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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

AIRPORT PASSENGER
SCREENING USING
BACKSCATTER
X-RAY MACHINES

Compliance with Standards

Committee on Airport Passenger Screening: Backscatter X-Ray Machines

National Materials and Manufacturing Board

Division on Engineering and Physical Sciences

and

Nuclear and Radiation Studies Board

Division on Earth and Life Sciences

image

THE NATIONAL ACADEMIES PRESS
Washington, DC
www.nap.edu

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

THE NATIONAL ACADEMIES PRESS    500 Fifth Street, NW    Washington, DC 20001

This study was supported by Contract/Grant No. HSHQDC-11-D-00009 between the National Academy of Sciences and the Department of Homeland Security. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.

International Standard Book Number-13: 978-0-309-37133-9
International Standard Book Number-10: 0-309-37133-3
DOI: 10.17226/21710

Cover Image: A common scene at a fictional airport employing passenger screening using a backscatter X-ray machine. Artist: Erik Svedberg. Image created by ray tracing, where computational rays of light backscatter, reflect, or are transmitted throughout the geometry of the scene to paint the full picture.

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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

images

The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Ralph J. Cicerone is president.

The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president.

The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president.

The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine.

Learn more about the National Academies of Sciences, Engineering, and Medicine at www.national-academies.org.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

COMMITTEE ON AIRPORT PASSENGER SCREENING: BACKSCATTER X-RAY MACHINES

HARRY E. MARTZ, JR., Lawrence Livermore National Laboratory, Chair

BARBARA J. McNEIL, Harvard Medical School, Vice Chair

SALLY A. AMUNDSON, Columbia University Medical Center

DAVID E. ASPNES, North Carolina State University

ARNOLD BARNETT, Massachusetts Institute of Technology

THOMAS B. BORAK, Colorado State University

LESLIE A. BRABY, Texas A&M University, College Station

MATS P.E. HEIMDAHL, University of Minnesota, Minneapolis

SANDRA L. HYLAND, Consultant, Falls Church, Virginia

SHELDON H. JACOBSON, University of Illinois, Urbana-Champaign

JAY S. LOEFFLER, Massachusetts General Hospital

C. KUMAR N. PATEL, Pranalytica, Inc.

MAURO SARDELA, University of Illinois, Urbana-Champaign

ZHI-MIN YUAN, Harvard School of Public Health

Staff

JAMES LANCASTER, Acting Director, National Materials and Manufacturing Board

ERIK B. SVEDBERG, Senior Program Officer, Study Director

OURANIA KOSTI, Senior Program Officer

HYEKYUNG (CLARISSE) KIM, Christine Mirzayan Science and Technology Policy Graduate Fellow

HEATHER LOZOWSKI, Financial Associate

NEERAJ P. GORKHALY, Research Associate

JOSEPH PALMER, Senior Project Assistant

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

NATIONAL MATERIALS AND MANUFACTURING BOARD

ROBERT E. SCHAFRIK, GE Aircraft Engines (retired), Chair

MICHAEL BASKES, Mississippi State University

JIM C.I. CHANG, North Carolina State University

JENNIE HWANG, H-Technologies Group

SANDRA L. HYLAND, Consultant, Falls Church, Virginia

SUNDARESAN JAYARAMAN, Georgia Institute of Technology

ROBERT H. LATIFF, R. Latiff Associates

MICHAEL F. MCGRATH, McGrath Analytics LLC

CELIA MERZBACHER, Semiconductor Research Corporation

EDWARD MORRIS, National Center for Defense Manufacturing

VINCENT J. RUSSO, Aerospace Technologies Associates, LLC

GREG TASSEY, University of Washington

HAYDN G. WADLEY, University of Virginia

BEN WANG, Georgia Institute of Technology

Staff

JAMES LANCASTER, Acting Director

ERIK B. SVEDBERG, Senior Program Officer

HEATHER LOZOWSKI, Financial Associate

NEERAJ P. GORKHALY, Research Associate

JOSEPH PALMER, Senior Project Assistant

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

NUCLEAR AND RADIATION STUDIES BOARD

ROBERT C. DYNES, University of California, San Diego, Chair

BARBARA J. McNEIL, Harvard Medical School, Vice Chair

JOHN S. APPLEGATE, Indiana University School of Law

DAVID J. BRENNER, Columbia University

MARGARET S.Y. CHU, M.S. Chu & Associates, LLC

MICHAEL L. CORRADINI, University of Wisconsin, Madison

TISSA H. ILLANGASEKARE, Colorado School of Mines

CAROL M. JANTZEN, Savannah River National Laboratory

ANNIE B. KERSTING, Lawrence Livermore National Laboratory

MARTHA S. LINET, National Institutes of Health

FRED A. METTLER, JR., New Mexico VA Health Care System

NANCY JO NICHOLAS, Los Alamos National Laboratory

LAWRENCE T. PAPAY,1 PQR, LLC

DANIEL O. STRAM, University of Southern California, Los Angeles

RICHARD J. VETTER, Mayo Clinic (retired)

SERGEY V. YUDINTSEV, Russian Academy of Sciences

Staff

KEVIN D. CROWLEY, Director

JENNIFER HEIMBERG, Senior Program Officer

OURANIA KOSTI, Senior Program Officer

TONI GREENLEAF, Administrative and Financial Associate

LAURA D. LLANOS, Administrative and Financial Associate

DARLENE GROS, Senior Program Assistant

_______________

1 Deceased on July 28, 2014.

Page viii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

Preface

The Department of Homeland Security (DHS) requested that the National Research Council (NRC) provide an independent study of the radiation exposures resulting from X-ray backscatter advanced imaging technology (AIT) systems used in screening travelers in U.S. airports. According to the Transportation Security Administration (TSA), a component of DHS responsible for the security of the transportation systems in the United States, AIT systems provide enhanced security benefits by detecting both metallic and non-metallic threat items, including weapons, explosives, and other concealed objects on passengers, some of which would not be detected by walk-through metal detectors.1 X-ray backscatter AITs were deployed in U.S airports in 2008 and subsequently removed from all airports by June 2013 due to privacy concerns. This removal was an effect of Congress stipulating in the FAA Modernization and Reform Act of 20122 that all TSA body scanners should have automatic target recognition, thus eliminating the need for a screener to view the image of the person being scanned, something manufacturers

_______________

1 General Accountability Office, Transportation Security Administration: Progress and Challenges Faced in Strengthening Three Key Security Programs, Statement of Stephen M. Lord, Director, Homeland Security and Justice Issues, Testimony Before the Committee on Oversight and Government Reform and Committee on Transportation and Infrastructure, U.S. House of Representatives, GAO-12-541T, March 26, 2012, http://oversight.house.gov/wp-content/uploads/2012/03/3-26-12-Joint-TI-Lord-Testimony.pdf.

2 U.S. House of Representatives, FAA Modernization and Reform Act of 2012 Conference Report to Accompany H.R. 658, 11th Congress, Report 112-381, February 1, 2012, http://www.gpo.gov/fdsys/pkg/CRPT-112hrpt381/pdf/CRPT-112hrpt381.pdf.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

failed to implement. TSA is looking to deploy a second-generation X-ray backscatter AIT equipped with privacy software to eliminate production of an image of the person being screened.

This study aims to address concerns about exposure to radiation from X-ray backscatter AITs raised by Congress, individuals within the scientific community, and others. It was carried out by a committee of experts appointed by the NRC. The Committee on Airport Passenger Screening: Backscatter X-Ray Machines consisted of 14 members with expertise that spans the disciplines relevant to the study task: radiation physics and dosimetry, radiation biology, diagnostic and therapeutic radiology, materials science, systems and electrical engineering, manufacturing testing and evaluation, aviation safety, software safety, and statistics.

Three factors made the committee’s task challenging:

  1. There were no X-ray backscatter AIT systems deployed in U.S. airports at the time the committee started and completed its examination. In fact, the committee did not have access to any machines until about 8 months after it was convened, and after that it had limited access to the AITs and limited time to complete its work.
  2. The X-ray backscatter AIT systems available to the committee for examination were located in facilities belonging to government agencies and either under preliminary testing or used as a reference. Therefore, no destructive testing could be done; the committee was thus unable to perform a complete examination of the systems’ safety interlocks, which prevent overexposures of the people being screened. Such an examination would have potentially involved damaging the machines while they were in operation to document whether the machines safely terminated operations in response to the destructive testing.
  3. Much of the information related to the design and operation of the AITs is excluded from public domain for reasons of national security or because of its proprietary and confidential nature.

Despite the above-mentioned factors, the committee was able to complete its radiation dose study of two X-ray backscatter AIT systems representing past and possibly future screening of travelers in U.S. airports. The committee hopes that its findings and recommendations will be useful to the general public and TSA, the sponsor, and others in evaluating the radiation exposure of any future X-ray backscatter AIT and examining the adequacy of the system design, including safety interlocks to avoid overexposures.

In closing, we thank the committee members for their exceptional efforts in carrying out this investigation and preparing this report. We and the committee

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
×

also thank the NRC staff for facilitating this study. Senior program officers Erik Svedberg and Ourania Kosti organized the committee meetings and the committee’s work and assisted the committee with report writing and review. Program assistant Joe Palmer and research associate Neeraj Gorkhaly managed the logistics of the meetings and all the daily tasks.

The committee also thanks those who were guest speakers at its meetings and who added to the committee members’ understanding of X-ray backscatter and the issues surrounding it:

Domenic Bianchini, Transportation Security Administration,

Wesley E. Bolch, University of Florida,

John Boone, University of California, Davis Medical Center,

Richard Burdette, Transportation Security Administration,

Frank Cartwright, Transportation Security Administration,

Jack Glover, National Institute of Standards and Technology,

David E. Hintenlang, University of Florida,

Larry T. Hudson, National Institute of Standards and Technology,

Daniel Kassiday, Food and Drug Administration,

Ronnie Minniti, National Institute of Standards and Technology,

Jill M. Segraves, Transportation Security Administration, and

Steve Smith, Tech84.

We also wish to thank Wesley E. Bolch, Shannon E. O’Reilly, Matthew R. Maynard, and Elliott J. Stepusin of the computation team and David E. Hintenlang and Sadije Redzovic of the physical dosimetry team in the Department of Biomedical Engineering at the University of Florida, Gainesville.

Harry Martz, Chair, and Barbara McNeil, Vice Chair
Committee on Airport Passenger Screening:
Backscatter X-Ray Machines

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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Acknowledgment of Reviewers

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report:

William Brinkman, Princeton University,

John Boone, University of California, Davis,

Carl Crawford, Csuptwo, LLC,

Ward Plummer, Louisiana State University,

David Schauer, International Commission on Radiation Units and Measurements,

Steven Simon, National Institutes of Health, and

Richard Toohey, M.H. Chew & Associates.

Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the views presented in the report, nor did they see the final draft of the report before its release. The review of this report was overseen by Etta D. Pisano, Medical University of South Carolina,

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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and Robert A. Frosch, Harvard University, who were responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this summary rests entirely with the committee and the institution.

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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2015. Airport Passenger Screening Using Backscatter X-Ray Machines: Compliance with Standards. Washington, DC: The National Academies Press. doi: 10.17226/21710.
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Passenger screening at commercial airports in the United States has gone through significant changes since the events of September 11, 2001. In response to increased concern over terrorist attacks on aircrafts, the Transportation Security Administration (TSA) has deployed security systems of advanced imaging technology (AIT) to screen passengers at airports. To date (December 2014), TSA has deployed AITs in U.S. airports of two different technologies that use different types of radiation to detect threats: millimeter wave and X-ray backscatter AIT systems. X-ray backscatter AITs were deployed in U.S. airports in 2008 and subsequently removed from all airports by June 2013 due to privacy concerns. TSA is looking to deploy a second-generation X-ray backscatter AIT equipped with privacy software to eliminate production of an image of the person being screened in order to alleviate these concerns.

This report reviews previous studies as well as current processes used by the Department of Homeland Security and equipment manufacturers to estimate radiation exposures resulting from backscatter X-ray advanced imaging technology system use in screening air travelers. Airport Passenger Screening Using Backscatter X-Ray Machines examines whether exposures comply with applicable health and safety standards for public and occupational exposures to ionizing radiation and whether system design, operating procedures, and maintenance procedures are appropriate to prevent over exposures of travelers and operators to ionizing radiation. This study aims to address concerns about exposure to radiation from X-ray backscatter AITs raised by Congress, individuals within the scientific community, and others.

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