NPL’s activities dosimetry for proton and ion therapy Hugo Palmans Radiation Dosimetry Team, National Physical Laboratory, Middlesex, UK

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 , 2 NMS projects , 1 NMS project , LIBRA (Laser induced proton and ion beams) , EMRP JRP7 WP Microbolometry with the aim of extending the scope of the quantiy of absorbed dose: SR project 2008, PhD UoS/NPL

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

Calorimetry: Graphite calorimetry for protons ( Palmans et al 2004, Phys Med Biol 49: ) T.k h cD . 

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

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

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

Alanine dosimetry: CCO experiment I depth (cm) dose per m.u. (Gy) diode alanine pellets response 1 response 2 response depth (cm) dose per m.u. (Gy) ion chamber alanine pellets response 1 response 2 response log(E eff ) relative effectiveness Bradshaw et al. (1962) Ebert et al. (1965) Hansen and Olsen (1985) Onori et al. (1997) Cuttone et al. (1999) Bartolotta et al. (1999) Fattibene et al. (2002) NPL1 (range scaled)

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

Ionization chamber dosimetry Ion recombination (Palmans et al 2006, Phys Med Biol 51:903-17) Ion chamber perturbations (Palmans 2006, Phys Med Biol 51: ongoing work) Geometry interrogation region Proton beam E d  /dE Depth (mm) D air per proton per cm 2 (Gy) Difference pdd and reconstruction Mobit et al Med. Phys. 27: MeV protons Jäkel et al Phys. Med. Biol. 45: GeV 12 C depth (mm) normalised dose (a.u.) Attix Capintec PR06 Reconstructed depth (mm) relative dose Reference PTW Markus Reconstructed Chamber # D w,NE2571 /D w,Ch C-C &PTW30002 A150-Al &NE2581 PMMA-Al &PTW30001 Nylon66-Al IC18 ExrT2

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 Microbolometer Energy absorption Absorber SquidSuperconductor NPL SRER project in collaboration with quantum detection group UoS/NPL PhD project

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?