Patent ID: 7120226

Claim:
A method for conducting a scan of a target sample for a potential threat, the method comprising: a) providing a source of photons incident upon the target sample such that some photons are scattered from the sample and some photons are transmitted through the sample; b) measuring an intensity of photons transmitted through at least a portion of the target sample; c) using the measured intensity of photons transmitted through the at least a portion of the target sample to identify at least one region of interest for further study; d) for at least one of the at least one regions of interest: i) measuring an energy spectrum of photons scattered from the region of interest; ii) using the energy spectrum of photons scattered from the region of interest 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 region of interest to determine whether a threat has been detected; iv) if a threat 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 region of interest; 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 a threat has been detected: A) determining whether the probability that the threat detection is a false positive signal exceeds a predetermined desired probability of obtaining a false positive result; B) if the probability that the threat 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 threat detection is a false positive signal does not meet or exceed the predetermined desired probability of obtaining a false positive result, identifying a positive threat detection event.