Radiological Source Term Estimation and Isotopic Identification With Parallel Log Domain Particle Filters

This article presents a parallel log-domain particle filtering algorithm combined with gamma spectrum unfolding to perform localization, identification, and evaluation of multiple point sources of various isotopes in an environment with attenuating obstacles. The method uses sets of precomputed atte...

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Bibliographic Details
Published in:IEEE transactions on nuclear science 2024-11, Vol.71 (11), p.2422-2431
Main Authors: Kemp, Samuel, Duce, Mackenzie, Kumar, Satvik, Erickson, Anna, Rogers, Jonathan
Format: Article
Language:English
Subjects:
Algorithms
Atmospheric measurements
Attenuation
Bayesian Estimation
Domains
Energy levels
Filters
Gamma ray spectrometers
Gamma rays
Isotopes
Isotopic Identification
Kernel
Kernels
Localization
Particle Filtering
Particle filters
Particle measurements
Photopeak
Radioisotopes
Source Localization
Source Term Estimation
source term estimation (STE)
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Description
Summary:This article presents a parallel log-domain particle filtering algorithm combined with gamma spectrum unfolding to perform localization, identification, and evaluation of multiple point sources of various isotopes in an environment with attenuating obstacles. The method uses sets of precomputed attenuation kernels that map the attenuation characteristics of the environment. These kernels are specific to the energy level of a photopeak of interest. The spectral measurements are deconvolved into count measurements of each photopeak. These count measurements are fed into a set of parallel particle filters using attenuation kernels computed for that photopeak's energy level. The individual regularized particle filters perform all likelihood calculations in the logarithmic domain to mitigate the effects of particle degeneracy. The output of each particle filter is combined to estimate which isotopes are present as well as their positions and strengths. The performance of the algorithm is characterized in a lab-scale environment using a mobile robot equipped with a gamma ray spectrometer in the presence of up to three different radioactive isotopes simultaneously. The sources were localized to within 10 cm, and their strengths were estimated within 10% of their true values. The isotopes were all correctly identified, and no spurious sources were reported.
ISSN:0018-9499
1558-1578
DOI:10.1109/TNS.2024.3467003