Posted on 11/30/2010 10:13:13 AM PST by Jubal Harshaw
Skin CancerThis of course, doesn't mean YOU are wrong, some kind of misanthropic malarky like this is a hallmark of an Obama, a Janet Reno, a Janet Napolitano, a Bill Ayers -- even a Soros. The plots of the evil are unending, yet they always backfire.People with brown skin often have a false sense of security when it comes to skin cancer. We tend to believe that our darker skin exempts us from this potential danger. It is true that people of color, those with increased skin pigmentation, have added protection against the UV rays of the sun. However, it is also true that those from African-American, Asian, Latino and Native American backgrounds usually have higher morbidity and mortality rates for several types of skin cancer than their white counterparts. This lower survival rate is a direct result of late detection or misdiagnosis. Because there is a dearth of research on brown skin, there is little literature available to healthcare professionals to help educate them on the different ways skin cancer can manifest itself in darker skin. For this reason, it is of the utmost importance that you choose physicians who are familiar with the unique characteristics of darker skin and ethnic skin care. This can literally make the difference between life and death.
In addition to choosing an informed physician, it is also very important for each individual to be self-educated about the different ways in which cancer affects brown skin. There are three types of skin cancer: malignant melanoma (MM) squamous cell carcinomas (SCC) and basal cell carcinomas (BCC). In general, persons with brown skin are less likely to develop BCC than their white counterparts. SCC (especially those that develop from scars or burns) and melanomas are more common in ethnic skin. However, melanoma remains the most deadly form of skin cancer in brown skin, due mainly to its potential for rapid spread, and to late diagnosis.
http://www.brownskin.net/cancer.html
Sounds like something my wife would say ...
... wait just a minute there ...
... Honey? ...
... is that you?
Jubal Harshaw
Since Sep 14, 2001
I can’t believe you’ve lasted since 2001. We don’t need this kind of conspiracy crap on Free Republic.
Are you trying to get me permanently off FR? Wow, you must be my wife!
Yes, that would make a lot of sense ... for a standard X ray device. Thing is, the TSA scanners are, well, scanners. They may not deliver a large total X ray dose (something that could be measured by a dosimetry badge), but the dose that they do deliver at any instant and spot is relatively intense and focused. The scanner is NOT the same as a standard Roentgen-type X-ray machine, so calculating radiation flux (which we do not know for these scanners) cannot be done just by knowing the air kerma (which we do know for these scanners) or by knowing the dosimetry badge readings (which we could get for the scanners in the manner you describe).
As a visual aid to the importance of radiation flux, you might want to look at this article (It describes the action of a laser rather than an X ray scanner, but the concept is the same):
http://nextbigfuture.com/2008/02/femtosecond-laser-can-change-any-metal.html
If you look at the pic of different colors of aluminum, note that years worth of normal light absorption does not make aluminum change color. Consider an aluminum beer can. The can may sit out in the sun for years, being hit with tens of watts worth of energy at a time, (depending on how bright the sun is), at wavelegnths from infrared to X-ray, and the aluminum generally will not undergo significant surface alterations (chemical alterations due to atmospheric interaction aside). That’s because, while the photonic energy delivered may be tens of watts, the intensity of that radiation is low (actually, in this case, it’s the same tens of watts).
The pics on the linked page, however, show the results of tens of MILIwatts (I think) of delivered light, delivered over the course of 1/2 hour. Total energy delivered by the laser is relatively small. The key is not the total amount of energy delivered; the key is the intensity with which those photons are delivered.
At most times and places during the femtosecond laser treatment described in the article, there is no laser light impinging on the aluminum disk. Approx 100,000 times per second, for a femtosecond at a time, however, a very intense (terrawat range) laser light impinges on the disk. The overall delivered power (the sort of thing that might be measured by a dosimeter) is low, but the point intensity (photon flux) is so high, when the laser is on, that the affected surface of the disk becomes a plasma, then re-cools (when the laser is off again) into a pitted, twisted set of shapes that, at the macro level, makes the surface of the disk appear to have changed color. Again: total energy delivered is low. Intensity is high. Result: visible changes in the physical properties of the aluminum disk being treated.
Intensity matters. Simple dosimeters can’t detect intensity. The TSA refuses to release figures relating to the intensity of the X-rays they deliver, and refuses to let anyone else measure that intensity.
This really is a simple concept, but I’m not so sure that I explained it well. If you don’t understand, please let me know, and I would be happy to try again.
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However, for gamma radiation, the generator head is one thing, and changing the time it is on, or changing the kilovolts running through the primary circuit will in fact cause either more gamma rays to emit, or in fact change the power of penetration of each ray, thus the intensity is variable. The dosiometer badge will in fact measure that, as it picks up the amount of gamma rays striking a particular place (the film in the badge).
The gamma rays pass through the subject, and the shadow of the object is what is recorded on the pickup screen, no doubt a digital screen in this case.
Changing colors of stuff out in the yard depends on the stuff. Color change can occur due to oxidation, or molecular breakdown of the components of the surface of the material. This can occur due to (mostly) ultraviolet, but also the entire spectrum of electromagnetic radiation.
If you cannot bezaddle with brilliance, then baffle with bullshit, eh?
OK, I guess I did not explain the concept clearly. Thanks for trying to stay with me; I’ll try again to explain. As for your part, you are not succeeding in either bedazzling me or baffling me, so I’m not 100% sure as to what you were referring with the last line of your last post.
I am NOT an expert on the Rapiscan scanners. No one outside the company, and perhaps the TSA, is an expert on these devices. I do NOT have inside knowledge on how they work. However, some aspects of their operation seem to be clear from general physical principles.
Firstly, note that the Rapiscan scanners are referred to as “scanners.” Scanning is NOT the same thing as a simple irradiation. Scanning refers to acquiring an image pixel-by-pixel or line-by-line. You may have a document scanner on your desk, for example; if so, you may wish to notice that the device probably delivers light to one line of a page at a time, images that line, then moves the light / sensor array, and images the next line. The overall energy delivery used for the acquisition of the whole image may be low, but, at any moment, the section being acquired is intensely illuminated.
Here’s another backyard example to illustrate the difference between regular illumination and scanning. Consider a group of ants in the sun. They can stay in the sun indefinitely, and be quite happy doing so. Now imagine a magnifying glass between the ants and the sun. By concentrating the sun’s energy on a smaller area, a hot spot can be created that is lethal to ants. The total amount of energy delivered to the group of ants is the same with and without the magnifying glass in place (actually, it’s a little less, since a real magnifying glass doesn’t have perfect transmittance), but the effect of the energy differs between with or without the glass in place.
In this example, moving the glass around (scanning) from ant to ant can lead to the rapid demise of all the ants — using no more energy than they would have absorbed just relaxing in the sun, were that magnifying glass not present.
A simple dosimeter in place of the ants would detect only the overall energy delivered through the glass. If the focus of the magnifying glass was scanned over the dosimeter (again, this is a simple dosimeter, not engineered to pick up intensity readings) then the dosimeter would react exactly as if the glass had not been in place. The ants, however, would still be dead.
Again: intensity matters. Intensity can’t be detected by all the same technologies (such as dosimeter badges) which detect other characteristics of radiation.
Also, there’s the fact that the Rapiscan backscatter scanners do NOT work by measuring gamma rays passing through a subject. Rather, contrary to your post, the Rapiscan backscatter scanners work by measuring, well, backscatter. The physics of the relatively high-energy wavicles that produce images via transmittance are slightly different than the physics of the lower energy wavicles that are used for backscatter images. Again, another analogy. I admit that this analogy may be wrong because neither I, nor anyone else in the general public, knows the operating parameters of the Rapiscan devices. However, the overall outlines of the analogy are likely correct.
So here’s the analogy: a standard X-ray passes through tissue like a high-speed, pointed-tip, non-hollow-point bullet. The backscatter device uses X rays that don’t pass through the body as much, more like a blunt bullet, or perhaps a hollow point. I am NOT trying to turn this thread into a gun thread, so I am NOT trying to say that hollow point bullets are deadlier than non-hollow points or vice versa. What is indisputable, however, is that, all other things being equal, the hollow-point bullet causes damage in a different pattern than the non-hollow point bullet.
In this case, we know the effects of the damage done by “non-hollow point bullets” (penetrating X-rays). We do NOT have the same knowledge about the damage done by “hollow-point bullets” that dump more of their energy at the skin (X-rays used by the Rapiscan Scanners). The X-rays used by the Rapiscan Scanners are an unknown quantity, in terms of their ability to cause cancer in the structures they do hit. The “hollow-point bullets” may be more dangerous than “non-hollow-points,” may be less dangerous, or, for all we know, may actually increase the health of the people who are exposed to them. Thing is, WE DO NOT KNOW, and our knowledge about how the “non-hollow-point bullets” work is only minimally helpful in predicting the effects of the “hollow-points.” It’s a pretty sure bet, however, that, if you wanted to maximize SKIN damage, you would choose “hollow-points” over “non-hollow-points.”
Now, the bullet analogy seemed to me a good way to illustrate the point, but, now that I’ve written it, I have a feeling this whole thread is going to wind up on the bang list, and the responses will soon include references to Glocks vs. Rugers vs. Colts. Sigh. Well, I’ll try to keep up. Thanks for reading.
The total amount of energy focused on the ant is the total amount of energy that the lens can collect on it's sunny side, focused to a pinpoint on the other side. It is not the amount of energy the ant is generally exposed to, as the amount of energy the ant is exposed to is somewhat comparible in size to the shadow he projects, area wise. The magnifier takes a large surface area (of the glass) and then focus it to a small point, so the same amount of energy (large surface area) focused to a small area (the pinpoint) in fact then delivers more energy per surface area. It's comaparision to the scanner is invalid. More appropriate would be to compare it to a laser.
The scanner, were it as intense in delivering gamma radiation as a standard radiographic exam, would show the dense material in the body, ie the bony skeleton on the image collector. It is actually a relatively light setting, with very little penetration.
The bedazzle/bullshit was not regards my post.
As a side, and a total disclaimer, I still object strongly to having them there, and frequent fliers should wear exposure badges.
I must get back to work now, as I have a few radiographic exams scheduled this am to conduct, and read.
Thanks for working with me here.
Regarding my analogies: OK, no analogy is perfect, so please let me try again to explain the analogies. The analogy with the ants was intentionally written about a group of ants, rather than one ant, to make visualization easier. So, let me add some details, so that the visualization is even more clear. The group of ants are in fixed positions, carapace-to-carapace, over, say, a 10 cm diameter circle. Some steady-handed grad student has carefully glued them in place one by one. The group of ants is then put in the sun for, say, 15 minutes. The total amount of sunlight falling on the ants is spread out over all the ants. The ants are radiated by the sun. The ants live.
A 10 cm diameter magnifying glass is then put over the 10 cm circle on which the ants have been placed. The total amount of sunlight falling on the entire group of ants is the same. Now, however, the light falling on the ants is not simply radiating them, but arranged in a scanning apparatus. The ant at the focal point of the magnifying glass is burned to death. The whole apparatus is adjusted to scan the next ant, and the next, and the next, for the next 15 minutes.
At the end of that 15 minutes, exactly the same amount of light hit the whole group of ants when the magnifying glass was in place, as during the 15 minutes the glass was not in place. The difference is that, during the 15 minutes the glass was in place, the ants all died. There is NO INCREASE in the total amount of energy delivered to the entire group of ants, just in the intermittent intensity of that energy. That change in intermittent intensity, however, was enough to make a significant difference to those ants. That, I hope, illustrates the potential differences between “normal” irradiation and scanning.
As for your statement “The scanner, were it as intense in delivering gamma radiation as a standard radiographic exam, would show the dense material in the body, ie the bony skeleton on the image collector” : I don’t think that’s so.
As background, please let me state that I think that your meaning of the word “intense” in your post suggests that the Rapiscan X-rays are the same wavelength as medical diagnostic X-rays, just using a smaller number of photons.
In contrast, the general assessment about the Rapiscan devices is that they do, instead, use lower-frequency, longer wavelength, X-rays, closer to the range of “soft” X-rays than to the “hard” X-rays used in medical imaging. That would explain why the X-rays are detected via scattering rather than via transmittance. The actual characteristics of the Rapiscan device are not public, so people are just guessing about the X-ray wavelengths being used. That said, many people believe that the X-rays from the Rapiscan device would NOT generate transmittance images if only it delivered as many photons as a standard medical X-Ray device. It’s not just the number of photons that is different than a medical X-ray device, but also (many believe) that there is a different set of wavelengths used.
I regret having to use the words “many believe” and “general assessment.” Someone knows exactly what are the wavelength characteristics of the Rapiscan devices ... but that information has not been made public.
Characterizing scanned, “soft” X-rays based on their air kerma, then trying to predict medical effects of those X-rays by using observations of the effects of non-scanned, “hard” X-rays with the same air kerma, is simply not valid with the current state of knowledge at this time. I have a feeling that, over the next few years, we may see an explosion of new knowledge regarding the effects of these scanned soft X-rays on human subjects, but that knowledge does not exist just yet.
Dont quit you day job just yet.
If I go to the doctor or the dentist for an x-ray, I presume the machine they use has to be approved by the FDA, as well as other regulatory agencies, and be calibrated on a periodic basis.
Have the backscatter or millimetre wave machines gotten FDA approval, and gone through testing to ensure that they are OK to use on people?
If not, yet another reason not to go through either.
To answer your question: the answer is NO!
There has been no significant pre-deployment clinical testing of the machines. The airline passengers are the test subjects. There is no significant training of the machine operators, there are no known standards for machine maintenance and adjustment, there is no known measurement provided or allowed for radiation flux generated by the machines, and the X ray wavelengths used are a matter of speculation.
A stated air kerma is provided, but, given that these machines have known substantial differences from “standard” X-ray equipment, the air kerma, even if accurate, is pretty meaningless. Those substantial differences include the facts that the Rapiscan devices scan their subjects rather than use simple irradiation, and they apparently use longer wavelength X-rays than do standard X-ray equipment.
In a few years, probably after this administration is over, I predict that there may be an explosion of skin cancer, particularly among those who are already susceptible to skin cancer (BTW, one of the largest risk factors for deadly skin cancer is pale skin). If that occurs, then a few years after that, dermatologists, medical journalists and the general public might start to notice the rise in skin cancer. All the usual culprits will probably be blamed: global warming, the ozone hole, BP and the oil spill, acid rain. Public Service Announcements will probably be made, urging people to ... well, to do some meaningless thing that has nothing to do with what caused the skin cancer. Speeches will be given about how this rise in skin cancer shows just how important it is to support government healthcare. And, if enough people do actually get skin cancer, a lot of lives will be cut short. In a way, the TSA is thus the American Chernobyl.
I’ve worked in the past, and may again, on devices to allow “bladelesss biopsy” (subepithelial, non-invasive, high-resolution imaging) of skin lesions. I’m putting together a research group now to develop other cancer detection techniques. Bladeless biopsy, or other cancer detection techniques, might become very popular if skin cancers become a lot more common. Maybe the Rapiscan company will thus make me rich. Still, I am bound to advise anyone who is interested, that the Rapiscan machines have important operating parameters that have not been released by the TSA. As stated above: if those operating parameters suggested that the machines are safe, they probably would have been released.
In my opinion, you’d have to be wildly optimistic to believe that you will be safe passing through those scanners, even once. I hope and pray that my opinion is wrong. I suppose we’ll find out.
many thanks for the information, I most certainly will NOT allow myself to go through something that has so many ‘unknowns’.
(Neither will I allow somebody who is NOT a Law Enforcement Officer to pat me down as if I am under suspicion of having committed a crime. No more flying for me till this @#$! stops; train or car for me (have done & will do 1,500 mile trip!))
Interesting thread Jubal. I pray you’re wrong but I think you’re right.
News regarding TSA policy:
http://www.slashgear.com/now-the-tsa-can-force-you-to-go-through-the-body-scanner-22419599/
This new policy implemented, like the TSA body scanners themselves, just before a major holiday. That’s when people are most likely to be travelling with their children. In case you thought the feds were above targeting children.
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