inside AlF3 Al Teflon= 1 cm MgF2 Al2O3 AlF3 Target: Al, water cooling inside target and Fe outside Lead + Antimony Extraction grid + water pipes Bismuth x z y y BSA with MCNP: EXAMPLE Epithermal column: 19 cm MgF2 + 6.5 cm Al + 10 cm MgF2 + 5 Al + 5 air; beam exit window 20x20 cm2 Distance: center of the source-beam exit window = 80 cm durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  10. Free beam parameters Neutron yield 1011 n/s- 120 kV, 300 mA Neutron yield 5 1012 n/s-160 kV, 1 A Recommended values for brain tumour treatment IAEA-TECDOC-1223 durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  11. Neutron spectra (Neutron yield 1011 n/s) durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  12. In phantom figures of merit Biological dose = DW = wg Dg + wn (DH +DN) + wB DB • Gamma dose “Dg”, combination of the doses deriving from the beam and the photons induced by 1H(n,g)2H capture reaction with the hydrogen in tissue. • Hydrogen dose “DH” or fast neutron dose due to proton-recoil reactions at the higher neutron energies (> 1 keV) in the tissue. • Thermal neutron dose “DN”, due to the thermal neutron capture mainly by nitrogen nuclei 14N(n,p)14C. • Boron dose “DB” , due to neutron capture reaction with boron. durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  13. Values used in all the simulations These are the weighting factors commonly used for brain tumour durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  14. The Anthropomorphic phantom ADAM durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  15. BSA with MCNP: EXAMPLE ICRU reference phantom implemented in MCNP by ENEA – Bologna SPINE KIDNEYS PANCREAS SPLEEN STOMACH ARM BONES RIB CAGE SURFACE BLADDER x SKIN ON TRUNK Liver segmentation y Cross section of the Anthropomorphic phantom ADAM durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  16. 10B 15 ppm in skin 10B 10 ppm in healthy liver 10B 60 ppm in tumour liver Liver Skin Soft tissue durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

  17. In phantom figures of merit Neutron yield = 1011 n/s Dose limit healthy tissue: 10 Gy-eq; TT = 10/1.16E-3 = 143.65 h If the neutron yield is equal to 5 1012 n/s, ADDR = 5.8 E-2 TT = 2.87 h durisi@to.infn.it, visca@to.infn.it - April 18th, 2005

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