Are you disputing the Kodak research?   (You don't say if you read the
TIB.)

If so, have you done your own research and how was it conducted?  
Haphazardly by trial and chance?  Or did you do controlled studies of
two sets of films of various speeds all containing images of the same
subject matter, one set not exposed to radiation and the other set put
through the typical airport visualization devices?

If so, then please explain where the Kodak research went wrong.

Francis A. Miniter

X-ray film works because some of the x-rays projected toward the patient and
film are absorbed in the patient and some go thru the patient and are
absorbed in the film.  If you make the film more effective at absorbing the
x-rays, you don't need as large a dose to the patient to get a useful image
on the film.  Thus, modern x-ray film is truly different from photographic
film.  While photo film will respond to x-rays (that's how x-rays were
discovered), modern x-ray films have additives in the emulsion to increase
the absorption of the x-rays.

In the late 80s, the US began switching from continuous beam x-ray machines
in airports to pulsed x-rays.  These were everywhere in the US air system by
the early 90s and expose the objects inside the machine much like an
electronic flash.  The pulse duration is very short, but enough to generate
an image on a CRT.  That image is held on the CRT for examination by the
operator.  A second look can be had by flashing the x-ray again.  The dose
from each flash is trivial - it won't even register on dosimeters designed
to monitor environmental background radiation, so it won't harm photographic
film.

Don't get the idea that this change was made to control the exposure of your
possessions as they go thru the machine.  There are very specific
regulations about how much radiation exposure is allowed for the people who
work at these machines, and meeting those regulations requires shielding the
x-ray machine.  That makes the machine heavy, VERY heavy, and that kind of
machine can't be moved easily or placed just anywhere.  When security was
increased and rows of these machines had to be used, the weight challenged
airport design and structuring.  Pulsed x-rays machines create so little
dose that shielding isn't needed, weight isn't an issue, and the problem
went away.

Bear in mind this applies to the US.  Obviously an airline security system
is only as secure as the weakest point of entry.  So when  the US began
leaning on other countries to implement security screening, they wanted the
US to provide ther hardware.  That's where all our old continuous beam x-ray
machines went - overseas.  You'll find them in use in eastern Europe, much
of Asia, Africa, South America, and island nations everywhere.  So gate
security x-ray machines in the US, western Europe, and Japan can be counted
on to do no harm to your film.  Elsewhere, be careful.

On the other hand, checked luggage is now subject to CT scan, and that
processWILL harm your film.  Because these machines are used in a separate
area not open to the public, the weight of shielding is not really a
problem, so the dose intensity doesn't have to be constrained the same way.
Add to this the idea that a CT scan makes multiple passes called slices in
its imaging process, and the total dose to the contents of a bag becomes
significant.  NEVER NEVER NEVER put your film in your checked luggage.

Lead lined film bags - do they really work?  Yes - with a qualifier.  The
lead will cut the x-ray field significantly, which makes the bag a dark
featureless blob on the gate security x-ray screen.  There is some degree of
adjustment available to the operator, but not much - that would defeat the
benefit of the pulsed system and increase worker exposure.  Even so, turning
up the intensity won't help them much.  The lead bag is more effective at
absorbing the lower energy x-rays and that causes the remaining x-rays that
get thru to be higher in energy. Higher energy makes them more effective at
passing right thru the film instead of being absorbed.  The qualifier is
that the bag helps with gate security x-rays, but not the CT scans - those
are just too intense to be affected very much by the small thickness of lead
in those bags.  I find the lead bags to be rather unnecessary for travel
within the US, but they seem to be a fairly good idea if you travel where
our old x-ray machines are being used.

Now, can we all agree that I don't have enough to do?

Bob in Las Vegas