Millimeter wave scanner

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Active millimeter wave unit

A millimeter wave scanner is a whole-body imaging device used for detecting objects concealed underneath a person’s clothing using a form of electromagnetic radiation. Typical uses for this technology include detection of items for commercial loss prevention, smuggling and screening at government buildings and airport security checkpoints. Several countries employ the scanners for security screening.[1]

It is one of the common technologies of full body scanner used for body imaging; a competing technology is backscatter X-ray. Millimeter wave scanners themselves come in two varieties: active and passive. Active scanners direct millimeter wave energy at the subject and then interpret the reflected energy. Passive systems create images using only ambient radiation and radiation emitted from the human body or objects.[2][3][4]

Technical details[edit]

With active scanners, the millimeter wave is transmitted from two antennas simultaneously as they rotate around the body. The wave energy reflected back from the body or other objects on the body is used to construct a three-dimensional image, which is displayed on a remote monitor for analysis.[2][dead link][non-primary source needed][3][1]

Privacy concerns[edit]

Historically, privacy advocates were concerned about the use of full body scanning technology because it used to display a detailed image of the surface of the skin under clothing, prosthetics including breast prostheses, and other medical equipment normally hidden, such as colostomy bags.[5] These privacy advocates called the images "virtual strip searches".[6] However, in 2013 the U.S. Congress prohibited the display of detailed images and required the display of metal and other objects on a generic body outline instead of the person's actual skin. Such generic body outlines can be made by Automatic Target Recognition (ATR) software. As of June 1, 2013, all full body scanners in use at U.S. airports have used ATR.[6]

Software imaging technology can also mask specific body parts.[1] Proposed remedies for privacy concerns include scanning only people who are independently detected to be carrying contraband, or developing technology to mask genitals and other private parts. In some locations, travelers have the choice between the body scan or a "patdown". In locations such as the UK and Australia, the scans are mandatory.[7][8][9]

In the United States, the Transportation Security Administration (TSA) claimed to have taken steps to address privacy objections. TSA claimed that the images captured by the machines were not stored. On the other hand, the U.S. Marshals Service admitted that it had saved thousands of images captured from a Florida checkpoint.[10] The officer sitting at the machine does not see the image; rather that screen shows only whether the viewing officer has confirmed that the passenger has cleared. Conversely, the officer who views the image does not see the person being scanned by the device.[11] In some locations, updated software has removed the necessity of a separate officer in a remote location. These units now generate a generic image of a person, with specific areas of suspicion highlighted by boxes. If no suspicious items are detected by the machine, a green screen instead appears indicating the passenger is cleared.

Concerns remain about alternative ways to capture and disseminate the image. Additionally, the protective steps often do not entirely address the underlying privacy concerns. Subjects may object to anyone viewing them in a state of effective undress, even if it is not the agent next to the machine, or even if the image is not retrievable.

Claims that images are immediately destroyed were questioned after Indian film star Shahrukh Khan said that his image was circulated by airport staff at Heathrow in London. This comment appears to be a joke according to one UK media outlet,[12] but reports of full-body scanner images being improperly and perhaps illegally saved and disseminated continue to emerge.[13]

Possible health effects[edit]

Millimeter wavelength radiation is a subset of the microwave radio frequency spectrum. Even at its high-energy end, it is still more than 3 orders of magnitude lower in energy than its nearest radiotoxic neighbour (ultraviolet) in the electromagnetic spectrum. As such, millimeter wave radiation is non-ionizing and incapable of causing cancers by radiolytic DNA bond cleavage. Yet, the WHO (World Health Organization) IARC (International Agency for Research in Cancer) in 2011 classified non-ionizing radiation such as millimeter waves or microwaves, as 2B, which means possibly carcinogenic to humans. Due to the shallow penetration depth of millimeter waves into tissue (typically less than 1 mm),[14] acute biological effects of irradiation are localized in epidermal and dermal layers and manifest primarily as thermal effects.[14][15][16][17] There is no clear evidence to date of harmful effects other than those caused by localised heating and ensuing chemical changes (expression of heat shock proteins, denaturation, proteolysis, and inflammatory response, see also mobile phone radiation and health). It should be noted however that the energy density required to produce thermal injury in skin is much higher than that typically delivered in an active millimeter wave scanner.[15][18][19][20][21][22]

The fragmented or misfolded molecules resulting from thermal injury may be delivered to neighbouring cells through diffusion and into the systemic circulation through perfusion. Increased skin permeability under irradiation exacerbates this possibility.[17] It is therefore plausible that the molecular products of thermal injury (and their distribution to areas remote from the site of irradiation) could cause secondary injury. Note that this would be no different from the effects of a thermal injury sustained in a more conventional fashion. Due to the increasing ubiquity of millimeter wave radiation (see IEEE 802.11ad), research into its potential biological effects is ongoing.[16][18][22]

Independent of thermal injury, a 2009 study funded by National Institute of Health, conducted by U.S. Department of Energy's Los Alamos National Laboratories Theoretical Division and Center for Nonlinear Studies and Harvard University Medical School found that terahertz range radiation creates changes in DNA breathing dynamics, creating apparent interference with the naturally occurring local strand separation dynamics of double-stranded DNA and consequently, with DNA function.[23] The same article was referenced by MIT Technology Journal article on October 30, 2009.

Millimeter wave scanners should not be confused with backscatter X-ray scanners, a completely different technology used for similar purposes at airports. The latter use the much more energetic (by more than 5 orders of magnitude) and ionizing X-rays and therefore concerns about their mutagenic potential are warranted a priority.


The efficacy of millimeter wave scanners in detecting threatening objects has been questioned. Formal studies demonstrated the relative inability of these scanners in detecting objects—dangerous or not—on the person being scanned.[24] Additionally, some studies suggested that the cost–benefit ratios of these scanners is poor.[25] As of January 2011, there had been no report of a terrorist capture as a result of a body scanner. In a series of repeated tests, the body scanners were not able to detect a handgun hidden in an undercover agent's undergarments, but the agents responsible for monitoring the body scanners were deemed at fault for not recognizing the concealed weapon.[26]

Millimeter wave scanners also have problems reading through sweat, in addition to yielding false positives from buttons and folds in clothing.[27] Some countries, such as Germany, have reported a false-positive rate of 54%.[28]


Passive millimeter wave unit

While airport security may be the most visible and public use of body scanners, companies have opted to deploy passive employee screening to help reduce inventory shrink from key distribution centers.[29][30][31]

The UK Border Agency (the predecessor of UK Visas and Immigration) initiated use of passive screening technology to detect illicit goods.[32]

As of April 2009, the U.S. Transportation Security Administration began deploying scanners at airports, e.g., at the Los Angeles International Airport (LAX).[1] These machines have also been deployed in the Jersey City PATH train system.[33] They have also been deployed at San Francisco International airport (SFO), as well as Salt Lake International Airport (SLC), Indianapolis International Airport (IND), Detroit-Wayne County Metropolitan Airport (DTW), Minneapolis-St. Paul International Airport (MSP), and Las Vegas International Airport (LAS).

Three security scanners using millimeter waves were put into use at Schiphol Airport in Amsterdam on 15 May 2007, with more expected to be installed later. The passenger's head is masked from the view of the security personnel.

Passive scanners are also currently in use at Fiumicino Airport, Italy.[34] They will next be deployed in Malpensa Airport.[35]

The federal courthouse in Orlando, Florida employs passive screening devices capable of recording and storing images.


Kelowna International Airport in Kelowna, British Columbia hosted the first such device in a Canadian airport. It was pulled from service in 2008 for undisclosed reasons, but may have simply been a test unit on loan.[36]

Scanners are currently in use at Pearson Airport in Toronto, Ontario (YYZ), Montréal – Pierre Elliott Trudeau International Airport, Quebec (YUL), Calgary International Airport, Alberta (YYC), Vancouver International Airport, British Columbia (YVR), Halifax Stanfield International Airport, Nova Scotia (YHZ), and the Winnipeg James Armstrong Richardson International Airport (YWG).

The Canadian Air Transport Security Authority held a trial of the scanners at Kelowna International Airport in 2008. Before the trial, the Office of the Privacy Commissioner of Canada (OPCC) reviewed a preliminary Privacy Impact Assessment and CATSA accepted recommendations from the OPCC.[37] In October 2009, an Assistant Privacy Commissioner, Chantal Bernier, announced that the OPCC had tested the scanning procedure, and the privacy safeguards that CATSA had agreed to would “meet the test for the proper reconciliation of public safety and privacy”.[38] In January 2010, Transport Canada confirmed that 44 scanners had been ordered, to be used in secondary screening at eight Canadian airports.[39] The announcement resulted in controversies over privacy, effectiveness and whether the exemption for those under 18 would be too large a loophole.[40][41][42]


The Ninoy Aquino International Airport in Manila installed body scanners from Smiths in all four airport terminals in 2015.[43] The scanners are not yet in use, and are controversial among some airport security screeners.[44]

Other applications[edit]

Scanners can be used for 3D physical measurement of body shape for applications such as apparel design, prosthetic devices design, ergonomics, entertainment and gaming.

See also[edit]


  1. ^ a b c d TSA: Imaging technology.
  2. ^ a b Mitchel Laskey (2010-03-17). "An Assessment of Checkpoint Security: Are Our Airports Keeping Passengers Safe?" (PDF). House Homeland Security Subcommittee on Transportation Security & Infrastructure Protection. 
  3. ^ a b Matthew Harwood (2010-03-05). "Companies Seek Full-Body Scans That Ease Health, Privacy Concerns". Security Management. 
  4. ^ Appleby, R (15 February 2004). "Passive millimetre–wave imaging and how it differs from terahertz imaging". Philosophical Transactions of the Royal Society. A: Mathematical, Physical and Engineering Sciences. 362 (1815): 379–393. doi:10.1098/rsta.2003.1323. Retrieved 31 December 2012. 
  5. ^ "Privacy Impact Assessment for TSA Whole Body Imaging" (PDF). Retrieved 2009-10-19. 
  6. ^ a b
  7. ^ Pilots criticize security as Britain makes body scanners mandatory – News & Advice, Travel. The Independent (2010-02-02). Retrieved on 2010-09-26.
  8. ^ Lundin, Leigh (2010-08-15). "You show me yours and …". Florida News. Orlando: Criminal Brief. Remember Homeland Security told the public the scanners aren’t capable of storing images? Someone forgot to tell the scanner at the federal courthouse in Orlando… 
  9. ^ Australia Airport Body Scanners - FAQ. Australian Government - TravelSECURE (2013-02-25). Retrieved on 2013-02-25.
  10. ^ MSNBC (2010-08-04). "Police agencies admit to saving body scan images". Retrieved 2010-08-10. 
  11. ^ The Daily Telegraph (2008-10-24). "Airport body scanners 'will expose personal dignity'". London. Retrieved 2010-01-03. 
  12. ^ Shah Rukh Khan's body scanner image was not printed, says Heathrow Airport | Mail Online. (2010-02-10). Retrieved on 2010-09-26.
  13. ^ One Hundred Naked Citizens: One Hundred Leaked Body Scans | Gizmodo (2010-11-16). Retrieved on 2010-11-16.
  14. ^ a b Nelson D.A.; Nelson M.T.; Walters T.J.; Mason P.A. (November 2000). "Skin Heating Effects of Millimeter-Wave Irradiation - Thermal Modeling Results". IEEE T. Microw. Theory. 48 (11): 2111–20. doi:10.1109/22.884202. Retrieved 2015-12-25. 
  15. ^ a b Millenbaugh N.J.; Kiel J.L.; Ryan K.L.; Blystone R.V.; Kalns J.E.; Brott B.J.; Cerna C.Z.; Lawrence W.S.; Soza L.L.; Mason P.A. (June 2006). "Comparison of blood pressure and thermal responses in rats exposed to millimeter wave energy or environmental heat". Shock. 25 (6): 625–32. doi:10.1097/01.shk.0000209550.11087.fd. PMID 16721271. Retrieved 2015-12-25. 
  16. ^ a b Zhadobov M.; Chahat N.; Sauleau R.; Le Quement C.; Le Drean Y. (April 2011). "Millimeter-wave interactions with the human body: state of knowledge and recent advances". Int. J. Microw. Wireless Technol. 3 (2): 237–47. doi:10.1017/S1759078711000122. Retrieved 2015-12-25.  "The biocompatibility of millimeter-wave devices and systems is an important issue due to the wide number of emerging body-centric wireless applications at millimeter waves. This review article provides the state of knowledge in this field and mainly focuses on recent results and advances related to the different aspects of millimeter-wave interactions with the human body. Electromagnetic, thermal, and biological aspects are considered and analyzed for exposures in the 30-100 GHz range with a particular emphasis on the 60-GHz band. Recently introduced dosimetric techniques and specific instrumentation for bioelectromagnetic laboratory studies are also presented. Finally, future trends are discussed."
  17. ^ a b Stewart D.A.; Gowrishankar T.R.; Weaver J.C. (August 2006). "Skin Heating and Injury by Prolonged Millimeter-Wave Exposure: Theory Based on a Skin Model Coupled to a Whole Body Model and Local Biochemical Release From Cells at Supraphysiologic Temperatures". IEEE T. Plasma Sci. 34 (4): 1480–93. doi:10.1109/TPS.2006.878996. Retrieved 2015-12-25. 
  18. ^ a b Moulder J.E. (June 2012). "Risks of Exposure to Ionizing and Millimeter-Wave Radiation from Airport Whole-Body Scanners". Radiation Research. 177 (6): 723–26. doi:10.1667/rr2897.1. Retrieved 2015-12-25. 
  19. ^ "Radiation Exposure and Cancer". Retrieved 1 December 2011. 
  20. ^ Ryan KL, D'Andrea JA, Jauchem JR, Mason PA (February 2000). "Radio frequency radiation of millimeter wave length: potential occupational safety issues relating to surface heating". Health Physics. 78 (2): 170–81. doi:10.1097/00004032-200002000-00006. PMID 10647983. Retrieved 2010-08-28.  "Thus, it is clear that RF radiation is not genotoxic and therefore cannot initiate cancer... the majority of such studies have shown that chronic exposure of animals to RF in the range of 435 to 2,450 MHz did not significantly alter the development of tumors in a number of animal cancer models... the same acceleration of skin cancer development and reduction in survival occurred in animals exposed to chronic confinement stress in the absence of RF exposure, suggesting that the RF effect could possibly be due to a non-specific stress reaction."
  21. ^ Mason, Patrick; Thomas J. Walters, John DiGiovanni, Charles W. Beason, James R. Jauchem, Edward J. Dick Jr, Kavita Mahajan, Steven J. Dusch, Beth A. Shields, James H. Merritt, Michael R. Murphy, Kathy L. Ryan (June 14, 2001). "Lack of effect of 94 GHz radio frequency radiation exposure in an animal model of skin carcinogenesis". Carcinogenesis. 22 (10): 1701–1708. doi:10.1093/carcin/22.10.1701. Retrieved 31 December 2012.  Cite uses deprecated parameter |coauthors= (help)
  22. ^ a b Nicolaz C.N.; Zhadobov M.; Desmots F.; Sauleau R.; Thouroude D.; Michel D.; Le Drean Y. (October 2009). "Absence of direct effect of low-power millimeter-wave radiation at 60.4 GHz on endoplasmic reticulum stress". Cell Biol. Toxicol. 25 (5): 471–8. doi:10.1007/s10565-008-9101-y. PMID 18685816. Retrieved 2015-12-25.  "Our data demonstrated the absence of significant changes in mRNA levels for BiP/GRP78. Our results showed that ER homeostasis does not undergo any modification at molecular level after exposure to low-power MMW radiation at 60.4 GHz. This report is the first study of ER-stress induction by MMW radiations."
  23. ^ Alexandrov BS, Gelev V, Bishop AR, Usheva A, Rasmunssen KØ, (October 2010). "DNA Breathing Dynamics in the Presence of a Terahertz Field". Physics Letters A/Physics-Bio PH. 374 (10). arXiv:0910.5294free to read. doi:10.1016/j.physleta.2009.12.077. 
  24. ^ German TV on the Failure of Full-Body Scanners. (2010-01-18). Retrieved on 2012-12-31.
  25. ^ Why Europe Doesn't Want an Invasion of Body Scanners. (2010-01-26). Retrieved on 2012-12-31.
  26. ^ Stinchfield, Grant. (2011-02-21) TSA Source: Armed Agent Slips Past DFW Body Scanner | NBC 5 Dallas-Fort Worth. Retrieved on 2012-12-31.
  27. ^ "Sweating Bullets: Body Scanners Can See Perspiration as a Potential Weapon". ProPublica. 2011-12-19. But two of Europe's largest countries, France and Germany, have decided to forgo the millimeter-wave scanners because of false alarms triggered by folds in clothing, buttons and even sweat. 
  28. ^ "Sweating Bullets: Body Scanners Can See Perspiration as a Potential Weapon". ProPublica. 2011-12-19. In Germany, the false positive rate was 54 percent, meaning that every other person who went through the scanner had to undergo at least a limited pat-down that found nothing. Jan Korte, a German parliament member who focuses on homeland security, called the millimeter-wave scanner "a defective product." 
  29. ^ Jennifer Brown (2011-01-03). "The ROI for detection". Canadian Security. 
  30. ^ Brendan Alexander (September 2008). "Streamlined Screening". Canadian Security. p. 26. 
  31. ^ Robert P. Daly (December 2008). "Facility Security:Security By The Layers". Security Products. p. 24. 
  32. ^ Brodie Clark (Volume 16.10). "Securing the border". Government Business. p. 25. Archived from the original on July 23, 2011.  Check date values in: |date= (help)
  33. ^ Marsico, Ron (2006-07-12) PATH riders to face anti-terror screening Program will begin at station in Jersey City. Star-Ledger
  34. ^ La Repubblica (2010-02-25). "Fiumicino, body scanners attivi da Giovedì 4 Marzo" (in Italian). Retrieved 2010-03-05. 
  35. ^ La Repubblica (2010-01-05). "Terrorismo, sì dell'Italia ai body scanner – Frattini: "Sicurezza prima della privacy"" (in Italian). Retrieved 2010-01-05. 
  36. ^ "Passengers virtually stripped naked by 3-D airport scanner". Canadian Broadcasting Corporation. 2008-06-20. Archived from the original on June 23, 2008. Retrieved 2008-06-20. 
  37. ^ Office of the Privacy Commissioner of Canada. "Report to Parliament 2008–2009 – Report on the Privacy Act". 
  38. ^ Bronskill, Jim (2009-10-30). "Privacy watchdog OKs 'naked' airport scanners". Toronto Star. Retrieved 2010-01-08. 
  39. ^ CBC News (2010-01-05). "Body scanners coming to Canadian airports". Retrieved 2010-01-08. 
  40. ^ "Airport scanners invade privacy: advocate". CBC News. 2010-01-05. Retrieved 2010-01-08. 
  41. ^ The Canadian Press (2010-01-05). "Airport scanner announcement ignites debate". CTV News. Retrieved 2010-01-08. 
  42. ^ Allison Jones (2010-01-06). "Security experts wary of Canada's airport scanner exemption for minors". Winnipeg Free Press. Retrieved 2010-01-08. 
  43. ^ "Full-body scanners ready for use in NAIA terminals". ABS-CBN News. 2015-08-07. Retrieved 2015-08-29. 
  44. ^ "NAIA screeners not impressed with new full-body scanners". ABS-CBN News. 2015-08-12. Retrieved 2015-08-29. 

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