For those needing portability, Rad Pro for Desktop works with Windows 8.1 tablets (just tested). Will not work with Surface tablets running Windows RT.
Select Activity Units                    cpm Enter Background     min Enter Background Count Time cpm Critical Level (Lc)   Select Sample Units     Select Correction Factor   Select Confidence Level     Counter and Scaler MDC/MDA Calculations                       min Select Instrument dpm/100cm2 Minimum Detectable Contamination (MDC) Counts Lower Limit of Detection (LLD) cpm Lower Limit of Detection (LLD) cm2 Enter Sample Area cpm/dpm Enter Efficiency Enter Sample Count Time
MDC Formulas
UK Radiation Adviser Nuclear Links Nuclear Jobs MARSSIM Nuclear Resources US Health Physics Society Author's Personal Website US Health Physics Consultant UK Radiation Protection Society NRRPT Study Kit and Classic RP College Textbook

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Classic MDA calculations for counters and static scanning instruments in the scaler mode.  US regulatory guide MARSSIM has recommended replacing the term MDA with MDC for minimum detectable concentration and minimum detectable contamination.  The choices above are varied enough so that MDC may be calculated for air samples, removable contamination, solids, liquids and total contamination.  Most modern texts have replaced the Lloyd Currie k^2 in the LLD (lower limit of detection) with the Lewis Brodsky 3.0 for a 95% confidence level factor so we have done the same.  All other confidence levels still use k^2.  LLD is expressed both in counts and cpm.  Lc, the crtical level is expressed in cpm.  The MDC output depends on the user choices.