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NPL’s activities dosimetry for proton and ion therapy

NPL’s activities dosimetry for proton and ion therapy. Hugo Palmans Radiation Dosimetry Team, National Physical Laboratory, Middlesex, UK hugo.palmans@npl.co.uk. Why proton dosimetry at NPL?. Only one low-energy centre in the UK for tumours of the eye (Clatterbridge Centre of Oncology: CCO)

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NPL’s activities dosimetry for proton and ion therapy

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  1. NPL’s activities dosimetry for proton and ion therapy Hugo Palmans Radiation Dosimetry Team, National Physical Laboratory, Middlesex, UK hugo.palmans@npl.co.uk

  2. Why proton dosimetry at NPL? • Only one low-energy centre in the UK for tumours of the eye (Clatterbridge Centre of Oncology: CCO) • Since then: fail bids for high-energy proton facilities from CCO, Oxford, Daresbury, etc and now BASROC and LIBRA + NRAG documents • In the mean time in USA (6+5), Japan (8), Germany (6), Italy (3), France (3), China (2) + new technologies (superconducting cyclotrons, dielectric wall accelerators, laser induced protons) • Recent proton dosimetry projects with the aim of getting it to the level of photon and electron beam dosimetry: SR project 2002-2003, 2 NMS projects 2004-2007, 1 NMS project 2007-2010, LIBRA (Laser induced proton and ion beams) 2008-2011, EMRP JRP7 WP3 2008-2010 • Microbolometry with the aim of extending the scope of the quantiy of absorbed dose: SR project 2008, PhD UoS/NPL 2008-2011

  3. Overview: 8 experiments or simulations, 1 slide each • Graphite calorimetry • Total absorption calorimetry • Water equivalence of graphite and other materials I: DD measurements • Water equivalence of graphite and other materials II: Faraday cup attenuation measurements • Alanine dosimetry • Ionization chamber dosimetry • Near future: Microbolometry • Distant future: Biosensors

  4. = D D c . T.kh Calorimetry: Graphite calorimetry for protons (Palmans et al 2004, Phys Med Biol 49:3737-49)

  5. Total absorption calorimetry (Palmans et al 2007 NPL report IR 4) • Proton beam energy determination using total absorption calorimetry requires knowledge of the escaping energy fraction • Simulations using PTRAN, MCNPX and Geant4

  6. Roos Plates Proton beam Proton beam Markus Markus Geant4 simulations: Roos Water equivalence of graphite I: PDD and TPR measurements

  7. Faraday cup Proton beam Monitor chamber Plates Guard To elec- trometer Faraday cup Plates • Factor 2 to 3 higher than expected from ICRU 63 tables: not as yet understood. • Hypothesis: wide angle secondary protons: Guard Water equivalence of graphite II: Faraday cup attenuation measurements

  8. 4.0 diode 3.5 alanine pellets response 1 3.0 response 2 2.5 response 3 0.70 dose per m.u. (Gy) 2.0 0.60 1.5 0.50 1.0 0.40 0.5 1.10 dose per m.u. (Gy) 1.00 0.30 0.0 0.90 ion chamber 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.20 alanine pellets 0.80 relative effectiveness depth (cm) Bradshaw et al. (1962) response 1 Ebert et al. (1965) 0.70 NPL1 (range scaled) response 2 0.10 Hansen and Olsen (1985) Onori et al. (1997) 0.60 response 3 Cuttone et al. (1999) Bartolotta et al. (1999) 0.50 0.00 Fattibene et al. (2002) 0.40 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.00 0.50 1.00 1.50 2.00 depth (cm) log(E ) eff Alanine dosimetry: CCO experiment I

  9. Plates Plates Plates Plates Markus Markus Markus Proton Proton Proton beam beam beam Alanine dosimetry: CCO experiment II OR

  10. Ion recombination (Palmans et al 2006, Phys Med Biol 51:903-17) Ion chamber perturbations (Palmans 2006, Phys Med Biol 51:3483-501 + ongoing work) 1.020 Geometry interrogation region Nylon66-Al Mobit et al. 2000 Med. Phys. 27:2780-2787 78 MeV protons Jäkel et al. 2000 Phys. Med. Biol. 45:599-607 3 GeV 12C 70.0 Proton beam (Gy) ExrT2 PMMA-Al 60.0 1.015 2 2 d /dE &PTW30001 E 50.0 2.5 4.5 w,Ch 3 40.0 A150-Al 4.0 IC18 per proton per cm 1.010 /D 1 &NE2581 2.0 30.0 3.5 3.0 20.0 w,NE2571 C-C 1.5 1.005 normalised dose (a.u.) air 2.5 relative dose 10.0 &PTW30002 D 2.0 D 1.0 5.0 0.0 1.5 reconstruction Difference pdd and Reference 0.0 1.000 1.0 Attix PTW-30006 0.5 Capintec PR06 Markus -5.0 0.5 Reconstructed Reconstructed 0.0 10.0 20.0 30.0 0.0 0.0 0.995 0.0 20.0 40.0 60.0 115.0 120.0 125.0 130.0 Depth (mm) depth (mm) depth (mm) 0 5 10 15 Chamber # Ionization chamber dosimetry

  11. Microbolometer Energy absorption Absorber Squid Superconductor Microbolometry • Absorbed dose to water OK for conventional photon and electron beams • Not sufficient for protons and carbon ions ->absorbed dose * biological quality factor • Need for physical quantity that is relevant for biological effect expressed by CCRI/BIPM • NPL SRER project in collaboration with quantum detection group • UoS/NPL PhD project

  12. Biosensor • A biochemical system with a relevant biological response to ionising radiation that can be determined physically in a reproducible (and preferably reversible) way. • Questions to explore: • Where is the need? • Level of complexity of response? • How good are biological effects understood? • Engineering of such a system?

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