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Re: Minimum Detectable Activity


You can refere to NCRP 58, and ANSI N13.30 for derivation, also if you can get 
a copy of NBS SP456, "the minimum detectable activity concept" would be very
usefull. If you need a copy let me know.

At 02:45 PM 8/22/96 -0500, you wrote:
>Hello fellow RADSEFERS,
>I came across an equation for calculating MDA based on statistical 
>analysis that states MDA = (4.65 x N^0.5 + 3) / ET where N is the number 
>of counts for the background in time T and E is the sensitivity of the 
>detector in cps/unit activity. Our specific problem regards leak testing 
>of selaed sources and this equation is suggested by the AECB (CANADA).
>I understand how the MDA is based on a given confidence level assuming 
>Poisson statistics but cant seem to see (or find) a good derivation of 
>this equation.  Cember (1996) presents this equation without a thorough 
>Please let me know if there is a better reference.
>Horacio J. Patrocinio
>Hotel-Dieu de Montreal Hospital
>Montreal, Canada
Mr. Rahim Ghanooni
Sr. Health Physicist
Certified Hazardous Material Manager (CHMM)

My opinion only.