Patient Release Criteria - NRC Reg. Guide 8.39

[Mack Richard <MRICHARD@WPO.IUPUI.EDU>]

Dear RADSAFERS:

Three RSO's and their staffs in the Indianapolis area have been working
on the release criteria and breast-feeding instruction requirements
required under the amended 10 CFR 35.75.  It is our intent to establish
"groups" of patients who may be released utilizing the calculational
methods in Appendix B of the guide.  We will determine which "group" a
patient fits into based upon several specific questions.  

One thing I noticed was a "boo boo" in example number 2 in the Reg
Guide appendix.  That example illustrated that a patient receving 200
mCis could be immediately released with a calculated effective dose
equivalent to a member of the public of 453 mrem.

The next section of Appendix B (B.3.) addresses methods to estimate
the effective dose equivalent to a member of the public from the internal
contamination pathway.  It states that if the effective dose equivalent
from the internal pathway is <10% of the external effective dose
equivalent, the internal pathway can be ignored.  

By my calculations, in example 2 where the patient received 200 mCis,
the effective dose equivalent received from the internal pathway would
be 200 mCis x 1E-05 x 53 rem/mCi or 0.106 rem (106 mrem).  In that
example, the effective dose equivalent from the internal pathway is 23%
of the external effective dose equivalent; however, no mention is made
in the example of the contribution from the internal pathway (oops!!).

In a related issue, one of the RSO's mentioned above has notified our
state agency about this new release criteria (we are not an Agreement
State).  Currently, the municipal incinerator in Indianapolis monitors all
waste coming into their facility for radioactivity.  About every hospital in
Indianapolis has had hospital waste rejected from the municipal
incinerator due to detected radioactivity.  In those cases, the source has
always been traced to contamination from in-patients undergoing
diagnostic procedures and not from inappropriate disposal of radioactive
material.  The state agency is alway notified when this occurs.

The state agency has also been notified several times about municipal
waste from residential areas that has set off these radiation detectors. 
In those cases, the waste hauler has to deal with the problem, usually
with assistance from the state (they end up digging through the waste to
find the source - what fun!!).  With this change in NRC regulations,
patients will probably be going home with higher levels of activity and
common sense makes us think that this will increase the frequency of
activity detected in residential waste.  While it's not our problem, we
wouldn't wish scavenging through municipal waste on our worst enemy.

Any ideas on how to deal with this problem?

Regards,
Mack Richard, M.S.


Mack L. Richard, M.S., R.S.O.
mrichard@wpo.iupui.edu
Phone:  (317) 274-0330    FAX:  (317) 274-2332