Polaris-LAMP: Multi-Modal 3-D Image Reconstruction With a Commercial Gamma-Ray Imager

• Published in: IEEE transactions on nuclear science 2021-10, Vol.68 (10), p.2539-2549
• Main Authors: Hecla, J., Knecht, K., Gunter, D., Haefner, A., Hellfeld, D., Joshi, T. H. Y., Moran, A., Negut, V., Pavlovsky, R., Vetter, K.
• Format: Article
• Language: English
• Subjects: 3-D gamma-ray imaging; 3D gamma-ray imaging; Airborne/spaceborne computers; Algorithms; Aperture imaging; Cadmium; Cadmium zinc tellurides; Coded aperture imagers; Commercial off-the-shelf technology; Compton imaging; Detectors; Gamma rays; Image processing; Image reconstruction; Imaging; Imaging techniques; Inertial sensing devices; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; Laser radar; Localization; Location awareness; Mapping; NUCLEAR PHYSICS AND RADIATION PHYSICS; Photons; Point sources; Radiation; RADIATION PROTECTION AND DOSIMETRY; Radiation sources; Scene data fusion; scene data fusion (SDF); Sensors; Simultaneous localization and mapping; Three-dimensional displays; Uranium; Uranium hexafluoride; Zinc telluride; Zinc tellurides
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2021.3110162

The Polaris-LAMP multi-modal 3-D gamma-ray imager is a radiation mapping and imaging platform which uses a commercial off-the-shelf (COTS) detector integrated with a contextual sensor localization and mapping platform. The integration of these systems enables a free-moving radiation imaging capability with proximity mapping, coded-aperture, and Compton imaging modalities, which can create 3-D reconstruction of photon sources from tens of keV to several MeV. Gamma-ray events are recorded using a segmented cadmium zinc telluride (CZT) detector (Polaris-H Quad by H3D Inc., Ann Arbor, MI, USA), while scene data are derived from a contextual sensor and computation package developed by Lawrence Berkeley National Laboratory which includes GPS, laser ranging, and inertial measurement sensors. An onboard computer uses these inputs to create rapidly updating pose (10 Hz) and 3-D scene estimates using a simultaneous localization and mapping (SLAM) algorithm. The precise gamma-ray event location and timing resolution of the Polaris CZT sensor enables Compton imaging above several hundred keV, while photon sources at lower images are localized using coded-aperture imaging techniques. The multi-modal imaging concept enables imaging of diverse radiation sources spanning from the 59-keV emission of 241 Am to the 1.1 and 1.3 MeV lines of 60 Co. This work focuses on the description of the operational principles of the detector system and demonstrating the 3-D imaging performance in a variety of source detection and mapping scenarios. As a proof of concept, we demonstrate mapping complex environments, including both point source and distributed-source environments using proximity, coded-aperture, and Compton imaging modalities. Furthermore, we show the successful use of the system to perform measurements in high-background environments through analysis of arrays of uranium hexafluoride cylinders at the Paducah UF6 project site.