Skin Dose from Tc-99m

["Kenneth W. Price" <75301.361@compuserve.com>]

Frank,

We have calculated Tc-99m skin doses using the activity versus time curve
and instruments which are calibrated to yield uC of Tc-99m on a surface
with the probe face at various distances..ie; contact, 0.5 cm.  You should
also use skin dose factors for an air-tissue interface.  The activity in 1
cm^2 is determined, the activity versus time curve integrated, and the skin
dose factor applied.  Skin dose factors from W.G. Cross et. all "Beta Ray
Dose Distributions From Skin Contamination", Rad. Protection and Dosimetry,
Vol. 40, No. 3, pp 149-168, 1992, are used.  We assume the activity is on
the skin surface.  Measurements over time are suggested as due to skin
sloughing and other mechanisms the activity falls off much more quickly
than using the radiological half life alone, thus providing for a more
realistic dose estimate.

Ken Price, RSO
University of Connecticut Health Center
Farmington, Ct.
75301.361@compuserve.com