Re: Metastron (Sr-89) and dialysis

[carol marcus <csmarcus@ucla.edu>]

At 10:26 AM 7/1/98 -0500, you wrote:
>>Date:         Tue, 30 Jun 1998 13:53:24 EDT
>>Reply-To: Medical Physics Mailing List <MEDPHYS@LISTS.WAYNE.EDU>
>>Sender: Medical Physics Listserver <medphys@cwis-20.wayne.edu>
>>From: "Leo E. Jablonski, M.S. DABR" <Leoski@AOL.COM>
>>Subject:      Metastron (Sr-89) and dialysis
>>To: MEDPHYS@LISTS.WAYNE.EDU
>>
>>Could anyone please provide me with info on any precautions if we administer 4
>>mCi of Sr-89 to a prostate CA patient with chronic renal failure who is
>>undergoing dialysis.  (1.46 MeV beta emitter with a 50.5 day T 1/2, 8 mm max
>>range in tissue.  I am unfamiliar with dialysis techniques and have scheduled
>>a visit to the dialysis center, but I imagine it is a closed system with
>>minimal chance of contaminating the dialysis unit.  Is this correct?  The
>>dialysis center is expressing concerns about contaminating their equipment.  I
>>see no problem with contamination unless the tubing were to break.  If we were
>>to administer the Sr-89 on a Friday and wait until Monday to give his dialysis
>>treatment, I would not expect an external radiation problem from the blood
>>traveling through the tubing (correct?)  We would store the tubing in
>>radioactive waste storage for the necessary ten half lives.  Comments are
>>appreciated.  Thanks
>>
>>Leoski@aol.com
>>Leo Jablonski, M.S. DABR
>>Lincoln, NE
>>
>>                    *****
>>Frequently Asked Questions (FAQ) for Medphys at:
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>Chris Alston
>alstonc@odrge.odr.georgetown.edu
>I am not here a representative of my employer.
>
>Dear Leo:

The dialysis equipment will not become contaminated.  The disposable plastic
set for the patient may have a small amount of contamination, but I don't
see any need to hold it for 10 halflives.  Unless the patient is kept in the
hospital as a radiation hazard, and he is not in this case, patient body
fluid contaminated articles are exempt.  Otherwise, you'd have to "decay
out" people's HOUSES for 80 days after Na-I-131 therapy, which we are
definitely not required to do.

I have a policy of holding up such exempt contaminated articles if I believe
they will trigger radiation detectors in sanitary landfills.  Sr-89
contaminated tubing will not do so.  The activity isn't high enough and the
brem is likely to get absorbed before it ever gets to the NaI detector.

I would suggest giving the patient the usual 4-5 mCi metastron dose, and
then starting dialysis around 6 hours later.  The Sr-89 goes to the bone
very quickly; about half is left for excretion, mainly via kidneys (or in
this case, dialysis).  I would dialyze daily for about 3 days and then
return the patient to his regular dialysis schedule (usually 3 times per
week).  Patients with renal failure often have enhanced excretion via liver
and bowel, so you might not dialyze off as much as you expect, but it will
come out in the stool.

I checked with Amersham on this, and they have no scientific data base on
this.  I did check with one physician who has done this, and that's where I
got the information that the tubing might have some contamination.

There is no external radiation hazard from the patient or the dialysis
machine, and the nurse need not minimize her attendance at the dialysis
session.  The specific brem equivalent of the gamma ray constant is 0.00314
R/hr per mCi at 1 cm in soft tissue, and 0.000843 in bone. Not a problem.

Ciao, Carol

Carol S. Marcus, Ph.D., M.D.
Division of Nuclear Medicine, Harbor-UCLA Medical Center
(310)222-2845
<csmarcus@ucla.edu>