[ RadSafe ] Re: Studies Quantify Cancer Risks From CT Scans

[Clayton J Bradt]

I agree fully with Mike. I would further add that it is one thing to use
LNT to extrapolate risk coefficients to dose ranges below the range of
observed effects as a purely academic exercise.  It is quite another to use
these extrapolated risk estimates to publish the number of additional
deaths expected from a given population dose. The latter is both
irresponsible and unprofessional.  Such projections are based upon a chain
of assumptions linking empirical data (e.g the Life Span Study)to future
events, which are themselves probably unobservable (e.g. additional cancer
deaths). Each individual assumption may in itself be reasonable, but when
linked together they cannot support their own weight, let alone support the
burden of public health policy decisions. Each assumption in the chain
amounts to another degree of separation between reality and policy.


Clayton J. Bradt
Principal Radiophysicist
NYS Dept. of Health

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Date: Tue, 15 Dec 2009 13:26:51 -0600
From: "Stabin, Michael" <michael.g.stabin at Vanderbilt.Edu>
Subject: [ RadSafe ] Re: Studies Quantify Cancer Risks From CT Scans
To: "radsafe at radlab.nl" <radsafe at radlab.nl>
Message-ID:

<AE2199B600823B4A9CC19B6E88BE05020FB7D1B529 at ITS-HCWNEM04.ds.Vanderbilt.edu>

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"... reducing radiation dosages, eliminating unnecessary and repeat
examinations, and creating searchable electronic medical records to collect
and track CT studies over time..." are all very worthy goals.

Everyone agrees. But can this not be done without scaring the general
public out of their wits so, that they avoid necessary CT scans? And
without suggesting that physicians are serial killers?

Carol Marcus notes to me that two patients "had CT scans for an unrelated
reason were found to have small localized kidney cancers.  Their kidney was
removed, and they were cured.  Otherwise, this cancer would not have become
obvious until it had spread and the patient would die.  Or, a patient with
new onset stroke is a candidate for TPA, a drug that lyses the clot.
However, if the patient had a hemorrhagic stroke, this drug would likely
kill them or make the stroke worse.  Many physicians would not use the drug
without knowing whether this was a garden variety stroke or the rarer
hemorrhagic type.  That's why they get CT scans."

I agree that some CTs and repeat CTs are not needed. I don't agree with
publishing these articles that suggest specific numbers of people are
keeling over dead in the streets every year because they had a CT, based
solely on the LNT hypothesis. NOT getting needed medical treatments
certainly causes morbidity and mortality; receiving diagnostic levels of
medical radiation may or may not cause excess cancers, we simply don't
know, and to claim that we do is irresponsible, espcially when this may
cost lives.


Mike

Michael G. Stabin, PhD, CHP
Associate Professor of Radiology and Radiological Sciences
Department of Radiology and Radiological Sciences
Vanderbilt University
1161 21st Avenue South
Nashville, TN 37232-2675
Phone (615) 343-4628
Fax   (615) 322-3764
e-mail     michael.g.stabin at vanderbilt.edu
internet   www.doseinfo-radar.com





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