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Engineering Aviation Security Environmentsâ Reduction of False Alarms in Computed Tomography- Based Screening of Checked Baggage Committee on Engineering Aviation Security Environmentsâ False Positives from Explosive Detection Systems National Materials and Manufacturing Board Division on Engineering and Physical Sciences THE NATIONAL ACADEMIES PRESS Washington, D.C. www.nap.edu
THE NATIONAL ACADEMIES PRESS 500 FIFTH STREET, NW WASHINGTON, DC 20001 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This study was supported by the Department of Homeland Security Cooperative Agreement 04-G-045 with the National Academy of Sciences, Award 0840104 from the National Science Foundation, and Award DE-FG02-08ER46534 from the Department of Energy. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the organizations or agencies that provided support for the project. International Standard Book Number- 13: 978-0-309-21479-7 International Standard Book Number- 10: 0-309-21479-3 This report is available in limited quantities from National Materials and Manufacturing Board 500 Fifth Street, NW Washington, DC 20001 nmmb@nas.edu http://www.national-academies.org/nmmb/ Additional copies of this report are available from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242 or (202) 334-3313; http://www.nap.edu. Copyright 2013 by the National Academy of Sciences. All rights reserved. Printed in the United States of America
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. C.D. (Dan) Mote, Jr., is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academyâs purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C.D. (Dan) Mote, Jr., are chair and vice chair, respectively, of the National Research Council. www.national-academies.org
COMMITTEE ON ENGINEERING AVIATION SECURITY ENVIRONMENTSâ FALSE POSITIVES FROM EXPLOSIVE DETECTION SYSTEMS SANDRA HYLAND, BAE Systems, Chair CHERYL BITNER, Pioneer UAV, Inc. R. GRAHAM COOKS, Purdue University CARL R. CRAWFORD, Csuptwo, LLC B. JOHN GARRICK, Executive Consultant, Laguna Beach, Calif. CONSTANTINE GATSONIS, Brown University GARY H. GLOVER, Stanford University SUBHASH R. LELE, University of Alberta HARRY E. MARTZ, JR., Lawrence Livermore National Laboratory WILLIAM Q. MEEKER, Iowa State University Staff EMILY ANN MEYER, Study Director TERI THOROWGOOD, Administrative Coordinator (until December 2009) LAURA TOTH, Program Assistant RICKY D. WASHINGTON, Executive Assistant v
NATIONAL MATERIALS AND MANUFACTURING BOARD ROBERT H. LATIFF, Consultant, Chair DENISE F. SWINK, Consultant, Vice Chair PETER R. BRIDENBAUGH, ALCOA (retired) VALERIE M. BROWNING, ValTech Solutions YET-MING CHIANG, Massachusetts Institute of Technology PAUL CITRON, Medtronic, Inc. (retired) GEORGE T. (RUSTY) GRAY II, Los Alamos National Laboratory CAROL A. HANDWERKER, Purdue University THOMAS S. HARTWICK, Consultant SUNDARESAN JAYARAMAN, Georgia Institute of Technology DAVID W. JOHNSON, Stevens Institute of Technology THOMAS KING, Oak Ridge National Laboratory MICHAEL F. McGRATH, Analytic Services, Inc. NABIL NASR, Rochester Institute of Technology PAUL S. PEERCY, University of Wisconsin-Madison ROBERT C. PFAHL, JR., International Electronics Manufacturing Initiative VINCENT RUSSO, Aerospace Technologies Associates, LLC KENNETH H. SANDHAGE, Georgia Institute of Technology ROBERT E. SCHAFRIK, GE Aviation HAYDN WADLEY, University of Virginia STEVEN WAX, Consultant Staff DENNIS I. CHAMOT, Acting Director ERIK SVEDBERG, Senior Program Officer HEATHER LOZOWSKI, Financial Associate LAURA TOTH, Program Assistant RICKY D. WASHINGTON, Executive Assistant vi
Preface The face of aviation security changed drastically in the wake of the terrorist attacks on the United States on September 11, 2001. Among the changes was the requirement, mandated by the Aviation and Transportation Security Act of 2001, 1 that as of December 31, 2003, all checked baggage on U.S. flights be scanned by explosive detection systems (EDSs) for the presence of any potential explosives threat. In most airports, this scanning is performed by a computed tomography (CT)-based device. Such devices are based on the same technology as that used for medical CT scanners, with minor modifications so that the scanners can perform in the significantly larger scale of operation required in airports. Medical scanners perform well in a clinical setting; however, modifying them to scan for explosives in an airport setting can result in shortcomingsâincluding those related to reliability and the false alarm rateâowing to the very different scale of operation and the resulting greater demands on the equipment. The Committee on Engineering Aviation Security EnvironmentsâFalse Positives from Explosive Detection Systems addresses some of these issues related to reliability and makes recommendations for research and administrative directions that may allow for a reduction in the false alarm rate. Throughout the study process, the committee balanced considerations related to a reduction in false alarms with concerns about increased risk of missed detection. The committee acknowledges with thanks those who spoke at meetings. The committee is also grateful for the support of National Research Council staff throughout this project. Sandra Hyland, Chair Committee on Engineering Aviation Security EnvironmentsâFalse Positives from Explosive Detection Systems 1 Public Law 107-71, signed into law November 19, 2001. vii
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 National Research Councilâs (NRCâs) 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: Peter Edic, GE Global Research, Maryellen L. Giger, University of Chicago, Peter Hovey, University of Dayton, Najmedin Meshkati, University of Southern California, Stephen Pollock, University of Michigan, Elan Scheinman, Reveal Imaging Technologies, and Ron Willey, Northeastern University. Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations, nor did they see the final draft of the report before its release. The review of this report was overseen by Hyla S. Napadensky, Napadensky Energetics, Inc. Appointed by the NRC, she was 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 report rests entirely with the authoring committee and the institution. viii
Contents SUMMARY AND RECOMMENDATIONS 1 1 INTRODUCTION 12 Background and Request for Study, 12 Distinctions in Terms and the Need for Data, 14 Study Process, 15 Report Structure, 15 2 OVERVIEW OF DEPLOYED EXPLOSIVE DETECTION SYSTEM TECHNOLOGIES 17 Overview of a Computed Tomography Scanner, 17 Image Reconstruction and Correction, 18 Automated Threat Recognition, 20 Fundamental Limitations of Computed Tomography-Based Explosive Detection Systems Based on the Physics of the Technology, 22 Image Artifacts, 23 Baggage Contents, 23 Material Density, 23 Dual-Energy Scanning, 24 Testing at the Transportation Security Laboratory, 24 Implementation Within an Airport Setting, 25 Shifting Emphasis, 25 Screening Process, 26 Discussion, with Related Finding and Recommendation, 28 3 ALTERNATIVE APPROACHES FOR THE REDUCTION OF FALSE ALARMS 29 An Alternative Approach: Multiple Scans Using Existing Technology, 29 Another Alternative Approach: Chemical Analyses, 31 X-Ray Diffraction Technology, 31 Incorporating Data from Other Sources, 32 4 INCENTIVIZING RESEARCH AND DEVELOPMENT TO DECREASE FALSE 34 ALARMS IN AN AIRPORT SETTING Addressing Concerns of Explosive Detection System Vendors, 34 The Need for a Long-Term Transportation Security Administration Plan, 34 Changes Needed for Dealing with Technological Improvements, 35 Incentives for Vendors, 36 Collaborative Contracting Methodology, 37 Performance-Based Logistics, 38 Overview of Performance-Based Logistics, 38 Advantage of Performance-Based Logistics, 38 Implementation Considerations for Performance-Based Logistics, 39 Technical Review Board, 40 ix
Fielding Considerations, 40 Data Collection and Analysis, 42 Program Management, 42 Approaches Other Than Performance-Based Logistics for Product Development and System Improvement, 43 Original Equipment Manufacturer Research and Development, 43 University and Laboratory Research and Development, 44 5 LESSONS FROM MEDICAL IMAGING FOR EXPLOSIVE DETECTION SYSTEMS 45 Computed Tomography in Medicine and in Explosive Detection Systems, 45 The Technology of Medical Computed Tomography Scanners, 46 Quantification with Computed Tomography, 46 Comparison of Computed Tomography (CT) for Medical Use and CT for Explosive Detection Systems, 46 Explosive Detection Systems and Medical Imaging, 49 Lessons Learned, 50 Image Standardization and Post-Processing Software Development, 50 Quality Control and Performance Monitoring, 51 6 DATA COLLECTION, MANAGEMENT, AND ANALYSIS 52 Background, 52 Transportation Security Administration Data, 52 Transportation Security Administration Data Management and Processing, 53 The Use of TSA Data in Quantitative Risk Assessment, 54 The Use of TSA Data for Process Monitoring, 54 The Use of TSA Data for Understanding the Root Causes of False Positives, 55 Other Uses or TSA Data for Process Improvement, 56 The Use of TSA Data from Red-Team Testing, 57 Discussion, 58 APPENDIXES A Biographies of Committee Members 61 B Quantifying the Risk of False Alarms with Airport Screening of Checked Baggage 64 C Chemistry-Based Alternatives to Computed Tomography-Based Explosives Detection 73 D Statistical Approaches to Reducing the Probability of False Alarms While Improving the 81 Probability of Detection E Statement of Task 86 F Acronyms and Definitions of Selected Terms 87 x