No Subject

[David Scherer <scherer@uiuc.edu>]

Dear Sir,

>All please note that it is vastly easier to do "real" dose estimates for
>patients in nuclear medicine, by which I mean giving them a single figure
>that reflects some sort of effective dose equivalent, than in the other
>branches of radiology.

Not true.  The package insert provides dose conversion factors for Standard
Man's geometry, based on a Monte Carlo calculation for the average metabolic
data determined during clinical trials.  It is very difficult to provide
"real," individual estimates of absorbed dose received by one particular
patient when metabolism is altered by some pathology.  

<snip>  The FDA and the States'
>x-ray control units have not yet endorsed the use of an EDE, nor are the data
>readily available to do the calculations, as they are for nuc med, thanks to
>Mike Stabin, Keith Eckerman and the rest of the crew in Oak Ridge.
>
In fact the same kind of dose conversions for diagnostic imaging have been
around for a number of years.  Twenty years ago the FDA published tables of
organ doses for common projections based on the ESE and beam HVL (assuming 1
m SID for tabletop and 2 m SID for chest).  However, these tables sufer from
the same shortcomings as the nuc med calculations.  Both are
order-of-magnitude guesstimates.  But since we can calculate to several
decimal points, we treat them as precise measurements.  Is it more ethical
to give patients no dosimetry or misleading information?

Dave Scherer
scherer@uiuc.edu

P.S. Let me reiterate the call for everyone to sign their messages.  The
only name I have for the fellow I'm responding too is Ccja@aol.com.