X-ray Security-Screening Standards for Homeland Security

With support from the Department of Homeland Security (DHS), the Radiation Interactions and Dosimetry Group facilitates the development and maintains technical-performance standards for five classes of x-ray security-screening systems that are used to detect bulk explosives and other illicit items: checkpoint cabinet, computed tomography, cargo/vehicle, human subjects, and left-behind objects (bomb squads). 

American National Standards Institute (ANSI) and International Electrotechnical Commission (IEC) working groups have been organized to develop standards for both radiation safety and technical performance, particularly image quality. The designations and current versions are shown in the table.

These projects produce test methods and x-ray test pieces appropriate for the application; in some cases minimum performance requirements are quantified. This year the ANSI N42.45 and ANSI N42.47 standards were completed and formally accepted through the Institute of Electrical and Electronics Engineers (IEEE) balloting process as well as two IEC standards related to cargo and whole-body imaging systems. A set of ANSI N42.45 test objects was fabricated for distribution to U.S. international partners in aviation security.

In related work, the group maintains a test bed for assessing the image quality of portable x-ray and imaging systems used by bomb squads for explosives and ordinance detection and for disarmament. The results of testing will be used to establish minimum image-quality standards and update a National Institute of Justice standard covering these systems. This facility has recently been augmented with an x-ray screening system of the type used in prisons and airports to scan humans without physically removing their clothing. These tools were employed to support the response of DHS in the aftermath of the 2009 Christmas-Day bombing attempt (see accompanying photo).

Image Description: 

Figure 1: Table of national and international x-ray and gamma-ray security screening standards developed by the Division for imaging systems intended primarily for bulk-explosives detection. 

Figure 2: X-ray images of ANSI N42.47 test object and anthropomorphic phantom (left) and corresponding photographs (right.