[Frameworks] X-Ray motion-pictures

[Scott Dorsey]

Okay, old guy tells stories.


Back in the twenties and thirties, doctors would employ open fluoroscopes,
with an X-ray source behind the patient and a fluorescent screen in front
of them.  X-rays passing through the patient would cause the screen to 
illuminate and the doctor could see what was going on inside in realtime.

Many of the old classic sequences that still show up in educational films
such as the man eating and man voicing different vowels and consonants,
were shot off the screen of an open fluoroscope.

This approach has some problems.... namely it takes a lot of radiation to
get a nice bright image, and all of that radiation (not just the backscatter)
is pointed at the doctor.  So although you can see open fluoroscopes in old
movies where W.C. Fields has swallowed his cigar, you will not see them in
use today.

Because doctors needed to see movement and didn't want to irradiate themselves
constantly, a number of manufacturers made cinefluoroscope systems with a 
Mitchell or Acme 35mm pin-registered camera movement, a very fast lens,
and a fluorescent screen all in one package.  The high speed Leitz Noctilux
lenses were originally designed for these applications.

These were in common use for heart imaging until maybe a decade ago, and
if you are looking for a film image you may be able to find cardiological
radiologists around with a film cineangography system.  These systems all
provide full aperture 35mm images.  So if you want 16mm you'd have to get
the lab to bump it down.

All of these systems today have been replaced with high resolution video
systems.  The nice thing about the video systems is that they result in
less radiation to the patient because the light sensor is faster than Tri-X.
These systems are small and convenient enough that some cardiologists will
have their own system rather than contracting it out to a radiologist.
The bad thing about them is that they tend to have more smear on motion
than the film systems because of the longer persistence phosphors.

Now... if you don't need to deal with human beings, you can pour a whole
lot more radiation into the object.  There are a bunch of fairly inexpensive
X-ray inspection systems for PC boards that give you realtime video with
decent resolution.  Not very high energy radiation since they just need to
be looking at thin board traces for the most part.

So... if I were looking to rent some time on a machine, I would ask a 
cardiologist if they could recommend a local radiology guy, or I would
talk to PC board fab people, depending on whether I was looking at people
or objects.  I have only done static x-rays, not moving ones, and there
aren't a lot of folks doing moving ones artistically today so it could be
really cool.
--scott


lens was originally designed