Imaging in airport security: Past, present, future, and the link to forensic and clinical radiology

Abstract

After an introduction to the beginnings of x-ray screening of baggage 41 years ago, this review article gives an overview of the state-of-the-art in imaging in security at airports as well as an outlook into future developments in this area. The imaging technologies discussed range from dual-energy x-ray systems to computed tomography and terahertz scanners. A PubMed search of “radiology” and “airport” revealed 36 scientific articles covering interdisciplinary topics ranging between imaging in airport security and forensic/clinical imaging. Apart from relying on the same technologies, common research interests and initiatives appear to be most fruitful in human factors aspects that are concerned with x-ray and CT image interpretation. By sharing the knowledge between disciplines, scientists, practitioners, and regulators can learn and benefit from each other.

Introduction

The concept that societies seek to protect their key assets has not changed in the course of the centuries. However, the nature of these assets, as well as the means employed for protection against enemies, evolved dramatically. One piece of critical infrastructure in our modern society is personal transportation, the most effective one being transportation by air. It is therefore not surprising that our society devised a protection scheme for air transportation that employs the best and newest technology available.

In the era before 1972, Security Officers (SOs) at airports performed hand searches for baggage that was to be taken on board of airplanes. As air traffic increased, this proved more and more difficult, especially at peak times, considering that a thorough hand search of one piece of cabin baggage might take several minutes. In order to increase both the security level and the processing capacity of the security control, Peil constructed an “Apparatus for baggage inspection” that included “an x-ray and fluoroscopic examination unit”, which was patented in 1972 [1]. This patent marked the beginning of a new era in security control at airports, in which imaging was to play a key role. At first, security professionals applied this technology without much knowledge of what x-ray image interpretation requires from the human operators at airports. In 1990, however, the United States decided that aviation security should be improved through the optimization of human factors elements [2], because it had become clear that the best possible imaging device only fulfills its purpose in combination with proficient screeners that are able to interpret the images correctly and efficiently. This marks the starting point for the development of a substantial body of research in human factors in x-ray screening in airport security. It further prepared the grounds to the later development of sophisticated training and certification methods for x-ray screeners who work at airport security control checkpoints.