Re: Skin Dose Assessment from Whole Body Contamination Meters

[JSBland@aol.com]

Mike, et. al.,

The measurements and expanded modeling you described seems most helpful to 
the industry.  And, being unable to attend Midyear, I would appreciate 
copies, as appropriate and available.  For skin dose calcs, the approach you 
developed provides a great tool.  

One of the concerns I was looking at was how to confirm that the PCM alarm 
was solely attributable to noble gases, that was the reason for the expanded 
modeling with MCNP to examine detection capability of the BNC NaI detector. 
During our testing, we had an interesting situation where an individual 
alarmed the portal monitor.  A measurement with the BNC detector (1 minute 
count with detector on chest) showed mostly Xe-133, but there was also a 
Co-58/60 component.  Removal of scrubs eliminated the cobalt.  Further 
examination identified the scrubs as having a very-low Co-58/60 contamination 
spot, but low enough to pass the screening done for re-use.  This type 
measurement, coupled with a frisk survey to eliminate potential skin 
contamination (i.e., elevated measurement with a thin-window GM detector at a 
discrete location versus generally disperse, elevated measurements) provides 
reasonable assurance that the alarm is solely attributable to the noble gas 
retention.

I was also curious about the actual EDE due to retained noble gases in the 
fat.  There is also a muscle component but at a much lower level.  Linking 
the Peterman model in Radiation Protection Dosimetry for determining  time 
dependent body/organ contents and MCNP modeling of the standard man model, 
and application of weighting factors, an EDE could be calculated.  This 
modeling can also be applied to other noble gases, such as radon and argon.  
This may have already been done, but I am not aware of it.  (Help from any 
sources out there is appreciated.)  

Stewart Bland
410-266-9174