[Oradlist] MEDHP-SEC: FW: article by brenner in BJR to replace effective dose (fwd)

Gibbs, S Julian s.julian.gibbs at vanderbilt.edu
Thu Jul 24 10:12:05 PDT 2008

Brenner is somewhat correct in that effective dose is a very crude 
estimate of dose to a population.  It is averaged over both sexes 
and all ages, so it is not at all accurate for application to a 
single person.
However, Brenner's argument implies that there is known risk from 
small radiation doses--clearly a large assumption.

---------- Forwarded Message ----------
Date: Thursday, July 24, 2008 12:18 PM -0400
From: dauerl at MSKCC.ORG
To: medhp-sec at hps1.org
Subject: MEDHP-SEC: FW: article by brenner in BJR to replace 
effective dose

Effective dose: a flawed concept that could and should be replaced.

Brenner DJ.

Center for Radiological Research, Columbia University Medical
Center, New York, NY 10032, USA. djb3 at columbia.edu

The effective dose is designed to provide a single number
proportional to the radiobiological "detriment" from a particular,
often inhomogeneous, radiation exposure, with detriment
representing a balance between carcinogenesis, life shortening and
hereditary effects. It is commonly used to allow a comparison of
the risks associated with different spatial dose distributions
produced by different imaging techniques. The effective dose
represents questionable science: two of the most important reasons
for this are that the tissue-specific weighting factors used to
calculate effective dose are a subjective mix of different
endpoints, and that the marked and differing age dependencies for
different endpoints are not taken into account. Importantly, the
effective dose is prone to misuse, with widespread confusion
between effective dose, equivalent dose and absorbed dose. It is
suggested here that effective dose could and should be replaced by
a new quantity that does not have these problems. An appropriate
new quantity could be "effective risk", which, like effective dose,
is a weighted sum of equivalent doses to different tissues; unlike
effective dose, where the tissue-dependent weighting factors are a
set of subjective committee-defined numbers, the weighting factors
for effective risk would simply be evaluated tissue-specific
lifetime cancer risks per unit equivalent dose. The resulting
quantity would perform the same comparative role as effective dose;
it would have the potential to be age- and, if desired,
gender-specific, just as easy to estimate, less prone to misuse,
more directly interpretable, and based on more defensible science.

PMID: 18443016 [PubMed - indexed for MEDLINE]

 Br J Radiol. 2008 Jul;81(967):521-3. Epub 2008 Apr 28.


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S. Julian Gibbs, DDS, PhD               Voice: 615-322-1477
Professor, Emeritus
Dept. of Radiology & Radiological Sciences
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