[ RadSafe ] New average annual medical dose

Tue Aug 14 15:01:57 CDT 2007

Hi everyone,

Related to the question posed by Wes Van Pelt, copied below is the Abstract 
from the recent NCRP meeting [ Advances in Radiation Protection in 
Medicine ] summary of the "Magnitude of Radiation Uses and Doses in the 
United States".

The summary below is  from a presentation given by Fred Metter, Jr. of the 
New Mexico Federal Regional Medical Center  This abstract reviews the major 
factors which have contributed to the sharp increase in average diagnostic 
radiation exposure over the past 20 years.

My thanks to Larry Dauer of Memorial Sloan Kettering for a link to the NCRP 
meeting Abstracts and a copy of the Meeting Summary.

See abstract below for above presentation.

Stewart Farber, MS Public Health
Consulting Scientist
Farber Technical Services
1285 Wood Ave.
Bridgeport, CT 06604
[203] 441-8433 [office]
[203] 522-2817 [cell]
email: radproject at sbcglobal.net
          radproject at aol.com
=================================

Advances in Radiation Protection in Medicine
April 16-17, 2007
Forty-Third Annual Meeting of the National Council on
Radiation Protection and Measurements (NCRP)

Diagnostic Radiology I
Cynthia C. Cardwell, Session Chair
9:15 am Magnitude of Radiation Uses and Doses in the United States:
NCRP Scientific Committee 6-2 Analysis of Medical Exposures
Fred A. Mettler, Jr.
New Mexico Federal Regional Medical Center

NCRP Scientific Committee 6-2 (SC 6-2) is
currently working to estimate the radiation
exposure of the U.S. population from all
sources and will produce an NCRP report in
2008. One subcommittee is specifically evaluating
medical patient exposures. The last comprehensive
evaluation regarding the types of
medical radiation procedures, their magnitude,
and annual per capita effective doses was
done more than two decades ago.
The medical subcommittee has examined a
variety of data sources, including commercial
surveys, Medicare, U.S. Department of
Veterans Affairs, and insurance carrier data.
The data sources are primarily from 2004 and
2005. These data files are the most comprehensive
for diagnostic and nuclear medicine
examinations, and less complete for interventional
procedures and radiation therapy. This
information has provided a realistic estimate of
the number and types of examinations being
done, as well as the breakdown by broad age
groups. The subcommittee also has collected
and analyzed data on the absorbed dose,
computed tomography (CT) dose index, and
other parameters necessary to estimate effective
dose per procedure and ultimately, collective
dose to the U.S. population. An issue that
remains is the most appropriate values of radiation
weighting factors to be used in estimating
effective doses for diagnostic x-ray and
nuclear medicine examinations.
What has become clear from this study is that
medical exposures have increased rapidly over
the past two decades, not only in number but
also in dose. The largest increase has come
from increased use of CT scanning procedures,
which have increased 10 to 15 % annually
while the U.S. population has increased at
<1 % per year. There were about three million
CT scans performed in the United States in
1980, and this number has grown to about 60
million CT scans in 2005 (an average of about
one scan for every five persons). Much of the
increase has come from an increasing number
of CT machines, newer and faster technology,
and new clinical uses of CT such as the evaluation
of pulmonary emboli, lung nodules, and
abdominal pain. Assuming a radiation weighting
factor of one, the effective doses from CT
scans range from 1 to 10 mSv per exam, and
many patients have more than one examination.
Collective effective doses from CT are
estimated to be in the range of 300,000
person-Sv annually.
Another large and rapidly growing source of
patient exposures is from cardiac nuclear medicine
studies, with an effective dose of about
10 mSv per examination. There are approximately
20 million nuclear medicine scans done
annually in the United States, of which about
two-thirds are cardiac studies. The collective
dose from nuclear medicine procedures on an
annual basis is estimated to be about 220,000
person-Sv. It is interesting to compare these
medical doses with the global collective dose
from the Chernobyl accident of about 600,000
person-Sv.
Currently, it appears that the increasing use of
medical radiation technology is likely to result
in per capita annual doses close to, or greater
than, the natural background exposure level in
the United States. However, it is important to
bear in mind that substantial clinical benefits
often result from exposures associated with
diagnostic and therapeutic medical radiation
procedures. It should, however, be noted that
age and illness of the medical population is
not taken into account with effective dose
calculations.
The SC 6-2 subcommittee is also addressing
potential increases in the use of radiation in
medicine, and the doses to which patients
have been exposed since 2005 and to which
they are likely to be exposed in the near future.
Areas of interest include, among other exposures
associated with the introduction of digital
filmless radiology systems, 64-slice CT scanners,
combined positron emission tomography
and CT scanners, combined single photon
positron emission tomography and CT scanners,
and CT screening for coronary artery
stenosis and calcification.
----- Original Message ----- 
From: "Wes Van Pelt" <WesVanPelt at verizon.net>
To: "'radsafe'" <radsafe at radlab.nl>
Sent: Tuesday, August 14, 2007 10:58 AM
Subject: [ RadSafe ] New average annual medical dose

A few weeks ago there was some discussion on a new revised estimate of
annual dose from diagnostic medical procedures (e.g., x-rays, CT, mamo,
etc.). I recall that the annual average medical dose went from about 70 to
about 250 mrem per year. A BIG increase!

I cannot find the reference(s) to this new estimate. Can anyone help?

Best regards,
Wes
Wesley R. Van Pelt, PhD, CIH, CHP
Wesley R. Van Pelt Associates, Inc.