P3D Re: X-Ray Scare: Fact or Fiction?

[jacob@xxxxxxxxxxxxxx (Gabriel Jacob)]

A few weeks ago it was reported by several P3D members about the 
Photographic and Imaging Manufacturer's Association (PIMA) news
release about the possible hazards of film and airline security
machines. It was also put on PIMA's web site.

For those that missed that information check out,
http://www.pima.net/new.htm

They have an Acrobat PDF format document with a more in-depth
report on the effects of the new security equipment at,
http://www.pima.net/xray.pdf

It basically says the same thing that was reported on P3D, that 
there is a definite hazard posed by these new machines. For
those without the appropriate pdf reader or don't feel like
downloading it, here is the report. The pdf file takes up
over 600k. The exact text based message below takes up 8k.
I can do without the fancy fonts and 1 logo! 

Gabriel

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PHOTOGRAPHIC AND IMAGING MANUFACTURERS ASSOCIATION, INC.

The CTX-5000SP and Camera Films The Photographic & Imaging
Manufacturers Association (PIMA) has completed a series
of tests evaluating the effects of the CTX-5000SP checked
baggage inspection system on photographic films. The
CTX-5000SP is the first checked baggage inspection system
to use computed tomography (CT) to screen airline passengers
checked baggage to detect explosives. The results show that,
under certain conditions, the CTX-5000SP has a detrimental
effect on camera films.

Background
During March 1997 the NAPM established an ad hoc task force
to study the effects of the CTX-5000SP on photographic films.
Participants included Agfa, Eastman Kodak, Fuji, Ilford,
Imation, Konica and Polaroid. Each manufacturer was invited to
contribute to the test design and to provide films for testing.
Arrangements were made to conduct tests using the CTX-5000SP
located at the Federal Aviation Administration (FAA) Technical
Center in Atlantic City, New Jersey. This study's goal was to
characterize the effects of the CTX-5000SP upon photographic
film. No attempt was made to ascertain the probability of film
transported in baggage through the CTX-5000SP being irradiated
by the highly energetic X-rays.

Test Design
The CTX-5000SP has two X-ray systems incorporated into its design.
The first X-ray system is similar to what is currently in use
to examine carry-on baggage. This system irradiates the entire
piece of baggage, resulting in an image that is analyzed by the
computer system to assess potential dangers. The image is then
displayed on a computer screen for operator assessment. The baggage
is then positioned under a second, thin X-ray beam, which scans
portions of the baggage as determined by the computer and/or
operator. This second scan has higher energy than the first and is
where the X-ray damage, if any, should occur on the film. Given
the nature of the CTX-5000SP, the second scan must occur in at least
a few locations on each piece of luggage.

To assess the X-ray exposure effects from the CTX-5000SP on typical
consumer silver halide films, a series of tests were conducted to
characterize the X-ray effects under normal operating conditions.
These tests were designed to assess the effects of both the standard
and high energy X-ray beams on the film. One challenge to the
experiments was to control where the high energy X-ray beam
irradiated the samples. To do this, the tested films were placed
into a piece of luggage along with a material used to simulate a
threat such that the film was as far from the simulant as possible.
This threat material caused the CTX-5000SP to scan its position, and
thus we were able to control when and where we irradiated the film
samples with the high energy X-rays.

Experiments
Four experiments were conducted. They were:

Experiment #1: Samples, unexposed to light, of each selected film
passed through the CTX-5000SP without receiving a direct scan from
the highly energetic X-ray beam. This system, as stated earlier,
is similar to what is currently in place to examine carry-on baggage
at U.S. airports. These films were exposed for 1, 5, 10 and 50
inspections.

Experiment #2: Samples, unexposed to light, of each selected film
passed through the CTX-5000SP and received a direct scan from the
highly energetic X-ray beam. These films were positioned perpendicular
to the X-ray beam.

Experiment #3: Samples, exposed to a subject, of each selected film
passed through the CTX-5000SP and received a direct scan from the
highly energetic X-ray beam. These films were scanned perpendicular,
parallel and at 45 degrees to the scanning plane of the X-ray beam.
We selected a low modulation scene (a model with a uniform background)
and bracketed the normal exposure by two under and over exposures in
one-stop increments. This scene was selected, as it was believed to
be a very critical scene for this type of X-ray damage.

Experiment #4: Samples, unexposed to light, of each selected film
were located close to a source which is scanned with the high energy
X-rays. This acts as a scattering site, and the samples were then
examined for the effects of scattered radiation. Each manufacturer
submitted films in the packaging formats they wished to test. Film
speeds ranged from 100 to 1000 speed, while formats included a
standard cassette, APS packaging, single use cameras and 120 film.
For Experiment #3, all scenes were exposed by Fuji Film's Sensitized
Products Photo Imaging Group in Carlstadt, N. J. For the color
negative films, Konica provided a standard C-41 process. Thus, all
manufacturers' films received the same exposure and processing.

Results and Evaluation
The processed films were visually examined under ideal lighting
conditions and magnifications. The films were examined by engineers
and technicians from all of the participating manufacturers. The
results were:

Experiment #1 failed to show any X-ray damage to the film by way of
visual inspection. Slight fogging did occur, but was determined only
by sophisticated scientific instruments. The amount of fog was
consistent with inspection systems for checked baggage currently
in place and operating under the FAA guidelines of less than 1
milliroentgen (1 mR) per inspection. The amount of fog varied with
the speed of the film and the number of passes through the X-ray
system. It would not be noticeable by the average consumer.

Experiment #2 resulted in an approximately 1 cm wide line of high
density on the photographic negative. The density of this
high-density line depends upon the speed of the photographic
emulsion. The high-density line becomes more photographically dense
as the film speed increases. However, the line is visible for all
emulsion speeds tested (100, 200, 400, 800 and 1000).

Experiment #3 again resulted in an approximately 1 cm-wide
high-density line of the photographic emulsions. The orientation
and shape of this line depends upon the orientation of the film
relative to the incident X-rays. Figure 1 shows the scene
selected. Figures 2 through 4 show the selected scene after
exposure to the highly energetic X-ray beam in the CTX-5000SP
for 200, 400, and 800 speed films respectively. In these prints,
the film was oriented perpendicular to the direction of the
incident X-rays. Figure 5 shows the same scene on 400 speed
film oriented parallel to the incident X-rays, while Figure 6
shows the film oriented at 45 degrees relative to the
incident X-rays. Additionally, Figures 7 and 8 show scenes
from negatives exposed to the high energy X-rays which, due
to scene content, do not show the X-ray damage.

Experiment #4 resulted in some additional fog due to
scattering. However, the fog level was not sufficient to cause
concern. Again, this fog is consistent with that expected from
a typical carry-on or checked baggage system operating under
the FAA guidelines of less than 1 mR per inspection. The amount
of fog varied with the speed of the film and the number of
passes through the X-ray system.

Conclusion
Testing by the PIMA Airport X-ray Task Force indicates that
the CTX-5000SP will cause significant fogging of all color
negative films with an ISO speed of 100 or higher when
the film sustains a direct hit by the machine's high intensity
X-ray beam. The orientation of this stripe is dependent upon the
orientation of the film relative to the X-ray beam. The density
of this stripe depends upon the film speed. Additionally,
whether this stripe is seen in the photographic print will
depend upon the scene content. Busy scenes with flowers,
foliage, etc. tend to obscure or lessen the X-ray effects.

Recommendation
In light of the above findings, it appears appropriate to warn
air travelers of the potential damage to their unprocessed
films that receive a CTX-5000SP inspection. The ways and
means of communicating the warning through the manufacturers,
retailers and the FAA will have to be developed.
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End of PHOTO-3D Digest 2672
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