RE:Cobalt-60 dose

["Luketina, Ivan" <ivan.luketina@cit.ac.nz>]

Not having seen tables of SI values I have puzzled over the conversion of
the air kerma constant to SI units and came up with the following:

If the specific gamma ray constant for Co-60 is 13.2 R/mCi-hr at 1 cm from
another posting then the conversion is from units of (R.cm^2)/(mCi.h) to
(microGy.m^2)/(GBq.h)

Using the air kerma K (Gy) = 0.00876 x exposure (R)
or   K (microGy) = 8760 x exposure (R)

1 cm^2 = 10^-4 m^2

1 mCi  =  3.7 x 10^7 Bq = 0.037 GBq

then the conversion factor becomes (8760 x 10^-4)/0.037 = 23.68 

and 13.2  (R.cm^2)/(mCi.h)  = 313 (microGy.m^2)/(GBq.h)

Perhaps someone with a table of SI values could confirm the 350
µSv.m²/(h.GBq) value or the accuracy of the above.


Ivan Luketina
Ivan.Luketina@cit.ac.nz


From:	Herwig Mandl <H.Mandl@lkasbg.gv.at <mailto:H.Mandl@lkasbg.gv.at> >
To:	"'radsafe@romulus.ehs.uiuc.edu'" <radsafe@romulus.ehs.uiuc.edu
<mailto:radsafe@romulus.ehs.uiuc.edu> >
Subject:	AW: Cobalt-60 dose
	Message-ID: <01BF1A15.2B7DBFC0@C1MM080.lkasbg.gv.at
<01BF1A15.2B7DBFC0@C1MM080.lkasbg.gv.at">mailto:01BF1A15.2B7DBFC0@C1MM080.lkasbg.gv.at> >


Doserateconstant for Co-60: 350 µSv.m²/(h.GBq).
Use SI-Units!
Herwig from Salzburg

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