You say that 99% of the time it's fine. If you go through the back scatter thingy, I'd say that 99% is a hopeful assumption. They are likely unsafe, and some small subset of people scanned may end up quite sick.
Are you making this up, ill-informed or do you not understand physics and radiation? I do not mean this as offensively as it will ultimately be read, so apologies
These scanners exposé you to less than 1/200th the radiation dose of a standard plane flight, and between 1/200th and 1/400th of a standard chest X-ray.
Yes, ionising radiation can cause cancer. But your chance of getting cancer anyway is 1 in 2.4.
I have no love of excessive security measures, and I personally don't think that we should ever unnecessarily cause people to be exposed to radiation, especially when other methods can do the same job without radiation, and even moreso when the efficacy of the scanners is unproven.
But I have a particular dislike of the psychogenic claims that arise around technologies that posit to do this or that, when the action of the machine or technology in question is noninvasive and especially when the action is not substantively different from normal daily exposures that every human receives anyway
Refs:
standard CXR 2.4x background radiation
Backscatter Imaging 6-7% of a days background radiation (0.25 microsiverts per 'scan =1.5hrs @ background radiation or 2 minutes of an airplane at altitude)
Would you take your same condescending tone against the 4 UCSF medical school professors who raised concerns about the backscatter x-rays? [1]
Their contention is that the argument that the backscatter x-rays are 1/200th of the dose you get from cosmic radiation on a flight is invalid, as the backscatter x-ray is specifically designed to direct the radiation to a very thin layer of surface tissue, whereas cosmic radiation is distributed throughout the entire body.
Yes, these professors were refuted by other UCSF radiology professors [2], but the science will not be settled until an independent study is conducted of the machines given the context of their potential for misuse and mis-calibration by individuals who are not radiology technicians.
So if you don't want your comment to come off as offensive, perhaps it would be wise to not start off with "Are you making this up, ill-informed or do you not understand physics and radiation?"
Thanks for chiming in matey, I take it you're a contrarian?
You pretty much back up my point. People who don't know the science should not comment in alarmist tones about it.
Fearmongering generally does more harm than good. In this case it seems like everyone hates the TSA, hates the full body scanners, objects to being dosed with radiation, and so psychogenic illnesses are claimed to be caused by the machine.
So the claims are false, the machines work like they're supposed to, it's just no one wants them there so hurdles are placed in the way of their implementation. Hurdles that are false.
I don't disagree that we should look further into the use, especially as I say above because there are other methods that do not use ionising radiation that seem to be just as effective
So yes, I would take the same attitude to the 3 UCSF Med school professors, just as I have to the world-famous neurosurgeon who told me as we microwaved our food in between surgeries that I had to 'wait for 3 seconds after it finishes or else the rays escape and can increase your risk for cancer' or the former head of the AMA who said during a lecture that 'there is a study that shows that homeopathy is active against cancer' with no supporting evidence. Position and title generally only qualify a person to make comments in a specific domain, as those 3 professors discovered when they got smacked down by the radiologists.
If people want to believe weird and wacky things, that's fine. If those things contravene the known laws of physics, then either there must be some spectacular evidence, at which point I will believe anything, or it simply isn't true.
Yes, your tone is offensive. I work with radiation emitting equipment daily. I am forced by regulation to ensure the equipment is safe and operated safely. Checks and stops are in place. This is the way it should be, and I am pleased my industry behaves this way. Backscatter imaging safety is unproven and falls outside the ALARA principle. You you quoting dose figures misses the point, background radiation is a whole body dose, CT abdo, is an abdo dose (mostly), back scatter imaging is to the skin only. What's the difference? Who knows, no decent testing done.
I apologise for the offensive tone, I ran afoul of some variant of Poe's law. That is not an excuse, discourse should be more civil than that.
you make the claim They are likely unsafe, and some small subset of people scanned may end up quite sick.
But there is still no evidence from what you are saying.
I felt, in another variation of Poe's law, that you were in fact making a claim re backscatter for people claiming sickness after moving through one. In the same manner that people claim that they can detect wifi signals and it makes them sick, or fluoride in the water is making them sick, or just why are there rainbows in our water these days?
Quoting figures I feel is even more relevant - if you are giving someone 1/200th of a CXR, you can't claim that the CXR is only penetrating the internal organs - some fraction, perhaps 1/200th (maybe less) is going to be absorbed by the skin too, because, as you would well know, that is how X-rays work.
The fact we have greater penetration at the higher energies used for a CXR or other diagnostic imaging does not rule out using the comparison to Backscatter X-rays. In fact, it can be used to validate it.
Please note again that I am not suggesting that these machines should be rolled out everywhere and that we should have to use them, because I think it's a stupid security measure.
Thanks for the response, and I agree with you by and large. Regarding the exact skin dosage (something the medical field goes to great lengths to minimise), the jury is out as far as i can tell, as testing of the equipment has been miminal. I wouldn't be that surprised if backscatter imaging did turn out to be safe, my problem with the technology is that it is basically untested and has not had its safety validated via independent large scale testing. With any health related screening test (especially one imposed on a massive population) there is a high bar set for causing minimal harm, as there should be. With backscatter screening there appears to be no decent safety checks, poorly qualified screeners, and worst of all, minimal/no evidence that the screening test catches any of the problems it's supposed to. I see it as a pointless radiation dose.
