[uulrich]

I never had any kind of problems w/ memory cards, notebooks and digital cameras. The risks of having x-rayed memory cards are similar of the risks spoiling your cell phone while passing security checks.

However, I don't know if cosmic radiation comes close to mR values of x-ray at airports but NASA does not certify any Quartz/LCD wrist watches for EVA and the only camera body w/ LCD screen used on EVA is a modified Nikon F5. The cosmic radiation can spoil the LCD indeed but apparently there is no impact w.r.t. the F5's memory.

That said, it may be wise to check-in with any electronic gadgets as cabin luggage. I used to travel w/ attache case from ZERO Albertan and as a result the security personnel blows up the x-ray in oder to look through the case itself. This indicates to me that x-ray film cases and such as just a rip off and belong to a category of fairy tales. If they cannot scan your items by their default settings they just increase the radiation until they gain a proper 'look-through.

When I pass security w/ a LOWEPRO Commercial (45 lbs. at check-in) and having some memory cards inside the bag they do not pay any attention to the cards and the other trimmings but they have a look at the lenses and bodies, performing 100% visual. It has always been the case that my luggage got hand checked. I refer to my film and digital bodies. I don't know if you saw my comments on X-Ray and Film in another thread but they don't mind about film and x-ray sensitivity OTOH. These guys ask you about ISO/ASA values and then blow up their xray scan to the maximum.

As far as your 'cumulative' is concerned I don't think so. Does not seem logically to me but I welcome other's opinion.