Re: eBay x-ray tubes & justified fears (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 5 Aug 2007 01:28:33 EDT
From: Mddeming@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: Re: eBay x-ray tubes & justified fears (fwd)

In a message dated 8/4/07 11:54:43 P.M. Eastern Daylight Time,  
tesla@xxxxxxxxxx writes:


---------- Forwarded message ----------
Date: Sat, 4 Aug 2007  09:51:43 -0700 (PDT)
From: William Beaty <billb@xxxxxxxxxx>
To:  Tesla list <tesla@xxxxxxxxxx>
Subject: eBay x-ray tubes &  justified fears

Um...  In hospitals they aim those at  people.  They did it to me, yet I'm
still  alive.



More's the pity. Now for some honesty: What you described was at extremely  
small, controlled current, from well insulated machines, for fractions of a  
second.

:)

High-voltage hobbyists will notice many tempting x-ray tubes  being
constantly listed on eBay.  I'd always assumed that they were  lethal.
But I've recently been wondering about the genuine danger of  common
sources of ionizing radiation, versus the hysterical overreaction  typical
of Americans.  Ra-dee-ation!  "Any risk is too much  risk?"  Yeah, right.
But specifically, if the radiation burns weren't  an issue, perhaps the
cancer risk isn't as high as I've always  imagined.  How much of our
opinion of x-ray tubes is based on  reality?

For example, if you stand outside in unshielded sunlight for a  couple of
hours, you receive a serious radiation burn, with skin peeling  and falling
off.  Yet the cancer risk is quite small, and people in  tropical countries
even ignore the problem entirely.  The effect might  be mostly limited to
the outer 1mm layers.  But make no mistake, it's  a genuine radiation burn.
 
 
Solar radiation produces surface damage and skin cancers, X-ray damage  is 
usually deeper tissue.



If you take a geiger counter along on a cross-country airline  flight, be
prepared for a surprise.  It starts clicking within seconds  of takeoff.
At cruising altitude it roars: ten or twenty counts per second  ( and
supposedly much higher during solar flares.)  But we aren't  terrified of
air travel because of this.  Should we be?

If you  look up the ratings for modern dental x-ray equipment, and
calculate the  exposure needed for the mildest of x-ray burns, guess what
the exposure  time is.  Seven thousand hours.  You'll heal too fast. You
can't  get an x-ray burn from a dental unit; increased cancer risk is the
only  danger, and it's the dental techs using the equipment every day who
should  worry.  (And how does the risk compare with other  real-world
acceptable risks, such as cancer from peanut butter, or the risk  from
solar UV in outdoor employment?)

The USA is weird about x-ray  tubes, but I'm starting to get skeptical
about the justification.  At  the science museum in Paris, "Palais de
Decouvertes," there's an exhibit  case with an unshielded Crookes-era x-ray
tube, a fluorescent plate, and a  sample object.  Press the button, and you
see the green glowing image;  bright enough that it's easily seen in a well
lit museum. The tube is  behind the fluorescent plate, so the x-rays are
aimed at your face!   Maybe the cancer risk ridiculously insignificant.
Or is that museum exhibit  a clear danger to the public?

Another example.  I was talking  about "shoe fitting" x-ray machines from
the 1950s, and one local guy  mentioned that he'd played with one of these
as a kid, and exposed himself  for at least tens of hours.  He lived in a
boring small town.   The shoe store next to the movie theater had one of
those  fluoroscopes.  Every weekend he and friends would stare at the  live
moving x-ray images of their feet for minutes at a time until the  salesman
chased them out.  So why isn't he dead?

Another one: a  guy at work got a CAT scan, then went home and took out his
geiger  counter.  He said that it sensed his body from many feet away,  and
fairly roared when the GM probe was held against his chest.  How  could
anyone survive such exposure?  Perhaps "roaring geiger counter"  isn't a
very good test of cancer risk.

So here's the important  questions:

If intensity is below the threshold for x-ray burns,  then what is
the cancer risk from common x-ray sources?   Specifically, how does it
compare with cancer risk of ionizing  radiation which EASILY causes
radiation burns: the risk of going  outside in the sun?  Or how dangerous
is an x-ray tube when  compared with the risk of working outdoors, or of
living in a  tropical country and getting huge amounts of hard UV
exposure every  day?

Also:  intensity being equal, (or if accumulated  exposure is equal,) how
much worse are x-ray frequencies when  compared with solar UV?  I
realize that UV produces surface  cancers which are easily noticed,
while x-rays cause hidden damage  deep inside.  But ignoring that fear,
how much worse for cancer  risk is a dental x-ray tube when compared
with a very dim UV sunlamp  which cannot produce a sunburn?  Tens of
times worse?   Thousands?  Or much less?  In other words, is our fear of
low-power x-ray tubes justified?


And finally:

Just this year  a research group discovered that x-ray cancer is not equal
for all  humans.  The risk depends on genetics.  (This is contrary to  what
everyone has always assumed.)  In a study of patients exposed to  a dose of
head x-rays in the 1950s, the incidence of cancer was  concentrated in
certain families.  Note that this was a major dose,  one intended to kill
ringworm infections, and which caused hair to fall  out.  People from
certain families got brain cancer.
 
That some people are more susceptible than others to any toxin (including  
radiation) has been well established for over a hundred years. Every substance  
has its own distribution curve. Guidelines must be set to protect ((+% of the  
population.



Odd thought: perhaps humans are immune to x-rays, but people  with a
certain genetic defect cannot tolerate even a small exposure, and  this
population has biased our stats.

Odder thought: for  Hiroshima-scale radiation exposure, I wonder if some
rare people never  aquired radiation sickness.  Imagine if some "human
cockroaches" exist  who would easily survive a nuke war.

William J.  Beaty                         






I think your viewpoint and attitude make you an excellent person for  
self-experimentation on X-ray dosing.
Let us know what happens. Just remember, those whom you consider  
over-cautious can be wrong a hundred thousand time with little harm done. You'll  only 
have to be wrong once to end the discussion.
 
Matt D.









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