Help | Contact Us
NukeWorker.com
NukeWorker Menu MDA vs. MDC

Author Topic: MDA vs. MDC  (Read 504 times)

0 Members and 1 Guest are viewing this topic.

Offline Bear3705

  • Lurker
  • Posts: 2
  • Total likes: 0
  • Karma: 0
  • Gender: Female
  • Tell Recruiters to use NukeWorker.com
MDA vs. MDC
« on: Jun 01, 2021, 10:58 »
What is the rational for using minimum detectable concentration over minimum detectable activity for portable friskers?

Offline Rennhack

Re: MDA vs. MDC
« Reply #1 on: Jun 01, 2021, 05:48 »
A frisker should be expressed as Lc (Critical detection level: the response level at which the detector output can be considered "above background", in net CPM), or MDCR (Minimum detectable count rate).
Neither of those items take into account detector efficiency, or unit conversions.  It is a 'pure' measure of an instruments ability to make that clicking sound with consistency. Independent of WHAT it is looking at.

MDA (Minimum detectable activity) adds those efficiencies.  But you would need to know the detector efficiency for your specific radionuclide(s) of interest.


Then there is LLD (Lower limit of detection), which factors in mass unit, area or volume.
or LD (Minimum significant activity level, i.e., the activity level that can be seen with a detector with a fixed level of certainty)

I guess I CAN remember things from 20 years ago.
« Last Edit: Jun 01, 2021, 06:06 by Rennhack »

Offline GLW

Re: MDA vs. MDC
« Reply #2 on: Jun 02, 2021, 08:48 »
A frisker should be expressed as Lc (Critical detection level: the response level at which the detector output can be considered "above background", in net CPM), or MDCR (Minimum detectable count rate).
Neither of those items take into account detector efficiency, or unit conversions.  It is a 'pure' measure of an instruments ability to make that clicking sound with consistency. Independent of WHAT it is looking at.

MDA (Minimum detectable activity) adds those efficiencies.  But you would need to know the detector efficiency for your specific radionuclide(s) of interest.


Then there is LLD (Lower limit of detection), which factors in mass unit, area or volume.
or LD (Minimum significant activity level, i.e., the activity level that can be seen with a detector with a fixed level of certainty)

I guess I CAN remember things from 20 years ago.









been there, dun that,... the doormat to hell does not read "welcome", the doormat to hell reads "it's just business"

Offline peteshonkwiler

  • Radiological Ergonomist
  • Very Heavy User
  • *****
  • Posts: 893
  • Total likes: 82
  • Karma: 179
  • Gender: Male
  • One small sheet in the nuclear ream.
Re: MDA vs. MDC
« Reply #3 on: Jun 03, 2021, 08:05 »
A frisker will detect alpha, beta, and gamma radiation.
MDC is more applicable for the different radiations and mix of nuclides present while MDA is more applicable when the isotopes are narrowed to those known to be present and/or for which the instrument is source checked.

A REM is a REM is a REM
Yea, though I walk through the boundaries of containment, I shall fear no dose, for my meters are with me.  My counters, air sample filters, and smears, they comfort me.

Offline Bear3705

  • Lurker
  • Posts: 2
  • Total likes: 0
  • Karma: 0
  • Gender: Female
  • Tell Recruiters to use NukeWorker.com
Re: MDA vs. MDC
« Reply #4 on: Jun 14, 2021, 06:36 »
Thank you both. That makes more sense to me. It was eating me alive.

Offline Rennhack

Re: MDA vs. MDC
« Reply #5 on: Jun 16, 2021, 09:44 »
Self consumption can be a slippery slope indeed. For an additional apertif, consider the fact that MDC is apriori and confident at a level of 0.95. Could come in handy in China. Raising local population dose limits will not affect the statistical variation(statistics) of counting instrumentation. ALARA applies to all humans, regardless if they have been trained or not.

 WTF

 


NukeWorker ™ is a registered trademark of NukeWorker.com ™, LLC © 1996-2021 All rights reserved.
All material on this Web Site, including text, photographs, graphics, code and/or software, are protected by international copyright/trademark laws and treaties. Unauthorized use is not permitted. You may not modify, copy, reproduce, republish, upload, post, transmit or distribute, in any manner, the material on this web site or any portion of it. Doing so will result in severe civil and criminal penalties, and will be prosecuted to the maximum extent possible under the law.
Privacy Statement | Terms of Use | Code of Conduct | Spam Policy | Advertising Info | Contact Us | Forum Rules | Password Problem?