PTCOG Report 1 PTCOG Publications Sub-Committee Task Group on Shielding Design and Radiation Safety of Charged Particle Therapy Facilities PTCOG REPORT 1 (Final version, 15 th January 2010) PTCOG Publications Report 1 © 2010 PTCOG All rights reserved 1 2 3 4 5 6 7 8 9 10 11 SHIELDING DESIGN AND RADIATION SAFETY OF CHARGED PARTICLE 12 THERAPY FACILITIES 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 PTCOG Publications Sub-Committee Task Group: 29 N.E. Ipe (Leader), Consultant, Shielding Design, Dosimetry & Radiation Protection, 30 San Carlos, California, U.S.A. 31 G. Fehrenbacher, G.S.I. Darmstadt, Germany 32 I. Gudowska, Stockholm University, Sweden 33 H. Paganetti, Massachusetts General Hospital, Boston, Massachusetts, USA 34 J.M. Schippers, PSI, Villigen, Switzerland 35 S. Roesler, CERN, Geneva, Switzerland 36 Y. Uwamino, RIKEN, Saitama, Japan 37 38 Advisors 39 D. T. L. Jones, Proton Therapy Centre, Ružomberok, Slovak Republic 40 and Department of Human Biology, University Cape Town, South Africa 41 A. Mazal, Institut Curie, Paris, France 42 A. Smith, M.D. Anderson Cancer Center, Houston, Texas, U.S.A. 43 44 Consultants 45 S. Ban, Radiation Science Center, High Energy Accelerator Research Organization 46 (KEK), Japan 47 H. Yashima, Division of Nuclear Engineering Science, Research Reactor Institute, Kyoto 48 University, Japan i PTCOG Publications Report 1 © 2010 PTCOG All rights reserved 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 SHIELDING DESIGN AND RADIATION SAFETY OF CHARGED PARTICLE 70 THERAPY FACILITIES ii PTCOG Publications Report 1 © 2010 PTCOG All rights reserved 71 CONTENTS 72 73 ACKNOWLEDGEMENTS ..................................................................................................................... ix 74 PREFACE ...................................................................................................................................................x 75 1. Introduction ...........................................................................................................................................1 76 1.1 Brief Overview of Charged Particle Therapy Facilities .............................................................1 77 1.2 Overview of Particle Accelerator Shielding...............................................................................5 78 1.3 Dose Quantities and Conversion Coefficients.........................................................................14 79 1.3.1 Protection and Operational Dose Quantities .............................................................14 80 1.3.2 Conversion Coefficients ............................................................................................19 81 1.4 Shielding Design and Radiation Safety....................................................................................23 82 2. Radiological Aspects of Particle Therapy Facilities .........................................................................24 83 2.1 Charged Particle Interactions....................................................................................................24 84 2.1.1 Electromagnetic Interactions of Charged Particles ..................................................25 85 2.1.1.1 Interaction of Charged Particles with Atomic Electrons ............................25 86 2.1.1.2 Interaction of Charged Particles with Nucleus...........................................28 87 2.1.2 Nuclear Interactions...................................................................................................28 88 2.1.2.1 Nucleon-Nucleus Interactions ...................................................................28 89 2.1.2.2 Heavy Ion-Nucleus Interactions .................................................................30 90 2.1.3 Hadron Interactions ...................................................................................................34 91 2.1.3.1 Hadronic or Nuclear Cascade .....................................................................34 92 2.1.3.2 Proton Interactions.....................................................................................37 93 2.1.4 Electromagnetic Cascade...........................................................................................39 94 2.2 Secondary Radiation Environment...........................................................................................39 95 2.2.1 Neutron Energy Classifications .................................................................................40 96 2.2.2 Neutron Interactions ..................................................................................................41 97 2.2.3 Protons: Neutron Yield, Energy Spectra, and Angular Distributions........................43 98 2.2.4 Ions: Neutron Yields, Energy Spectra, and Angular Distribution............................53 99 2.3 Beam Losses and Sources of Radiation....................................................................................59 100 2.3.1 Cyclotrons..................................................................................................................59 101 2.3.1.1 Energy Selection System (ESS) .................................................................62 102 2.3.2 Synchrotrons..............................................................................................................64 103 2.3.3 Beam Transport Line.................................................................................................68 104 2.3.4 Treatment Rooms ......................................................................................................68 105 2.3.4.1 Fixed Beam Rooms ....................................................................................69 106 2.3.4.2 Gantry Rooms.............................................................................................71 107 2.3.5 Beam Shaping and Delivery......................................................................................71 108 2.4 New Technologies ....................................................................................................................72 109 2.4.1 Single-Room Systems................................................................................................72 110 2.4.2 FFAG.........................................................................................................................79 111 2.4.3 Laser Acceleration.....................................................................................................79 iii PTCOG Publications Report 1 © 2010 PTCOG All rights reserved 112 3. Shielding Design Considerations.........................................................................................................81 113 3.1 Regulatory Requirements .........................................................................................................81 114 3.1.1 Radiological Areas ...................................................................................................82 115 3.1.2 Dose Limits for Various Countries............................................................................86 116 3.2 Primary and Secondary Shielding Barriers ..............................................................................88 117 3.3 Use Factors ...............................................................................................................................88 118 3.4 Occupancy Factor .....................................................................................................................89 119 3.5 Workload ..................................................................................................................................90 120 3.5.1 Example for Workload Calculations and Usage Assumptions..................................92 121 3.5.2 Beam Parameters Used for Shielding Calculations...................................................95 122 3.6 Self-Shielding of Beam Line Components.............................................................................100 123 3.7 Calculational Methods............................................................................................................100 124 3.7.1 Analytical Methods..................................................................................................100 125 3.7.2 Monte Carlo Calculations........................................................................................104 126 3.7.3 Monte Carlo Computational Models ......................................................................105 127 3.7.3.1 Carbon Ions..............................................................................................106 128 3.7.3.2 Protons ......................................................................................................116 129 3.7.4 Other codes .............................................................................................................118 130 3.8 Shielding Materials and Transmission ...................................................................................118 131 3.8.1 Shielding Materials..................................................................................................118 132 3.8.1.1 Earth..........................................................................................................119 133 3.8.1.2 Concrete and Heavy Concretes.................................................................119 134 3.8.1.3 Steel ..........................................................................................................123 135 3.8.1.4 Polyethylene