Fwd: prostate implant source strength and rad. safety

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Forwarded message:
From:	physics@EXECPC.COM (Tyler Lembcke)
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: 97-08-26 22:03:07 EDT

At 09:13 AM 8/26/97 -0400, George Xu (xug2@rpi.edu) wrote:
>I am interested in konwing the radiation doses to nurses and doctors from
>the implanted sources.  Would someone tell me what procedures are being used
>to make sure the nurses are not getting too much dose.  I assume the patient
>will get a large amount of whole body dose (or doses to nearby organs), but
>that risk is smaller than the cancer the patient already has.  For permanent
>implants, what about doses to their family members?  I-125 has a half life
>of 60 days which means the activity will be significant for  a long time,
>although the 35 KeV gamma ray is relatively low.  Thanks for any comment!

George,

We have never had a measurable exposure rate at a distance of one meter from
a patient post implant, after nearly 200 implants.
To ensure the Nursing staff gets no exposure while they set up the O.R as we
load needles, we load on one side of the O.R., while they set up the Urology
table on the other side. We position the L-block behind which we load such
that we face away from the nursing staff while loading.  Thus the block
shields both us and the nurses.  Measurements in the OR during implantation
show 0.00 mR above BG on the cold side of the OR.  The only ones getting any
exposure during implantation are the urologist and the oncologist, and that
is primarily to their hands.  We've badged all the O.R. personnel, but have
never had any reading above BG.  The calculated exposure rate to the person
most likely to receive it (the spouse) is used as part of the NRCs new
release criteria.  We calculate it based on the measured exposure rate at
one meter. Since we measure  0.0 mR/hr at one meter , that exposure to the
spouse is listed as 0.0 mR.  Of course, that is not entirely accurate, since
I at least cuddle up to my wife at night.  The exposure rate at the patients
surface typically reads 3.5-5.5 mR/hr (anterior, right over the prostate).
We have had two patients with surface rates somewhat higher, 10.5 and 14.0
mR/hr, but in both cases the reading at one meter was 0.0 so we let them go!!

Regards,

Tyler
Tyler M. Lembcke, M.S.
Radiation Oncology Physicist
St. Luke's Medical Center
Dept. Rad. Onc.
P.O. Box 2901
2900 W. Oklahoma Ave
Milwaukee, WI 53201-2901
USA
Office: (414) 649-6560
Fax:    (414) 649-5309
physics@execpc.com
http://www.execpc.com/physics/index.htm

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