Preconception and prenatal radiation exposure : health effects and protective guidance : recommendations of the National Council on Radiation Pretection and Measurements, May 24, 2013

Cover 1 Preface 4 Contents 8 1. Executive Summary 16 1.1 Background and Purpose 16 1.2 Ionizing Radiation Exposures of Reproductive Relevance 16 1.3 Preconception Ionizing Radiation Risks 16 1.4 Pregnancy Risks from Ionizing Radiation 17 1.5 Ionizing Radiation Risk to the Nursing Infant 19 1.6 Mitigation of Ionizing Radiation Risk for Pregnant or Potentially-Pregnant Women 22 1.7 Risks to the Embryo or Fetus During Magnetic-Resonance Imaging 23 1.8 Risks to the Embryo or Fetus from Other Radiofrequency Sources 24 1.9 Risks to the Embryo or Fetus from Ultrasound Imaging 25 1.10 Communicating Benefits and Risks 26 2. Introduction 28 2.1 Background and Purpose 28 2.2 Scope of this Report 30 2.3 Gestational Age Conventions 30 3. Ionizing Radiation Exposures of Reproductive Relevance 32 3.1 Quantities, Units, and Related Concepts in this Report 32 3.2 Primary Sources of Ionizing Radiation Exposure to Pregnant Women 35 3.2.1 Medical Care 35 3.2.2 Occupational Exposure 37 3.2.3 Ubiquitous Background Exposure 43 3.3 Principles of Ionizing Radiation Protection 44 3.4 Dose-Response Relationships for Stochastic Effects 46 4. Preconception Ionizing Radiation Risks 48 4.1 Importance of Preconception Exposures 48 4.2 Biology of Human Gametogenesis 49 4.3 Detecting Radiation Damage in Sperm and Eggs 50 4.4 Detecting Human Germ-Cell Mutagenesis in Offspring: Theory 54 4.5 Human Germ-Cell Mutagenesis: Practice 55 4.5.1 Endpoints for Studies of Mutagenesis 58 4.5.2 Relative Biological Effectiveness 63 4.6 Heritable Disease in Exposed Populations 63 4.6.1 Residential Exposures from High or Enhanced Background Radiation 65 4.6.2 Japanese Atomic-Bomb Survivors 66 4.6.3 Exposed Occupational Groups 66 4.6.4 Mutations in Minisatellite Deoxyribonucleic Acid Sequences 68 4.6.5 Medical Groups 69 4.6.6 Summary of Heritable Disease in Exposed Populations 72 5. Pregnancy Risks from Ionizing Radiation 73 5.1 General Principles 73 5.1.1 Background Pregnancy Risks 73 5.1.2 Embryonic and Fetal Developmental Stages and the Deleterious Dose 73 5.1.3 Types of Effects 80 5.1.4 Protraction and Fractionation 81 5.1.5 The All-or-None Phenomenon 85 5.1.6 Lack of Indirect Effect on a Shielded Embryo During Maternal Irradiation 90 5.1.7 Evaluation of the Evidence for Radiation-Induced Effects 94 5.1.8 Relative Biological Effectiveness 97 5.2 Risks and Outcomes 98 5.2.1 Mental Retardation and Other Neurological Effects 98 5.2.2 Congenital Malformations (birth defects) 111 5.2.3 Growth Retardation 118 5.2.4 Embryonic and Fetal Death (miscarriage and stillbirth in humans) 122 5.2.5 Adult Diseases 124 5.2.6 Oncogenic Effects of In Utero Irradiation 127 5.3 Guidance for Diagnostic and Fluoroscopically-Guided Interventional Procedures 165 6. Radiation Risk to the Nursing Infant 166 6.1 Radiopharmaceuticals Administered to the Mother 166 6.2 Brachytherapy 169 6.3 Environmental Exposure to Radioiodine 171 7. Mitigation of Ionizing Radiation Risk for Pregnant or Potentially-Pregnant Women 172 7.1 Pregnancy Testing and Documentation 172 7.1.1 Introduction 172 7.1.2 Assessment of Pregnancy 173 7.1.3 Methods for Pregnancy Assessment 175 7.1.4 Documentation of Pregnancy and Pregnancy Policy Considerations 178 7.1.5 Summary of Pregnancy Assessment 179 7.2 Managing Dose and Mitigating Exposure 180 7.2.1 Medical Diagnostic Imaging 180 7.2.2 Radiation Therapy 190 7.2.3 Occupational Exposure 195 7.2.4 Accidental or Deliberate Exposure 197 8. Nonionizing Modalities and Sources 201 8.1 Risks to the Embryo or Fetus During Magnetic-Resonance Imaging 201 8.1.1 Introduction 201 8.1.2 Effect of Radiofrequency Electromagnetic Fields 202 8.1.3 Effect of Time-Varying Magnetic Field Gradients 206 8.1.4 Effect of Static Magnetic Fields 207 8.1.5 Clinical Guidelines for Magnetic-Resonance Imaging in Pregnant Patients 209 8.1.6 Use of Contrast Agents 211 8.2 Risks to the Embryo or Fetus from Other Radiofrequency Sources 211 8.2.1 Introduction 211 8.2.2 Limits for Human Exposure to Radiofrequency Sources (300 kHz to 300 GHz) 212 8.2.3 Electromagnetic Field Interactions 213 8.2.4 Current Safety Standards 214 8.2.5 Nonthermal Effects 215 8.2.6 Thermal Effects 217 8.3 Risks to the Embryo or Fetus from Ultrasound Imaging 218 8.3.1 Introduction 218 8.3.2 Nature of Ultrasound 219 8.3.3 Epidemiology 228 8.3.4 Areas of Special Concern 234 8.3.5 Safety Guidelines 237 9. Communicating Benefits and Risks 238 9.1 State of Knowledge and Practice of Medical Professionals 238 9.2 Professional Counseling 239 9.3 Information Resources for Professionals 241 9.4 State of Public Knowledge 242 9.5 Information Resources for Members of the Public 243 10. Conclusions and Recommendations 245 10.1 Conclusions 245 10.2 Recommendations 249 Appendix A. Radiation Exposure Consultations 252 A.1 Introduction 252 A.2 Ionizing Radiation 252 A.3 Nonionizing Modalities and Sources 254 A.4 Examples of Consultations 254 A.4.1 Diagnostic X-Ray Studies When the Abdomen and Pelvis are Not Exposed 254 A.4.2 Diagnostic X-Ray Studies that Directly Expose the Abdomen and Pelvis 255 A.4.3 Diagnostic Nuclear Medicine Studies 256 A.4.4 Ionizing Radiation Therapy with Radionuclides that Exposes the Abdomen and Pelvis 256 A.4.5 External High-Dose Radiation Therapy During Pregnancy 256 A.4.6 Family Members or Friends Receiving External-Beam Radiation Therapy 257 A.4.7 Family Members or Friends Administered Radioactive Material for Diagnosis or Therapy 257 A.4.8 Exposure to the Sperm from Diagnostic X-Ray Studies 259 A.4.9 Exposure to the Sperm from Radiation Therapy 260 A.4.10 Exposure from Communication Microwave Sources 260 Appendix B. Radiation Exposure Questions and Answers 261 B.1 Single Questions and Answers 261 B.2 A More Complex Consultation 266 Appendix C. Example Forms 271 C.1 Pre-examination Pregnancy Determination 271 C.2 Informed Consent for X-Ray Examinations of Pregnant or Potentially-Pregnant Patient 272 Abbreviations, Acronyms and Symbols 273 Glossary 274 References 291 Scientific Committee 358 The NCRP 365 Officers 365 Members 366 Distinguished Emeritus Members 366 Lauriston S. Taylor Lecturers 367 NCRP Publications 375 Reports 375 Commentaries 381 Proceedings of the Annual Meeting 382 Lauriston S. Taylor Lectures 384 Symposium Proceedings 385 Statements 386 Other Documents 386