Probabilistic uncertainty estimator

• US 8,335,670 B2
• Filed: 03/19/2007
• Issued: 12/18/2012
• Est. Priority Date: 03/17/2006
• Status: Active Grant

• Current Assignee: Mirion Technologies Incorporated (American Capital Limited)
• Original Assignee: Canberra Industries, Inc. (American Capital Limited)
• Inventors: Bronson, Frazier, Atrashkevich, Valery
• Primary Examiner(s): Thangavelu, Kandasamy
• Assistant Examiner(s): MOLL, NITHYA JANAKIRAMAN
• Application Number:
  US12/293,343
• Publication Number:
  US 20090292493A1
• Time in Patent Office: 2,101 Days
• Field of Search: 703/2, 702/85, 702/179
• US Class Current: 703/2
• CPC Class Codes: G01T 7/005 calibration techniques stabilization of spectrometer G01T1/40

Abstract

A system for determining the calibration factor uncertainty of a radiation sensor. A computing device accepts a mathematical model of the sensor, sample, and other items affecting the calibration factor, wherein each known mathematical model parameter is assigned its normal dimensions or values and each not-well-known parameter is assigned a variable with an upper and lower limit, and a shape parameter that describes the parameter may vary within or about the limits. Random values consistent with the upper and lower limits and shape parameters for each of the variable parameters in the model are then selected, to create a mathematical model of one possible variation of source-detector measurement configuration. The selection and calibration factor computation are then repeated a large number of times and statistical parameters describing the calibration factor and uncertainty are then computed. Another embodiment performs the steps at different energies for spectroscopic detectors.

Claims

1. A calibration factor uncertainty estimation system comprising:

(a) a module for receiving a signal from a spectroscopic detector;

(b) a radiation source/sensor mathematical model (RSMM), said RSMM further comprises known radiation source/sensor physical parameters (RSPP) and radiation source/sensor variable parameters (RSVP); and

(c) a computing device, configured to accept said RSMM;

wherein;

said RSVP are assigned a lower source/sensor parameter value (LSPV) and an upper source/sensor parameter value (USPV) and a source/sensor shape parameter (SSHP) describing how said RSVP may vary between said LSPV and said USPV; and

said computing device executes machine instructions operable to execute steps comprising;

(1) selecting statistically random radiation source/sensor values (RRSV) for each RSVP, wherein said RRSV lies between said LSPV and said USPV and wherein said RRSV varies based on said SSHP;

(2) computing radiation source/sensor calibration factors (RSCF) for said RSMM using said RSPP and said RRSV values;

(4) computing the individual mean and standard deviation of each of said RSCF to determine the source/sensor calibration factor uncertainty estimation (SCFU) of each of said RSCF, wherein said RSCF and said SCFU are applied to the signal from a spectroscopic detector to produce an estimate of the radiation level sensed by said spectroscopic detector using the RSCF, and the estimated uncertainty of said radiation level.

2. The calibration factor uncertainty estimation system of claim 1 wherein said steps (3)-(4) are executed for one or more radiation energy values.