Fwd: Background Equivalent Radiation Time - BERT - a refresher course

[Ccja@aol.com]

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Forwarded message:
From:	jrcamero@FACSTAFF.WISC.EDU (JOHN CAMERON)
Sender:	medphys@LISTS.WAYNE.EDU (Medical Physics Listserver)
Reply-to:	MEDPHYS@LISTS.WAYNE.EDU (Medical Physics Mailing List)
To:	MEDPHYS@LISTS.WAYNE.EDU (Multiple recipients of list MEDPHYS)
Date: 97-09-23 17:30:15 EDT

>I'm looking for some reference to the term "BERT".  Could anyone direct
>me to a resource that may define and use this term?

My first publication of this old idea was in 1989 and the following short
article appeared in the AAPM Newsletter, HPS Newsletter, Physics & Society
News & other places in the early 90s. It was rejected by the ACR Bulletin
as being insulting to the NCRP. It has appeared in some RT type journals
but  never in a US publication for radiologists. The idea is simple, honest
and satisfying to most patients.
        NCRP Report No. 117 page 51 endorsed the idea but it has not been
promoted. by the NCRP or any one else. I would love to see the idea be
adopted for the description of all radiation to patients and the public.
If the fall out from Three Mile Island the public would have realized how
trivial it was.  I welcome your feedback. Best wishes, John Cameron

 A RADIATION UNIT FOR THE PUBLIC by John R. Cameron*
2678 SW 14th Dr., Gainesville, FL 32608-2050
Phone: 352/371-9865; Fax: 352/371-9866   e-mail: jrcamero@facstaff.wisc.edu
(This article is not copyrighted and may be reproduced freely.)

        The public has an exaggerated fear of insignificant amounts of
ionizing radiation, such as from a medical x-ray. The fear of radiation is
made worse by not understanding the scientific jargon used to describe it.
This article describes a radiation unit based on natural radiation that is
easily understood by patients, news reporters and the general public.
        The quantity is called ionizing radiation, which will often be
shortened to radiation. The unit for measuring ionization radiation is time
- "Background Equivalent Radiation Time." BERT is the number of hours,
days, weeks, months or years that would give an adult the same "effective
dose" from natural or background radiation. To estimate the amount of BERT
I suggest using an average background rate of 3 mSv (300 mrem) per year,
even though the background varies somewhat over the earth. (I thank my
colleague, Professor H.T. Richards for suggesting the name for the unit.)
In describing radiation BERT would not be mentioned. The amount of
radiation would be given in weeks, months or years of natural radiation.
For example, compare the information in the following statements> "Your
x-ray study gave you about 1 mSv (100 mrems) of effective dose.: OR "Your
x-ray study gave you radiation equal to about four months of natural
radiation."
        It is easy to use the new unit. You have to remember that natural
radiation background is about 3 mSv or 300 mrem per year. Once you estimate
the effective dose in mSv or mrem you can figure the days, weeks, months or
years of natural radiation. For example,  the BERT for 1 mrem is roughly
one day and the BERT for 1 mSv is about four months. Radiation that strikes
only part of the body, such as medical x-rays, is not as hazardous as the
same amount of radiation to the whole body. For example, the risk from 1 Gy
to your lungs is equivalent to risk of  0.12 Sv  or 120 mSv to the whole
body. Other organs have similar factors to convert dose equivalent to
effective dose.
        Typical BERTs of ionizing radiation from medical x-rays are: a
dental bitewing, about one week; a chest x-ray about ten days; a mammogram,
about three months; and a barium enema x-ray study, about one year. These
values vary greatly from one medical center to another. The BERT for the
average amount of radiation to the public from diagnostic x-rays each year
is about seven weeks. Of course, some people receive much more than others.
The BERT  for the average amount of radiation we receive each year from
nuclear power plants is less than one day even for people who live in the
vicinity of a nuclear power plant. The BERT for a transatlantic flight is
about five days.
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*The author is Professor Emeritus at U. of Wisconsin-Madison, Depts. of
Medical Physics, Radiology and Physics. He is a Visiting Professor at the
University of Florida, Depts. of Radiation Oncology and Physics.  He is
happy to give a free talk about health effects of radiation to any group at
any level.


Check out ELECTRONIC MEDICAL PHYSICS WORLD - EMPW - which links to AAPM,
IOMP etc.at  http://www.medphysics.wisc.edu/~empw and the Bibliography of
books and journals in Medical Physics and related fields at
http://www.medphysics.wisc.edu/~cameron.

John R. Cameron, 2571 Porter Rd., P.O. Box 405, Lone Rock, WI 53556-0405
Phones: 608/583-2160;  Fax: 608/583-2269
At the end of September we return to our home at 2678 SW 14th Dr.,
Gainesville, FL 32608   phones : 352/371-9865; Fax 352/371-9866

my  e-mail all year is: jrcamero@facstaff.wisc.edu