Controversies in Medical Physics: a Compendium of Point/Counterpoint Debates Volume 2 Edited by: Colin G. Orton and William R. Hendee American Association of Physicists in Medicine One Physics Ellipse College Park, Maryland, 20740 Published by: American Association of Physicists in Medicine One Physics Ellipse College Park, MD 20740. Phone: (301) 209 3350 Fax: (301) 209 0862 ISBN: 978-1-936366-22-4 © Copyright by the American Association of Physicists in Medicine. All rights reserved. No part of this book may be used or reproduced in any manner whatsoever without written permission from the publisher, except for brief quotations embodied in critical articles or reviews. December, 2012 2 TABLE OF CONTENTS List of contributors 6 Preface 9 CHAPTER 1: General Radiation Therapy 10 1.1. Tumor hypoxia is an important mechanism of radioresistance in hypofractionated radiotherapy and must be considered in the treatment planning process 10 1.2. Pulsed reduced dose rate radiation therapy is likely to become the treatment modality of choice for recurrent cancers 15 1.3. Hypofractionation is a proven safe and effective modality for postoperative whole-breast radiotherapy for early breast cancer patients 20 1.4. The linear-quadratic model is inappropriate to model high dose per fraction effects in radiosurgery 25 1.5. PDT is better than alternative therapies such as brachytherapy, electron beams, or low-energy x rays for the treatment of skin cancers 30 1.6. High intensity focused ultrasound may be superior to radiation therapy for the treatment of early stage prostate cancer 35 1.7. QA procedures in radiation therapy are outdated and negatively impact the reduction of errors 40 1.8. Vendor provided machine data should never be used as a substitute for fully commissioning a linear accelerator 44 1.9. The traditional L-shaped gantry for radiotherapy linear accelerators will soon become obsolete 49 CHAPTER 2:Highly Conformal Radiotherapy: IMRT, Tomotherapy, Stereotactic Radiosurgery, Proton Therapy 53 2.1. Helical tomotherapy will ultimately replace linear accelerator based IMRT as the best way to deliver conformal radiotherapy 53 2.2. It is STILL necessary to validate each individual IMRT treatment plan with dosimetric measurements before delivery 58 2.3. EPID dosimetry must soon become an essential component of IMRT quality assurance 62 2.4. Radiochromic film is superior to ion chamber arrays for IMRT quality assurance 66 2.5. Co-60 tomotherapy is the treatment modality of choice for developing countries in transition toward IMRT 71 2.6. Only a single implanted marker is needed for tracking lung cancers for IGRT 75 2.7. It is not appropriate to “deform” dose along with deformable image registration in adaptive radiotherapy 80 2.8. To ensure that target volumes are not underirradiated when respiratory motion may affect the dose distribution, 4D dose calculations should be performed 84 2.9. Within the next 10–15 years protons will likely replace photons as the most common type of radiation for curative radiotherapy 88 2.10. We do not need randomized clinical trials to demonstrate the superiority of proton therapy 93 2.11. The adoption of new technology in radiation oncology should rely on evidence-based medicine 97 CHAPTER 3: Brachytherapy 102 3.1. Miniature x-ray tubes will ultimately displace Ir-192 as the radiation sources of choice for high dose rate brachytherapy 102 3 3.2. Intensity modulated electronic brachytherapy will soon become the brachytherapy treatment of choice for irregularly shaped tumor cavities or those closely bounded by critical structures 107 CHAPTER 4: Imaging: mammography, CT, PET, molecular imaging, MRI 111 4.1. Cone beam x-ray CT will be superior to digital x-ray tomosynthesis in imaging the breast and delineating cancer 111 4.2. Molecular breast imaging will soon replace x-ray mammography as the imaging modality of choice for women at high risk with dense breasts 116 4.3. Ultrasonography is soon likely to become a viable alternative to x-ray mammography for breast cancer screening 121 4.4. Recent data show that mammographic screening of asymptomatic women is effective and essential 126 4.5. Computer-aided detection should be used routinely to assist screening mammogram interpretation 132 4.6. Office-based cone-beam and digital tomosynthesis systems using flat-panel technology should not be referred to as CT units 137 4.7. PET/CT will become standard practice for radiotherapy simulation and planning 142 4.8. PET-based GTV definition is the future of radiotherapy treatment planning 146 4.9. Genomics, functional and molecular imaging will pave the road to individualized radiation therapy 151 4.10. The physics components of the ACR MRI Accreditation Program are overly tedious and beyond what is needed to ensure good patient care 156 CHAPTER 5: Ionizing Radiation Protection, Standards and Regulations 160 5.1. Exposure limits for emergency responders should be the same as the prevailing limits for occupational radiation workers 160 5.2. The use of bismuth breast shields for CT should be discouraged 164 5.3. Radiation therapists should not have to wear personnel dosimetry badges 169 5.4. The use of effective dose for medical procedures is inappropriate 173 5.5. Backscatter x-ray machines at airports are safe 178 CHAPTER 6: Education 183 6.1. A professional doctoral degree that does not require dissertation research is an appropriate alternative to a Ph.D. as preparation for a career in medical physics 183 6.2. All graduate medical physics programs should have an original research component 187 6.3. Most residency programs for radiation oncology physicists do not reflect the heightened importance of medical imaging 191 6.4. Medical Physics residency programs in nonacademic facilities should affiliate themselves with a university-based program 195 CHAPTER 7: Professional Issues 199 7.1. Bright young physicists should be advised to avoid careers in radiation therapy 199 7.2. The 2014 initiative is not only unnecessary but it constitutes a threat to the future of medical physics 203 4 7.3. The 2014 initiative can have potentially unintended negative consequences for medical physics in diagnostic imaging and nuclear medicine 207 7.4. The shortage of radiation oncology physicists is addressable through remote treatment planning combined with periodic visits by consultant physicists 211 7.5. The terminal M.S. degree is no longer appropriate for students interested in a career in clinical medical physics in the United States 215 7.6. Medical physics graduate programs should adjust enrollment to achieve equilibrium between graduates and residents 219 7.7. Authorization to practice as a medical physicist is sometimes better achieved by registration rather than licensure 223 7.8. Medical physicists should be allowed by States to image and treat, just like radiologic technologists 227 7.9. Radiotherapy physicists have become glorified technicians rather than clinical scientists 231 7.10. The Chief Information Technology Officer in a Radiation Oncology department should be a medical physicist 235 7.11. Radiation departments should be certified to provide certain new technologies such as IGRT 239 7.12. The title “radiation oncology physicist” should be changed to “oncologic physicist” 243 7.13. The professions of Medical Physics and Clinical Engineering should be combined into a single profession “Clinical Science and Technology” 247 7.14. Physicists who are responsible for high-tech radiotherapy procedures should have to be specially credentialed 252 7.15. The h index is the best measure of a scientist’s research productivity 257 CHAPTER 8: General Topics 261 8.1. Despite widespread use there is no convincing evidence that static magnets are effective for the relief of pain 261 8.2. There is currently enough evidence and technology available to warrant taking immediate steps to reduce exposure of consumers to cell-phone-related electromagnetic radiation 265 8.3. Preparation for a terrorism-related radiation event should be no different from that for a biological or chemical event 269 8.4. Medical Physics should adopt double-blind peer review of all manuscripts 274 5 CONTRIBUTORS Salahuddin Ahmad, Ph.D.: University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma Howard Ira Amols, Ph.D.: Memorial Sloan-Kettering Cancer Center, New York, New York Clive Baldock, Ph.D.: University of Sydney, Sydney, New South Wales 2006, Australia Stephen Balter, Ph.D.: Columbia University Medical Center, New York, New York John E. Bayouth, Ph.D.: University of Iowa, Iowa City, Iowa Stanley H. Benedict, Ph.D.: University of Virginia Health System, Charlottesville, Virginia Tewfik Bichay, Ph.D.: Saint Mary's Health Care, Grand Rapids, Michigan Caridad Borrás, D.Sc.: Radiological Physics and Health Services Consultant, Washington, D.C. Collin D. Brack, MBA: University of Texas Medical Branch, Galveston, Texas David J. Brenner, Ph.D., D.Sc.: Columbia University, New York, New York Dean W. Broga, Ph.D.: Virginia Commonwealth University, Richmond, Virginia Stephen L. Brown, Ph.D.: Henry Ford Hospital, Detroit, Michigan Lisa A. Burgess, M.S.: William Beaumont Hospital, Royal Oak, Michigan Jay W. Burmeister, Ph.D.: Wayne State University School of Medicine, Detroit, Michigan Terry M. Button, Ph.D.: University Hospital, SUNY Stony Brook, Stony Brook, New York Stewart Carlyle Bushong, Sc.D.: Baylor College of Medicine, Houston, Texas Patrick F. Cadman, M.Sc.: Saskatoon Cancer Centre, Saskatoon, Saskatchewan S7N 4H4, Canada Daliang Cao, Ph.D.: Swedish Cancer Institute, Seattle, Washington David J. Carlson, Ph.D: Yale University School of Medicine, New Haven, Connecticut Lili Chen, Ph.D.: Fox Chase Cancer Center, Philadelphia, Pennsylvania Indra J. Das, Ph.D.: Indiana University—School of Medicine, Indianapolis, Indiana Rupak K. Das, Ph.D.: University of Wisconsin, Madison, Wisconsin Slobodan Devic, Ph.D.: SMBD Jewish General Hospital, McGill University, Montréal, Québec Sonja Dieterich, Ph.D.: Stanford University Hospital, Stanford, California Scott Dube, M.S.: Queen of the Valley Medical Center, Napa, California Howard R.