Isotope Cystogram

[scherer@uiuc.edu (David Scherer)]

>RADSAFE MESSAGE:
>
>G'day all
>
>A question for all you Nuke Med people:-
>
>My son will soon have an isotope cystogram to determine if there is reflux
>from his bladder to his kidneys. He will be about 18 months old at the time
>of the procedure.
>
>1.      What activity of Tc99m is typically used
>
>2.      What imaging time is required
>
>3.      Approx what dose would you expect him to receive
>
>
>Thankyou

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>
>RESPONSE:
>
>A recent textbook (Pediatric Nuclear Medicine, S. Treves,
>Springer-Verlag, 1995) states that for study of vesicoureteric reflux
>(VUR), typically about 30-70 MBq (1-2 mCi) is used, and a series of
>10-second frames, but the text is not clear on the total time needed per
>study.  It is necessary to void the bladder at some point, which can be
>encouraged in older children.  I know that I have been asked in the past
>for dose estimates for bladder residence times up to a half-hour, but I
>would think that this would be an upper limit.  I'm sure the physician will
>discuss this with you in advance.  The text claims dose estimates for the
>bladder wall of 0.18-0.27 mGy, to the ovaries of 10-20 mGy and "less"
>(than the ovaries) for the testes.  I estimate radiation doses of 1.6E-3, 3.2
>E-3, and 4.7E-3 mGy/MBq to the testes for 10, 20, and 30 minutes
>residence times, 1.3E-4, 2.5E-4, and 3.8E-4 mGy/MBq to the kidneys,
>3.4E-2, 6.8E-2, and 1.0E-1 mGy/MBq to the bladder wall, and 2.4E-3,
>4.8E-3, and 7.2E-3 mSv/MBq effective dose.  This uses the closest model
>that I have for your case - that of a 1-year old (9.8 kg total body).  If the
>child is larger, the doses will be somewhat lower.  Please contact me if I
>can be of further help.
>
>Mike Stabin
>Radiation Internal Dose 
>  Information Center
>Oak Ridge Institute for 
>  Science and Education
>P.O. Box 117
>Oak Ridge, TN  37831-0117
>423-576-3449  ph
>423-576-8673  fax
>stabinm@orau.gov  Internet
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>"It ain't that there's too many fools in the world, it's just
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>