Patent ID: 8259900
Filing Date: 2012-09-04
Classification: G01N,G01V

Abstract:
1. A method for conducting a scan of a target sample for a potential item of interest, the method comprising: a) providing a source of photons incident upon the target sample such that some photons are scattered from the target sample; b) for at least one portion of interest in the target sample, determining if an incident photon beam intensity into said portion of interest is attenuated as a result of interactions between incident beam photons and portions of the target sample between the said portion of interest and an incident beam source such that the said incident photon beam intensity into the said portion of interest is below a desired flux; c) if the incident photon beam intensity into the said portion of interest is below the desired flux, altering an angular orientation between the target sample and the incident photon beam such that the incident photon beam passes through different portions of the target sample than previously in reaching the portion of interest such that the attenuation of the incident photon beam intensity is reduced; d) for the said at least one portion of interest in the target sample: i) measuring an energy spectrum of photons scattered from the said at least one portion of interest in the target sample; ii) using the energy spectrum of photons scattered from the said at least one portion of interest in the target sample to compute a detection probability and a probability of obtaining a false positive result; iii) using the measured energy spectrum of photons scattered from the said at least one portion of interest in the target sample to determine whether an item of interest has been detected; iv) if an item of interest has not been detected: A) determining whether the detection probability meets or exceeds a predetermined desired detection probability; B) if the detection probability meets or exceeds the predetermined desired detection probability, ending the scan for the said at least one portion of interest in the target sample; and C) if the detection probability does not meet or exceed the predetermined desired detection probability, adjusting one or more system parameters and repeating steps (i) through (iv); and v) if an item of interest has been detected: A) determining whether the probability that the item of interest detection is a false positive signal exceeds a predetermined desired probability of obtaining a false positive result; B) if the probability that the item of interest detection is a false positive signal meets or exceeds the predetermined desired probability of obtaining a false positive result, adjusting one or more system parameters and repeating steps (i) through (v); and C) if the probability that the item of interest detection is a false positive signal does not meet or exceed the predetermined desired probability of obtaining a false positive result, identifying a positive item of interest detection event.