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While traveling by air here in India, one is instructed to remove all electronics like cell phones / media players / laptops and pass them thru the X-ray scanners separate from the rest of one's hand baggage (carry-on).

Is a modern-day DSLR (specifically a Nikon D90 / D3100) and the SD card contained within affected? Is is safe to pass it thru or do I insist on a manual check and bypass the X-ray machine if possible?

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8 Answers 8

up vote 17 down vote accepted

I've done a lot of travel with dSLR equipment and cards, I've never had an issue, it's safe to send through. The issue, historically, was with film since x-rays are light and could affect the film.

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@Reid - Thanks! –  John Cavan Jan 5 '11 at 4:39
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Actually the issue, historically, was with intensity. For several years now you can put your films into modern X-Ray-scanners at the airport with about the same effect as on memory cards: insignificant (although existing). –  Leonidas Jan 5 '11 at 14:35
    
no problem! @Leonidas - AFAIK, there's a lot of debate about where the threshold lies: what speed film can be scanned what number of times. I'm not aware of anyone who's argued that there's a speed which can be scanned an unlimited number of times. –  Reid Jan 5 '11 at 14:38
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There is a threshold, of course, as there is a threshold for flash-memory to be affected noticeable by (the ionizing) X-rays. Older generations of X-Ray-machines used more intensity, thus darkening your films fast. It is the same with the CCDs of X-Ray-machines as with camera-CCDs: they got better/more sensitive, so intensity of the "lighting source" could be and was lowered. Of course flash-memory still benefits from being digital instead of analogue ... –  Leonidas Jan 6 '11 at 4:55

It's completely safe for the equipment. From what I can tell, it's not really a question about the x-rays affecting the device, it's being able to determine if they are shells around bombs. If I recall correctly, the Lockerbie bombing was done with a laptop shell around the bomb; other complicated electronics could also be used in a similar fashion. By placing these devices separately from the rest of your luggage, the screeners have a better view of the equipment and its internals.

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The lovely chaps at security will swab for explosives if your jeans have set the metal detector off, they'll also look very scared trying to get the camera back in its bag ;) –  Rowland Shaw Jan 4 '11 at 21:49
    
Yes, the equipment won't receive a different radiation dose whether it's in or out of the bag, unless you manage to position it behind an opaque object or wrap it in tinfoil. –  Reid Jan 5 '11 at 4:04
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@Reid-- that's not technically true, depending on the way that the radiation machine is configured. If there are a lot of low-energy photons emitted from the machine, they would get absorbed by the bag or container, rather than the outer surface of the camera. Higher energy photons would just pass right through. Some medium energy photons are absorbed by the bag; that's why the bag is detectable by the machine. –  mmr Jan 5 '11 at 5:09
    
But if we're talking about the memory card and electronics, it seems immaterial whether radiation is absorbed by the camera's shell or the luggage. –  Reid Jan 5 '11 at 16:03
    
@Reid, absolutely. But the idea of 'radiation dose' actually has real, quantifiable numbers behind it, so much so that I had to learn about dosimetry (en.wikipedia.org/wiki/Dosimetry) when studying x-ray radiation and imaging. Now, whether the differences in dose is significant is another issue, and one that can be determined by putting a meter in the bag and outside the bag, etc. When not inside luggage, there is a higher chance that more photons will hit the electronics, but for the most part, they won't do anything if they do. –  mmr Jan 6 '11 at 16:10

Yes. It is completely safe. You have nothing to worry about.

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It is quite safe, but only due to low-level-radiation digital X-rays on the scanners side and modern error-correction, fault-tolerance, sometimes chance on the users side. If you knock out a bit with X-Rays in a common picture-file today, you won't notice - one bit in four MByte-files will mostly be at a place where you'll never notice the difference.

Errors ARE introduced into flash and volatile ram, look for "soft error" if you want to know more, there are some papers.

If you're paranoid: backup your files on to something magnetic or off-site and then just move on. If not, nevertheless do backup the files. As for the camera - if it is affected (settings scrambled), just reset it as you would without knowledge about the source. Its firmware is in non-volatile PROM and much harder to change (read: safe).

PS: The wish for removing the electronics and putting them separately though the X-Ray really stems from a better view. I was asked several times to separate my bag full of gadgets, as they could not identify anything in my three layers of laptop, palmtop, camera, power supplies and batteries. Two times now they also have mistaken a part of my side-bag of the palmtop (Psion) for a knife :)

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Is the sensor affected by x-rays? Or more specifically, can it be damaged by x-rays? –  Therealstubot Aug 14 '12 at 22:55

MicroSD cards (like in your phone) seem to be very susceptible to corruption. Two different phones, on two different trips, at two different time (January 2012 and March 2012) resulted in total loss of all data on different microsd cards. They both corrupted after going through the second time, on the return trip.

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X-rays can corrupt Flash memory, depending on dosage and exposure time.

X-rays are ionizing radiation (as opposed to light, which isn't). That means that an X-ray photon has so much energy that when it hits an atom it is able to knock off an electron, generating electrical charge. If enough high-energy photons hit anything, a significant amount of charge (read voltage) can be generated. That's how Geiger counters work - they measure that charge.

Flash memory is written by applying electrival voltage to it, so if it is briefly exposed to strong x-rays or not-so strong ones for a longer time, eventually those electrons will hit enough atoms to build the charge necessary to corrupt some bits. It's like playing a battleship game where X-rays are shells fired at random and the Flash memory bits are the ships - keep shooting and eventually you'll hit something.

I know for a fact that airplane electronics occasionally have memory corruption issues because of X-rays and cosmic rays, which are stronger at flying altitudes and much worse around the poles (look up "Van Allen Belts" in Wikipedia). As a matter of fact, when you fly over the poles you can get a dose of radiation equivalent to several chest X-rays. There's a very interesting post from a guy who found that the memory card in this camera was blank after flying to japan; my guess would be that the cosmic rays corrupted it in flight. (see http://www.visajourney.com/forums/topic/193644-memory-card-deleted-after-flight/)

As for X-ray scans, my guess is that the dosage is low and short enough to pose a very small risk for Flash memory, but it is not zero. Remember the battleship analogy - sometimes your very first shot can hit a ship.

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My Minolta digital camera produced a perfect picture right before I arrived at the airport. The next picture after passing security was a big white (like over exposed) blob hardly showing the details of the pictures with lines through it. All subsequents pictures I took were like that. The pictures that were on the card prior were not damaged. My phone also was damaged , the screen turned white, and I had to order another one while waiting for my plane.(again right after passing security). Weird coincidences???? I don't think so.

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Airport X-ray scanners recently damaged two of my SD cards to the point where they were unusable. I've had to send them back to the manufacturer to get replaced.

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that will have been metal detectors, not X-ray scanners (unless those were turned up illegally to radiation levels high enough to kill you or the operator with a single blast). Your cards and camera get exposed to more X-rays during a 2 hour flight than during the security check. –  jwenting Jan 30 '12 at 6:51
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It depends on the nature of the security check: some machines do expose people to relatively large amounts of radiation. But you have an excellent point, @jwenting: unless the cards were used immediately before and after the scan, it's not possible to pin down the cause of any subsequent problems. All one can legitimately say is that the cards were damaged during the period between last successful use and when the problems were first noticed. –  whuber Jan 30 '12 at 19:35
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@whuber that too. Was commenting on the technical issues, X radiation at the levels used in curbside scanners won't harm electronic components unless the machines are seriously malfunctioning. –  jwenting Jan 31 '12 at 6:19

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