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Rapiscan Backscatter Scanners – Reflection and Absorption.

October 30, 2010

Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the pacifists for lack of patriotism, and exposing the country to greater danger.
~Herman Göring at the Nuremberg trials

It is time to dispel one or two myths about the scanners and delve deeper into the health debate. Let’s look seriously at how these machines really work.

Image kindly donated to Scrap the Scanners by John Wild (

Meet John Wild. This British man was visiting a security trade fair in London in 2006 when he was invited by the Rapiscan sales team to be scanned. John managed to persuade them to print off and give him a copy of his scan. It is a hugely significant image in that it is the only Advanced Imaging Technology image publicly available that has not been ceded by the manufacturers in its public relations exercises. It is also the only full-body scanned image that has not passed through a ‘gaussian blur’ filter in Photoshop and been cooled by a calming soft blue tint. Moreover, it is the only image from a Rapiscan Secure 1000 security scanner that does not include guns or other weapons. On a level of public perception, this last point is essential. Firstly, in 2009, more than 2.5 billion people flew on commercial flights around the world and only one boarded a flight with a weapon – and a dud at that. Secondly, it is not the job of the scanners to detect metallic objects, such as guns or knives. The metal detector arches do that job before an airline passenger is goaded into a full-body scanner. The job of the scanners is to detect “non-metallic weapons”, such as those used by Richard Reid in 2001 or Abdulmutallab in 2009. Whether or not the scanners are capable of doing that is something we will return to later on. However, there do not exist ANY images of  full-body scanned people carrying the popular explosives TATP and PETN, precisely the substances they are supposed to be looking for.

This is NOT a photograph.

The old adage is that “a picture tells a thousand stories”, and it was never truer for this image. But let’s just look at a few of those stories:

It is essential to understand that the image we can see of John is NOT a black and white photograph, even if it appears similar to one. In fact, it has very little to do with conventional photography as we know it. A traditional black and white photo is made from the reaction of reflected light radiation on photographic film. The more light that is reflected off a surface, the whiter the area on the photograph, while less reflected light gives a darker tone. The overall result is a patchwork of light and dark areas depending on how much light radiation was reflected off the subjects in the image. These differences in lightwave radiation exposure are what define the image of a photograph. BUT, the above is not a photograph. So In the absence of natural light below the subject’s clothing, what produces the light and dark tones that make up the representation of the naked body in a full-body scanner?

The Backscatter Method.

Rapiscan’s backscatter machine bombards its subject with ionising radio waves from head to toe. The idea is that the photons from this radiation are given sufficient energy to penetrate the clothing of the subject, but not the whole body. Once the photons, which progressively lose penetrative power, encounter something dense enough and their penetrative energy has diminished enough, these photons then bounce off the subject and scatter in all directions. A small percentage bounce back to the reader inside the machine.

The readings are then calculated and electronically rendered so as to produce an image like the one above. The Rapiscan software renders the image in such a way that it appears similar to a black and white photograph, and therefore easy to recognise, read and process.


A myth has been floating around ever since these machines were introduced onto the market that says backscatter radiation does not penetrate skin. This is pure propaganda on behalf of the industry and establishment. As you will see, the penetrative power of this radiation is far greater than ever previously thought.

So to make the image easier to understand, I am going to undo one aspect of the Rapiscan image rendering and invert the picture of John.

Rapiscanned - down to the bone

There are two concepts to consider. The first is reflection. We know that the radiation is powerful enough to penetrate clothing, but unlike gamma radiation not enough to pass through the entire body. I think it is safe to assume that it cannot pass through metal or similarly solid material and would simply reflect back off giving the most pronounced reading. In the case of the buttons on John’s trousers and the loose change in his pocket, we can see that they are now represented in white (or black before inversion). Apart from the bright background, the next brightest white features are John’s bones.

Clearly visible and recognisable we can see the tibia (shins), all the bones of the feet, the patella (knees), suggestions of the pelvic girdle (hips), sternum, clavicle and ribs. Thus we have instantly dispelled the myth of non-penetration of the backscatter radiation.

It is clear why we can see the bones we see and not others. All the above mentioned bones are close to thinner areas of skin. None are hidden behind large muscles or typical accumulations of fat.

Perhaps more worrying is not the whiter-looking bones revealed in the scan, but the other important bone covered by only a thin layer of skin – the cranium. In the image below the familiar outline of the skull is easily seen. The question now arises of why it is not as white as the other bones we can see. If white + black = grey, and white represents reflection, what does the black represent and what is happening to cause the thin bone of the cranium to appear grey and not bright white like the tibia?

Partially penetrated skull visible .


We now understand the the more pronounced white areas of John’s scan represent dense and brittle areas such as thick bone that reflect a certain anount of radiation. Now we need to establish what provokes the other end of the scale – the black areas. For the most part, we can see that these are the opposite – soft and fleshy areas such as the belly, calves, shoulders, cheeks, buttocks, etc. So why does the scanner pick these up as being opposites to the tibia (shin bone). Well, in terms of radiation dosage, the opposite of the reflection seen in John’s white bones can only be absorption. This absorbing of energy is essential in the process. If all the energy were simply reflected away, the previous image of John would simply appear as a white silhouette.

All areas of John’s body are being penetrated by the radiation of the scanner, but only those with dense, brittle material directly below the skin (bones) are bouncing  photons back towards the reader on the scanner with any efficiency. Those softer, fleshier areas, such as his belly, are doing the opposite of reflection and absorbing the radioactive energy inside and storing it as it is then too weak to continue its journey out the other side and exit its victim’s body. It stands to reason that if the backscatter waves have nothing significant to bounce off they will keep on penetrating until they have lost their penetrative power. Then, the energy just sits there – cooling … ionising.

This idea was better expressed by a group of 4 scientists working at the University of California earlier this year. In a letter of concern addressed to Obama’s science advisor the group urged the government to review and re-test the backscatter equipment. They had realised that a lot of the energy that was penetrating the skin did not have sufficient oomph to exit again and was therefore “depositing energy beneath the skin”. Their warnings have gone unheeded and the popularity of the Rapiscam monster continues to grow with airport security firms.

The question remains then of how much of a dose we are receiving from these machines. The University of California studies instantly dismiss the UK and US governments’ measurements in micro Sierverts as they do not take into account the type of radiation in question. In effect, what our governments have done is the equivalent of saying “Don’t worry. Our studies have shown that you are unlikely to drown in a foot deep of boiling water.” The parameteres of the study were entirely irrelevant.

Is there any point to the scanners?

So, we can see how the rays from the Rapiscan machine penetrate leather (no sign of John’s shoes) , tough muscles like the calves and fleshy areas such as the belly. The effect they have is of little or no reading on the scanner due to their absorbent nature. I am left asking myself just how efficient these scanners are at detecting liquid or powdered explosives, the job that originally justified their implementation. Rapiscan has never produced a single image (that was not obviously Photoshopped) that demonstrated to the public that these machines were fit their purpose. We have seen plenty of scan images that show how they can detect guns and knives, but not explosives. We already have much cheaper and safer metal detectors arches to detect such weapons.

How long is it going to be before we see mass cases of skin cancer? What about in children? And let’s not forget to keep an eye on those miscarriage figures. Since February this year Heathrow airport has Rapiscanned more than a quarter of a million people. If you times that by all of the airports in the world using this technology you can get an idea of the extent of the danger. No one can be certain. The only thing you can be sure of is that once our governments have admitted that cancer is on the increase, there will be lengthy arguments about who and what is to blame before scanner withdrawal is even considered. Recently, Dr David Brenner at Columbia University in New York claimed that the health risk was underestimated and that the actual dosage being received was some 20 times the official figures.

I’m going to up the ante a little: Considering what we have seen and understanding now that radiation absorption is essential to this kind of image creation, I’m going to add another zero to Dr Brenner’s estimation.

Refuse the scan.

Sam Edi

Scrap the Scanners


Hate to tell you that I told you so, but after I wrote this, the inventor of the backscatter monster sent this letter to Obama’s Science Advisor. In it, he inadvertently confesses that penetration of radiation forms part of the imaging process… as we already suspected and in contra to what Rapiscan PR wold have us believe.

Note 2:

US Government official report claims that up to 100 people WILL die each year due to scanner use at US airports. Remember that is ‘DIE’, not suffer cancer, thyroid disfunction, etc. And, I am sure you will agree, being from the source of the problem, it is safe to assume that figure is rather conservative.

21 Comments leave one →
  1. teri permalink
    October 30, 2010 12:20 pm

    I was radiated 2 years ago unwittingly while goign thru Schipol Airport (Amsterdam) . This was before the big fuss was made about these machines . I was the only member of my party with a US passport and the only one senis horrible machine (weird, no?).
    I’m sick of being a treated like a criminal just because I choose to fly. I can only imagine how people with interesting sounding names or with passports from countries which are now our so called enemies must be treated.
    Welcome to HELL>

  2. October 30, 2010 7:25 pm

    This is an extremely valuable and informative article.
    Thank you very much for this.

  3. October 30, 2010 10:49 pm

    You have the UNCONDITIONAL RIGHT to OPT-OUT and especially to OPT-OUT your kids!

    These machines totally invade your privacy, maybe give you cancer, and allows the thugs in TSA and other passengers to steal your stuff. Remember, you must remove your wallet, belt, all cash, paper, your boarding pass, passport, EVERYTHING before entering the strip search machine. Anybody can take your stuff.

    Click on my name above or google “DONT SCAN US” or go to:
    for important safety and privacy information as well as actual images, not the propaganda that TSA is spewing.

  4. October 31, 2010 9:58 pm

    Unfortunately Wimpiw if you live in or travel to the UK you do NOT have the unconditional right to a pat-down. You either have the naked scan or you do not fly.

  5. Ed Andrews permalink
    November 13, 2010 5:31 am

    Good article, and in particular the analysis of absorbtion seems to raise some concerns. I do have several technical comments. It is stated:

    “. . . bombards its subject with ionising radio waves from head to toe” …The frequency, as I understand it, is in the part of the spectrum between microwaves and infrared. That is not ionizing.

    “Once the electrons, which progressively lose penetrative power, encounter something dense enough ” … Electromagnetic waves are not projecting “electrons”. They are photons, or electromagnetic fields, if you wish, that penetrate. The only time an electromagnetic field will result in electrons, is when it comes in contact with a piece of metal, and an electric current is induced in the metal. The metal already contains the electrons, the EM wave just causes them oscillate.

    Gamma radiation, mentioned in the article, is also comprised of photons, but since the wavelength is much, much less, their energy is correspondingly greater. (Energy = h (constant) times frequency)

    “. . . but only those with dense, brittle material directly below the skin (bones) are bouncing electrons back towards . . .” … It would some portion of the EM wave that is reflected back, not electrons.

    • November 13, 2010 8:39 am

      The scanner in the article is the Rapiscan Secure 1000 backscatter scanner. Don’t confuse it with the Millimetre Wave scanner produced by Smiths Detection or L3. The Rapiscan model does produce ionsing radiation, while the others operate within the Terrahertz field.

      Why are their 2 types? Basically the MMw type is for airport operators concerned by the carcinogenic effects of the technology, while Rapiscan’s clients actually want to see below your clothes. That is to say, the MMw scanners are enormously ineffective and incapable of detecting, for example, most explosives used by terrorists today (see “Duff and Dangerous) article on same site) . The Rapiscan model presents a much clearer image of the subject, but I think the images of John Wild speak for themselves – these are more dangerous than the manufacturer is letting on.

      What no one knows yet is how much of a danger they really are. The same with the MMw scanners. No testing has been done, therefore we cannot say for sure. I do not believe that the MMw scanners are so innocuous. Even many airports warn pregnant women and people with pacemakers not to go through the metal detector arches.

      About the electron/photon confusion – thanks, I’ve changed it

      Thanks for the comment

      • Ed Andrews permalink
        November 14, 2010 4:42 am

        Thanks for the reply. I just assumed the Rapiscan was in the terrahertz wavelength because it was stated in the article that “it bombards its subject with .. radio waves”. I always regard radio waves as being somewhat lower in frequency than infrared. As its the other type which uses Xrays, then ionization is valid, and a concern. So you might wish to remove the reference to “radio waves.”

        I have also read that the terrahertz scanners (Mmw scanners) can damage DNA. I think they said it was because it can unwind the helix. Something totally new to me.

    • November 13, 2010 3:48 pm

      I have heard from someone working in the scanner industry that the Rapiscan machines use Caesium-137 as an isotope, although this has not been confirmed yet.

      • November 13, 2010 4:53 pm

        That is not true. The Rapiscan uses an FDA approved X-Ray tube from Varion, very similar to the tube used in CT scanners, but much lower power, and designed for continuous duty operation. A classic X-Ray generator setup, complete with aluminum attenuation, to filter out “off” frequency x-rays, thereby improving the image quality.

      • November 13, 2010 9:24 pm

        Interesting. Thanks for that W.
        Where did you get the info from?

  6. Connie permalink
    November 29, 2010 3:39 am

    Look up Terahertz waves and check out this video at 6 min 15 sec.

  7. Don permalink
    December 3, 2010 10:51 am

    The picture produced by the machine was not inverted to make it more user friendly. Dark indeed shows absorbtion and white shows higher scattering. The lower power x-rays are more likely to be absorbed via the photoelectric effect by higher numbered elements (metal), the best return actually comes from lower number elements such as H, C, N, O which happens to be our base construction materials.

    The leg bones you see in the front view are actually the creases ironed into his pant legs which increased the cross section of materials the x-rays had to travel through (more absorbtion). The “lower absorbtion” from the leg muscles in the rear view is actually just higher reflectance from the pant material being stretched tighter and possibly sweat from the calves. Higher scattering off the face is most likely caused by sweat as well. Not quite sure on the shoulder edges as I would have expected darker…unless he had previously been wearing a coat/jacket and his shirt was retaining the water.

    • December 3, 2010 10:50 pm

      Thanks for the thoughtful comment Don, but the lines on John’s legs are most definitely his tibia and not, as you said, “the creases ironed into his pant legs”. There is an abundance of Rapiscan produced images available on the internet with the same effect:

      John tells me he that he was scanned in winter and therefore was wearing a thick winter suit and woollen coat, none of which leave any trace on the scan, not even his leather shoes.

      I understand the concept of ‘scattering’ and probably should have mentioned it in the text. Just like bouncing a ball 90º against a wall will cause the ball to come back to you and at 45º make it bounce off at a 90º angle away from you. Flash photography works in the same way, illuminating the parts of the subject directly facing the camera in white and those parts at a 45º angle in grey – clearly. But I’m not convinced that is the whole story with the scans, although it probably contributes. The effect of both scattering and absorption would explain the intensely dark areas on the shoulders, for example. However, the scatter principle does not explain the intensely dark areas on the cheeks, eye sockets, nasal cavities and calves – all area that could easily be facing the scanner reader at a 90º angle.

      • Don permalink
        December 4, 2010 8:23 pm

        Ok. I’ll give you the leg bones in the legs. The radiation has definitely penetrated the thin skin…and none has reflected back, but has been absorbed (photoelectric effect).

        Unfortunately I cannot argue with your view on how the “reflectivity” is actually happening since your explanation makes sense. The fact that any scattering that does occur is actually more likely to happen in the lower atomic weight elements is counter-intuitive. I don’t need to convince you though because we still come to the same end result.

        We agree that some non-insignificant amount of radiation is being absorbed by your body.

        I was actually fine with body scanners until I read this which shows how the dosage they provide was measured.

        ****At the top of page 7 they give the x-ray spectrum used by the Rapidscan secure 1000****. They note in the article since they were only worried about the maximum energy that they did not adjust the photon counts to account for sensitivity, which may mean that 10kev peak you see has a lot more counts (obviously this is the portion being used in the detection process and you’d pick a tube that generated a lot more soft x-rays than hard.

        1) You’re still being blasted by a full spectrum of x-rays up to 50kev. You’re getting hit with hard and soft x-rays. Again properly calibrated I think the 10kev peak would actually be bigger, but either way you’re getting blasted with a lot of 37kev x-rays also. Hard x-rays start above 12kev.

        2) But wait…they use a 10×1800 ionization chamber to measure dosage. That chamber has a 33kev energy dependance which means they only measured dosage relating to everything to the right of the 33kev marker (+ or – 5%).

        3) Maybe only the dosage from the really energetic x-rays matter…eh…thats it. Oh, except for a typical medical x-rays they purposely block those lower x-rays (beam hardening) to improve picture, but also to reduce the overall dose you are receiving. So we didn’t measure anything to the left of that 33kev line.

        4) Again I think that 10kev line is actually a lot more dense since that is the part of the spectrum they use and they are going to try to filter anything else out they can…. If those 10kev particles are all mainly getting absorbed in that first micron of skin and then the rest of this spectrum is getting progressively absorbed a bit deeper…. that means a huge dose is absorbed in a very small cross-sectiion…a dose that was never measured.

      • Don permalink
        December 4, 2010 8:26 pm

        Slight correction/addition and then I’ll shut up since the replies are getting put into narrower and narrower columns.

        Don – ” The fact that any scattering that does occur is actually more likely to happen in the lower atomic weight elements is counter-intuitive.”

        should be

        The fact that any scattering that does occur FOR SOFT X-RAYS is actually more likely to happen in the lower atomic weight elements is counter-intuitive.

  8. Mom permalink
    December 15, 2010 8:01 pm

    There are a few petitions going around against these scanners, but the link below will take you to a petition from a New Jersey Senator who is actually willing to go to bat against these scanners. Help him to help you.

    Sign the petition:

    You don’t have to live in New Jersey to sign it.

  9. February 11, 2012 11:21 pm

    Just re-read Don’s comments – first time in ages. Really significant stuff. Thanks Don.

  10. Susan permalink
    August 31, 2012 11:31 pm

    I hadn’t flown since 2011 and managed to avoid the Scanners because usage was more random- even in the UK. This year 2012 was different. All the metal detectors are partitioned off and everyone is directed into the Rapidscan Device. My 6 Flights so far this year- 2012- show a big difference in how Opt Out is handled by airport and by Security Personnel. First trip to SEA was most efficient, personnel were timely and professional for the most part. There was also a longer line of people opting out when I flew that time. LAX was one of the worst and possibly because my flight was international. The worst for me was having my return plane so late I didn’t have the time I usually allow to Opt Out. I tried anyway, but was treated rudely and told no one was available. When I asked how long to have someone available, I was told they couldn’t tell me. I asked for a ball park time – 10,15,20 minutes? I was told they couldn’t tell me. I went through the scanner since my time was almost up to catch my plane. Even with this I was still pulled out of line and searched. The Woman Security person did not use ‘back of the hands’ and grabbed my breasts rather aggressively using her open hands and grabbing me. When I questioned why I still was searched she answered in a very condescending tone, it was because the scanner was unclear over my chest area. I was wearing a thin top, so to me , I was clearly being ‘punished’. I just got out of there since Airport Security can get a lot worse than this. Next Flights were family trip to Hawaii –SEA again, 4 adults. We all agreed to opt out. It was my Son’s 1st flight and he was told he couldn’t opt out and sent through the scanner before we could stop him. That same security person was pushing everyone through and looked very annoyed when the remaining 3 insisted on opting out. We got faster service since the baggage check people were complaining about all the luggage messing up their area. Hawaii wasn’t too bad until our last flight. We were pulled out of line and waited a long time. This gave me plenty of time to see reactions of people. Some were confused and got into our line. They were immediately pulled out and put through the scanner. Some looked at us like we were criminals or crazy, one joined our line and stayed. We waited while Security personnel were just standing around. Finally the baggage security person went over and pleaded to have us assisted. He even gave us a thumbs us and said he agreed with us. My person lectured me at the end and grabbed my ticket writing down L3 Technology. She told me to go to the Gov. site where I’s find out how safe these scanners are. Well, that’s how I found your site – thanks. And, yes, where is the protests over these machines !


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