Re: Minimum Detectable Activity

[Ning_Liu@NOTES.YMP.GOV]

  It is originally derived from the following reference,

  Currie, L. A., 1968.  Limits for qualitative detection and quantitative
  determination.  Analytical Chemistry.  Vol. 40, No. 3, pg 586-593.

  Hope this helps.

  Ning Liu
  SAIC, Las Vegas


  To:       radsafe @ romulus.ehs.uiuc.edu at pmdfpo@YMPGATE
  cc:        (bcc: Ning Liu)
  From:     patrocih @ ERE.UMontreal.CA at pmdfpo@YMPGATE
  Date:     08/22/96 11:52:00 AM
  Subject:  Minimum Detectable Activity


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
derivation.

Please let me know if there is a better reference.


Horacio J. Patrocinio
Hotel-Dieu de Montreal Hospital
Montreal, Canada