Re: pedoscope

["LEE COLLINS" <nlco@imag.wsahs.nsw.gov.au>]

In March 1997, Prof. John Cameron, well known in Medical Physics, 
posted a reply on the MEDPHYS newsgroup on the same issue. If John 
will forgive me, I have reproduced the relevant part of that message 
below :

Dear Colleagues, Now that items about erythema from fluoroscopes has
dwindled some of you may be interested in a case report. A young man who
graduated from High School in 1928 took a job as a tester at a shoe
fluoroscope factory in Milwaukee Wisconsin . [His daughter-in-law, a
secretary in the Dept. of Radiology at UW-Madison, gave me the following
account. I won't vouch for its complete accuracy but the main items are
correct.
        The owner of the factory insisted that he test the shoe
fluoroscopes by looking at his own feet in the machines. After some period
of time - years I think - he developed radiation symptoms to his feet. Over
a period of many decades they surgically removed more and more of his lower
limbs. The removals were not due to cancer but to tissue destruction. He
died at about age 70 without his lower limbs but not from cancer!
        In 1958 shoe fluoroscopes were "outlawed" in nearly all states.
Some states did it by requiring that shoe fluoroscopes could only be
operated by an MD. I obtained a shoe fluoroscope for teaching purposes. The
output at the sole of the shoe was about 100 R/min.(It was against the
state law for me and UW to have such a unit. There was a very stiff fine
per day for such an offense. I calculated that the fine was in the 5 figure
bracket. Nevertheless I registered the unit with the state!0  A timer
limited the exposure to about 5 seconds. Of course, the button could be
pushed many times. I have never heard an estimate of the cumulative dose to
the population from shoe fluoroscopy but it must have been significant,
especially the gonadal dose. Many kids liked to stop in the shoe store to
see the bones in their feet when nobody was looking! Being from a farm and
never having been in a shoe store since I had older brothers, I missed out
on my chances of getting this experience.
        I occassionally demonstrated the leakage radiation from the shoe
fluoroscope when I was teaching introductory physics. A student held a loud
GM counter in the far corner of the large lecture room.(about 20 m from
the unit) - a momentary burst from the fluoro gave a great increase in the
output of the GM counter. I had calculated the exposure to students in the
front row and found they would receive much less than 1 mR and I didn't
worry about it. After a few years I stopped doing the demonstration
primarily over the concern that I might be setting a bad example.
        In 1958 I measured the output from an unamplified fluoro in the
local VA hospital and found it to be about 100 R/min at the skin - I put in
some filter.  It was still to be a few years before image intensified
fluoroscopy was to become generally available.


Lee Collins

>      A friend of mine recently purchased a "pedoscope" while on vacation in 
>      England.  Does anyone know any sources of information on these devices 
>      (used in shoe stores to aid in fitting).  Also, if there were any old 
>      regulations on their use, that also would be of interest.  He has the 
>      unit on display in his radiology practice and would like to include 
>      some information on their use/regulation/etc.
>      
>      joe guido
>      joseph_guido@radian.com
> 

********************************
Lee Collins MSc FACPSEM
Chairman, Division of Allied Health
Medical Physics Dept.
Westmead Hospital
Westmead   NSW  2145  Australia

Phone : +61 2 9845 6533
Fax   : +61 2 9891 5385
email : lee.collins@imag.wsahs.nsw.gov.au
********************************