Radiation Risk Of Airport Full Body Scanners

Thursday, December 31, 2009

Body scanners have revolutionized the practice of medicine since they were first introduced into routine clinical practice in 1974. Companies are coming out with faster scanners that take more comprehensive pictures. A millimeter wave scanner is a whole body imaging device used for airport security screening. It is one of two common technology used for body imaging; the other is the backscatter X-ray. In comparison to x-rays from medical applications, the backscattered x-rays are considered high energy. A "high energy x-ray beam" moves rapidly over the person's form and a high resolution image of the person's nude body. Here is the question, Are They Safe? There are no known “safe” doses of radiation in terms of radiation-induced cancer risk.

CT (computed tomography) scanners is a rotating x-ray device to create hundreds of individual images reconstructed into a three dimensional view of the body by computers. Many readers have heard of these scans. MRI technology also produces fast scans. MRI scanners also provide sharper, clearer images of the body. They help physicians detect cancerous tumors, debilitating diseases and other ailments at earlier stages of development. You may have heard the term ‘3T,’ the “T” in “3T” refers to “tesla” a unit used to measure the magnetic strength of the MRI scanners. Current CT scanners are able to image the entire human body within seconds, and provide high definition images with an incredibly detailed view of organs and tissues. Scanner use low doses of radiation, but many older machines rely on higher doses. Scanners are for particular procedures they are not standardized, and a wide variance in doses can be delivered to the subjects. Security scanners use millimeter waves, these are the scanners used in Airports. As these complex and powerful diagnostic imaging machines continued to grow, so will the potential risk of radiation-induced cancers from radiation exposure administered during body scans at Airport Security.

A number of private radiology imaging centers offer “body scans” for clinically healthy people who are interested in having their internal organs examined for any early signs of diseases. Physicians have become so dependent on these machines that they request a scan for many visits. The same theory has turned to airport security; a full body scan will be requested before boarding a plane, screening the healthy with low dosages of radiation. Medical implants such as cardiac and neural stimulation leads could be affected by the electrical field produced by a pulse generator and significantly alter (either increase or decrease) the waveform of a pacemakers pulse.

Airport Full Body Scanners work by Millimeter wave technology. This band has a wavelength of ten to one millimetre, giving it the name millimeter band or millimetre wave. These waves are considered Extremely High Frequency, the highest radio frequency band. EHF runs the range of frequencies from 30 to 300 gigahertz, they are also sometimes abbreviated MMW or mmW. These bands are also known as terahertz radiation. Terahertz radiation may interfere directly with DNA. The force generated is small but the waves disturb double-stranded DNA, creating bubbles in the double strand. These scanners provide exceptionally clear views of subjects by combining data from multiple X-ray images, but the increased exposure to X-rays, which cause mutations in DNA that, can lead to cancer. X-rays are considered ionizing (penetrating) radiation, ionizing radiation in any dose causes genetic mutations, which set all living cells exposed on the path to cancer. Cancers associated with high dose exposure include leukemia, breast, bladder, colon, liver, lung, esophagus, ovarian, multiple myeloma, prostate, nasal cavity/sinuses, pharyngeal, laryngeal, pancreatic and stomach cancers. Clothing and organic materials are translucent in most mm-wave bands. Perfect for detecting objects on subjects at airports. The scanner does allow the screener to see detailed images of body parts, as I explained with CT and MRI scanners.

Whole body scans of healthy people may be creating more problems than they solve by exposing healthy people to radiation. The risk for radiation over exposure may be small for single subject, but the number subject exposed to airport body scans will increase they risk by the millions. A normal CT scan of the chest is the equivalent of about 100 chest X-rays. Some scanners are equivalent of 440 conventional X-rays. The traditional X-ray machine detects hard and soft materials by the variation in transmission through the target. The backscatter X-ray detects the radiation that reflects back from the target. Several studies have suggested that people have been unnecessarily exposed to radiation from CTs or have received excessive amounts of radiation. A person undergoing a backscatter scan receives approximately 0.005 – 0.009 millirems of radiation. 1 mrem per year is a negligible dose of radiation, and 25 mrem per year from a single source is the upper limit of safe radiation exposure. Widespread overuse of body scanners and variations in radiation caused by different machines could subject many to radiation doses that could ultimately lead to thousands of new cancer cases and deaths.

It’s Gonna Be BEDLAM!

11 deacons spoke:

nataraj said...

There are two issues, Health hazzard and Privacy.

Health hazzard can be resolved by statistical / economic calculations, by considering various probabilitities of terrorism attacks, radiation diseases and economics of air disaster, and health costs. Kindly also note that many modern gadgets( including even a concrete wall ) are already exposing us to small radiation doses 24 hours a day. Please leave the decision on competent analysts on this issue. There are people having PhD in Decision Theory.


Regarding privacy, I find a major contradiction. We worry if my full body is seen indirectly at airport on computer screen by a person of same sex, to prevent death by air crash. On the other hand we do not worry to give direct view of our private parts to medical staff of any sex, just to treat a minor health problem!

Nataraj Bhattacharya, Raipur, India

Randy Knudson said...

MONDAY, NOVEMBER 2, 2009

Dr. Mittleman who has been involved in thz research for years responds to the DNA damage claim on my blog. In particular read the last paragraph. I believe the claim is nonsense.
____________________________________________

I have seen that report about the idea of DNA damage by THz radiation. I remain skeptical. The experimental evidence for any kind of THz-induced damage (other than merely by heating) is so far not repeatable. This recent paper is purely theory, assuming a very specific and detailed model for the dynamics of a DNA chain which may not correspond to reality. The way that they include the solvent damping (i.e., the effects of all those water molecules lying around) is not clear. In fact there doesn't seem to be any accounting for the fact that the water is going to absorb most of the incident field, which might heat up the water but would have no other effect on the solvated DNA. I can't say that they're wrong, but being an experimentalist, I am going to need to see experimental results before I buy this mechanism.

The bottom line here is that the world is awash in THz radiation. Every room-temperature object is emitting THz radiation just by virtue of being at room temperature. In fact, the power (per unit bandwidth) in that ambient THz field is larger than the power in most (though not all) artificial THz sources. This makes it hard to imagine how a typical (weak) THz source could give rise to any biological effects. It could be that this mechanism is relevant to real-world situations, but I think the burden of proof remains in the camp of those who say there is a non-thermal effect.

IdiotZoo said...

This paper is quite interesting. I don't understand much of this so am relying on interpretations and quotes from the paper's authors.

Concerns around THz radiation relate to the possibility of inducing resonance in DNA. Because this is non-linear it can be hard to recreate reliably.

I think more work needs to be done.

DontcallmeDarling said...

I find it amusing that Nataraj think that the potential risk for health issues can be resolved by statistics. You would make a great policy writeer or dictator. Individuals are involved here, potentially being x-rayed dozens of times a year. Whether the liklihood of a terrorist attack is high or low, the proposal on the table now is to scan all and sundry except children (so far). So set aside the statistically benign individuals who never travel and childred and consider the impact/risk of health issues of those who WILL be scanned because they WILL travel because no one has the luxury of riding a boat across the ocean or across the country for work.

Gary said...

You used a lot of buzzwords in this blog. Apparently, however, you don't know what they mean. You have confused and mixed the terms, using X-rays and mmW radiation interchangeably. They are not, not even remotely. Health hazard? You'll have to prove that (which you can't, by the way). Your "science" is bad, pure and simple. 300GHz (300 gigahertz ... 300 x 10^9 Hz) is microwave radiation, not X-rays. X-rays are much, much higher frequency and consequently have much shorter wavelength. X-rays are on the order of 30 petahertz (30 x 10^15 Hz), with a resolution of 1 nanometer (1 x 10^-9 meter). X-rays penetrate the flesh and softer tissues, and in some cases the bone tissues. A mmW full body scanner uses microwaves, at very low power, and cannot penetrate more than a few millimeters. At low power, where imagery is concerned, microwaves are not harmful. They simply can't damage DNA. They do not have enough energy or enough penetration of tissue, and have wavelengths way too long, to cause cellular damage like that. Let's think about this for a moment: A typical DNA strand is less than 1 nm long (that's 1 x 10^-9 meter). 300GHz microwaves (used in full body scanners at airports) have a wavelength of 1mm (1 x 10^-3 meter). Electromagnetic radiation with a wavelength of 1mm cannot interact with an object that is 33,333 times smaller than it is (DNA). It is impossible. X-rays with shorter wavelength can possibly interact with with something that small, because the shortest wavelength X-rays are "smaller" than DNA. In terms of radiation hazard, like you have suggested here, there is no hazard at all. It's simply not possible. The kind of scare tactic nonsense in this blog is shameful. I think you should apologize for contributing to the paranoia this type of misinformation causes.

Randy Knudson said...

bravo Gary! I would like your permission to copy and repost your comments on the seemingly endless number of blogs that are spewing this garbage out.

Steve said...

ACR hiding the opinion of truly independent experts makes it look like there is something to hide:

http://www.acr.org/SecondaryMainMenuCategories/NewsPublications/FeaturedCategories/CurrentHealthCareNews/More/AirportWholeBodyScanners.aspx
" Mayo Clinic neuroradiologist Peter Kalina, M.D., FACR questions the use of even small doses of ionizing radiation in nonmedical applications. “The amount of radiation may be extremely small and safe, but parents have to grasp that their four-year-old child is being subjected to radiation. Some parents will be concerned,” he says.

Columbia University professor of radiation oncology and public health David J. Brenner, Ph.D., is uncomfortable with the mandatory scanning of untold thousands of pregnant women and children at airports every year. Brenner, an expert in low-dose radiation risk, embraces the ALARA principle that advocates use of radiation “As Low as Realistically Achievable.” Brenner notes that about 5 percent of the general population is radiosensitive, among them women who carry the BRCA1 and BRCA2 breast cancer genes, and individuals prone to ataxia telangiectasia, an inherited neurodegenerative disease that causes severe disability.

Kalina is concerned about a potential scenario in which a less-developed nation might adopt backscatter scanning technology, but fail to keep its scanners calibrated. “As a traveler,” he says, “I don’t know who’s checked that machine or equipment. Can I be sure there won’t be a larger dose of radiation coming from it?”"

Bedlam said...
This comment has been removed by the author.
Bedlam said...

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Till BeDLAm black you out turn on the real high beam. Surprise.... I AM THE DR. -Insane to your brain- it is BEDLAMS duty to inform the public of ANY physical risk from radiation/biohazards. BeDlAm be glowing BAABY!!! Fool-Keep believing there is no dangers here Gary and Steve. Ten years from now you will be sing another story. Come join BEDlam's bchoir. Flat note. Ant,AT,and @ Gary, nice try Knucklehead flow that make you act REAL DUMB (A typical DNA strand is less than 1 nm long (that's 1 x 10^-9 meter).Go back to school!!! Im not talking about a typical DNA strand, BEDLAM (that's me) did mention a double strand. Get out my space, where youfrom! Aiy! Aiyyo-yo-yo, yo! Let me fuck up your mind! link from bloomberg.

http://www.bloomberg.com/apps/news?pid=20601209&sid=aoG.YbbvnkzU

Airport Body Scanning Raises Radiation Exposure, Committee Says

By Jonathan Tirone

Feb. 5 (Bloomberg) -- Air passengers should be made aware of the health risks of airport body screenings and governments must explain any decision to expose the public to higher levels of cancer-causing radiation, an inter-agency report said.

Pregnant women and children should not be subject to scanning, even though the radiation dose from body scanners is “extremely small,” said the Inter-Agency Committee on Radiation Safety report, which is restricted to the agencies concerned and not meant for public circulation. The group includes the European Commission, International Atomic Energy Agency, Nuclear Energy Agency and the World Health Organization.

A more accurate assessment about the health risks of the screening won’t be possible until governments decide whether all passengers will be systematically scanned or randomly selected, the report said. Governments must justify the additional risk posed to passengers, and should consider “other techniques to achieve the same end without the use of ionizing radiation.”

3-D Imaging

A backscatter x-ray is a machine that can render a three- dimensional image of people by scanning them for as long as 8 seconds, the report says. The technology has also raised privacy issues in countries including Germany because it yields images of the naked body.

The Committee cited the IAEA’s 1996 Basic Safety Standards agreement, drafted over three decades, that protects people from radiation. Frequent exposure to low doses of radiation can lead to cancer and birth defects, according to the U.S. Environmental Protection Agency.

To contact the reporter on this story: Jonathan Tirone at jtirone@bloomberg.net
Last Updated: February 5, 2010 04:31 EST

Randy Knudson said...

terahertz is non-ionizing.

Bedlam said...

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