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Mon Jan 29 14:42:24 GMT 2007

In a message dated 1/29/2007 8:22:56 AM Central Standard Time,  
brombwi1 at memorialhealth.com writes:

Whenever I disagree with Dr Mattox I tend to wait out the feeling  and
the urge usually passes. However the 1/2000 leukemia rate for CT  scan
seems to me to be flawed on it's face. CT scanning started in the  early
80's and by mid 80's was common. We now have 20-25  year follow  up and
the rates of leukemia overall are falling except in the youg  pediatric
age group  (
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abst
ract&list_uids=12712476
).  Unless you postulate that the lag time b/w expsure and result has  not
yet  been reached (reasonable ?) I find it hard to believe that  the
exposure risk is that high. That is not to say that the risk  is
non-existant, however.

Bill, 

I believe that you are 5 years or more short on that estimation. The  little 
hospital in Central ILL that I worked at back in 1976 had just received  one 
of the then new CAT scanners. I'm suspecting that the slow, single beam  
scanners back then delivered on the same order of magnitude of radiation as the  new 
32/64 beam machines, based both on duration of beam (it often took a second  
or more to complete a spin) and detector sensitivity (which have undergone at  
least a quantum leap if not two [pun intended] in the past 30 years).

I agree with your estimation that the risk is both overstated and non zero.  
I believe that the lag time for the development of other radiation induced  
cancers (dating back to the fluoroscopic foot measuring devices from the 1940s  
and 50s, if not before, and the atomic blast exposures of the 1940s and 50s) 
was  somewhat less than 30 years.

ck
Charles S. Krin, DO FAAFP

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