RE: Minimum Detectable Activity

["North, David" <DNorth@Lifespan.org>]

A simple method for finding your MDA for a radionuclide to 99% confidence:
Determine the counter's sensitivity in "counts/time/activity", e.g. cpm/uCi.
Take a background count for the same time you will use for your sample
counts. Take the square-root of the background count to estimate the
standard deviation, multiply by 3 and divide by your sensitivity. The answer
will be your MDA in units of activity.

David L. North, Sc.M. DABR
Associate Physicist
Department of Medical Physics
Rhode Island Hospital
593 Eddy St.
Providence, RI 02903
ph: (401)444-5961
fax: (401)444-4446
dnorth@lifespan.org

> ----------
> From: 	Amoling, Ron
> Reply To: 	radsafe@romulus.ehs.uiuc.edu
> Sent: 	Tuesday, June 13, 2000 15:17
> To: 	Multiple recipients of list
> Subject: 	Minimum Detectable Activity
> 
> Hello
> 
> Does anyone have a quick and easy equation for calculating the Minimum
> Detectable Activity (MDA) for an instrument?  In this case, the instrument
> is a liquid scintillation counter.  My references are not with me at the
> office today......
> 
> Thanks,
> Ron Amoling
> RSO
> Joslin Diabetes Center
> amolingr@joslin.harvard.edu
> 
> 
> --
> ************************************************************************
> The RADSAFE Frequently Asked Questions list, archives and subscription
> information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
> 
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html