Scanning machines

[Mikey]

I seem to recall a newspaper article somewhere telling us that the type of

security scanner used in Canada for the full body scans is different than the one the Americans use.

Supposedly the Canadian version uses sound wave technology(?) vs the American one

that uses x-ray technology. Again supposedly, sound waves don't injure the

person being scanned whereas the x-ray used by the Americans is a proven

carcinogen (can cause cancer).

Does anyone know about this and if so .... is it true?

[Don Hudson]

Here you go:

Types of Scanners

There are two types of full-body scanning systems: one uses millimetre-wave technology and the other uses x-ray technology.

The scanning systems currently used in Canada are millimetre-wave scanners, which do not emit x-rays. The millimetre-wave body scanner works by projecting low-level millimetre-wave, radio-frequency (RF) energy above and around the passenger's body. The RF energy is reflected back from the body and from objects concealed on the body to produce a three-dimensional image. Only a small portion of the RF energy transmitted by the device is absorbed within a thin layer (1 mm) of the body's surface.

X-ray scanners emit low levels of x-rays, which are a form of electromagnetic ionizing radiation. This type of scanner is not in use in Canadian airports.

Safety of Full-Body Scanners Used in Canada

The millimetre-wave scanners do not pose a risk to human health and safety. Health Canada has assessed the technical information on these devices and concluded that the radiofrequency energy emitted by the device is well within Canada's guidelines for safe human exposure.

The electromagnetic non-ionizing radiation used in these scanners is based on millimetre wave technology and does not pose a risk to human health and safety, from either single or repeated exposures.

Information Source at Health Canada

The key in this debate is information from knowledgable sources.

In April, 2010, the following was sent to the TSA by the undersigned, expressing concern regarding radiation levels of TSA Scanning machines.

Crews already receive higher doses of high-energy radiation than even most passengers due to the frequency of travel. There are a number of peer-reviewed papers and cohort studies on the issue of high altitude radiation leaving little doubt regarding the issue and the risk of exposure to unacceptable levels of radiation. The issue is about 20 years old now and should have been addressed when the issue was first understood then. It is still not understood and not enough information is known about the current security techniques. Here is the letter and the memo to the TSA:

"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 Xrays 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 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 mutagenesisprovoking 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 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. xx 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."

Edited for accurate reproduction of text

[Mikey]

Thank you gentlemen:

I appreciate the replies coming so quickly .... you both must be

quite on top of the subject.

I made the request for info as my spouse is a B. Cancer survivor and

as we travel frequently into the U.S. by air, I am concerned that she

get the least amount of radiation possible.

Having said that I am also concerned that she not be subject to the style

of "pat down" searches that seem to be in use in recent days. I have no desire to

spend time in cells for smacking some overly-intrusive security inspector nor do

I want to go to the hassle of having my name removed from the "no fly" list for doing so.

I read in the National Post just yesterday that a group of senators in the U.S. had put forward a

bill reaffirming that the border inspection folks will be held accountable for all transgressions occurring

during their inspections to the same degree that a normal individual would be held to account for

sexual assault, lewd or inappropriate touching, etc. etc.

Hopefully it will do some good.

Or maybe the Americans can simply buy our machines ...... I am told we make good ones that don't

kill you or make you sick.

Thanks again.

[J.O.]

Whether it's directly related to the scanners in Canada or not, the letter that Don has posted raises some serious concerns, but typical of a government department (DHS) that is hell bent on doing whatever it wants, these concerns seem to be largely ignored. A story on one of the US news shows this morning (I can't recall which one) was also troubling. It was claimed that these new scanners would not have picked up the underwear bomb that was supposed to have set off this new level of screening in the first place.

[DEFCON]

The 'pat down' employed during security checking is little more than window dressing, just ask a cop or anyone actually trained and experienced in searching people.

A serious question; what will be done next week when the 'terrorist' decides to start sticking his explosive material up his butt? Seriously; with hundreds of millions to billions being spent on this scanning technology, what's next?

[Airbus_rookie]

Boroscope?

[Don Hudson]

Further to the joint letter from concerned faculty members of the University of California at San Francisco posted earlier Link to original letter posted on Scribd, Bruce Schneier's Blog on Security recently posted the following:

January 20, 2011

Cost-Benefit Analysis of Full-Body Scanners

Research paper from Mark Stewart and John Mueller:

"The Transportation Security Administration (TSA) has been deploying Advanced Imaging Technologies (AIT) that are full-body scanners to inspect a passenger's body for concealed weapons, explosives, and other prohibited items. The terrorist threat that AITs are primarily dedicated to is preventing the downing of a commercial airliner by an IED (Improvised Explosive Device) smuggled on board by a passenger. The cost of this technology will reach $1.2 billion per year by 2014.

"The paper develops a cost-benefit analysis of AITs for passenger screening at U.S. airports. The analysis considered threat probability, risk reduction, losses, and costs of security measures in the estimation of costs and benefits. Since there is uncertainty and variability of these parameters, three alternate probability (uncertainty) models were used to characterise risk reduction and losses. Economic losses were assumed to vary from $2-50 billion, and risk reduction from 5-10%. Monte-Carlo simulation methods were used to propagate these uncertainties in the calculation of benefits, and the minimum attack probability necessary for AITs to be cost-effective was calculated.

"It was found that, based on mean results, more than one attack every two years would need to originate from U.S. airports for AITs to pass a cost-benefit analysis. In other words, to be cost-effective, AITs every two years would have to disrupt more than one attack effort with body-borne explosives that otherwise would have been successful despite other security measures, terrorist incompetence and amateurishness, and the technical difficulties in setting off a bomb sufficiently destructive to down an airliner. The attack probability needs to exceed 160-330% per year to be 90% certain that AITs are cost-effective."

Posted on January 20, 2011 at 1:39 PM • 29 Comments

To receive these entries once a month by e-mail, sign up for the Crypto-Gram Newsletter.

[Maverick]

I will not allow my children to ever go through one of these scanners, period.

There are enough sources of radiation and wi-fi exposure that I can not control, this is one that I can.

I recently flew to the states and opted for the patdown search for my family. When you're standing three inches from your child during a patdown the security primates are much more respectful!