Re: skin contamination to skin dose assessment

[Bob Burns <sra@crl.com>]

In our "Practical Radiation Shielding" course, we tell students a good rule of thumb for beta dose rate to skin 
is 7 rad/hr per micro-curie per cm^2, plus or minus 20% or so.  This value is based on work published by Jack 
Healy in 1971 [1].  Healy published curves of dose rate per micro-curie per cm^2 versus maximum beta energy for 
different source and absorber thicknesses.  Upon inspection, one sees that a value of 7 +/- 20% rad/hr per 
micro-curie per cm^2 envelops all of the given curves for maximum beta energies between 250 keV and 3 MeV, with 
the exception of the case of a zero thickness source on bare skin (absorber thickness = 7 mg/cm^2), where 7 +/- 
20% only bounds this curve up to a maximum beta energy of 750 keV or so.  For a zero-thickness source on bare 
skin, the skin dose rate per micro-curie per cm^2 is bounded between 8.5 and 9.2 for maximum beta energies 
between 750 keV and 3 MeV (according to Healy).

[1]	Healy, J. W.; "Surface Contamination: Decision Levels", LA-4558-MS, Los Alamos Scientific Laboratory, 
	September, 1971.

Bob Burns, CHP
Shonka Research Associates, Inc.
(770) 509-7606
sra@crl.com