Counting Statistics currie_mda_calc
Currie Detection Limits & Minimum Detectable Activity (MDA)
Applies standard Currie (1968) and MARLAP / ISO 11929 hypothesis testing statistics (α = β = 0.05) to evaluate instrument critical decision levels and minimum detectable activity.
L_C = 1.645 σ_0; L_D = 2.71 + 3.29 σ_0; MDA = L_D / (t_s × ε × Y)
RADCALC HEALTH PHYSICS & NUCLEAR ENGINEERING WORKSHEET
Currie Detection Limits & Minimum Detectable Activity (MDA) (Currie MDA)
Domain: Counting Statistics & Detection Limits · Tool ID:
currie_mda_calc · Engine: 100% Local Browser WASM L_C = 1.645 σ_0; L_D = 2.71 + 3.29 σ_0; MDA = L_D / (t_s × ε × Y)
Operational Notes:
Guided Stepper Workflow All Input Parameters & Solver
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CLIENT-SIDE 3D SIMULATION Currie Detection Limits & Minimum Detectable Activity (MDA) 3D Transport Field
Interactive 3D Geometry & Particle Transport
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Normalized Base-Unit & WebMCP Tool Payload currie_mda_calc
1. Input & Solved Parameter Ledger
| Role | Symbol | Parameter Name | Entered / Display Value | Normalized Base Unit | Definition |
|---|
2. ISO 11929 / MARSSIM Counting Lab QA
Governing Equation & Parameters
Decision Threshold LC = 1.645 × √(2 Rb ts); Detection Limit LD = 2.71 + 3.29 × √(2 Rb ts); MDA in Bq or pCi
| Symbol | Parameter | Default Unit | Definition |
|---|---|---|---|
| R_b | Background Count Rate | cpm | Instrument background count rate in counts per minute. |
| t_s | Sample Count Time | min | Duration of sample counting in minutes. |
| t_b | Background Count Time | min | Duration of dedicated background counting in minutes. |
| ε | 4π Detection Efficiency | fraction | Absolute 4π detector counting efficiency (0.001 to 1.0). |
| Y | Radiation Branching Yield | fraction | Fractional radiation emission yield per nuclear disintegration. |
| W | Sample Quantity / Aliquot Factor | dimensionless | Sample aliquot factor (mass in g, volume in L, or wipe area ratio). |
| MDA | Minimum Detectable Activity | Bq | Minimum detectable activity concentration in Becquerels. |
Health Physics Notes & Related Calculators
Operational Guidance & Physics Assumptions
- Critical Level (L_C): The net count threshold above which an observed sample is declared statistically positive with 95% confidence (5% false positive α risk).
- Detection Limit (L_D): The true net activity required to ensure a 95% probability of detection (5% false negative β risk); includes the 2.71 Currie offset.
- Equal count time assumption (t_s = t_b) yields σ_0 = √(2 * R_b * t_s).
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