RE: rule of thumb

["Eric Cowdrey" <ericc@cancercare.mb.ca>]

The referenced section of the Rad Health Handbook is actually talking about
beta sources, but the same formula would apply to gamma emitters.

You simply make the assumption that all energy associated with (the betas or
gammas) is absorbed in the medium.

The dose rate is the same at all points in the infinite medium and equals:

C (uCi/cm**3) x 3.7 x 10**4 (dps/uCi) x E (MeV) x 1.6 x 10**-13 (J/Mev) x
10**7 (ergs/J)

x p**-1 (g/cm**3)**-1 x 10**-2 (ergs/g/rad)**-2 x 3600 (sec/h)

= 2.13 EC/p


**************************************************************

Eric Cowdrey, M.Sc. (Physics)
Radiation Protection Officer
Department of Medical Physics
CancerCare Manitoba
675 McDermot Avenue
Winnipeg, Manitoba    R3E 0V9
CANADA

Tel (204) 787-2166
Fax (204) 775-1684
mailto:ericc@cancercare.mb.ca

Industrial hygiene in Manitoba: http://aiha.cancercare.mb.ca


-----Original Message-----
From: radsafe@romulus.ehs.uiuc.edu
[mailto:radsafe@romulus.ehs.uiuc.edu]On Behalf Of Michael McNaughton
Sent: Monday, August 28, 2000 2:49 PM
To: Multiple recipients of list
Subject: rule of thumb


Dear radsafers

can you point me to a derivation of the rule of thumb for the gamma dose
rate in an infinite medium or solution: dose rate (rad/h) = 2.12 EC/rho; it
is listed on pages 52 and 54 of the Rad Health Handbook, (1992 edition).

Thanks, mike
Mike McNaughton
Los Alamos National Lab.
email: mcnaught@LANL.gov or mcnaughton@LANL.gov
phone: (505)667-6130
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