Re: Iodine capsules and radiophobia

[David Scherer <scherer@uiuc.edu>]

Please allow me to clarify.  I am sorry if my post did not make my points clearly.

>I thought that the 10% was probably a little high. We found less than 0.1%
>from NaI solutions that are used at our facility and these are at neutral pH
>- the worst possible situation. We get the iodine in a septum vial and then
>vent it using needles thru TEDA charcoal filters and 200 mCi doses usually
>have less than 20 microcuries. We have never used capsules so I can't say
>how much they release but I am sure that it is much, much less.
>

What I said was up to 10 percent can appear on the surface of the gelatin capsules, not as airborne activity.  (I specifically said that not all of this 10 percent will vaporize.  There are potential hazards from transferrable surface contamination and from airborne activity when initially opened.)  You report is that <0.1 percent of NaI solution in a septum vial will vaporize.  I would suggest that NaI on the surface of a capsule is quite susceptible to volitilization; the overall airborne activity for a freshly opened shipment may comparable in the two cases.  I believe both warrant radiation protection measures.

>10%??  of therapeutic doses??!!  "not all will vaporize"??   (presumably
>inhaled? or just open it in the mouth?)  really??  :-)  And here I had no idea 
>the practice of nuclear medicine was this bad! 
>
>     I guess 10-4 is a little low, huh?  :-)
>
As I said, not all of the surface contamination will vaporize.  A lot of it will remain on the capsule and be ingested by the pt as part of the dose.  Suppose your estimate is off by a order of magnitude, as suggested by the experience at Syracuse with stock solutions.  Does that warrant a fume hood and/or charcoal filter?

>Doses to the technician way beyond diagnostic levels right to therapeutic
>levels? Wow. Terrifying. 
>
>I guess there is a purpose to "rad protection" :-)  I never knew how dangerous 
>these practices could be!?  (made to sound!)  Pretty frightening.  "Fear
>producing!" 
>
None of this has to be terrifying.  Given reasonable, even modest, safety controls none of this is "fear producing."  Most technologists and radiopharmacists that I've worked with are quite confortable with the engineering controls that mitigate these hazards.  I'm glad we agree that rad protection has a purpose.

>Maybe we should we just kill nuclear medicine now rather than a "slow death",
>along with the rest of nuclear science and technology on the altar of more rad 
>protection? 
>
How does any of this imply that nuclear medicine is "bad" or in mortal peril?  Ventillation controls have been used in nuclear medicine labs for decades without "killing" it.  Just who is the fear monger here?

Dave Scherer
scherer@uiuc.edu