Re: Epidemiological evidence of lung cancer risk

[csmarcus <csmarcus@ucla.edu>]

At 08:05 AM 1/13/02 -0800, Ted de Castro wrote:

> Right off hand I'd say that if you
>
> are concerned about risks to staff
>
> from these procedures - you are doing something wrong!
>
>
> I have been away from this particular aspect of our profession for
>
> some
>
> time and so could be wrong. Would someone a bit "closer to the
>
> action"
>
> care to comment?
>
>
> I find it hard to believe that there are not engineered controls
>
> commonly in place and in use to preclude staff risk from these
>
> procedures.
>
>
> Lam Hoi Ching wrote:
>
> > 
>
> > Dear radsafers,
>
> >     I am in search of the epidemiology evidence
>
> of lung cancer risk for
>
> > radiation staff in Nuclear Medicine. Those ventilation  scans
>
> involve the
>
> > use of Xenon, Krypton and Technegas are radioactive gases which pose
>
> risk
>
> > due to lung dose but epidemiogical evidence is lacking.
>
> >     Thank you for any advice.
>
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Dear Radsafers:


I recommend that this "fear of risk" be completely

forgotten.  There is none.  The lung doses to technologists

would be miniscule because the procedures are done in a closed

system.  In addition, noble gases are breathed in and breathed out,

so internal dose to the lung is not an issue.  A small quantity may

transiently stay in the body in fatty tissue, but not in the lungs. 

In addition to being a noble gas, Kr-81m has a 13 second halflife, but

has not been used in the USA for many years because of cost.  Can

anyone afford it?  Technegas is not used in the USA---it

never got past our FDA.  Pertechnegas almost made it through, but

again, never did.  The lung dose from background radon is probably

orders of magnitude higher than the lung dose from escaped Xe-133, which

is used, or Tc-99m-DTPA aerosol, which is also used.  I

expect that external, whole body doses are higher than any inhaled lung

dose, and no one has seen any problems from the low whole body doses that

nuclear medicine technologists receive.


Perhaps our friend from Hong Kong would like to submit a detailed,

credible model and the associated internal dosimetry that has him

worried?


Ciao, Carol


Carol S. Marcus, Ph.D., M.D., ABNM, FACNP

Prof. of Radiological Sciences and of Radiation Oncology, UCLA


<csmarcus@ucla.edu>