DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE 1 ICRP ref 4831-9482-1403 2 17 June 2014 3 4 Annals of the ICRP 5 6 7 ICRP PUBLICATION 1XX 8 9 10 11 Radiological protection in cone beam 12 computed tomography (CBCT) 13 14 15 16 Editor-in-Chief 17 C.H. CLEMENT 18 19 Associate Editor 20 N. HAMADA 21 22 23 24 Authors on behalf of ICRP 25 M.M. Rehani, R. Gupta, S. Bartling, G. C. Sharp, R. Pauwels, 26 T. Berris, J. M. Boone 27 28 29 30 PUBLISHED FOR 31 The International Commission on Radiological Protection 32 by 33 34 [SAGE logo] 35 36 Please cite this issue as ‘ICRP, 201Y. Radiological Protection in Cone Beam 37 Computed Tomography (CBCT). ICRP Publication 1XX, Ann. ICRP 4X (0).’ 38 1 DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE 39 40 CONTENTS 41 42 EDITORIAL ................................................................................................................... 5 43 44 ABSTRACT .................................................................................................................... 6 45 46 PREFACE ....................................................................................................................... 7 47 48 MAIN POINTS ............................................................................................................... 9 49 50 GLOSSARY ................................................................................................................. 12 51 52 1. INTRODUCTION .................................................................................................... 15 53 1.1. History of development ...................................................................................... 16 54 1.2. Current standards in radiological protection in CBCT ...................................... 17 55 1.3. Responsibilities of different stakeholders .......................................................... 18 56 1.4. Why is it important to know CBCT doses? ....................................................... 18 57 1.5. Safety in perspective .......................................................................................... 19 58 1.6. Scope of the document ....................................................................................... 20 59 1.7. References .......................................................................................................... 20 60 61 2. CBCT TECHNOLOGY ............................................................................................ 22 62 2.1. Introduction ........................................................................................................ 22 63 2.2. Technological issues .......................................................................................... 22 64 2.2.2. Detector ....................................................................................................... 22 65 2.2.3. Gantry ......................................................................................................... 23 66 2.3. Clinical scenarios where CBCT is used ............................................................. 26 67 2.4. References .......................................................................................................... 27 68 69 3. THE BIOLOGICAL EFFECTS OF RADIATION .................................................. 29 70 3.1. Introduction ........................................................................................................ 29 71 3.2. Tissue reactions .................................................................................................. 29 72 3.3. Stochastic effects ............................................................................................... 31 73 3.4. Individual differences in radiosensitivity ........................................................... 31 74 3.5. References .......................................................................................................... 32 75 76 4. PRINCIPLES OF RADIOLOGICAL PROTECTION FOR PATIENTS AND WORKERS 77 ........................................................................................................................... 34 78 4.1. Justification ........................................................................................................ 34 79 4.2. Optimisation ....................................................................................................... 35 80 4.3. Requirements for imaging facilities ................................................................... 35 81 4.4. References .......................................................................................................... 36 82 83 5. ASSESSING PATIENT DOSES IN CBCT ............................................................. 37 84 5.1. Dosimetry in CBCT ........................................................................................... 37 85 5.2. Point of care scanning and physicians clinic based CBCT systems .................. 37 86 5.3. C-arm CBCT systems ........................................................................................ 38 2 DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE 87 5.4. A unified approach to CT dosimetry ................................................................. 38 88 5.5. Tracking and reporting of radiation dose ........................................................... 39 89 5.6. Epilogue ............................................................................................................. 39 90 5.7. References .......................................................................................................... 39 91 92 6. OPTIMISATION OF PATIENT AND WORKER DOSES IN CBCT .................... 40 93 6.1. Introduction ........................................................................................................ 40 94 6.2. Factors influencing dose to the patient .............................................................. 41 95 6.2.1. Equipment dependent factors ...................................................................... 41 96 6.2.2. Operator dependent factors ......................................................................... 45 97 6.2.3. Patient-specific factors ................................................................................ 50 98 6.2.4. Factors influencing dose to worker ............................................................. 52 99 6.3. Limitations of CBCT ......................................................................................... 54 100 6.3.1. Detector dynamic range and reduced contrast resolution ........................... 55 101 6.3.2. Scatter ......................................................................................................... 55 102 6.3.3. Temporal resolution .................................................................................... 55 103 6.3.4. Artefacts ...................................................................................................... 55 104 6.3.5. Hounsfield Unit consistency ....................................................................... 55 105 6.3.6. Geometric distortion ................................................................................... 56 106 6.4. Future developments .......................................................................................... 56 107 6.4.1. Novel scan trajectories ................................................................................ 56 108 6.4.2. Advanced methods for exposure control .................................................... 56 109 6.4.3. Novel reconstruction algorithms and compressed sensing ......................... 57 110 6.5. References .......................................................................................................... 58 111 112 7. RADIATION DOSE MANAGEMENT IN SPECIFIC APPLICATIONS OF CBCT61 113 7.1. Introduction ........................................................................................................ 61 114 7.2. CBCT in radiotherapy ........................................................................................ 62 115 7.2.1.Accounting for imaging dose in radiotherapy ............................................. 64 116 7.3. Neurointerventions ............................................................................................. 65 117 7.3.1. Dose to workers from CBCT in neuroradiology procedures ...................... 67 118 7.4. Vascular interventions ....................................................................................... 67 119 7.5. Non-vascular interventions ................................................................................ 69 120 7.5.1. Dose to worker in non-vascular interventions ............................................ 70 121 7.6. Orthopaedics/Surgery ........................................................................................ 71 122 7.7. Urology .............................................................................................................. 72 123 7.8. ENT and head diagnostics or surgery ................................................................ 72 124 7.9. Dental (oral and maxillofacial) .......................................................................... 73 125 7.10. Breast ............................................................................................................... 75 126 7.11. References ........................................................................................................ 77 127 128 8. TRAINING CONSIDERATIONS FOR CBCT ......................................................