[ RadSafe ] bakscatter xray

Tue Nov 16 04:49:28 CST 2010

A couple of things here, please bear with me.

1.
Apparently these units operate at 28kV - in the UK, 28kV is the energy commonly used to take xrays of the breast in mammography. At this energy, xrays DO pass through soft tissue and form an image on a receptor. It is accepted that the national breast screening program NBSP will cause a small number of cancers within the breast due to the use of ionising radiation - however, more lives will be saved rather than lost.

I understand that doses used in these backscatter devices are low, but I would like to see independent measurements of dose published in a peer reviewed journal.

2.
Why do we even need to use millimetre wave / xray. Several years ago, SONY brought out a "night vision" video camera which when coupled with a IR filter, could "see through" clothing. I'm sure with a little application, a simple high speed mass screening device can be manufactured. (Why is it, whenever I hear of these devices, I think of the film starring Arnold Schwarzenegger: "Total Recall".)

3.
Hmm, does the US recognise the conflict with the "Enhanced patdown" and Human Rights?

Many say that national security is more important, however, from the UN we get this - (copied from Wiki for speed). Is the 2nd paragraph being followed?

Human rights vs National Security

With the exception of non-derogable human rights (international conventions class the right to life, the right to be free from slavery, the right to be free from torture and the right to be free from retroactive application of penal laws as non-derogable), the UN recognises that human rights can be limited or even pushed aside during times of national emergency - although

" the emergency must be actual, affect the whole population and the threat must be to the very existence of the nation. The declaration of emergency must also be a last resort and a temporary measure " - United Nations.

Rights that cannot be derogated for reasons of national security in any circumstances are known as peremptory norms or jus cogens. Such United Nations Charter obligations are binding on all states and cannot be modified by treaty.

4.
Let's look at individual articles, specifically 1, 3, 5, 12, 13 from the Universal declaration of Human rights :

Article 1

All human beings are born free and equal in dignity and rights. They are endowed with reason and conscience and should act towards one another in a spirit of brotherhood

Article 3
Everyone has the right to life, liberty and security of person.

Article 5
No one shall be subjected to torture or to cruel, inhuman or degrading treatment or punishment.

Article 12
No one shall be subjected to arbitrary interference with his privacy, family, home or correspondence, nor to attacks upon his honour and reputation. Everyone has the right to the protection of the law against such interference or attacks.

Article 13
Everyone has the right to freedom of movement and residence within the borders of each state.
Everyone has the right to leave any country, including their own, and to return to their country.

Given the article forwarded to the list by Terry, I can see a conflict with these Articles.

Article 1 is violated by failing to be treated with dignity. It could be argued that the "spirit of brotherhood" is being violated by both parties.

Article 3 is violated by the "passenger" by failing to agree to the security of others by refusing screening. However, his liberty is being violated by being put in a situation where his dignity must be compromised or he must pay a fine.

Article 5 - the "enhanced patdown" is widely described as being degrading. Look at forms dedicated to airline staff and you will see what I mean.

Article 12 - backscatter/millimetre wave scanners "see through" clothing, revealing intimate personal details, thus violating privacy.

Article 13 - by failing to freely release the passenger from the screening area after he refused screening, freedom of movement has been violated.

On a personal note, I refuse to travel by air at the moment, not through fear of terrorism, but primarily through the intrusive, excessive and mis-targeted "security" process at the airport.

Please discuss ...

Dave

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Jeff Terry
Sent: 15 November 2010 22:27
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] bakscatter xray

Sorry, I may have missed if someone else posted this but be careful, if refusing the backscatter treatment.

Here is a story of someone who refused:
http://johnnyedge.blogspot.com/2010/11/these-events-took-place-roughly-between.html

He may have made himself eligible for a $10000.00 leaving the airport without being screened fine.

Definitely, some odd video worth watching (listening).

Of course, Homeland Security Chief Janet Napolitano replies that travelers should "use our common sense."

http://politics.blogs.foxnews.com/2010/11/15/dhs-chief-says-abandoning-airport-scanners-would-be-irresponsible-ca-man-warns-tsa-not-to

Of course, common sense is something that the U. S. government exudes.

I wonder if I can get myself in trouble with another DHS Secretary.

Jeff

Jeff Terry
Asst. Professor of Physics
Life Science Bldg Rm 166
Illinois Institute of Technology
3101 S. Dearborn St.
Chicago IL 60616
630-252-9708
terryj at iit.edu

On Nov 14, 2010, at 8:57 PM, conrad sherman wrote:

> here is the letter from ucsf and response
>
> LETTER OF CONCERN
>
>
> We are writing to call your attention to serious concerns about the potential health risks of the recently adopted whole body backscatter X-ray airport security scanners.This is an urgent situation as these X-ray scanners are rapidly being implemented as a primary screening step for all air travel passengers.
>
> Our overriding concern is the extent to which the safety of this scanning device has been adequately demonstrated.This can only be determined by a meeting of an impartial panel of experts that would include medical physicists and radiation biologists at which all of the available relevant data is reviewed.
>
> An important consideration is that a large fraction of the population will be subject to the new X-ray scanners and be at potential risk, as discussed below.This raises a number of 'red flags'.Can we have an urgent second independent evaluation?
>
> The Red Flags
>
> The physics of these X-rays is very telling: the X-rays are Compton-Scattering off outer molecule bonding electrons and thus inelastic (likely breaking bonds).
>
> Unlike other scanners, these new devices operate at relatively low beam energies
>
> (28keV).The majority of their energy is delivered to the skin and the underlying
>
> tissue. Thus, while the dose would be safe if it were distributed throughout the volume of the entire body, the dose to the skin may be dangerously high.
>
> The X-ray dose from these devices has often been compared in the media to the cosmic ray exposure inherent to airplane travel or that of a chest X-ray. However, this comparison is very misleading: both the air travel cosmic ray exposure and chest X- rays have much higher X-ray energies and the health consequences are appropriately understood in terms of the whole body volume dose.In contrast, these new airport scanners are largely depositing their energy into the skin and immediately adjacent tissue, and since this is such a small fraction of body weight/vol, possibly by one to two orders of magnitude, the real dose to the skin is now high.
>
> In addition, it appears that real independent safety data do not exist.A search, ultimately finding top FDA radiation physics staff, suggests that the relevant radiation quantity, the Flux [photons per unit area and time (because this is a scanning device)] has not been characterized.Instead an indirect test (Air Kerma) was made that emphasized the whole body exposure value, and thus it appears that the danger is low when compared to cosmic rays during airplane travel and a chest X-ray dose.
>
> In summary, if the key data (flux-integrated photons per unit values) were available, it would be straightforward to accurately model the dose being deposited in the skin and
>
> Letter of Concern -- Page 2
>
> adjacent tissues using available computer codes, which would resolve the potential concerns over radiation damage.
>
> Our colleagues at UCSF, dermatologists and cancer experts, raise specific important concerns:
>
> .A) The large population of older travelers, >65 years of age, is particularly at risk from the mutagenic effects of the X-rays based on the known biology of melanocyte aging.
>
> .B) A fraction of the female population is especially sensitive to mutagenesis- provoking radiation leading to breast cancer.Notably, because these women, who have defects in DNA repair mechanisms, are particularly prone to cancer, X-ray mammograms are not performed on them.The dose to breast tissue beneath the skin represents a similar risk.
>
> .C) Blood (white blood cells) perfusing the skin is also at risk.
>
> .D) The population of immunocompromised individuals--HIV and cancer patients (see above) is likely to be at risk for cancer induction by the high skin dose.
>
> .E) The risk of radiation emission to children and adolescents does not appear to have been fully evaluated.
>
> .F) The policy towards pregnant women needs to be defined once the theoretical risks to the fetus are determined.
>
> .G) Because of the proximity of the testicles to skin, this tissue is at risk for sperm mutagenesis.
>
> .H) Have the effects of the radiation on the cornea and thymus been determined? Moreover, there are a number of 'red flags' related to the hardware itself. Because this
>
> device can scan a human in a few seconds, the X-ray beam is very intense. Any glitch in power at any point in the hardware (or more importantly in software) that stops the device could cause an intense radiation dose to a single spot on the skin.Who will oversee problems with overall dose after repair or software problems?The TSA is already complaining about resolution limitations; who will keep the manufacturers and/or TSA from just raising the dose, an easy way to improve signal-to-noise and get higher resolution?Lastly, given the recent incident (on December 25th), how do we know whether the manufacturer or TSA, seeking higher resolution, will scan the groin area more slowly leading to a much higher total dose?
>
> After review of the available data we have already obtained, we suggest that additional critical information be obtained, with the goal to minimize the potential health risks of
>
> Letter of Concern -- Page 3
>
> total body scanning. One can study the relevant X-ray dose effects with modern molecular tools.Once a small team of appropriate experts is assembled, an experimental plan can be designed and implemented with the objective of obtaining
>
> information relevant to our concerns expressed above, with attention paid to completing the information gathering and formulating recommendations in a timely fashion.
>
> We would like to put our current concerns into perspective.As longstanding UCSF scientists and physicians, we have witnessed critical errors in decisions that have seriously affected the health of thousands of people in the United States.These unfortunate errors were made because of the failure to recognize potential adverse outcomes of decisions made at the federal level.Crises create a sense of urgency that frequently leads to hasty decisions where unintended consequences are not recognized. Examples include the failure of the CDC to recognize the risk of blood transfusions in the early stages of the AIDS epidemic, approval of drugs and devices by the FDA without sufficient review, and improper standards set by the EPA, to name a few. Similarly, there has not been sufficient review of the intermediate and long-term effects of radiation exposure associated with airport scanners. There is good reason to believe that these scanners will increase the risk of cancer to children and other vulnerable populations. We are unanimous in believing that the potential health consequences
>
> need to be rigorously studied before these scanners are adopted.Modifications that reduce radiation exposure need to be explored as soon as possible.
>
> In summary we urge you to empower an impartial panel of experts to reevaluate the potential health issues we have raised before there are irrevocable long-term consequences to the health of our country.These negative effects may on balance far outweigh the potential benefit of increased detection of terrorists.
>
> October 12, 2010
>
> Dr. John P. Holdren
> Assistant to the President for Science and Technology
> Director, Office of Science and Technology Policy
> Executive Office of the President
> New Executive Office Building
> 725 17th St. NW
> Washington, DC 20502
>
> Dear Dr. Holdren,
>
> Thank you for sharing the April 6 letter you received regarding general-use full-body x-ray screening systems used for airport security. As with all x-ray security products, justified application demands a balancing act: The radiation dose delivered must be sufficient to do the job---in this case to identify security threats---while presenting no more than a miniscule risk to people being scanned, including special populations.
>
> The overriding concern expressed in the letter is the extent to which the safety of the security devices has been adequately demonstrated. Since 1990, the Food and Drug Administration (FDA) has regulated manufacturers to ensure the radiation safety of full-body x-ray security screening systems. The FDA consulted its Technical Electronic Product Radiation Safety Standards Committee (TEPRSSC) about these products during several meetings from 1998 through 2003. TEPRSSC is the independent advisory committee to FDA with expertise in electronic product radiation issues. This expert committee raised several issues during these meetings and FDA responded by initiating work on a consensus radiation safety standard through the American National Standards Institute (ANSI) and Health Physics Society (HPS). FDA assembled a working group of experts that included representatives from manufacturers, security agencies, and other regulatory agencies. The working group produced a national standard, /Radiation Safety for Personnel Security Screening Systems Using X-rays/^1 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn1> /, /which was published in July 2002. The 2002 standard required facilities to ensure that no individual scanned received an effective dose in excess of 0.25 mSv (25 mrem) in any 12-month period. The standard also provided other guidelines specific to the radiation safety aspects of the design and operation of these systems. This annual dose limit is based on the National Council of Radiation Protection and Measurements^2 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn2> (NCRP) recommendations for the annual effective dose limit for individual members of the general public^3 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn3> . NCRP's dose limitation recommendations for the general public were made with the understanding that the general public includes special populations that are more sensitive to radiation, such as children.
>
> In September 2002 FDA asked the NCRP to undertake a study that led to NCRP Commentary No. 16 (2003/), Screening of Humans for Security Purposes Using Ionizing Radiation Scanning Systems/. The committee that prepared this commentary included representatives from the Milton S. Hershey Medical Center, Columbia University, FDA's Center for Devices and Radiological Health, the U.S. Environmental Protection Agency, and the /NCRP Secretariat /consulting staff. This commentary introduced the concept of general-use and limited-use systems. Commentary No. 16 recommended g eneral-use systems should not exceed the dose limit set in the 2002 standard and can be used mostly^4 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn4> without regard to the number of individuals scanned or the number of scans per individual in a year.
>
> FDA brought the issue of consistent federal evaluation and justification of security screening practices that used ionizing radiation to the Interagency Steering Committee on Radiation Standards (ISCORS)^5 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn5> . ISCORS was established to foster early resolution and coordination of regulatory issues associated with radiation standards and guidelines. ISCORS published /Guidance for Security Screening of Humans Utilizing Ionizing Radiation /(2008) to assist Federal agencies in determining when the use of ionizing radiation for security screening of humans is warranted and to provide guidelines for establishing a radiation safety program. The Transportation Security Administration (TSA), FDA, Occupational Safety and Health Administration, National Institute of Standards and Technology (NIST), U.S. Army Center for Health Promotion and Preventive Medicine, Nuclear Regulatory Commission, Environmental Protection Agency, Federal Bureau of Prisons, Department of Energy, Customs and Border Protection, Central Intelligence Agency, Maryland Department of the Environment, and Pennsylvania Bureau of Radiation Protection collaborated in developing this federal guidance.
>
> Since publication of the original 2002 standard, a number of new system designs have been developed, including portal systems, multi-source systems, vehicle scanners meant for screening occupied vehicles, scanners for inspecting casts and prosthetic devices, and scanners using a radioisotope as the source of radiation. New uses for these systems include the use of vehicle and cargo scanners to inspect people and the limited use of higher-dose systems as defined in NCRP Commentary No. 16. Consequently, FDA and NIST chaired a working group to revise the national standard^6 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn6> . The revised standard, /Radiation Safety for Personnel Security Screening Systems Using X-Ray or Gamma Radiation/^7 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn7> , was published November 2009. It includes requirements that cover these new designs and uses. This standard applies to security screening systems in which people are intentionally exposed to primary beam x-rays and provides guidelines specific to radiation safety in the design and operation of these systems.The standard covers doses to individuals scanned, safety systems, operational procedures, information to provide to screened individuals, training for operators, and other issues. The revised standard retained the annual effective dose limit for members of the public of 0.25 mSv (25 mrem). This standard defines a /general-use /x-ray screening system as one that delivers less than 1/1000 of this dose per screening (0.25 µSv (25 µrem)). The rationale for the annual and per screening dose limits is presented in the standard^8 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn8> .
>
> TSA requires that the full-body x-ray security systems approved for deployment (Advanced Imaging Technology (AIT)) conform to the requirements in the 2009 standard for general-use systems. Surveys of the recently deployed backscatter x-ray personnel security screening systems have been performed by an independent party to confirm compliance with the radiation dose-per-screening limits for general-use of the 2009 standard.  All systems surveyed to date have been found to comply with the general-use dose-per-screening limit in that standard.  In addition, our independent survey teams are gathering area radiation dose data by mounting dosimeters on (within the inspection zone) select systems.
>
> Regarding the specific "Red Flag" issues raised in the letter:
>
> First, the letter is correct to note that the TSA-deployed product is a recent model. However, the specification for the x-ray tube for the deployed model is almost identical to the original 1991 product. The stated concern was, "The majority of their energy is delivered to the skin and the underlying tissue." We agree. However, the concern that "the dose to the skin may be dangerously high" is not supported. The recommended limit for annual dose to the skin for the general public is 50,000 µSv^9 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn9> . The dose to the skin from one screening would be approximately 0.56 µSv^10 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn10> when the effective dose for that same screening would be 0.25 µSv^11 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn11> . Therefore the dose to skin for the example screening is at least 89,000 times lower than the annual limit.
>
> Second, radiation safety protection quantities are stated as 'effective dose'^12 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn12> . NCRP Commentary No. 16 says, "The purpose of effective dose^13 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn13> is to place on a common scale the radiation doses: (1) from different types of ionizing radiation that have different biological effectiveness, and (2) in different organs or tissues that have different radiation sensitivities." Comparing effective doses from different sources is appropriate. The comparison between the effective dose from cosmic ray exposure or a medical diagnostic chest x-ray and the effective dose from a security screening is intended to be a clear means of risk communication.
>
> The third point relates to a concern "that real independent safety data do not exist." In fact, independent safety data do exist. Independent measurements have been made on various versions of this product and all results are consistent with the dose specified by the manufacturer. Examples include:
>
>   * Sandia National Laboratories, measurements made July 1991.
>     Published as Sandia Report: /Evaluation Tests of the SECURE 1000
>     Scanning System/ (1992), National Technical Information Service,
>     DE92013773
>   * FDA, dose measurements re-verified via computational evaluation,
>     September 15, 1998
>   * N43.17 working group, measurements made at Folsom State Prison on
>     November 15, 1999
>   * FDA & NIST, Assessment for TSA, July 21, 2006
>   * Johns Hopkins University Applied Physics Laboratory (JHU APL),
>     Assessment for TSA, October 2009
>
> Fourth is the concern that "the relevant radiation quantity, the Flux [photons per unit area and time (because this is a scanning device)] has not been characterized." We disagree that flux is the appropriate quantity. The air kerma (or skin entrance exposure) for one screening can be determined by a direct measurement of the total charge produced in the air contained in an ion chamber during one complete screening when the meter is correctly calibrated^14 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn14> . Additionally, measurements to determine the amount of material required to reduce the intensity of the x-ray exposure by half^16 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn16> are necessary to convert air kerma (or exposure) to effective dose^15 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn15> . These measurements can most practically be made ---and indeed have been repeatedly made--- at locations where these products are installed and can be made without altering a scanner's normal operation. These are the same sorts of measurements made to characterize the output of medical x-ray systems^17 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn17> .
>
> Fifth is the assertion that "if the key data (flux-integrated photons per unit values) were available, it would be straightforward to accurately model the dose being deposited in the skin and adjacent tissues using available computer codes [. . .]" In fact, we have done better. FDA and NIST used software called PCXMC^18 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn18> to estimate the individual organ doses and to calculate effective dose. This analysis was part of an evaluation performed under contract for TSA. The input information required by the PCXMC program required considerably more information than simply the x-ray flux. Its parameters include 1) the x-ray tube anode angle, 2) anode voltage, 3) total filtration, 4) x-ray field size, 5) location of the field on the body, 6) focus-to-skin distance (FSD), and 7) entrance skin exposure. Every parameter was measured, calculated, or verified by indirect measurement. The modeling results revealed that the dose to the skin is approximately twice the effective dose^19 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn19> .
>
> The letter continues: "[. . .] which would resolve the potential concerns over radiation damage." Direct measurements of the exposure or air kerma from one screening combined with measurements to determine the half-value layer provide sufficient information to adequately estimate the effective dose. There are a number of available publications by groups of recognized experts regarding the biological effects of ionizing radiation and the risk of detriment related to the effective dose. These documents include /Health Risks from Exposure to Low Levels of Ionizing Radiation/ : BEIR VII Phase 2 (2006) and NCRP report no. 115 /Risk Estimates for Radiation Protection/, as well as the documents that specifically address security screening of people with ionizing radiation mentioned in this letter.
>
> Other specific concerns expressed in the letter are based on the assumption that a screening results in skin or other organ doses that are orders of magnitude higher than the effective dose per screening. The dose to other organs is less than, equal to, or at most approximately three times the effective dose^20 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn20> for the deployed product. The annual dose limit for security screening is the same as the NCRP recommendations for the annual effective dose limit for the general public including special populations^21 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn21> . An individual would have to receive more than 1000 screenings to begin to approach the annual limit.
>
> With regard to concerns about the hardware itself, the standard requires that products have safety systems to terminate emission of the primary beam in the event of any system problem that could result in abnormal or unintended radiation emission. The scan motion cannot be adjusted. If the scan motion were intentionally redesigned and changed to scan the groin at a slower rate than the rest of the body, the point of measurement to determine the dose per screening would also change. The dose per screening measurement must be made at the point of maximum exposure in order to comply with the standard. Manufacturers are required to report changes to a product's performance specifications when those changes can affect radiation safety, as would be the case with any change to dose per screening.
>
> These products have been available commercially in the United States since 1992. Manufacturers of any type of electronic product that emits radiation -- including full-body x-ray security systems -- are required to notify FDA immediately upon discovery of any accidental radiation occurrence or radiation safety defect. TSA policy is to require a survey of x-ray systems annually, after any maintenance that could affect radiation shielding, and after any impacts that could affect radiation shielding. FDA regulations require notifications if the manufacturer or FDA determines that an electronic product emits radiation unnecessary to the accomplishment of its primary purpose creating a risk of injury, including genetic injury, to any person. Such a product is then considered to have a radiation safety defect. Unless a manufacturer can provide evidence that a significant risk to public health is not created by a defect, the manufacturer is required to repair, repurchase, or replace its products. Raising the dose delivered without gaining a commensurate increase in safety could be grounds to declare that a product emits radiation unnecessary to the accomplishment of its primary purpose and thus has a radiation safety defect. Products and practices that comply with the American national radiation safety standard^22 <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm#_ftn22> do not present a significant risk to public health.
>
> In summary, the potential health risks from a full-body screening with a general-use x-ray security system are miniscule. Several groups of recognized experts have been assembled and have analyzed the radiation safety issues associated with this technology. These experts have published recommendations, commentaries, technical reports, and an American national radiation safety standard as a result of their analyses. This technology has been available for nearly two decades and we have based our evaluation on scientific evidence and on the recommendations of recognized experts. Public meetings were held to discuss these products with FDA's advisory panel (TEPRSSC), and the American national radiation safety standard was available for public comment both before its initial publication and before its recently published revision. There are numerous publications regarding the biological effects of radiation and the appropriate protection limits for the general public that apply to these products. As a result of these evidence-based, responsible actions, we are confident that full-body x-ray security products and practices do not pose a significant risk to the public health.
>
> We enclose a list of references to some of the relevant reports, commentaries, and the current safety standard. If you have any further questions or concerns, please contact either of the individuals listed below.
>
> Sincerely yours,
>
>
> John L. McCrohan
> Deputy Director for Technical and Radiological Initiatives
> Office of Communication, Education, and Radiation Programs
> Center for Devices and Radiological Health
> Food and Drug Administration
>
> Karen R. Shelton Waters
> Deputy Assistant Administrator / Chief Administrative Officer
> Designated Safety and Health Official
> Transportation Security Administration
>
> Enclosure
>
> *REFERENCES *
>
>   * ANSI/HPS N43.17-2009 /Radiation Safety for Personnel Security
>     Screening Systems Using X-Ray or Gamma Radiation/
>     (http://hps.org/hpssc/)
>         o More information on the ANSI standards setting process is
>           available on the ANSI website
>           (http://www.ansi.org/standards_activities/overview/overview.aspx?menuid=3
>           )
>   * Interagency Steering Committee on Radiation Standards (ISCORS),
>     /Guidance on Security Screening of Humans Using Ionizing Radiation
>     (GSSHUIR) /Report
>     (http://www.iscors.org/doc/GSSHUIR%20July%202008.pdf)
>   * NCRP commentary 16, /Screening of humans for security purposes
>     using ionizing radiation scanning systems/ (2003)
>     (http://www.ncrppublications.org/Commentaries/16)
>         o Press release regarding commentary no. 16 (May 26, 2010)
>           (http://www.ncrponline.org/Press_Rel/Commentaries/Comm_16_Press_Release.pdf)
>   * /NCRP Statement 10, Recent Applications of the NCRP Public Dose
>     Limit Recommendation for Ionizing Radiation/(2004)
>     (http://www.ncrponline.org/Publications/Statements/Statement_10.pdf)
>   * NCRP report no. 115 /Risk Estimates for Radiation Protection /(1993)
>   * NCRP report no. 116 /Limitation of Exposure to Ionizing Radiation/
>     (1993)
>     (http://www.ncrppublications.org/index.cfm?fm=Product.AddToCart&pid=9143114606
>     <http://www.ncrppublications.org/index.cfm?fm=Product.AddToCart&pid=9143114606>)
>   * /NCRP rep/ort no. 160, /Ionizing Radiation Exposure of the
>     Population of the United States (2009)/
>     (http://www.ncrppublications.org/Reports/160)
>   * HPS Position Statement /Use of Ionizing Radiation for Security
>     Screening Individuals/
>     (http://hps.org/documents/securityscreening_ps017-1.pdf)
>   * American College of Radiology (ACR) /Statement on Airport
>     Full-body Scanners and Radiation
>     /(http://www.acr.org/SecondaryMainMenuCategories/NewsPublications/
>     FeaturedCategories/CurrentACRNews/archive/StatementonAirportFullbodyScanners.aspx
>     <http://www.acr.org/SecondaryMainMenuCategories/NewsPublications/FeaturedCategories/CurrentACRNews/archive/StatementonAirportFullbodyScanners.aspx>).
>   * U.S. Transportation Security Administration's (TSA) web site
>     regarding advanced imaging technology
>     (http://www.tsa.gov/approach/tech/imaging_technology.shtm).
>   * Information on laws and regulations applicable to manufacturers of
>     people screening security systems that use x-rays is available on
>     FDA's /X-Ray & Particulate Products other than Medical Diagnostic
>     or Cabinet/ page (http://www.fda.gov/Radiation-EmittingProducts/
>     RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/ucm116416.htm
>     <http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/ucm116416.htm>
>     )
>   * The concept of justification based on a societal benefit appears
>     in the International Commission on Radiological Protection (ICRP)
>     report 60 (see paragraph S14).
>     (http://www.icrp.org/downloadDoc.asp?document=docs/Summary_B-scan_ICRP_60_Ann_ICRP_1990_Recs.pdf)
>   * Health Physics Society fact sheet on Environmental radiation
>     (http://hps.org/documents/environmental_radiation_fact_sheet.pdf)
>   * Security screening with x-rays was discussed at several Technical
>     Electronic Product Radiation Safety Standards Committee (TEPRSSC)
>     meetings
>     (http://www.fda.gov/AdvisoryCommittees/CommitteesMeetingMaterials/Radiation-EmittingProducts/TechnicalElectronicProductRadiationSafetyStandardsCommittee/default.htm).
>     The last discussion took place during the October 1, 2003 meeting
>     (http://www.fda.gov/ohrms/dockets/ac/cdrh03.html#TechnicalElectronicProduct).
>   * Sandia Report: Evaluation Tests of the SECURE 1000 Scanning System
>     (http://www.ntis.gov/search/product.aspx?ABBR=DE92013773)
>   * Health Risks from Exposure to Low Levels of Ionizing Radiation:
>     BEIR VII Phase 2 (2006)
>     (http://www.nap.edu/openbook.php?record_id=11340&pag
>     <http://www.nap.edu/openbook.php?record_id=11340&pag>)
>   * Assessment of the /Rapiscan Secure 1000 ® Body Scanner for
>     Conformance with Radiological Safety Standards/. July 21, 2006,
>     produced for TSA, measurements made at FDA, report completed at
>     NIST (http://www.tsa.gov/research/reading/index.shtm)
>   * /Radiation Safety Engineering Assessment Report for the Rapiscan
>     Secure 1000 in Single Pose Configuration/,Johns Hopkins University
>     Applied Physics Laboratory, Assessment for TSA, October 2009 and
>     revised August 2010 (http://www.tsa.gov/research/reading/index.shtm)
>
> ------------------------------------------------------------------------
>
> ^1 ANSI/HPS N43.17-2002 /Radiation Safety For Personnel Security Screening Systems Using X-rays/
>
> ^2 NCRP was founded in 1964 by the U.S. Congress to "cooperate with the International Commission on Radiological Protection, the Federal Radiation Council, the International Commission on Radiation Units and Measurements, and other national and international organizations, governmental and private, concerned with radiation quantities, units and measurements and with radiation protection."
>
> ^3 NCRP report no. 116 /Limitation of exposure to ionizing radiation/ (1993); pages 45-47, 56
>
> ^4 "Mostly" refers to the unlikely situation where individuals are routinely screened so many times in one 12-month period that the annual dose limit would be exceeded. For example, an individual can be screened 19 times each week and would not receive more than the annual dose limit.
>
> ^5 Initial presentation October 20, 2003
>
> ^6 1st work group meeting May 11, 2006
>
> ^7 ANSI/HPS N43.17-2009 /Radiation Safety for Personnel Security Screening Systems Using X-Ray or Gamma Radiation/
>
> ^8 Ibid (ANSI/HPS N43.17-2009): "Various organizations have studied the biological effects of ionizing radiation exposure. The National Council on Radiation Protection and Measurements (NCRP) reviewed two independent studies, one by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR 1988) and the other by the National Academy of Sciences/National Research Council, Committee on the Biological Effects of Ionizing Radiation, known as BEIR V (NAS/NRC 1990). Based on this review, the NCRP recommends that, for radiation protection purposes, an incremental lifetime risk of fatal cancer of 5% per sievert be used for the general population (NCRP 1993). The 5% per sievert risk is also consistent with the more recent BEIR VII report (NAS/NRC 2006). Application of this risk estimate means that each 0.01 ?Sv (1 ?rem) of effective dose received is considered to contribute 5 × 10^-10 (one chance in two billion) to an individual's risk of contracting a fatal cancer during his or her lifetime. These low-dose estimates assume a "linear no-threshold" relationship between radiation exposure and health effects.
>
> Both the NCRP and the International Commission on Radiological Protection (ICRP) recommend that members of the general population who are frequently exposed to ionizing radiation not exceed an annual effective dose of 1 mSv (100 mrem) from all man-made, non-medical sources (NCRP 1993; ICRP 2007). Further, the NCRP recommends that institutions ensure that the individuals they expose do not repeatedly exceed the 1 mSv yearly limit from all non-medical sources. Information relating to other sources of radiation exposure may be difficult to obtain, so institutions have the option to ensure that the radiation sources under their own control do not contribute to an individual more than an annual effective dose of 0.25 mSv (25 mrem).
>
> General-use systems operating in accordance with this standard produce a maximum reference effective dose of 0.25 ?Sv (25 ?rem) per screening. Therefore, an individual may be screened up to 1,000 times each year without exceeding the annual 0.25 mSv (25 mrem) limit. The associated incremental risk of death is 1 in 80,000,000 per screening."
>
> ^9 NCRP report no. 116 /Limitation of exposure to ionizing radiation/ (1993), page 56
>
> ^10 FDA & NIST Assessment of the /Rapiscan Secure 1000® Body Scanner for Conformance with Radiological Safety Standards/. July 21, 2006, produced for TSA. This skin dose is an estimate based on dose modeling. This estimate is only for products with very similar x-ray output. The difference between skin and effective dose is smaller for products that use higher energy or more filtration.
>
> ^11 The actual dose per screening specification is 0.05 µSv or less http://www.rapiscansystems.com/rapiscan-secure-1000-single-pose-health.html. The JHU APL assessment report confirms that the product meets this specification.
>
> ^12 NCRP report no. 158/Uncertainties in the Measurement and Dosimetry of External Radiation/, page 22
>
> ^13 Radiation doses from exposures that may result in delayed stochastic effects are expressed in the quantity effective dose (/E/):
>
> E =
>
>
>
> ?/w/_T /H/_T ,
>
>
>
> ^T
>
> where /H/_T is the equivalent dose in an organ or tissue T, and /w/_T is the tissue weighting factor that accounts for the radiation sensitivity of organ or tissue T.
>
> ^14 ANSI/HPS N43.17-2009 /Radiation Safety for Personnel Security Screening Systems Using X-Ray or Gamma Radiation,/ section 'C.3.2 Calibration'
>
> ^15 This quantity is called the half-value layer (HVL). HVL is often expressed in terms of the thickness of aluminum required.
>
> ^16 ANSI/HPS N43.17-2009 /Radiation Safety for Personnel Security Screening Systems Using X-Ray or Gamma Radiation,/ section '6.0 Dose Limitation' and 'A.1 Reference Effective Dose'
>
> ^17 Nationwide Evaluation of X-Ray Trends (NEXT) (http://www.fda.gov/Radiation-EmittingProducts/RadiationSafety/ NationwideEvaluationofX-RayTrendsNEXT/default.htm <http://www.fda.gov/Radiation-EmittingProducts/RadiationSafety/NationwideEvaluationofX-RayTrendsNEXT/default.htm>)
>
> ^18 Servomaa, A. and Tapiovaara, M. Organ dose Calculation in Medical X Ray Examinations by the Program PCXMC. Radiation Protection Dosimetry 80, 213-219 (1998).
>
> ^19 FDA & NIST Assessment of the /Rapiscan Secure 1000® Body Scanner for Conformance with Radiological Safety Standards/. July 21, 2006, produced for TSA.
>
> ^20 FDA & NIST Assessment (2006); Our dose modeling reveals that a screening that delivers 0.25 µSv effective dose would deliver approximately 0.12 µSv to the uterus or 0.69 µSv to the testes. This estimate applies to products with very similar x-ray output.
>
> ^21 NCRP Statement 10/, Recent Applications of the NCRP Public Dose Limit Recommendation for Ionizing Radiation/ (2004) and NCRP report no. 116 /Limitation of exposure to ionizing radiation/ (1993).
>
> ^22 ANSI/HPS N43.17-2009 /Radiation Safety for Personnel Security Screening Systems Using X-Ray or Gamma Radiation/
>
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