Relevant Facts Regarding the Use of Ionising Radiation Screening Devices in Airports
An Information Paper from theInter-Agency Committee on Radiation Safety (IACRS) 1
Introduction
The objective of the Inter-Agency Committee on Radiation Safety (IACRS) 2 is to promoteconsistency and co-ordination of policies with respect to areas of common interest inradiation protection and safety. Areas of common interest to the members of the IACRS, who
are represented by experts in the different fields of radiation safety, include applying
principles, criteria and standards of radiation protection and safety and translating them into
regulatory terms; coordinating research and development; advancing education and training;
promoting widespread information exchange; facilitating the transfer of technology andknow-how; and providing services in radiation protection and safety.
The IACRS has for some time been aware of issues concerning the radiological protection
aspects of using X-ray body scanners, and discussed these at previous IACRS meetings, mostrecently January 2010. As a result, the IACRS has consolidated the following relevant facts
and information for internal use of its member organizations, which may also make itavailable to interested governments responsible for taking decisions concerning the use ofsuch scanners. Further detail concerning a few significant approaches to guidance is provided
in annex.
Background
The failed attempt to blow up a plane from Amsterdam to Detroit on 25 December 2009 by
the use of explosive powder sewn into his underwear has sparked new calls to step up
security at airports. Much of the attention has focused on the new or increased use of bodyscanners that can reveal objects concealed beneath a passenger's clothing. Within the remit ofradiation protection it should be considered whether those body scanner technologies using
ionizing radiation represent a health risk to the individuals being scanned and the operating
personnel. In terms of possible public health impact, the global airport traffic statistics
indicate that the total number of air passengers is over 4.8 billion per year, and thatinternational passenger traffic accounts for 42 percent of that global traffic. Therefore, thenumber of individuals who could be exposed to radiation might be significant, including
screened people, employees who operate the security screening systems, employees who
happen to work nearby and other members of the general public. 3
Description of Commonly Available Technologies
Four types of body scanners are capable of detecting concealed items worn on a person’s
body, and of indicating detection by means of an alarm. Two systems use machine-generated
X-rays, the third uses machine-generated high-frequency, non-ionising radio-waves, and thefourth does not use any machine-generated radiation but detects the non-ionising radio-waves
naturally generated by the human body. In all cases, a human operator may be an integral part

1

This document is an IACRS product and may not necessarily represent the official position of any participatingorganisation.
2
For information concerning the IACRS please consult the web site: http://www.iacrs-rp.org/
3
Airport Council international (ACI) member airports, representing approximately 98 percent of global airport
traffic, report that the total number of passengers rose marginally in 2008 to 4.874 billion passengers, compared
to 4.869 billion in 2007, according to ACI Annual World Airport Traffic Reports (WATR)

of the system, but newer systems process images automatically and humans need only be
involved if suspicious objects are detected causing an alarm.
Individual body scanners based on two types of X-ray devices have been available for
decades. Back-scattered X-rays are used to image objects concealed beneath the passenger's
clothing while transmission X-rays can also image objects concealed within the body (e.g.
swallowed, hidden in body cavities or implanted under the skin). Both technologies can
produce high-quality still images in about 20-30 seconds.
The other types of commonly used body scanners are based on non-ionising technologies andare currently available and have been in test-use for some time. The current technologies
include different non-ionizing techniques using radio-waves (millimetre-wave and THz
imaging), or thermal and multi-band imaging. These techniques can only detect objects
concealed beneath clothing. At present, the most developed and wide-spread technology is
the millimetre-wave, which can provide high-quality still images, in 3D, in about 2 to 3
seconds.
Radiation Exposure from X-ray Body Scanners
Body scanners based on non-ionising technologies do not expose the people being scanned toionizing radiation. X-ray body scanners will expose the people being scanned, although thedose to the scanned person is very low. Generally, the radiation dose to the scanned
individual from a backscatter system will be much lower than the dose from a transmission
system. Typically a single scan of an individual will result in the person receiving a radiationdose of 0.1 μSv from a backscatter X-ray scan, and about 5 μSv from a transmission X-ray
scan. Radiation doses are cumulative, so an individual’s total dose will depend on the numberof scans performed (some passengers require 4 scans per screening procedure) and on thefrequency with which the individual travels. To put this into perspective, during any single
year, every individual on earth will be exposed to natural, background radiation to a level of,on average, about 3000 μSv. In flight, galactic cosmic rays (GCRs) are a major source ofradiation exposure to the aircrew and passengers, with dose rates significantly higher than atground level. In-flight doses vary with flight path (latitude, altitude and duration) but, for thesake of comparison, the typical total effective dose due to GCRs for a transatlantic flight (e.g.
from Europe to North America) is on the order of 50 μSv. In this context, radiation protection
issues related to the use of X-ray body scanners should be assessed and balanced against thedirect and indirect benefits of such scans as input to government decisions concerning thejustification of use of such scanners.
Privacy Issues
Privacy issues are a major concern in the use of body scanners, particularly in the case ofbackscatter systems since this technology produces an image of the naked human body.
Measures are being taken to resolve these concerns by situating the personnel interpreting theimages in a separate location, without contact with the person under inspection, and throughthe implementation of software to mask faces and private areas (in these cases image analysis
may be automated). In some countries the screener and the screened person have to be of thesame gender, and in some countries children are not screened.
Radiation Protection Issues
In assessing the possible use of X-ray body scanners, three radiation protection issues may beof relevance with regard to the government decision whether or not to justify their use. First,
although the individual exposures are very low, the exposure experienced by the scannedpopulation as a whole will depend on whether all passengers are systematically scanned, or
alternatively whether passengers are selected for scanning randomly or on the basis of
specific criteria. The manner in which passengers would be selected would be needed inorder to appropriately assess the full radiological protection impact of scanner use.
Second, the use of X-ray body scanners on sensitive groups, such as pregnant women andchildren, could be assessed separately during government consideration of justification.
Thirdly, an activity causing radiation exposure can be viewed as justified if its net benefit isgreater than its net detriment.
Requirements for X-ray Body Scanner Use in the International Basic Safety Standards(BSS) 4The current draft text of the International BSS addresses non-medical imaging of humans in
all its guises, including security screening. The default position is that such deliberate
exposure of persons is normally deemed to be not justified, but that there may be exceptional
circumstances in which a country may wish to consider such radiation use. For suchcircumstances, the requirements in the draft BSS set out a framework to ensure appropriate
radiation protection for all parties, including persons being irradiated.
First and foremost the proposed use of radiation, such as security screening at an airport,
would be subject to the process of justification, with the responsibility for this process lying
with government. If after due process the decision by government is made that a particular
practice of non-medical imaging of humans is appropriate, then each instance of such apractice would be subject to authorization with appropriate conditions and would be subject
to regulatory control. In particular, for the case of security screening, exposed persons would
be protected through optimization, with dose constraints, and the application of the publicdose limits.
There is a further requirement on standards of equipment performance, and another on theneed to inform persons that they may choose an alternative technique that does not use
ionizing radiation, if available (e.g hand search).
Trends in X-ray Body Scanner Use
Several organisations and countries have implemented requirements and policies regarding
the use of X-ray scanners in airports. The information presented below has been collected by
the IACRS for this information paper and is not exhaustive. It is simply intended to provide
some examples of the various approaches adopted in different regions/countries.
The European Union4
The European Commission was given a mandate by the European Parliament to establish
common rules for civil aviation security following the 11 September 2001 terrorist attacks in
the United States. Rules were upgraded in 2008 to better address concealed liquids. However,an attempt by the Commission to implement more specific rules regarding body screening
techniques was rejected by the European Parliament due to concerns related to health, privacy
and data protection.

4

Further discussion of this guidance is provided in Annex

Such techniques are not explicitly addressed in the current EURATOM BSS, but any use ofionising radiation is subject to requirements for justification, optimization and dose
limitation. The draft EURATOM BSS establishes requirements similar to those of the draft
International BSS, including requirements for justification, regulatory control, dose
constraints and dose limits and availability of alternative techniques. Transmission scanningsystems are not used for aviation security in the EU, and while some EU Member States
recently announced plans to install body scanners at airports they are mostly opting for a nonionizing technology.
The United States 5
In the United States, there are no specific legislative requirements for the justification and useof body scanners using ionising radiation. The Interagency Steering Committee on Radiation
Standards (ISCORS) is an interagency body made up of those federal organisations having
regulatory authority with respect to radiation protection issues. The agencies represented on
the committee include the U.S. Environmental Protection Agency, U.S. Nuclear Regulatory
Commission, U.S. Department of Energy, U.S. Department of Defense, U.S. Department ofHomeland Security, U.S. Department of Transportation, the Occupational Safety and HealthAdministration of the U.S. Department of Labor, the U.S. Department of Health and Human
Services, and any successor agencies. In July 2008 the ISCORS developed a guidance
document to assist Federal agencies in determining when the use of ionizing radiation for
security screening of humans is warranted.
The recommendations presented in this guidance are based on the three basic principles ofradiation safety: (1) justification of the use of ionizing radiation, (2) optimization of radiation
exposure, and (3) limitation of the radiation dose.
Japan
Security screening using ionizing radiation is neither performed nor planned in Japanese
airports.
Germany
The German Federal Office for Radiation Protection (BfS) conducted an evaluation on
aspects of radiation protection for whole-body scanners available (in the German language)
on: http://www.bfs.de/de/elektro/papiere/body_scanner.html
In the evaluation BfS distinguishes between:
1) Backscatter technology with X-rays;
2) Passive scanners that make use of millimetre/terahertz radiation emitted by the body itself;
3) Active backscatter scanners based on millimetre/terahertz radiation.
BfS favours the use of passive scanners (2) over the use of backscatter technologies that add
artificial radiation to improve the contrasts in the picture - either in the millimetre/terahertz
range (3) or X-rays (1). The BfS rejects the use of X-rays for this purpose.

5

Further discussion of this guidance is provided in Annex

The Czech Republic
The Czech regulatory body has rejected the request for installation of whole body (X-ray
backscatters) scanners at the airports in the country. The justification for this decision is that:o There is non-negligible risk associated with radiation involved, mainly for frequent
flyers, and the problem of scanning of children and pregnant women is not solved
o Alternative techniques (body search) may satisfy an equivalent level of security

References• ANSI / HPS Standard: N43.17-2009: Radiation Safety for Personnel Security Screening
Systems Using X-Ray or Gamma Radiation, American National Standards Institute, Inc.
Approved August 2009• National Council on Radiation Protection and Measurements. Screening of Humans for
Security Purposes Using Ionizing Radiation Scanning Systems, NCRP Commentary No.
16. (National Council on Radiation Protection and Measurements, Bethesda, Maryland)(2003).
• International Electrotechnical Commission. Radiation protection instrumentation - X-ray
systems for the screening of persons for security and the carrying of illicit items. (IEC62463) In preparation. 2009.
• US ISCORS Technical report 2008-1, Guidance for security screening of humans
utilizing ionizing radiation (2008)..
• R. Bütikofer, E.O. Flückiger, B. Pirard, and L. Desorgher, Effective radiation dose forselected intercontinental flights during the GLEs on 20 January 2005 and 13 December
2006, In Proc. 21st European Cosmic Ray Symposium, 2009.
•

ACI Annual World Airport Traffic Reports:
http://www.airports.org/cda/aci_common/display/main/aci_content07_c.jsp?zn=aci&cp=
1-5-54_666_2__

ANNEX
Further Details on Guidance from the Draft International Basic Safety Standards, fromthe European Union, and from the United States

Draft Requirements from the DRAFTInternational Basic Safety Standards
Pertaining to Non-Medical Imaging of Humans
3.20 Human imaging using radiation for the detection of concealed objects for security or
anti-smuggling purposes shall normally be deemed to be not justified. If, in exceptional
circumstances, the justification of such imaging is to be considered, the requirements of paras
3.60 to 3.67 shall apply.
3.60. The government shall ensure that the use of ionizing radiation in the imaging of
humans for purposes other than medical diagnosis or treatment be subject to the system ofprotection and safety as required by these Standards.
3.61. The government shall ensure that the measures described in para. 3.16 for thejustification of practices are applied to any imaging procedure that exposes humans toradiation not intended for diagnostic or therapeutic purposes. The justification process shallconsider, inter alia,(a) Appropriateness of the radiation equipment for the proposed use.
(b) The use of alternative techniques that do not utilize ionizing radiation.
(c) The benefits and detriments of implementing the procedure.
(d) The benefits and detriments of not implementing the procedure.
(e) Evaluation of various radiation technologies available, including the effectiveness andlimitations of the procedures.
(f) Availability of sufficient resources to safely conduct the imaging procedure during theintended period of use.
(g) The impact of any legal or ethical issues which may be raised by the use of thetechnology.
3.62. If it has been determined through the process specified in para 3.60 that a particular
practice of human imaging is justified, then, such a practice shall be subject to regulatory
control.
3.63. The regulatory body, in cooperation with other relevant authorities, agencies andprofessional bodies as appropriate, shall establish the requirements for regulatory control ofthe practice, including periodic review of the justification.
3.64. For human imaging conducted by medical staff using medical radiological equipment,
which exposes humans to radiation for occupational, legal or health insurance purposes
without reference to clinical indications:(a) The government shall ensure, as a result of consultation between other relevant
authorities, professional bodies and the regulatory body, the establishment of dose
constraints for such human imaging procedures.
(b) The registrant or licensee shall ensure that the appropriate optimization requirements
for medical exposures specified in paras 3.162 to 3.178 are applied, with the
exception that dose constraints as set in (a) are to be used instead of diagnostic

reference levels.
3.65. Inspection procedures , using inspection imaging devices, which intentionally expose
humans for the purpose of detection of concealed weapons, contraband or other objects on orwithin the body shall be considered as giving rise to public exposure, and registrants andlicensees shall ensure that the requirements for public exposure in planned exposure
situations are met and, in particular, that optimization of protection and safety is subject toany dose constraints set by the government or regulatory body.
3.66. Registrants and licensees shall ensure that all persons that are about to be exposed toradiation for inspection procedures, are informed about the possibility of choosing analternative technique that does not use ionizing radiation, where available.
3.67. The registrant or licensee shall ensure that, whether imported into or manufactured in
the country where it is used, any inspection imaging device used for the detection ofconcealed objects and for security purposes conforms to applicable standards of theInternational Electrotechnical Commission (IEC), the International Organization forStandardization (ISO) or to equivalent national standards.

European Union
EC legislation regulating the use of body scanners at airports
Following the events of 11 September 2001, the Commission has been given a mandate in thefield of aviation security. In result, Regulation (EC) No 2320/2002 of the European
Parliament and of the Council of 16 December 2002 establishing common rules in the field ofcivil aviation security was adopted. In 2008 the EC legislation was updated (Regulation (EC)No 300/2008), one of the main reasons being the need to detect liquids held in hand baggage
and on the human body. Commission's proposal (DG TREN, Directorate F) for addressing
the detection of liquid explosives carried on a person's body relied on the introduction of theappropriate body screening techniques in the list of optional screening methods provided by
the EC legislation. This proposal has been rejected by the European Parliament due toconcerns related to health, privacy and data protection.
EURATOM legislation regulating the use of body scanners
X-ray body scanners are not explicitly considered in the current EURATOM legislation but,
as with any other technique applying ionizing radiation, they fall under the provision of theCouncil Directive 96/29/EURATOM (BSS) and the radiation protection requirements forjustification, optimization and dose limitation apply. Non-ionizing radiation techniques (likethe millimetre-wave) fall out of the scope of the EURATOM BSS.
In the latest draft of the recast EURATOM BSS the body scanners are grouped together withother deliberate exposures of humans for non-medical reasons under the new definition of'Non-medical imaging exposures'. Special emphasis is put on the need for justification andregulatory control of those practices. Exposure from body scanners is categorized as public
exposure and the dose limit and the requirements for optimization with the use of dose
constraints apply. The draft EURATOM BSS requires that alternative techniques, which do
not involve exposure to ionising radiation, are available to the exposed individuals where theexposure is routinely carried out for security purposes.

Guidance from the United States
The guidance provided by the IACORS anticipates that the decision to perform security
screening of humans will be made by an authority at the appropriate organizational level, andin accordance with the legal authorities of that agency. The guidance also clearly notes thatthe decision involves many factors in addition to radiation protection. The overall benefit
must outweigh the risks associated with the chosen security screening method. Prior to
conducting security screening of humans, the responsible executive should obtain legal
advice and consider the operation, the current threat assessment, physical security, andcultural/social issues, to determine when security screening of humans is justified. An
institution should gather sufficient information and data to properly carry out each of thefollowing assessments:
1) Define the need2) Evaluate options3) Evaluate privacy concerns
4) Assess radiation risks from the technology and the net benefit of implementation
5) Evaluate agency’s ability to implement the practice
After due consideration of the findings from the five steps listed above, the agency should
document its decision process.
If a Federal agency decides to implement a security screening practice that uses ionizing
radiation, it should establish and maintain an effective radiation safety program. The scope of
any radiation safety program should be commensurate with the potential risks associated withthe security screening practice. In particular, the adoption of limited-use systems requires asignificantly higher level of control and documentation than general-use systems. Therefore,
each agency (or organization within an agency) will need to tailor their radiation safety
program to their specific needs.
In the United States, the radiation protection programs in each of the States have jurisdiction
with regard to most machine produced radiation, including X-rays. Thus the States may also
have responsibilities, depending on the arrangements in place at an airport within a particularState.
For the use of state and federal organizations regulating these devices, the American National
Standards Institute, in association with the American Health Physics Society, has issued
standards regarding the use of these security screening systems based on the radiation dose to
the screened individuals as follows:o General-use systems should adhere to an effective dose of 0.1 μSv or less per scan,and can be used mostly without regard to the number of individuals scanned or thenumber of scans per individual in a year For a system to be general-use it must
incorporate adequate engineering controls to assure the dose limit is never exceeded.
o Limited-use systems include all other ionizing radiation scanning systems that require
effective doses per scan greater than 0.1 μSv and less than or equal to 10 μSv.
This standard also established a limit of no more than 0.25 mSv (250 μSv ) annual effective
dose to an individual from any one security screening venue. From a radiation protection
standpoint, these systems should be used with discretion in terms of the number ofindividuals scanned and the number of scans per individual in a year.