Re: Guidelines for Protection of Pregnant Nurses

[mikeg@SLAC.Stanford.EDU (Michael P. Grissom)]

This situation, to the best of my knowledge, has never led
to the need to make a recommendation for therapeutic abortion!

First, nursing personnel are instructed in the nature of brachy-
therapy hazards (which include staying behind the portable
shields in the room, set up to allow visitors into the room
while maintaining their space at less than 2 mR/h).  I presume
that would be true for the graduate student as well (it pays
to read the precautions in the patient's chart and be at least
sufficiently trained/briefed to recognize radiation signs,
postings, barriers, and what their purposes are).  I would note
here that the use of unsealed Cs-137 sources is very rare now
(and a significant hazard for the radsafe staff!) so the use
of sealed sources (needles, seeds, etc.) loaded in tubes and/or
applicators of various types would be the likely source 
configuration.

Second, the protection guidelines for the embryo fetus (that is,
no more than 500 mrem during the entire gestation period and no
more than 50 mrem per month) would not be exceeded during any
normal brachytherapy inpatient stay.  Even Wes's "emergency"
removal of the sources would not likely exceed the 50 mrem limit
on a one time basis since most applicator/seed arrays can be 
removed in very few minutes (the advantage of afterloading).

Third, ACR guidelines do not recommend even considering
therapeutic abortion at TEDEs of less than 10 rem (0.1 Sv, with 
the embryo/fetus receiving all of this dose equivalent).  If 
anyone is aware of any nursing service personnel ever having 
received a dose of this magnitude from a Cs-137 brachytherapy 
patient, I'd like to know about it too!  Generally, nursing 
service personnel receive from no recorded dose (that is, zero 
using TLDs) up to a few 10's of mrem in difficult cases where 
the patient requires more attendance than the average.  I have
seen cases where several brachytherapy patients could lead to
a challenge of the 50 mrem per month guide for pregnant nursing
staff personnel.  In very active wards where several brachy-
therapies are being conducted, I have advised rotating the
nursing service staff (and in fact not having pregnant nurses
attend to brachytherapy patients if staff was sufficient).  In
any case, we used supplemental dosimeters (PICs) to ensure that
pregnant nurses who chose to continue to work did not exceed
the guidelines since the radsafe staff checked the logs every
shift change.

As always, these are only my personal opinions and not those of
any of my employers.

>A graduate student (a nurse in our hospital) has asked me some 
>questions with which radsafers may be able to help.  Given that 
>nurses caring for patients getting radiotherapy with 137Cs,
>routinely wear film badges, is there any circumstance in which 
>radiation exposure could occur which would justify therapeutic 
>abortion?
>             John Goldsmith <gjohn@bgumail.bgu.ac.il>
-----------------------
Michael P. Grissom
mikeg@slac.stanford.edu
Phone:  (415) 926-2346
Fax:    (415) 926-3030